dog and food experiment

Pavlov’s Dogs Experiment and Pavlovian Conditioning Response

Saul McLeod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

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Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

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Like many great scientific advances, Pavlovian conditioning (aka classical conditioning) was discovered accidentally. Ivan Petrovich Pavlov (1849–1936) was a physiologist, not a psychologist.

During the 1890s, Pavlov researched salivation in dogs in response to being fed. He inserted a small test tube into the cheek of each dog to measure saliva when the dogs were fed (with a powder made from meat).

Pavlov predicted the dogs would salivate in response to the food in front of them, but he noticed that his dogs would begin to salivate whenever they heard the footsteps of his assistant, who was bringing them the food.

When Pavlov discovered that any object or event that the dogs learned to associate with food (such as the lab assistant) would trigger the same response, he realized that he had made an important scientific discovery.

Accordingly, he devoted the rest of his career to studying this type of learning.

Pavlovian Conditioning: Theory of Learning

Pavlov’s theory of learning, known as classical conditioning, or Pavlovian conditioning, posits that behaviors can be learned through the association between different stimuli.

Classical conditioning (later developed by Watson, in 1913) involves learning to associate an unconditioned stimulus that already brings about a particular response (i.e., a reflex) with a new (conditioned) stimulus, so that the new stimulus brings about the same response.

Pavlov developed some rather unfriendly technical terms to describe this process:

• Neutral Stimulus (NS) : A stimulus that initially does not elicit a particular response or reflex action. In other words, before any conditioning takes place, the neutral stimulus has no effect on the behavior or physiological response of interest. For example, in Pavlov’s experiment, the sound of a metronome was a neutral stimulus initially, as it did not cause the dogs to salivate.
• Unconditioned Stimulus (UCS): This is a stimulus that naturally and automatically triggers a response without any learning needed. In Pavlov’s experiment, the food was the unconditioned stimulus as it automatically induced salivation in the dogs.
• Conditioned Stimulus (CS): This is a previously neutral stimulus that, after being repeatedly associated with an unconditioned stimulus, comes to trigger a conditioned response. For instance, in Pavlov’s experiment, the metronome became a conditioned stimulus when the dogs learned to associate it with food.
• Conditioned Response (CR): This is a learned response to the conditioned stimulus. It typically resembles the unconditioned response but is triggered by the conditioned stimulus instead of the unconditioned stimulus. In Pavlov’s experiment, salivating in response to the metronome was the conditioned response.
• Unconditioned Response (UR): This is an automatic, innate reaction to an unconditioned stimulus. It does not require any learning. In Pavlov’s experiment, the dogs’ automatic salivation in response to the food is an example of an unconditioned response.

Pavlov’s Dog Experiment

Pavlov (1902) started from the idea that there are some things that a dog does not need to learn. For example, dogs don’t learn to salivate whenever they see food. This reflex is ‘hard-wired’ into the dog.

Pavlov showed that dogs could be conditioned to salivate at the sound of a bell if that sound was repeatedly presented at the same time that they were given food.

Pavlov’s studies of classical conditioning have become famous since his early work between 1890 and 1930. Classical conditioning is “classical” in that it is the first systematic study of the basic laws of learning (also known as conditioning).

Pavlov’s dogs were individually situated in secluded environments, secured within harnesses. A food bowl was positioned before them, and a device was employed to gauge the frequency of their salivary gland secretions.

The data from these measurements were systematically recorded onto a rotating drum, allowing Pavlov to meticulously monitor the rates of salivation throughout the course of the experiments.

First, the dogs were presented with the food, and they salivated. The food was the unconditioned stimulus and salivation was an unconditioned (innate) response. (i.e., a stimulus-response connection that required no learning).

Unconditioned Stimulus (Food) > Unconditioned Response (Salivate)

In his experiment, Pavlov used a metronome as his neutral stimulus. By itself, the metronome did not elicit a response from the dogs. 

Neutral Stimulus (Metronome) > No Response

Next, Pavlov began the conditioning procedure, whereby the clicking metronome was introduced just before he gave food to his dogs. After a number of repeats (trials) of this procedure, he presented the metronome on its own.

As you might expect, the sound of the clicking metronome on its own now caused an increase in salivation.

Conditioned Stimulus (Metronome) > Conditioned Response (Salivate)

So, the dog had learned an association between the metronome and the food, and a new behavior had been learned.

Because this response was learned (or conditioned), it is called a conditioned response (and also known as a Pavlovian response). The neutral stimulus has become a conditioned stimulus.

Temporal contiguity

Pavlov found that for associations to be made, the two stimuli had to be presented close together in time (such as a bell).

He called this the law of temporal contiguity. If the time between the conditioned stimulus (bell) and the unconditioned stimulus (food) is too great, then learning will not occur.

‘Unconditioning’ through experimental extinction

In extinction, the conditioned stimulus (the bell) is repeatedly presented without the unconditioned stimulus (the food).

Over time, the dog stops associating the sound of the bell with the food, and the conditioned response (salivation) weakens and eventually disappears.

In other words, the conditioned response is “unconditioned” or “extinguished.”

Spontaneous recovery

Pavlov noted the occurrence of “spontaneous recovery,” where the conditioned response can briefly reappear when the conditioned stimulus is presented after a rest period, even though the response has been extinguished.

This discovery added to the understanding of conditioning and extinction, indicating that these learned associations, while they can fade, are not completely forgotten.

Generalization

The principle of generalization suggests that after a subject has been conditioned to respond in a certain way to a specific stimulus, the subject will also respond in a similar manner to stimuli that are similar to the original one.

In Pavlov’s famous experiments with dogs, he found that after conditioning dogs to salivate at the sound of a bell (which was paired with food), the dogs would also salivate in response to similar sounds, like a buzzer.

This demonstrated the principle of generalization in classical conditioning.

However, the response tends to be more pronounced when the new stimulus closely resembles the original one used in conditioning.

This relationship between the similarity of the stimulus and the strength of the response is known as the generalization gradient.

This principle has been exemplified in research, including a study conducted by Meulders and colleagues in 2013.

Impact of Pavlov’s Research

Ivan Pavlov’s key contribution to psychology was the discovery of classical conditioning, demonstrating how learned associations between stimuli can influence behavior.

His work laid the foundation for behaviorism, influenced therapeutic techniques, and informed our understanding of learning and memory processes.

Behaviorism: Pavlov’s work laid the foundation for behaviorism , a major school of thought in psychology. The principles of classical conditioning have been used to explain a wide range of behaviors, from phobias to food aversions.

Therapy Techniques: Techniques based on classical conditioning, such as systematic desensitization and exposure therapy , have been developed to treat a variety of psychological disorders, including phobias and post-traumatic stress disorder (PTSD).

In these therapies, a conditioned response (such as fear) can be gradually “unlearned” by changing the association between a specific stimulus and its response.

• Little Albert Experiment : The Little Albert experiment, conducted by John B. Watson in 1920, demonstrated that emotional responses could be classically conditioned in humans. A young child, “Little Albert,” was conditioned to fear a white rat, which generalized to similar objects. 

Educational Strategies: Educational strategies, like repetitive learning and rote memorization, can be seen as applications of the principles of classical conditioning. The repeated association between stimulus and response can help to reinforce learning.

Marketing and Advertising: Principles from Pavlov’s conditioning experiments are often used in advertising to build brand recognition and positive associations.

For instance, a brand may pair its product with appealing stimuli (like enjoyable music or attractive visuals) to create a positive emotional response in consumers, who then associate the product with it.

Critical Evaluation

Pavlovian conditioning is traditionally described as learning an association between a neutral conditioned stimulus (CS) and an unconditioned stimulus (US), such that the CS comes to elicit a conditioned response (CR). This fits many lab studies but misses the adaptive function of conditioning (Domjan, 2005).

From a functional perspective, conditioning likely evolves to help organisms effectively interact with biologically important unconditioned stimuli (US) in their natural environment.

For conditioning to happen naturally, the conditioned stimulus (CS) can’t be arbitrary, but must have a real ecological relationship to the US as a precursor or feature of the US object.

Pavlovian conditioning prepares organisms for important biological events by conditioning compensatory responses that improve the organism’s ability to cope.

The critical behavior change from conditioning may not be conditioned responses (CRs), but rather conditioned modifications of unconditioned responses (URs) to the US that improve the organism’s interactions with it.

Evidence shows conditioning occurs readily with naturalistic CSs, like tastes before illness, infant cues before nursing, prey sights before attack. This conditioning is more robust and resistant to effects like blocking.

Traditional descriptions of Pavlovian conditioning as simply the acquired ability of one stimulus to evoke the original response to another stimulus paired with it are inadequate and misleading (Rescorla, 1988).

New research shows conditioning is actually about learning relationships between events, which allows organisms to build mental representations of their environment.

Just pairing stimuli together doesn’t necessarily cause conditioning. It depends on whether one stimulus gives information about the other.

Conditioning rapidly encodes relations among a broad range of stimuli, not just between a neutral stimulus and one eliciting a response. The learned associations allow complex representations of the world.

Recently, Honey et al. (2020, 2022) presented simulations using an alternative model called HeiDI that accounts for Rescorla’s findings. HeiDI differs by allowing reciprocal CS-US and US-CS associations. It uses consistent learning rules applied to all stimulus pairs.

The simulations suggest HeiDI explains Rescorla’s results via two mechanisms:

• Changes in US-CS associations during compound conditioning, allowing greater change in some US-CS links
• Indirect influences of CS-CS associations enabling compounds to recruit associative strength from absent stimuli

HeiDI integrates various conditioning phenomena and retains key Rescorla-Wagner insights about surprise driving learning. However, it moves beyond the limitations of Rescorla-Wagner by providing a framework to address how learning translates into performance.

HeiDI refers to the authors of the model (Honey, Dwyer, Iliescu) as well as highlighting a key feature of the model – the bidirectional or reciprocal associations it proposes between conditioned stimuli and unconditioned stimuli.

H – Honey (the lead author’s surname), ei – Bidirectional (referring to the reciprocal associations), D – Dwyer (the second author’s surname), I – Iliescu (the third author’s surname).

• Domjan, M. (2005). Pavlovian conditioning: A functional perspective.  Annu. Rev. Psychol. ,  56 , 179-206.
• Honey, R.C., Dwyer, D.M., & Iliescu, A.F. (2020a). HeiDI: A model for Pavlovian learning and performance with reciprocal associations. Psychological Review, 127, 829-852.
• Honey, R. C., Dwyer, D. M., & Iliescu, A. F. (2022). Associative change in Pavlovian conditioning: A reappraisal .  Journal of Experimental Psychology: Animal Learning and Cognition .
• Meulders A, Vandebroek, N. Vervliet, B. and Vlaeyen, J.W.S. (2013). Generalization Gradients in Cued and Contextual Pain-Related Fear: An Experimental Study in Health Participants .  Frontiers in Human Neuroscience ,  7 (345). 1-12.
• Pavlov, I. P. (1897/1902). The work of the digestive glands. London: Griffin.
• Pavlov, I. P. (1928). Lectures on conditioned reflexes . (Translated by W.H. Gantt) London: Allen and Unwin.
• Pavlov, I. P. (1927). Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex . Translated and edited by Anrep, GV (Oxford University Press, London, 1927).
• Rescorla, R. A. (1988). Pavlovian conditioning: It’s not what you think it is .  American Psychologist ,  43 (3), 151.
• Pavlov, I. P. (1955). Selected works . Moscow: Foreign Languages Publishing House.
• Watson, J.B. (1913). Psychology as the behaviorist Views It. Psychological Review, 20 , 158-177.
• Watson, J. B., & Rayner, R. (1920). Conditioned emotional reactions.  Journal of experimental psychology ,  3 (1), 1.

Further Reading

• Logan, C. A. (2002). When scientific knowledge becomes scientific discovery: The disappearance of classical conditioning before Pavlov. Journal of the History of the Behavioral Sciences, 38 (4), 393-403.
• Learning and Behavior PowerPoint

What was the main point of Ivan Pavlov’s experiment with dogs?

The main point of Ivan Pavlov’s experiment with dogs was to study and demonstrate the concept of classical conditioning.

Pavlov showed that dogs could be conditioned to associate a neutral stimulus (such as a bell) with a reflexive response (such as salivation) by repeatedly pairing the two stimuli together.

This experiment highlighted the learning process through the association of stimuli and laid the foundation for understanding how behaviors can be modified through conditioning.

What is Pavlovian response?

The Pavlovian response, also known as a conditioned response, refers to a learned, automatic, and involuntary response elicited by a previously neutral stimulus through classical conditioning. It is a key concept in Pavlov’s experiments, where dogs learned to salivate in response to a bell.

When did Pavlov discover classical conditioning?

Ivan Pavlov discovered classical conditioning during his dog experiments in the late 1890s and early 1900s. His seminal work on classical conditioning, often called Pavlovian conditioning, laid the foundation for our understanding of associative learning and its role in behavior modification.

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Pavlov's Dogs and the Discovery of Classical Conditioning

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Sean is a fact-checker and researcher with experience in sociology, field research, and data analytics.

Jules Clark/Getty Images

• Pavlov's Theory

Pavlov's dog experiments played a critical role in the discovery of one of the most important concepts in psychology: Classical conditioning .

While it happened quite by accident, Pavlov's famous experiments had a major impact on our understanding of how learning takes place as well as the development of the school of behavioral psychology. Classical conditioning is sometimes called Pavlovian conditioning.

Pavlov's Dog: A Background

How did experiments on the digestive response in dogs lead to one of the most important discoveries in psychology? Ivan Pavlov was a noted Russian physiologist who won the 1904 Nobel Prize for his work studying digestive processes.

While studying digestion in dogs, Pavlov noted an interesting occurrence: His canine subjects would begin to salivate whenever an assistant entered the room.

The concept of classical conditioning is studied by every entry-level psychology student, so it may be surprising to learn that the man who first noted this phenomenon was not a psychologist at all.

In his digestive research, Pavlov and his assistants would introduce a variety of edible and non-edible items and measure the saliva production that the items produced.

Salivation, he noted, is a reflexive process. It occurs automatically in response to a specific stimulus and is not under conscious control.

However, Pavlov noted that the dogs would often begin salivating in the absence of food and smell. He quickly realized that this salivary response was not due to an automatic, physiological process.

Pavlov's Theory of Classical Conditioning

Based on his observations, Pavlov suggested that the salivation was a learned response. Pavlov's dog subjects were responding to the sight of the research assistants' white lab coats, which the animals had come to associate with the presentation of food.

Unlike the salivary response to the presentation of food, which is an unconditioned reflex, salivating to the expectation of food is a conditioned reflex.

Pavlov then focused on investigating exactly how these conditioned responses are learned or acquired. In a series of experiments, he set out to provoke a conditioned response to a previously neutral stimulus.

He opted to use food as the unconditioned stimulus , or the stimulus that evokes a response naturally and automatically. The sound of a metronome was chosen to be the neutral stimulus.

The dogs would first be exposed to the sound of the ticking metronome, and then the food was immediately presented.

After several conditioning trials, Pavlov noted that the dogs began to salivate after hearing the metronome. "A stimulus which was neutral in and of itself had been superimposed upon the action of the inborn alimentary reflex," Pavlov wrote of the results.

"We observed that, after several repetitions of the combined stimulation, the sounds of the metronome had acquired the property of stimulating salivary secretion."

In other words, the previously neutral stimulus (the metronome) had become what is known as a conditioned stimulus that then provoked a conditioned response (salivation).

To review, the following are some key components used in Pavlov's theory:

• Conditioned stimulus : This is what the neutral stimulus becomes after training (i.e., the metronome was the conditioned stimulus after Pavlov trained the dogs to respond to it)
• Unconditioned stimulus : A stimulus that produces an automatic response (i.e., the food was the unconditioned stimulus because it made the dogs automatically salivate)
• Conditioned response (conditioned reflex) : A learned response to previously neutral stimulus (i.e., the salivation was a conditioned response to the metronome)
• Unconditioned response (unconditioned reflex) : A response that is automatic (i.e., the dog's salivating is an unconditioned response to the food)

Impact of Pavlov's Research

Pavlov's discovery of classical conditioning remains one of the most important in psychology's history.

In addition to forming the basis of what would become behavioral psychology , the classical conditioning process remains important today for numerous applications, including behavioral modification and mental health treatment.

Principles of classical conditioning are used to treat the following mental health disorders:

• Obsessive-compulsive disorder (OCD)
• Panic attacks and panic disorder
• Substance use disorders

For instance, a specific type of treatment called aversion therapy uses conditioned responses to help people with anxiety or a specific phobia.

A therapist will help a person face the object of their fear gradually—while helping them manage any fear responses that arise. Gradually, the person will form a neutral response to the object.

Pavlov’s work has also inspired research on how to apply classical conditioning principles to taste aversions . The principles have been used to prevent coyotes from preying on domestic livestock and to use neutral stimulus (eating some type of food) paired with an unconditioned response (negative results after eating the food) to create an aversion to a particular food.

Unlike other forms of classical conditioning, this type of conditioning does not require multiple pairings in order for an association to form. In fact, taste aversions generally occur after just a single pairing. Ranchers have found ways to put this form of classical conditioning to good use to protect their herds.

In one example, mutton was injected with a drug that produces severe nausea. After eating the poisoned meat, coyotes then avoided sheep herds rather than attack them.

A Word From Verywell

While Pavlov's discovery of classical conditioning formed an essential part of psychology's history, his work continues to inspire further research today. His contributions to psychology have helped make the discipline what it is today and will likely continue to shape our understanding of human behavior for years to come.

Adams M. The kingdom of dogs: Understanding Pavlov’s experiments as human–animal relationships . Theory & Psychology . 2019;30(1):121-141. doi:10.1177/0959354319895597

Fanselow MS, Wassum KM.  The origins and organization of vertebrate Pavlovian conditioning .  Cold Spring Harb Perspect Biol.  2015;8(1):a021717. doi:10.1101/cshperspect.a021717

Nees F, Heinrich A, Flor H.  A mechanism-oriented approach to psychopathology: The role of Pavlovian conditioning .  Int J Psychophysiol.  2015;98(2):351-364. doi:10.1016/j.ijpsycho.2015.05.005

American Psychological Association. What is exposure therapy?

Lin JY, Arthurs J, Reilly S. Conditioned taste aversions: From poisons to pain to drugs of abuse. Psychon Bull Rev . 2017;24(2):335-351. doi:10.3758/s13423-016-1092-8

Gustafson, C.R., Kelly, D.J, Sweeney, M., & Garcia, J. Prey-lithium aversions: I. Coyotes and wolves. Behavioral Biology. 1976; 17:  61-72.

Hock, R.R. Forty studies that changed psychology: Explorations into the history of psychological research. (4th ed.).  New Jersey: Pearson Education; 2002.

• Gustafson, C.R., Garcia, J., Hawkins, W., & Rusiniak, K. Coyote predation control by aversive conditioning.   Science. 1974; 184:  581-583.
• Pavlov, I.P. Conditioned reflexes .  London: Oxford University Press; 1927.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Learn More Psychology

• Behavioral Psychology

Pavlov's Dogs and Classical Conditioning

How pavlov's experiments with dogs demonstrated that our behavior can be changed using conditioning..

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One of the most revealing studies in behavioral psychology was carried out by Russian physiologist Ivan Pavlov (1849-1936) in a series of experiments today referred to as 'Pavlov's Dogs'. His research would become renowned for demonstrating the way in classical conditioning (also referred to as Pavlovian conditioning ) could be used to cultivate a particular association between the occurrence of one event in the anticipation of another.

• Conditioning
• Stimulus-Response Theory
• Reductionism in Psychology
• What Factors Affect Classical Conditioning?
• Imprinting and Relationships

Pavlov's Dog Experiments

Pavlov came across classical conditioning unintentionally during his research into animals' gastric systems. Whilst measuring the salivation rates of dogs, he found that they would produce saliva when they heard or smelt food in anticipation of feeding. This is a normal reflex response which we would expect to happen as saliva plays a role in the digestion of food.

Did You Know?

Psychologist Edwin Twitmyer at the University of Pennsylvania in the U.S. discovered classical conditioning at approximately the same time as Pavlov was conducting his research ( Coon, 1982 ). 1 However, the two were unaware of each other's research in this case of simultaneous discovery , and Pavlov received credit for the findings.

However, the dogs also began to salivate when events occurred which would otherwise be unrelated to feeding. By playing sounds to the dogs prior to feeding them, Pavlov showed that they could be conditioned to unconsciously associate neutral, unrelated events with being fed 2 .

Experiment Procedure

Pavlov's dogs were each placed in an isolated environment and restrained in a harness, with a food bowl in front of them and a device was used to measure the rate at which their saliva glands made secretions. These measurements would then be recorded onto a revolving drum so that Pavlov could monitor salivation rates throughout the experiments.

He found that the dogs would begin to salivate when a door was opened for the researcher to feed them.

This response demonstrated the basic principle of classical conditioning . A neutral event, such as opening a door (a neutral stimulus , NS) could be associated with another event that followed - in this case, being fed (known as the unconditioned stimulus , UCS). This association could be created through repeating the neutral stimulus along with the unconditioned stimulus, which would become a conditioned stimulus , leading to a conditioned response : salivation.

Pavlov continued his research and tested a variety of other neutral stimuli which would otherwise be unlinked to the receipt of food. These included precise tones produced by a buzzer, the ticking of a metronome and electric shocks .

The dogs would demonstrate a similar association between these events and the food that followed.

NEUTRAL STIMULUS (NS, eg. tone) > UNCONDITIONED STIMULUS (UCS, eg. receiving food)

when repeated leads to:

CONDITIONED STIMULUS (CS, eg. tone) > CONDITIONED RESPONSE (CR, eg. salivation)

The implications for Pavlov's findings are significant as they can be applied to many animals, including humans.

For example, when you first saw someone holding a balloon and a pin close to it, you may have watched in anticipation as they burst the balloon. After this had happened multiple times, you would associate holding the pin to the balloon with the 'bang' that followed. Like Pavlov's dogs, classical conditioning was leading you to associate a neutral stimulus (the pin approaching a balloon) with bursting of the balloon, leading to a conditioned response (flinching, wincing or plugging one's ears) to this now conditioned stimulus.

• Craik & Lockhart (1972) Levels of Processing Theory

Let us look now at some of the nuances of Pavlov's findings in relation to classical conditioning.

'Unconditioning' through experimental extinction

Once an animal has been inadvertently conditioned to produce a response to a stimulus, can this association ever be broken?

Pavlov presented the dogs with a tone which they would come to associate with food. He then played the tone but did not follow that by rewarding the dogs with food.

After he made the sound without food numerous times, the dogs' produced less saliva as the conditioning underwent experimental extinction - a case of 'unlearning' the association.

When experimental extinction occurs, is the association permanently broken?

Pavlov's research would suggest that it remains but is inactive after extinction, and can be re-activated by reinstating, for example, the food reward, as it was given during the original conditioning. This phenomenon is known as spontaneous recovery .

Forward Conditioning vs Backward Conditioning

During conditioning, it is important that the neutral stimulus (NS) is presented before the unconditioned stimulus (UCS) in order for learning to take place. This forward conditioning is more likely to lead to a conditioned response than when the neutral stimulus is presented after the conditioned stimulus has been provided ( backward conditioning ).

In the case of Pavlov's dogs, the tone must be played to the subject prior to the food being provided. Making a sound after the dogs have been fed may not lead to a conditioned association being made between the events.

Carr and Freeman (1919) attempted both forward and backward conditioning in rats, between a buzzer sound and closed doors in a maze. They found backward conditioning to be ineffective when compared to forward conditioning. 4

Delay Conditioning vs Trace Conditioning

We may use forward conditioning in one of two forms:

Delay Conditioning - when the unconditioned stimulus is provided prior to and during the unconditioned stimulus - there is a period of overlap where the neutral and unconditioned stimulus are given simultaneously, e.g. a buzzer sound begins, and after 10 seconds, food is given whilst the buzzer continues.

Trace Conditioning - when there is a delay after the unconditioned stimulus has been provided before the unconditioned stimulus is presented to the subject, e.g. buzzer sounds for 10 seconds, stops and after 10 seconds of silence (the trace interval ), food is presented.

Discussing delay conditioning, Pavlov (1927) asserted that the longer the delay between the stimuli, the more delayed the response would be 5 .

Temporal Conditioning

So far, we have looked at conditioning in which a neutral stimulus is key to eliciting a desired response. However, if an unconditioned stimulus is provided at regular intervals, even without a preceding neutral stimulus, animals' sense of timing will enable conditioning to take place, and a response may occur in time with the intervals.

For example, in a study in which rats were fed at either random or regular intervals, Kirkpatrick and Church (2003) found that the subjects underwent temporal conditioning in the anticipation of food when they were fed at set intervals. 6

Generalisation

Pavlov noticed that once neutral stimulus had been associated with an unconditioned stimulus, the conditioned stimulus could vary and the dogs would still generate a similar response. For example, once specific tone of buzzer sound was associated with food, differing toned buzzer sounds would solicit a conditioned response.

Nonetheless, the closer the stimulus was to the original stimulus used in conditioning, the clearer the response would be. This correlation between stimulus accuracy and response is referred to as a generalisation gradient , and has been demonstrated in studies such as Meulders et al (2013) . 7

Modern Classical Conditioning

Pavlov's dog experiments are still discussed today and have influenced many later ideas in psychology. The U.S. psychologist John B. Watson was impressed by Pavlov's findings and reproduced classical conditioning in the Little Albert Experiment (Watson, 1920), in which a subject was unethically conditioned to associate furry stimuli such as rabbits with a loud noise, and subsequently developed a fear of rats. 8

• Behavioral Approach

The numerous studies following the experiments, which have demonstrated classical conditioning using a variety of methods, also show the replicability of Pavlov's research, helping it to be recognised as an important unconscious influence of human behavior. This has helped the theory to be recognised and applied in many real life situations, from training dogs to creating associations in today's product advertisements.

Continue Reading

• Coon, D.J. (1982). Eponymy, obscurity, Twitmyer, and Pavlov. Journal of the History of Behavioral Science . 18 (3). 255-62.
• Pavlov, I.P. (1927). Conditioned Reflexes: An investigation of the physiological activity of the cerebral cortex. Retrieved from http://psychclassics.yorku.ca/Pavlov/ .
• Craik, F.I.M. and Lockhart, R.S. (1972). Levels of Processing: A Framework for Memory Research. Journal of Verbal Learning and Visual Behavior . 11 (6). 671-684.
• Carr, H. and Freeman A. (1919). Time relationships in the formation of associations. Psychology Review . 26 (6). 335-353.
• Pavlov, I.P. (1927). Conditioned Reflexes: An investigation of the physiological activity of the cerebral cortex. Retrieved from http://psychclassics.yorku.ca/Pavlov/lecture6.htm .
• Kirkpatrick, K and Church, R.M. (2003). Tracking of the expected time to reinforcement in temporal conditioning processes. Learning & Behavior . 31 (1). 3-21.
• Meulders A, Vandebroek, N. Vervliet, B. and Vlaeyen, J.W.S. (2013). Generalization Gradients in Cued and Contextual Pain-Related Fear: An Experimental Study in Health Participants. Frontiers in Human Neuroscience , 7 (345). 1-12.
• Watson, J.B. and Rayner, R. (1920). Conditioned Emotional Reactions. Journal of Experimental Psychology . 3 (1). 1-14.
• Watson, J.B. (1913). Psychology as the Behaviorist Views It. Psychological Review . (Watson, 1913). 20 . 158-177.

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Pavlov’s Dog: The Psychology Experiment That Changed Everything

Pavlov’s Dog is a well-known experiment in psychology that has been taught for decades. Ivan Pavlov , a Russian physiologist, discovered classical conditioning through his experiments with dogs. He found that dogs could be trained to associate a sound with food, causing them to salivate at the sound alone.

The experiment began with Pavlov ringing a bell every time he fed his dogs. After a while, the dogs began to associate the sound of the bell with food and would salivate at the sound alone, even if no food was present. This became known as a conditioned response, where a previously neutral stimulus (the bell) became associated with a natural response (salivating).

The experiment has been used to explain many psychological phenomena, including addiction, phobias, and anxiety. It has also been applied in therapy, where patients can learn to associate positive experiences with previously negative stimuli. The Pavlov’s Dog experiment is a crucial part of psychology’s history and continues to be studied today.

Pavlov’s Life and Career

Ivan Pavlov was a Russian physiologist who lived from 1849 to 1936. He is best known for his work in classical conditioning, a type of learning that occurs when a neutral stimulus is consistently paired with a stimulus that elicits a response. Pavlov was born in Ryazan, Russia, and studied at the University of St. Petersburg, where he received his doctorate in 1879.

Pavlov’s early research focused on the digestive system, and he discovered that the secretion of gastric juice was not a passive process but rather a response to stimuli. This led him to develop the concept of the conditioned reflex, which he explored in detail in his famous experiments with dogs.

In these experiments, Pavlov trained dogs to associate the sound of a bell with food presentation. Over time, the dogs began to salivate at the sound of the bell, even when no food was present. This demonstrated that a neutral stimulus (the bell) could become associated with a natural response (salivation) through repeated pairings with a stimulus that elicits that response (food).

Pavlov’s work had a profound impact on the field of psychology, and his ideas continue to influence research today. He was awarded the Nobel Prize in Physiology or Medicine in 1904 for his work on the physiology of digestion. Still, his legacy is best remembered for his contributions to the study of learning and behavior.

Classical Conditioning

Classical conditioning is a type of learning that occurs when a neutral stimulus is repeatedly paired with a stimulus that naturally elicits a response. Over time, the neutral stimulus becomes associated with the natural stimulus and begins to produce the same response. Russian physiologist Ivan Pavlov first studied this type of learning in the late 1800s.

One of the most famous examples of classical conditioning is Pavlov’s experiment with dogs. In this experiment, Pavlov rang a bell every time he fed the dogs. Eventually, the dogs began to salivate at the sound of the bell, even when no food was present. The sound of the bell had become associated with the food, and the dogs had learned to associate the two stimuli.

Classical conditioning can be used to explain a variety of behaviors and responses. For example, a person who has been in a car accident may develop a fear of driving. The sound of screeching tires or the sight of a car may become associated with the traumatic experience, causing the person to feel anxious or fearful when driving.

Classical conditioning can also be used to treat certain types of phobias and anxiety disorders. By gradually exposing a person to the feared stimulus in a safe and controlled environment, the person can learn to associate the stimulus with safety and relaxation rather than fear and anxiety.

Classical conditioning is a powerful tool for understanding how we learn and respond to environmental stimuli. By understanding the principles of classical conditioning, we can better understand our behaviors and emotions, as well as those of others around us.

Pavlov’s Experiments

Pavlov’s experiments with dogs revolutionized the field of psychology and laid the foundation for the study of classical conditioning. In this section, we will explore two aspects of his experiments: salivating dogs and conditioned responses.

Salivating Dogs

Pavlov observed that dogs would salivate when presented with food. However, he also noticed that the dogs would start salivating before the food was presented. This led him to hypothesize that the dogs were responding not just to the food but to other associated stimuli, such as the sound of the food being prepared or the sight of the person who fed them.

To test his hypothesis, Pavlov began a series of experiments where he would ring a bell before presenting the dogs with food. After a few repetitions, the dogs began to salivate at the sound of the bell alone, even when no food was present. This demonstrated that the dogs had learned to associate the sound of the bell with the presence of food and were responding accordingly.

Conditioned Response

Pavlov’s experiments with dogs led to the discovery of the conditioned response, the learned response to a previously neutral stimulus. In the case of Pavlov’s dogs, the sound of the bell was originally a neutral stimulus. Still, it became associated with food and, therefore, elicited a response (salivation) from the dogs.

The conditioned response is an essential concept in psychology, as it helps to explain how we learn to respond to various stimuli in our environment. For example, if we have a positive experience with a particular food, we may develop a conditioned response to the sight or smell of that food, even if we are not hungry.

Pavlov’s experiments with dogs were groundbreaking in psychology and led to the discovery of classical conditioning and the conditioned response. By demonstrating that animals (and humans) can learn to respond to previously neutral stimuli, Pavlov paved the way for further research into the mechanisms of learning and behavior.

Significance in Psychology

Pavlov’s dog experiment has been a significant discovery in psychology. It has paved the way for developing various theories and has been instrumental in understanding human behavior. In this section, we will discuss the significance of Pavlov’s dog experiment in the context of behaviorism and learning theories.

Behaviorism

Pavlov’s dog experiment has been a cornerstone in the development of behaviorism. Behaviorism is a school of thought in psychology that emphasizes the importance of observable behavior rather than internal mental states. Pavlov’s experiment demonstrated how a stimulus-response connection could be formed through conditioning. This concept has been used to explain various behaviors, such as phobias and addictions.

Learning Theories

Pavlov’s dog experiment has also been significant in developing learning theories . Learning theories are concerned with how people acquire new knowledge and skills. Pavlov’s experiment demonstrated how classical conditioning could teach animals new behaviors. This concept has been used to explain various learning phenomena, such as the acquisition of language and the development of social skills.

In conclusion, Pavlov’s dog experiment has been a significant discovery in psychology. It has been instrumental in the development of behaviorism and learning theories. By understanding the principles of classical conditioning, we can better understand human behavior and how we learn new skills and behaviors.

Implications in Modern Psychology

Pavlov’s dog experiments have had a significant impact on modern psychology. His theory of classical conditioning has become a cornerstone of behaviorism, a school of thought that dominated psychology in the early 20th century. Today, it continues to influence psychologists and researchers in various fields.

One of the most significant implications of Pavlov’s work is the understanding of how learning takes place. His experiments showed that animals, including humans, can learn through association. This concept has been applied in many areas of modern psychology, including education, advertising, and even politics.

For example, in education, classical conditioning can improve students’ learning by associating positive experiences with specific subjects or activities. In advertising, classical conditioning can create positive associations between a product and a particular emotion or experience, influencing consumers’ purchasing decisions.

Moreover, Pavlov’s work has also contributed to developing other learning theories, such as operant conditioning, which focuses on the consequences of behavior rather than the stimuli that precede it. These theories have been used to explain various human behaviors, from addiction to language acquisition.

Pavlov’s dog experiments have had a lasting impact on modern psychology. His theory of classical conditioning has contributed to our understanding of how learning takes place and has been applied in various fields, from education to advertising. His work has also influenced the development of other learning theories, making it a crucial part of studying human behavior.

Criticism and Controversies

While Pavlov’s experiments have been foundational in psychology, they have also been subject to criticism and controversy. Here are a few examples:

• Animal cruelty:  Some critics argue that Pavlov’s experiments on dogs were cruel and unethical. The dogs were often subjected to painful surgeries and kept in small cages for long periods. While these practices were common in the early 20th century, they would not be acceptable by today’s ethical standards.
• Oversimplification of behavior:  Pavlov’s experiments focused on classical conditioning, which suggests that behavior is determined solely by external stimuli. However, this oversimplifies the complex nature of human behavior, which is influenced by various factors, including genetics, environment, and personal experience.
• Limited generalizability:  Pavlov’s experiments were conducted on dogs, which may not accurately reflect human behavior. While some of the principles of classical conditioning may apply to humans, it is essential to recognize that there are also significant differences between species.
• Misinterpretation of results:  Pavlov’s work has been subject to misinterpretation over the years. For example, many people believe that Pavlov’s dogs learned to salivate at the sound of a bell because they associated it with food. However, this is only partially accurate. The dogs learned to associate the sound of the bell with the experimenter’s presence, who would then provide the food.

Frequently Asked Questions

What were the basic features of classical conditioning discovered by pavlov.

Classical conditioning is a type of learning in which a neutral stimulus becomes associated with a meaningful stimulus, resulting in a behavioral response. Pavlov discovered that when a neutral stimulus (such as a bell) was repeatedly paired with a meaningful stimulus (such as food), the neutral stimulus alone could elicit the same response (such as salivation) as the meaningful stimulus.

What was the purpose of Pavlov’s dog experiment?

Pavlov’s dog experiment was designed to study the process of classical conditioning. He wanted to understand how dogs learn to associate a neutral stimulus (such as a bell) with a meaningful stimulus (such as food) and how this association leads to a behavioral response (such as salivation).

How did Pavlov’s experiments contribute to the development of psychology?

Pavlov’s experiments were groundbreaking in the field of psychology. They provided evidence for the concept of classical conditioning, which has since been used to explain a wide range of human and animal behaviors. Pavlov’s work also paved the way for the development of behaviorism, a school of psychology that emphasizes the importance of observable behavior in understanding human and animal psychology.

What is the Pavlovian response and how does it work?

The Pavlovian response is a learned response to a previously neutral stimulus. It works by pairing the neutral stimulus with a meaningful stimulus, which leads to the formation of an association between the two. Once the association is formed, the neutral stimulus alone can elicit the same response as the meaningful stimulus.

How is Pavlovian conditioning used in dog training?

Pavlovian conditioning is often used in dog training to teach dogs new behaviors or to modify existing ones. For example, a trainer might use a clicker (a neutral stimulus) to signal to a dog that it has performed a desired behavior (a meaningful stimulus), and then reward the dog with a treat. Over time, the dog will learn to associate the clicker with the reward and will perform the desired behavior without the need for a treat.

What is the Pavlovian response in humans and how is it studied?

The Pavlovian response in humans is similar to that in dogs: it involves the formation of an association between a neutral stimulus and a meaningful stimulus, resulting in a learned response. This response has been studied in a variety of contexts, including addiction, phobias, and taste aversions. Researchers use a variety of methods to study the Pavlovian response in humans, including brain imaging techniques and behavioral experiments.

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Ivan Pavlov and the Theory of Classical Conditioning

Benjamin Spall

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Pavlov’s Dog Experiments

Ivan Pavlov, a Russian physiologist, is renowned for his groundbreaking research on classical conditioning. Pavlov’s dog experiments have become one of the most iconic studies in the field of psychology. Pavlov’s dog experiments involved a simple yet ingenious setup to measure the saliva of dogs in response to a stimulus (food).

Pavlov observed that dogs naturally salivated when presented with food, an automatic response known in classical conditioning as the unconditioned response (UR). Pavlov utilized this natural reflex as a baseline for his research. In Pavlov’s dog experiments, Pavlov theorized that dogs could be conditioned to associate a neutral stimulus (such as a bell) with a reflexive response (such as salivation) by repeatedly pairing the two stimuli together.

Key Definition:

Pavlov’s dogs experiments refer to a series of experiments conducted by Ivan Pavlov in the late 19th century. He discovered he could condition a dog to salivate at the sound of a bell. Pavlov’s research is a prominent element in the upcoming behaviorist movement occurring during that at time.

History of the Classical Conditioning of the Pavlov Dogs.

Ivan Pavlov was born on September 14, 1849 in the small Russian town of Ryazan. One of Pavlov’s primary subjects of research was the physiology of digestion. He observed and meticulous recorded the digestive process in dogs. As far back as 1890, he noted that an interesting phenomenon occurred around feeding and sham feeding time with the gastric secretion. He was especially interested in the secretion of gastric juices at the mere sight of food. This psychic component of a physiological occurrence became the subject of his later investigations, providing substantial empirical support for the behaviorist movement and the concept of classical (Pavlovian) conditioning.

His observations later motivated the transition from the physiology of digestion to the psychology of reflexes. One of the chief impetus for this transition, in addition to his observations, was a booklet he read in his youth from Mikhailovich Sechenov, the father of Russian physiology, entitled Reflexes of the Brain.

The Involvement of the Psychic Component in Physiological Processes

“It became increasingly obvious to Pavlov that a ‘psychic’ component was of unexpected large significance in the content of digestive secretions” ( Kimble, 1967, p. 29 ). The basic concept in Pavlovian conditioning is that “the ultimate nature of conditioning was that intense (dominant) activity (excitation) set up in one neural center by the unconditioned stimulus (US) attracted to itself the weaker activity (excitation) initiated by other stimuli present at approximately the same time” ( Kimble, p.35 ). Basically, when food excites the salivary glands at the same time as an unconditioned stimulus is present (such as a bell or flash of light), the two elements merge, creating a temporary connection.

“Neurons that fire together, wire together.” ~Donald Hebb (1949)

The ultimate outcome of this temporary wiring is that now the US (the bell or the flashing light) excites the primary reflex. In the Pavlov experiments this refers to the reflexive excretion of saliva. After conditioning, the bell would begin the flow of digestive juices without the presence of food.

The Experiments

The experiments required measuring the flow of saliva. To do this, Pavlov and his lab assistances performed a simple operation, making “a permanent fistula of the parotid duct—that is, a small opening is made to lead from the gland to the external surface of the cheek and a small tube is cemented to this outlet” ( Watson, 2012, pp. 26-27 ). Researchers were than able to measure and record the drops of saliva coming from the gland.

To test the concept of classical conditioning, Pavlov introduced a neutral stimulus, typically the sound of a bell, before presenting the dogs with food. Initially, the bell had no inherent association with salivation. However, after repeatedly pairing the bell with the food, the dogs began to associate the bell with the forthcoming meal. After a “psychic” connection was formed between the bell and the forthcoming meal, the bell would excite the digestive gland and drops of saliva would flow from the parotid duct.

Palov explains that by connecting the unconditioned stimulus to a conditioned stimulus through repeated presentation ‘there is established…a temporary relation between the activity of a certain organ and the phenomena of the external world (1928). He later presents that “if a new, formerly indifferent stimulus, entering into the cerebrum, meets in the nervous system at the moment, a focus of strong excitation, this newly arriving stimulation begins to concentrate, and to open a road, as it were, to this focus, and through it onward to the corresponding organ, becoming in this way a stimulator of that organ” ( Horsley, 1928, p. 124 ).

This acquired response, known as the conditioned response (CR), demonstrated the process of classical conditioning.

Temporary Connection

A primary point is that these conditioned responses are temporary. For them to continue, they need continual reinforcement. A concept primary to later behaviorism theories. Over time, without reinforcement, the conditioned response weakens and then becomes extinct.

Excitation and Inhibition

While we mainly focus on the excitation of physiological states in connection to conditioned responses, Pavlov’s experiments also equally examined inhibitory reactions to stimuli. Just as experience can condition non-primary stimuli in the environment to excite reflexive responses, experience can also condition non-primary stimuli to inhibit the excitation of reflexive responses. If food is presented, but a bitter substance given to the dog after presenting the food, soon the dog quits salivating at the presences of food. A brain creates a temporary connection between the food and the bitter taste.

Pavlov presented that “the inhibition of the conditioned reflex is observed also in the converse case When you have a combination of agents acting as a conditioned stimulus, in which, as has been already stated, one of the agents by itself produces almost no effect, then frequent repetition of the powerfully acting stimulus alone, without the other one, leads to a marked inhibition of its action, almost to the point of its annihilation” ( Horsley, 1928, p. 92 ).

Pavlov explains, “one must simply state that all the highest nervous activity, as it manifests itself in the conditioned reflex, consists of a continual change of these three fundamental processes—excitation, inhibition, and disinhibition” ( Horsley, p. 128 ). Gregory Kimble wrote that “excitation and inhibition are so closely related in Pavlovian thought that there is little point in attempting to treat them separately” ( Kimble, 1967 ).

Individual Differences

Typically, when we review research, such as Pavlov’s dog experiments we envision uniform responses, equally applicable to all the dogs. Behavior is never so easy. Every behavior is a complex intertwining of biological foundations and past learning. Each dog, just as individual human being, brought their own personality to the lab. These biological sensitivities strongly influenced the dogs conditioning and extinguishing of learned behavioral reactions.

Pavlov mentioned four personality types in the dogs. He refers to melancholic, phlegmatic, choleric, and sanguine personalities. The melancholic and phlegmatic he distinguished as inhibited in terms of movement. The choleric and sanguine groupings he described as inhibited. Inhibited and uninhibited translate well with extrovert- introvert personalities, similar to those dominated by the behavior activation system (BAS) compared to those dominated by the behavioral inhibition system (BIS).

Based upon these personality classifications, Pavlov found differences in the ways dogs reacted to stimuli and the rate of conditioning and extinguishing of behaviors. For instance, he found that the sanguine dogs were easier to excite salivatory response with a conditioned stimulus than it was to inhibit such a response. In contrast, Pavlov discovered that the melancholic animals were difficult to elicit a salivary response with a conditioned stimulus but once reinforcement was discontinued the stimulus quickly acquired the capacity to inhibit responses ( Robinson, 2011 ).

The Significance of Pavlov’s Research

Pavlov’s groundbreaking findings challenged the prevailing belief that reflexes were solely innate. His work showed that animals are capable of forming conditioned responses through the association of stimuli. This discovery had far-reaching implications, not only for the field of psychology but also for understanding the mechanisms of learning and behavior.

Pavlov considers the organism’s ability to adapt to environmental signals as a survival mechanism. He presented in one of his lectures that “these temporary relations and its law (reinforcement by repetition and weakening if not repeated) play an important role in the welfare and integrity of the organism, by means of it the fitness of the adaptation between the activity of the organism and the environment becomes more perfect” ( Horsley, 1928 ).

Our bodies reflexively react to environmental cues, perhaps, relying on predictive coding , without exposure to the ultimate stimuli of our excitement. Basically, our repertoire of motivating stimuli expands through growing complex connections between stimuli in our environment and personal goals. These connections allow automatic processes to reflexively respond in preparation to perceived opportunity and threats. The advance warning system gives the organism a competitive advantage for survival.

Habits and Pavlovian (Classical) Conditioning

Jeremy Dean PhD., Author of is the founder and author of PsyBlog , wrote, “the bathroom, car, and coffee shop are like Pavlov’s bell, unconsciously reminding us of long-standing patterns of behavior, which we then enact again, in exactly the same way as before” ( 2013, Dean, Kindle location:166 ). Basically, environmental cues are neurotically connected to behaviors. This can work for or against our desired ending. Accordingly, constructing environments to nudge behaviors we desire can be an important component of successful change. Markedly, this is especially true when the desire is extinction of habitual behavioral responses.

Many habits stick because their connection to unconscious reflexes, responding to environmental cues. Accordingly, as long as we stay in the same environment, the cues will keep exciting internal processes to continue acting in ways we which we could stop.

Fear Learning

Fear learning, often studied through fear conditioning, is a type of associative learning where an individual learns to predict and avoid danger based on previous experiences. It involves the association of a neutral stimulus (like a tone) with an aversive stimulus (such as an electric shock), leading to the expression of fear responses to the originally neutral stimulus or context. This process is crucial for survival, enabling one to anticipate and evade potential threats. However, it can also lead to problems when the acquired fear responses are not extinguished even when there’s no longer a threat, or when it results in maladaptive behavior.

Fear Learning is Classical Conditioning

Lisa Feldman Barrett PhD., explains that ‘fear learning’ is just a fancy name for ‘classical conditioning’ ( Barrett, 2018, p. 271 ). Steven Southwick and Dennis Charney explain that “the brain’s limbic system links the fear that accompanies a traumatic event to sights, sounds, odors, time of day, weather conditions, and other ordinarily neutral stimuli that are present during the frightening event. These contextual stimuli can then become fear-conditioned cues that are capable of triggering fear by themselves because of their previous association with danger” ( Southwick & Charney, 2018, Kindle location: 2,110 ).

The neurobiology of fear learning involves brain regions such as the amygdala, hippocampus, and prefrontal cortex, which play roles in the acquisition, consolidation, and extinction of fear memories. Understanding fear learning has implications for treating conditions like phobias and post-traumatic stress disorder, as it informs therapeutic approaches that aim to modify or extinguish maladaptive fear responses

Joseph LeDoux, a brain scientist who specializes in the neurobiology of fear, explains that “If an animal is lucky enough to survive one dangerous encounter, its brain should store as much about the experience as possible” ( LeDoux, 2003. Kindle location: 2,151 ). Certainly, when we view classical conditioning from this outside of the lab perspective, it is clear why this conditioning contributes to an organism’s survivability. However, when these conditioned responses go askew, such as in post-traumatic stress disorder, they can dramatically impact our lives.

A Few Words by Psychology Fanatic

Pavlov’s dog experiments remain a keystone in psychology, illustrating the principles of classical conditioning through simple to understand research. While psychology continues to expand in understanding and scope, the early principles so clearly presented by Pavlov remain. Accordingly, much of Pavlov’s early findings remain relevant to both the scientist, therapist and even for the lay person trying to adopt new behaviors or extinguish old habits.

We may all benefit from taking a few moments to mindfully examine and identify some of the classically conditioned responses ingrained into our lives. Perhaps, once we identify the conditioned responses, we may use the knowledge to improve our lives.

Last Update: April 18, 2024

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References:

Asratyan, Ezra.A. ( 2022 ) I.P. Pavlov. His Life and Work.

Barrett, Lisa Feldman ( 2018 ) How Emotions Are Made: The Secret Life of the Brain. Mariner Books; Illustrated edition.

Dean, Jeremy  (2013).  Making Habits, Breaking Habits: Why We Do things, Why We Don’t and How to Make any change Stick . Da Capo Lifelong Books; Illustrated edition.

Horsley, W. (1928) Lectures on Conditioned Reflexes Vol 1.

Kimble, Gregory ( 1967 ). Foundations of Conditioning and Learning. ‎Irvington Publishers.

LeDoux, Joseph ( 2003 ). Synaptic Self: How Our Brains Become Who We Are. Penguin Books.

Robinson, David L. ( 2011 ). Brain, Mind and Behaviour: A New Perspective on Human Nature. 

Southwick, Steven, Charney, Dennis ( 2018 ) Resilience: The Science of Mastering Life’s Greatest Challenges. Cambridge University Press; 2 edition.

Watson. John B. (1924/ 2012 ). Behaviorism. Forgotten Books.

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Ivan Pavlov

Ivan Pavlov (second right)

Wellcome Collection

While researching digestion in dogs , Ivan Pavlov noticed that the dogs began to drool as soon as they saw the white coats of the people who fed them; before they could even see or smell their food.

At the time, most research on the function of organs was done by dissecting corpses. Pavlov realised it would be much more informative to perform experiments on living animals . His staff operated on the dogs so that their digestive secretions could be collected and studied over time.

With his innovative methods, he demonstrated the role of the nervous system in controlling digestion – an achievement that earned him a Nobel Prize in 1904. But his drooling dogs gave him an opportunity to go further: he saw that salivation was a quantifiable outcome that he could use to study the mind.

Drooling in the presence of food is an innate response, which Pavlov called an unconditional reflex. For dogs to drool in response to other stimuli that are associated with food, they must learn the association. That makes it a conditional reflex.

Pavlov trained his dogs to start salivating in response to all sorts of stimuli, but in contrast to many popular accounts, never a bell, according to Daniel Todes’ biography Ivan Pavlov: A Russian Life in Science .

Pavlov believed what he learned from dogs was completely transferable to humans , and advocated strongly that psychology was amenable to the scientific method . His theory of classical conditioning inspired BF Skinner’s work on operant conditioning, which applies to voluntary behaviours rather than reflexes. Sam Wong

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In an experiment when dogs are presented with food, dogs would begin to salivate however the dogs then started to salivate in the presence of the technicians who would usually feed them. This was not expected to happen, the dogs were to simply salivate on seeing their food only.

It was back in 1897 , Soviet-Russian physiologist Ivan Pavlov conducted this dog experiment and when he found this unusual behavior he looked to investigate this further.

Before meal times the dogs would hear a bell rung referred to as the neutral stimulus at which point they would be given their food known as the unconditioned stimulus. After a few repetitions , the dogs started to salivate in response to the bell though there was no food.

Pavlov concluded that the neutral stimulus (ringing of the Bell) after being repeatedly paired with an unconditioned stimulus (the food) started to turn into a conditioned stimulus producing the conditioned response, salivation.

Yes, this sounds perfectly sweet and really not a bad experiment for the dogs themselves. Well, you are yet to discover the flipped side of the coin.

Pavlov’s Experimentation Did Not End With Animals

Pavlov had surgically implanted a crude device embedded into dogs’ throats to measure the saliva excreted and Pavlov’s experimentation did not end with animals.

Pavlov took his research on to human testing. He also discovered how the brain learns to see the new stimuli as a particular signal that links various reflexes to them. This is how animals in the wild learn to hunt or escape being hunted.

They learn to apply their reflexes to new situations based on experiences they’ve had before. If this could be applied to animals. Surely, it must be applicable to humans also.

Of course, measurements would still have to be taken. Saliva rates needed to be measured and that would again involve the use of a surgical implant embedded into the throat.

Unsurprisingly there were not many willing volunteers in the early 1900s . Russia did, however, have plenty of orphans and an absence of child welfare laws. Now at this point, Pavlov’s researchers suggested to purchases children , and the human experiments began.

The child would be put under heavy anesthetic and the implant was fixed into the orphan’s throat. When they awoke they would be tied to a laboratory chair with their hands bound so they would be unable to remove the device and taped their mouths open.

After that, the salivation was measured just like the dogs. A squeeze of pressure on the chance wrist (the neutral stimulus) was made, and a cookie was (the unconditional stimulus) presented.

Then the fitted drip tubes on their throats would measure their saliva however it was thought that despite the same research conditions the emotional stress proved too great to provide any useful results from this child experimentation

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Classical Conditioning – The Pavlov’s Dogs Experiment

Have you ever heard a song or tune from your childhood and felt an instant rush of nostalgia or happiness? That tune and the happiness/nostalgic feeling are interconnected by association, which we call Classical Conditioning.

Classical Conditioning is a psychological phenomenon in which one learns by pairing two or more stimuli to create an association. It is the process of creating a link between a conditioned stimulus and a conditioned response.

Who Discovered Classical Conditioning ?

The phenomenon of Classical Conditioning was discovered by Ivan Pavlov. Ivan Pavlov was a Russian Physiologist who was interested in understanding canine physiology and was especially interested in their digestive systems.

He began to observe dogs and their eating patterns to identify when they begin to salivate. Through his observations, he believed that dogs begin to salivate when they heard the bell that was rung before the food was presented.

To prove his theory, Pavlov built a machine that would accurately determine and measure the amount of saliva produced when the food was presented. Thus began the infamous Pavlov’s dogs experiment.

What is the Pavlov’s Dogs Experiment ?

Pavlov initially placed the food in front of the dog and recorded the level of salivation. He did this a couple of times to measure and assess why the dog was salivating.

After the first couple of trials, he began to ring a bell. He would ring the bell and wait approximately 5 seconds before presenting the food. The dogs continued to salivate only when the food was present. However, after repetitive exposure to the bell and the food, the dogs began to salivate upon hearing the bell.

This means that the dog began to associate the bell with food. This leads to salivation when hearing the bell.

Core Concept Of Classical Conditioning

This experiment led to the discovery of a type of learning called Classical Conditioning (as termed by Pavlov). The experiment was conducted in 1906 and was a major catalyst in the development and understanding of learning and behaviour theories.

The experiment consists of 4 different elements. These are:

1) Unconditioned Stimulus

This is a certain object or stimulus that triggers an automatic/involuntarily bodily response. This is an unconscious process and has not been previously learnt. In this case, the food is considered to be the unconditioned stimuli.

For example, for a student, the smell of the food from the mess/canteen is considered to be the unconditioned stimuli.

2) Unconditional Response

This is the automatic and involuntary response that occurs when presented with the object or the stimulus. This response is generally unlearnt and usually occurs due to the processes of the Central Nervous System (CNS). In this case, the salivation of the dogs is the Unconditioned Response.

For example, the hunger and salivation of the student are considered to be the unconditioned response.

3) Conditioned Stimulus

This is also known as the Neutral Stimulus. This stimulus is presented repeatedly until the association between the object and the response is formed. If the object is repeatedly presented (in this case the food), it will start to evoke the same response. In this case, the bell is considered to be the conditioned stimulus.

For example, the lunch bell is paired with the smell of the food. Hence the bell is associated with lunchtime. Therefore, the bell becomes the conditioned stimulus.

4) Conditioned Response

This is the response obtained after repeated exposure to the conditioned stimulus (which is the bell). This is the response that occurs once the stimulus and response have been associated. The conditioned response is salivating upon hearing the bell.

For example, the bell is now associated with the food from the mess/canteen. Hence, the student may get hungry/salivate upon hearing the sound of the bell. This indicates that classical conditioning has occurred.

Common Example – Conditioning Theory Of Learning

A great example of this is when you smell your mom’s perfume. You may have grown up used to the smell of your mom’s perfume. The perfume reminds you of your mother and the great times you shared when you were growing up. You are exposed to the perfume several times while growing up; you begin to associate it with happiness.

Several years later, if you catch a sniff of the perfume in a supermarket, you may associate it with happiness without actually consciously thinking of your childhood or your mother. This is due to learning by association otherwise known as Classical Conditioning.

There are three other aspects that we must understand and take into account when learning about classical conditioning. They are:

a) Extinction

This is a phenomenon in which the conditioned stimulus (i.e. the bell) is presented excessively without the unconditioned stimulus (i.e. dog food). This overexposure results in the process of unlearning. Eventually, the bell will no longer result in a conditioned response.

For example, while training children to potty train, the parents might give a reward every time the child uses the toilet. However, over time as the child continues to use the toilet, the parent will stop providing the rewards. Due to the overexposure, the child will eventually continue the behavior without association.

b) Generalization

This occurs when the conditioned stimulus is generalized, and therefore causes a conditioned response. For example, the dog may generalize the sound of other bells and may begin to salivate.

This can be found in the case of Little Albert. He was taught to fear a white rabbit using classical conditioning. However, he began to generalize that phobia to other objects of similar shape, size and colour. He also began to fear other objects such as mice, hamsters etc. This is known as generalization.

c) Discrimination

This is the opposite response to Generalization. This occurs when the person/ animal can discriminate between different stimuli and therefore will not produce the same reaction to the different stimuli.

This can be seen when one has a very certain phobia. For example, a person who has a phobia of cockroaches may not have a phobia of spiders or other insects even though they are similar.

What are the applications of Classical Conditioning in Psychology ?

Classical Conditioning has helped several psychologists understand how people learn and behave. Classical Conditioning helped pave the way for understanding certain pathological conditions (i.e. phobias, drug dependency and aversions) and their treatments. These include:

a) Phobias and Systematic Desensitization

A famous experiment conducted by John B Watson called Little Albert helps us understand how phobias are formed. Watson used the same method of classical conditioning to instil fear in a little boy named Albert. Albert was initially presented with a small rat for the first few trials.

After the first few trials, the rat was presented with a loud noise. Although Albert was initially not afraid of the rat, the association between the rat and the loud noise was formed. This resulted in causing him extreme fear when he saw the rat. This resulted in Albert having a phobia of rats.

Classical Conditioning can also be used to help get ready for phobias. This is usually done using a method of Systematic Desensitization. This treatment works by creating a hierarchy of fear. The client will identify and rank their fears from lowest to highest.

For example, a client who has a fear of lizards may feel fear at 10% while talking about them, 30% fear while looking at a picture, 50% watching a video of a lizard and 70% of fear while one is in the room.

The therapist then begins to work up the hierarchy while pairing deep breathing exercises.

For example, the therapist shows the client an image of a lizard and then guides them through deep breathing. This is repeated several times until the client no longer feels scared to see an image. They then move on to the next stage of the hierarchy.

This is what the hierarchy for herpetophobia (Fear of Lizards) would look like.

Vicarious Conditioning is the occurrence of developing fear and becoming conditioned due to watching someone else.

For example, if you watch your mother running away from a spider, you may also become conditioned into thinking that spiders are something that evokes fear. This may lead to arachnophobia later on.

b) Drug Dependency and Aversion Therapy

Drugs cause a feeling of “ecstasy” or a “high”. This feeling of high results in the user repeatedly using. The feeling of ecstasy and the substance become paired, thus the user will continue to use the substance. They may even become extremely dependent on it, resulting in an abuse disorder.

Aversion Therapy is a treatment method used to combat abuse disorder. This is behavioural therapy method in which there is a pairing between unwanted behaviour and discomfort.

For example, someone who is addicted to alcohol may be required to snap a rubber band on their wrist every time they think of alcohol.

c) Classical Conditioning and Attitude Formation

Classical Conditioning has shown a significant outcome in attitude formation. Classical Conditioning has shown the ability to determine and change a person’s attitude/ feelings towards a particular object.

For example, a child grows up seeing her mother react negatively to Native Americans. Every time her mother comes across someone of Native American descent, she gets angry. She begins to associate anger with the Native Americans. She may begin to view them negatively and may even grow up and treat them the same.

Hence, classical conditioning has affected her attitude towards a certain race. This is attitude formation.

Ivan Pavlov’s experimentation with learning and behaviour caused a ripple effect throughout the psychological community. It promoted the development of several other theories of learning. It also helped us understand human behaviour and helped in the evolution of treatment methods.

So next time you come across Pavlov and Classical Conditioning, I hope this article rings a bell.

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Communication Theory

Pavlov's Experiment

Pavlov performed a famous set of experiments on dogs that demonstrated classical conditioning. By the end of the experiment, the dogs paired a tone with meat powder and began to salivate when they heard a tone, which is a stimulus that previously wouldn't have elicited a response.

Unconditioned stimulus and response

• In the experiments, the dogs salivated each time meat powder was presented to them.
• The meat powder in this situation was an unconditioned stimulus (UCS).
• The dogs’ salivation was an unconditioned response (UCR).
• Meat powder (UCS) → salivation (UCR).

Classical conditioning

• In classical conditioning, a neutral stimulus is presented immediately before an unconditioned stimulus.
• Pavlov would sound a tone (like ringing a bell) and then give the dogs the meat powder.
• The tone was the neutral stimulus (NS).
• Tone (NS) + meat powder (UCS) → salivation (UCR).

Conditioned stimulus

• When Pavlov paired the tone with the meat powder repeatedly, the previously neutral stimulus (the tone) also made the dogs salivate.
• The neutral stimulus became the conditioned stimulus (CS).
• Eventually, the dogs began to salivate to the tone alone, just as they previously had salivated at the sound of the assistants’ footsteps.

• Tone (CS) → salivation (CR).

Behaviourism

Behaviourism is the psychological approach of observing and controlling behaviour, which incorporates elements of Pavlov's classical conditioning.

• Behaviourism is a school of thought that arose during the first part of the 20th century, which incorporates elements of Pavlov’s classical conditioning.
• Behaviourism is the psychological approach of observing and controlling behaviour.

Object of study

• A major object of study by behaviourists was learned behaviour and its interaction with inborn qualities of the organism.
• Behaviourism commonly used animals in experiments under the assumption that what was learned using animal models could partly be applied to human behavior.

The role of behaviourism

• Behaviourism dominated experimental psychology for several decades, and its influence can still be felt today.
• Behaviourism is largely responsible for establishing psychology as a scientific discipline through its objective methods and experimentation.

Real world uses of behaviourism

• In behavioural and cognitive-behavioural therapy.
• In classroom settings.
• In informing research on environmental influences on human behaviour.

1 Social Influence

1.1 Social Influence

1.1.1 Conformity

1.1.2 Asch (1951)

1.1.3 Sherif (1935)

1.1.4 Conformity to Social Roles

1.1.5 BBC Prison Study

1.1.6 End of Topic Test - Conformity

1.1.7 Obedience

1.1.8 Analysing Milgram's Experiment

1.1.9 Agentic State & Legitimate Authority

1.1.10 Variables of Obedience

1.1.11 Resistance to Social Influence

1.1.12 Minority Influence & Social Change

1.1.13 Minority Influence & Social Impact Theory

1.1.14 End of Topic Test - Social Influences

1.1.15 Exam-Style Question - Conformity

1.1.16 Top Grade AO2/AO3 - Social Influence

2.1.1 Multi-Store Model of Memory

2.1.2 Short-Term vs Long-Term Memory

2.1.3 Long-Term Memory

2.1.4 Support for the Multi-Store Model of Memory

2.1.5 Duration Studies

2.1.6 Capacity Studies

2.1.7 Coding Studies

2.1.8 The Working Memory Model

2.1.9 The Working Memory Model 2

2.1.10 Support for the Working Memory Model

2.1.11 Explanations for Forgetting

2.1.12 Studies on Interference

2.1.13 Cue-Dependent Forgetting

2.1.14 Eye Witness Testimony - Loftus & Palmer

2.1.15 Eye Witness Testimony Loftus

2.1.16 Eyewitness Testimony - Post-Event Discussion

2.1.17 Eyewitness Testimony - Age & Misleading Questions

2.1.18 Cognitive Interview

2.1.19 Cognitive Interview - Geiselman & Fisher

2.1.20 End of Topic Test - Memory

2.1.21 Exam-Style Question - Memory

2.1.22 A-A* (AO3/4) - Memory

3 Attachment

3.1 Attachment

3.1.1 Caregiver-Infant Interaction

3.1.2 Condon & Sander (1974)

3.1.3 Schaffer & Emerson (1964)

3.1.4 Multiple Attachments

3.1.5 Studies on the Role of the Father

3.1.6 Animal Studies of Attachment

3.1.7 Explanations of Attachment

3.1.8 Attachment Types - Strange Situation

3.1.9 Cultural Differences in Attachment

3.1.10 Disruption of Attachment

3.1.11 Disruption of Attachment - Privation

3.1.12 Overcoming the Effects of Disruption

3.1.13 The Effects of Institutionalisation

3.1.14 Early Attachment

3.1.15 Critical Period of Attachment

3.1.16 End of Topic Test - Attachment

3.1.17 Exam-Style Question - Attachment

3.1.18 Top Grade AO2/AO3 - Attachment

4 Psychopathology

4.1 Psychopathology

4.1.1 Definitions of Abnormality

4.1.2 Definitions of Abnormality 2

4.1.3 Phobias, Depression & OCD

4.1.4 Phobias: Behavioural Approach

4.1.5 Evaluation of Behavioural Explanations of Phobias

4.1.6 Depression: Cognitive Approach

4.1.7 OCD: Biological Approach

4.1.8 Evidence for the Biological Approach

4.1.9 End of Topic Test - Psychopathy

4.1.10 Exam-Style Question - Phobias

4.1.11 Top Grade AO2/AO3 - Psychopathology

5 Approaches in Psychology

5.1 Approaches in Psychology

5.1.1 Psychology as a Science

5.1.2 Origins of Psychology

5.1.3 Reductionism & Problems with Introspection

5.1.4 The Behaviourist Approach - Classical Conditioning

5.1.5 Pavlov's Experiment

5.1.6 Little Albert Study

5.1.7 The Behaviourist Approach - Operant Conditioning

5.1.8 Social Learning Theory

5.1.9 The Cognitive Approach 1

5.1.10 The Cognitive Approach 2

5.1.11 The Biological Approach

5.1.12 Gottesman (1991) - Twin Studies

5.1.13 Brain Scanning

5.1.14 Structure of Personality & Little Hans

5.1.15 The Psychodynamic Approach (A2 only)

5.1.16 Humanistic Psychology (A2 only)

5.1.17 Aronoff (1957) (A2 Only)

5.1.18 Rogers' Client-Centred Therapy (A2 only)

5.1.19 End of Topic Test - Approaches in Psychology

5.1.20 Exam-Style Question - Approaches in Psychology

5.2 Comparison of Approaches (A2 only)

5.2.1 Psychodynamic Approach

5.2.2 Cognitive Approach

5.2.3 Biological Approach

5.2.4 Behavioural Approach

5.2.5 End of Topic Test - Comparison of Approaches

6 Biopsychology

6.1 Biopsychology

6.1.1 Nervous System Divisions

6.1.2 Neuron Structure & Function

6.1.3 Neurotransmitters

6.1.4 Endocrine System Function

6.1.5 Fight or Flight Response

6.1.6 The Brain (A2 only)

6.1.7 Localisation of Brain Function (A2 only)

6.1.8 Studying the Brain (A2 only)

6.1.9 CIMT (A2 Only) & Postmortem Examinations

6.1.10 Biological Rhythms (A2 only)

6.1.11 Studies on Biological Rhythms (A2 Only)

6.1.12 End of Topic Test - Biopsychology

6.1.13 Top Grade AO2/AO3 - Biopsychology

7 Research Methods

7.1 Research Methods

7.1.1 Experimental Method

7.1.2 Observational Techniques

7.1.3 Covert, Overt & Controlled Observation

7.1.4 Self-Report Techniques

7.1.5 Correlations

7.1.6 Exam-Style Question - Research Methods

7.1.7 End of Topic Test - Research Methods

7.2 Scientific Processes

7.2.1 Aims, Hypotheses & Sampling

7.2.2 Pilot Studies & Design

7.2.3 Questionnaires

7.2.4 Variables & Control

7.2.5 Demand Characteristics & Investigator Effects

7.2.6 Ethics

7.2.7 Limitations of Ethical Guidelines

7.2.8 Consent & Protection from Harm Studies

7.2.9 Peer Review & The Economy

7.2.10 Validity (A2 only)

7.2.11 Reliability (A2 only)

7.2.12 Features of Science (A2 only)

7.2.13 Paradigms & Falsifiability (A2 only)

7.2.14 Scientific Report (A2 only)

7.2.15 Scientific Report 2 (A2 only)

7.2.16 End of Topic Test - Scientific Processes

7.3 Data Handling & Analysis

7.3.1 Types of Data

7.3.2 Descriptive Statistics

7.3.3 Correlation

7.3.4 Evaluation of Descriptive Statistics

7.3.5 Presentation & Display of Data

7.3.6 Levels of Measurement (A2 only)

7.3.7 Content Analysis (A2 only)

7.3.8 Case Studies (A2 only)

7.3.9 Thematic Analysis (A2 only)

7.3.10 End of Topic Test - Data Handling & Analysis

7.4 Inferential Testing

7.4.1 Introduction to Inferential Testing

7.4.2 Sign Test

7.4.3 Piaget Conservation Experiment

7.4.4 Non-Parametric Tests

8 Issues & Debates in Psychology (A2 only)

8.1 Issues & Debates in Psychology (A2 only)

8.1.1 Culture Bias

8.1.2 Sub-Culture Bias

8.1.3 Gender Bias

8.1.4 Ethnocentrism

8.1.5 Cross Cultural Research

8.1.6 Free Will & Determinism

8.1.7 Comparison of Free Will & Determinism

8.1.8 Reductionism & Holism

8.1.9 Reductionist & Holistic Approaches

8.1.10 Nature-Nurture Debate

8.1.11 Interactionist Approach

8.1.12 Nature-Nurture Methods

8.1.13 Nature-Nurture Approaches

8.1.14 Idiographic & Nomothetic Approaches

8.1.15 Socially Sensitive Research

8.1.16 End of Topic Test - Issues and Debates

9 Option 1: Relationships (A2 only)

9.1 Relationships: Sexual Relationships (A2 only)

9.1.1 Sexual Selection & Human Reproductive Behaviour

9.1.2 Intersexual & Intrasexual Selection

9.1.3 Evaluation of Sexual Selection Behaviour

9.1.4 Factors Affecting Attraction: Self-Disclosure

9.1.5 Evaluation of Self-Disclosure Theory

9.1.6 Self Disclosure in Computer Communication

9.1.7 Factors Affecting Attraction: Physical Attributes

9.1.8 Matching Hypothesis Studies

9.1.9 Factors Affecting Physical Attraction

9.1.10 Factors Affecting Attraction: Filter Theory 1

9.1.11 Factors Affecting Attraction: Filter Theory 2

9.1.12 Evaluation of Filter Theory

9.1.13 End of Topic Test - Sexual Relationships

9.2 Relationships: Romantic Relationships (A2 only)

9.2.1 Social Exchange Theory

9.2.2 Evaluation of Social Exchange Theory

9.2.3 Equity Theory

9.2.4 Evaluation of Equity Theory

9.2.5 Rusbult’s Investment Model

9.2.6 Evaluation of Rusbult's Investment Model

9.2.7 Relationship Breakdown

9.2.8 Studies on Relationship Breakdown

9.2.9 Evaluation of Relationship Breakdown

9.2.10 End of Topic Test - Romantic relationships

9.3 Relationships: Virtual & Parasocial (A2 only)

9.3.1 Virtual Relationships in Social Media

9.3.2 Evaluation of Reduced Cues & Hyperpersonal

9.3.3 Parasocial Relationships

9.3.4 Attachment Theory & Parasocial Relationships

9.3.5 Evaluation of Parasocial Relationship Theories

9.3.6 End of Topic Test - Virtual & Parasocial Realtions

10 Option 1: Gender (A2 only)

10.1 Gender (A2 only)

10.1.1 Sex, Gender & Androgyny

10.1.2 Gender Identity Disorder

10.1.3 Biological & Social Explanations of GID

10.1.4 Biological Influences on Gender

10.1.5 Effects of Hormones on Gender

10.1.6 End of Topic Test - Gender 1

10.1.7 Kohlberg’s Theory of Gender Constancy

10.1.8 Evaluation of Kohlberg's Theory

10.1.9 Gender Schema Theory

10.1.10 Psychodynamic Approach to Gender Development 1

10.1.11 Psychodynamic Approach to Gender Development 2

10.1.12 Social Approach to Gender Development

10.1.13 Criticisms of Social Theory

10.1.14 End of Topic Test - Gender 2

10.1.15 Media Influence on Gender Development

10.1.16 Cross Cultural Research

10.1.17 Childcare & Gender Roles

10.1.18 End of Topic Test - Gender 3

11 Option 1: Cognition & Development (A2 only)

11.1 Cognition & Development (A2 only)

11.1.1 Piaget’s Theory of Cognitive Development 1

11.1.2 Piaget's Theory of Cognitive Development 2

11.1.3 Schema Accommodation Assimilation & Equilibration

11.1.4 Piaget & Inhelder’s Three Mountains Task (1956)

11.1.5 Conservation & Class Inclusion

11.1.6 Evaluation of Piaget

11.1.7 End of Topic Test - Cognition & Development 1

11.1.8 Vygotsky

11.1.9 Evaluation of Vygotsky

11.1.10 Baillargeon

11.1.11 Baillargeon's studies

11.1.12 Evaluation of Baillargeon

11.1.13 End of Topic Test - Cognition & Development 2

11.1.14 Sense of Self & Theory of Mind

11.1.15 Baron-Cohen Studies

11.1.16 Selman’s Five Levels of Perspective Taking

11.1.17 Biological Basis of Social Cognition

11.1.18 Evaluation of Biological Basis of Social Cognition

11.1.19 Important Issues in Social Neuroscience

11.1.20 End of Topic Test - Cognition & Development 3

11.1.21 Top Grade AO2/AO3 - Cognition & Development

12 Option 2: Schizophrenia (A2 only)

12.1 Schizophrenia: Diagnosis (A2 only)

12.1.1 Classification & Diagnosis

12.1.2 Reliability & Validity of Diagnosis

12.1.3 Gender & Cultural Bias

12.1.4 Pinto (2017) & Copeland (1971)

12.1.5 End of Topic Test - Scizophrenia Diagnosis

12.2 Schizophrenia: Treatment (A2 only)

12.2.1 Family-Based Psychological Explanations

12.2.2 Evaluation of Family-Based Explanations

12.2.3 Cognitive Explanations

12.2.4 Drug Therapies

12.2.5 Evaluation of Drug Therapies

12.2.6 Biological Explanations for Schizophrenia

12.2.7 Dopamine Hypothesis

12.2.8 End of Topic Test - Schizoprenia Treatment 1

12.2.9 Psychological Therapies 1

12.2.10 Psychological Therapies 2

12.2.11 Evaluation of Psychological Therapies

12.2.12 Interactionist Approach - Diathesis-Stress Model

12.2.13 Interactionist Approach - Triggers & Treatment

12.2.14 Evaluation of the Interactionist Approach

12.2.15 End of Topic Test - Scizophrenia Treatments 2

13 Option 2: Eating Behaviour (A2 only)

13.1 Eating Behaviour (A2 only)

13.1.1 Explanations for Food Preferences

13.1.2 Birch et al (1987) & Lowe et al (2004)

13.1.3 Control of Eating Behaviours

13.1.4 Control of Eating Behaviour: Leptin

13.1.5 Biological Explanations for Anorexia Nervosa

13.1.6 Psychological Explanations: Family Systems Theory

13.1.7 Psychological Explanations: Social Learning Theory

13.1.8 Psychological Explanations: Cognitive Theory

13.1.9 Biological Explanations for Obesity

13.1.10 Biological Explanations: Studies

13.1.11 Psychological Explanations for Obesity

13.1.12 Psychological Explanations: Studies

13.1.13 End of Topic Test - Eating Behaviour

14 Option 2: Stress (A2 only)

14.1 Stress (A2 only)

14.1.1 Physiology of Stress

14.1.2 Role of Stress in Illness

14.1.3 Role of Stress in Illness: Studies

14.1.4 Social Readjustment Rating Scales

14.1.5 Hassles & Uplifts Scales

14.1.6 Stress, Workload & Control

14.1.7 Stress Level Studies

14.1.8 End of Topic Test - Stress 1

14.1.9 Physiological Measures of Stress

14.1.10 Individual Differences

14.1.11 Stress & Gender

14.1.12 Drug Therapy & Biofeedback for Stress

14.1.13 Stress Inoculation Therapy

14.1.14 Social Support & Stress

14.1.15 End of Topic Test - Stress 2

15 Option 3: Aggression (A2 only)

15.1 Aggression: Physiological (A2 only)

15.1.1 Neural Mechanisms

15.1.2 Serotonin

15.1.3 Hormonal Mechanisms

15.1.4 Genetic Factors

15.1.5 Genetic Factors 2

15.1.6 End of Topic Test - Aggression: Physiological 1

15.1.7 Ethological Explanation

15.1.8 Innate Releasing Mechanisms & Fixed Action Pattern

15.1.9 Evolutionary Explanations

15.1.10 Buss et al (1992) - Sex Differences in Jealousy

15.1.11 Evaluation of Evolutionary Explanations

15.1.12 End of Topic Test - Aggression: Physiological 2

15.2 Aggression: Social Psychological (A2 only)

15.2.1 Social Psychological Explanation

15.2.2 Buss (1963) - Frustration/Aggression

15.2.3 Social Psychological Explanation 2

15.2.4 Social Learning Theory (SLT) 1

15.2.5 Social Learning Theory (SLT) 2

15.2.6 Limitations of Social Learning Theory (SLT)

15.2.7 Deindividuation

15.2.8 Deindividuation 2

15.2.9 Deindividuation - Diener et al (1976)

15.2.10 End of Topic Test - Aggression: Social Psychology

15.2.11 Institutional Aggression: Prisons

15.2.12 Evaluation of Dispositional & Situational

15.2.13 Influence of Computer Games

15.2.14 Influence of Television

15.2.15 Evaluation of Studies on Media

15.2.16 Desensitisation & Disinhibition

15.2.17 Cognitive Priming

15.2.18 End of Topic Test - Aggression: Social Psychology

16 Option 3: Forensic Psychology (A2 only)

16.1 Forensic Psychology (A2 only)

16.1.1 Defining Crime

16.1.2 Measuring Crime

16.1.3 Offender Profiling

16.1.4 Evaluation of Offender Profiling

16.1.5 John Duffy Case Study

16.1.6 Biological Explanations 1

16.1.7 Biological Explanations 2

16.1.8 Evaluation of the Biological Explanation

16.1.9 Cognitive Explanations

16.1.10 Moral Reasoning

16.1.11 Psychodynamic Explanation 1

16.1.12 Psychodynamic Explanation 2

16.1.13 End of Topic Test - Forensic Psychology 1

16.1.14 Differential Association Theory

16.1.15 Custodial Sentencing

16.1.16 Effects of Prison

16.1.17 Evaluation of the Effects of Prison

16.1.18 Recidivism

16.1.19 Behavioural Treatments & Therapies

16.1.20 Effectiveness of Behavioural Treatments

16.1.21 Restorative Justice

16.1.22 End of Topic Test - Forensic Psychology 2

17 Option 3: Addiction (A2 only)

17.1 Addiction (A2 only)

17.1.1 Definition

17.1.2 Brain Neurochemistry Explanation

17.1.3 Learning Theory Explanation

17.1.4 Evaluation of a Learning Theory Explanation

17.1.5 Cognitive Bias

17.1.6 Griffiths on Cognitive Bias

17.1.7 Evaluation of Cognitive Theory (A2 only)

17.1.8 End of Topic Test - Addiction 1

17.1.9 Gambling Addiction & Learning Theory

17.1.10 Social Influences on Addiction 1

17.1.11 Social Influences on Addiction 2

17.1.12 Personal Influences on Addiction

17.1.13 Genetic Explanations of Addiction

17.1.14 End of Topic Test - Addiction 2

17.2 Treating Addiction (A2 only)

17.2.1 Drug Therapy

17.2.2 Behavioural Interventions

17.2.3 Cognitive Behavioural Therapy

17.2.4 Theory of Reasoned Action

17.2.5 Theory of Planned Behaviour

17.2.6 Six Stage Model of Behaviour Change

17.2.7 End of Topic Test - Treating Addiction

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As a college student, B. F. Skinner gave little thought to psychology. He had hoped to become a novelist, and majored in English. Then, in 1927, when he was twenty-three, he read an essay by H. G. Wells about the Russian physiologist Ivan Pavlov. The piece, which appeared in the Times Magazine , was ostensibly a review of the English translation of Pavlov’s “Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex.” But, as Wells pointed out, it was “not an easy book to read,” and he didn’t spend much time on it. Instead, Wells described Pavlov, whose systematic approach to physiology had revolutionized the study of medicine, as “a star which lights the world, shining down a vista hitherto unexplored.”

That unexplored world was the mechanics of the human brain. Pavlov had noticed, in his research on the digestive system of dogs, that they drooled as soon as they saw the white lab coats of the people who fed them. They didn’t need to see, let alone taste, the food in order to react physically. Dogs naturally drooled when fed: that was, in Pavlov’s terms, an “unconditional” reflex. When they drooled in response to a sight or sound that was associated with food by mere happenstance, a “conditional reflex” (to a “conditional stimulus”) had been created. Pavlov had formulated a basic psychological principle—one that also applied to human beings—and discovered an objective way to measure how it worked.

Skinner was enthralled. Two years after reading the Times Magazine piece, he attended a lecture that Pavlov delivered at Harvard and obtained a signed picture, which adorned his office wall for the rest of his life. Skinner and other behaviorists often spoke of their debt to Pavlov, particularly to his view that free will was an illusion, and that the study of human behavior could be reduced to the analysis of observable, quantifiable events and actions.

But Pavlov never held such views, according to “Ivan Pavlov: A Russian Life in Science” (Oxford), an exhaustive new biography by Daniel P. Todes, a professor of the history of medicine at Johns Hopkins School of Medicine. In fact, much of what we thought we knew about Pavlov has been based on bad translations and basic misconceptions. That begins with the popular image of a dog slavering at the ringing of a bell. Pavlov “never trained a dog to salivate to the sound of a bell,” Todes writes. “Indeed, the iconic bell would have proven totally useless to his real goal, which required precise control over the quality and duration of stimuli (he most frequently employed a metronome, a harmonium, a buzzer, and electric shock).”

Pavlov is perhaps best known for introducing the idea of the conditioned reflex, although Todes notes that he never used that term. It was a bad translation of the Russian uslovnyi , or “conditional,” reflex. For Pavlov, the emphasis fell on the contingent, provisional nature of the association—which enlisted other reflexes he believed to be natural and unvarying. Drawing upon the brain science of the day, Pavlov understood conditional reflexes to involve a connection between a point in the brain’s subcortex, which supported instincts, and a point in its cortex, where associations were built. Such conjectures about brain circuitry were anathema to the behaviorists, who were inclined to view the mind as a black box. Nothing mattered, in their view, that could not be observed and measured. Pavlov never subscribed to that theory, or shared their disregard for subjective experience. He considered human psychology to be “one of the last secrets of life,” and hoped that rigorous scientific inquiry could illuminate “the mechanism and vital meaning of that which most occupied Man—our consciousness and its torments.” Of course, the inquiry had to start somewhere. Pavlov believed that it started with data, and he found that data in the saliva of dogs.

Pavlov’s research originally had little to do with psychology; it focussed on the ways in which eating excited salivary, gastric, and pancreatic secretions. To do that, he developed a system of “sham” feeding. Pavlov would remove a dog’s esophagus and create an opening, a fistula, in the animal’s throat, so that, no matter how much the dog ate, the food would fall out and never make it to the stomach. By creating additional fistulas along the digestive system and collecting the various secretions, he could measure their quantity and chemical properties in great detail. That research won him the 1904 Nobel Prize in Physiology or Medicine. But a dog’s drool turned out to be even more meaningful than he had first imagined: it pointed to a new way to study the mind, learning, and human behavior.

“Essentially, only one thing in life is of real interest to us—our psychical experience,” he said in his Nobel address. “Its mechanism, however, was and still is shrouded in profound obscurity. All human resources—art, religion, literature, philosophy, and the historical sciences—all have joined in the attempt to throw light upon this darkness. But humanity has at its disposal yet another powerful resource—natural science with its strict objective methods.”

Pavlov had become a spokesman for the scientific method, but he was not averse to generalizing from his results. “That which I see in dogs,” he told a journalist, “I immediately transfer to myself, since, you know, the basics are identical.”

Ivan Pavlov was born in 1849 in the provincial Russian city of Ryazan, the first of ten children. As the son of a priest, he attended church schools and the theological seminary. But he struggled with religion from an early age and, in 1869, left the seminary to study physiology and chemistry at St. Petersburg University. His father was furious, but Pavlov was undeterred. He never felt comfortable with his parents—or, as this biography makes clear, with almost anyone else. Not long after “The Brothers Karamazov” was published, Pavlov confessed to his future wife, Seraphima Vasilievna Karchevskaya, who was a friend of Dostoyevsky’s, that he identified with the rationalist Ivan Karamazov, whose brutal skepticism condemned him, as Todes notes, to nihilism and breakdown. “The more I read, the more uneasy my heart became,” Pavlov wrote in a letter to Karchevskaya. “Say what you will, but he bears a great resemblance to your tender and loving admirer.”

Pavlov entered the intellectual world of St. Petersburg at an ideal moment for a man eager to explore the rules that govern the material world. The tsar had freed the serfs in 1861, helping to push Russia into the convulsive century that followed. Darwin’s theory of evolution was starting to reverberate across Europe. Science began to matter in Russia in a way it hadn’t before. At the university, Pavlov’s freshman class in inorganic chemistry was taught by Dmitri Mendeleev, who, a year earlier, had created the periodic table of the elements as a teaching tool. The Soviets would soon assign religion to the dustbin of history, but Pavlov got there ahead of them. For him, there was no religion except the truth. “It is for me a kind of God, before whom I reveal everything, before whom I discard wretched worldly vanity,” he wrote. “I always think to base my virtue, my pride, upon the attempt, the wish for truth , even if I cannot attain it.” One day, while walking to his lab at the Institute for Experimental Medicine, Pavlov watched with amazement as a medical student stopped in front of a church and crossed himself. “Think about it!” Pavlov told his colleagues. “A naturalist, a physician, but he prays like an old woman in an almshouse!”

Pavlov was not a pleasant person. Todes presents him as a volatile child, a difficult student, and, frequently, a nasty adult. For decades, his lab staff knew to stay away, if at all possible, on his “angry days,” and there were many. As a member of the liberal intelligentsia, he was opposed to restrictive measures aimed at Jews, but in his personal life he freely voiced anti-Semitic sentiments. Pavlov once referred to “that vile yid, Trotsky,” and, when complaining about the Bolsheviks in 1928, he told W. Horsley Gantt, an American scientist who spent years in his lab, that Jews occupied “high positions everywhere,” and that it was “a shame that the Russians cannot be rulers of their own land.”

In lectures, Pavlov insisted that medicine had to be grounded in science, on data that could be explained, verified, and analyzed, and on studies that could be repeated. Drumming up support among physicians for the scientific method may seem banal today, but at the end of the nineteenth century it wasn’t an easy sell. In Russia, and even to some degree in the West, physiology was still considered a “theoretical science,” and the connection between basic research and medical treatments seemed tenuous. Todes argues that Pavlov’s devotion to repeated experimentation was bolstered by the model of the factory, which had special significance in a belatedly industrializing Russia. Pavlov’s lab was essentially a physiology factory, and the dogs were his machines.

To study them, he introduced a rigorous experimental approach that helped transform medical research. He recognized that meaningful changes in physiology could be assessed only over time. Rather than experiment on an animal once and then kill it, as was common, Pavlov needed to keep his dogs alive. He referred to these studies as “chronic experiments.” They typically involved surgery. “During chronic experiments, when the animal, having recovered from its operation, is under lengthy observation, the dog is irreplaceable,” he noted in 1893.

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The dogs may have been irreplaceable, but their treatment would undoubtedly cause an outcry today. Todes writes that in early experiments Pavlov was constantly stymied by the difficulty of keeping his subjects alive after operating on them. One particularly productive dog had evidently set a record by producing active pancreatic juice for ten days before dying. The loss was a tremendous disappointment to Pavlov. “Our passionate desire to extend experimental trials on such a rare animal was foiled by its death as a result of extended starvation and a series of wounds,” Pavlov wrote at the time. As a result, “the expected resolution of many important and controversial questions” had been delayed, awaiting another champion test subject.

If Pavlov’s notes were voluminous, Todes’s own investigations are hardly modest. He spent years researching this biography and has made excellent use of archives in Russia, Europe, and the United States. No scholar of Pavlov or of the disciplines he inspired will be able to ignore this achievement. The book’s eight hundred and fifty-five pages are filled with a vast accumulation of data, although the reader might have been better served if Todes had left some of it out. No minutia appears to have been too obscure to include. Here is Todes describing data that Pavlov had assembled from one extended experiment: “The total amount of secretion in trials 6 and 8 is too low, and the slope of these curves diverges markedly at several points from that in trial 1. Trial 9 fits trial 1 more snugly than does trial 5 in terms of total secretion, but the amount of secretion more than doubles in the second hour, contrasting sharply with the slight decline in trial 1. Trial 10 is again a good fit in terms of total amount of secretion, but the amount of secretion rises inappropriately in the fourth hour.” The diligent reader can also learn, in excruciating detail, what time Pavlov took each meal during summer holidays (dinner at precisely 12:30 P . M ., tea at four, and supper at eight), how many cups of tea he typically consumed each afternoon (between six and ten), and where the roses were planted in his garden (“around the spruce tree on the west side of the veranda”). It’s hard not to wish that Todes had been a bit less devoted to his subject’s prodigious empiricism.

For more than thirty years, Pavlov’s physiology factory turned out papers, new research techniques, and, of course, gastric juice—a lot of it. On a good day, a hungry dog could produce a thousand cubic centimetres, more than a quart. Although this was a sideline for Pavlov, the gastric fluids of a dog became a popular treatment for dyspepsia, and not just in Russia. A “gastric juice factory” was set up for the purpose. “An assistant was hired and paid thirty rubles a month to oversee the facility,” Todes writes. “Five large young dogs, weighing sixty to seventy pounds and selected for their voracious appetites, stood on a long table harnessed to the wooden crossbeam directly above their heads. Each was equipped with an esophagotomy and fistula from which a tube led to the collection vessel. Each ‘factory dog’ faced a short wooden stand tilted to display a large bowl of minced meat.” By 1904, the venture was selling more than three thousand flagons of gastric juice annually, Todes writes, and the profits helped increase the lab budget by about seventy per cent. The money was helpful. So was the apparent demonstration that a product created in an experimental laboratory could become useful to doctors all over the world.

At the turn of the century, Pavlov had begun focussing his research on “psychic secretions”: drool produced by anything other than direct exposure to food. He spent most of the next three decades exploring the ways conditional reflexes could be created, refined, and extinguished. Before feeding a dog, Pavlov might set a metronome at, say, sixty beats a minute. The next time the dog heard a metronome at any speed, it would salivate. But when only that particular metronome setting was reinforced with food the dog became more discriminating. Pavlov deduced that there were colliding forces of “excitation” and “inhibition” at play—so that, at first, the stimulus spreads across the cerebral cortex and then, in the second phase, it concentrates at one specific spot.

As his formulations and models grew more complex, Pavlov was encouraged in his hope that he would be able to approach psychology through physiology. “It would be stupid to reject the subjective world,” he remarked later. “Our actions, all forms of social and personal life are formed on this basis. . . . The question is how to analyze this subjective world.”

Pavlov was sixty-eight and had been famous for years when Lenin came to power, and Todes is at his best in describing the scientist’s relationship with the regime that he would serve for the rest of his life. Pavlov harbored no sentimental attachment to the old order, which had never been aggressive in funding scientific research. The Bolsheviks promised to do better (and, eventually, they did). Yet Pavlov considered Communism a “doomed” experiment that had turned Russia back into a nation of serfs. “Of course, in the struggle between labor and capital the government must stand for the protection of the worker,” he said in a speech. “But what have we made of this? . . . That which constitutes the culture, the intellectual strength of the nation, has been devalued, and that which for now remains a crude force, replaceable by a machine, has been moved to the forefront. All this, of course, is doomed to destruction as a blind rejection of reality.”

Lenin had too many other problems to spend his time worrying about one angry scientist. At first, Pavlov, his wife, and their four children were treated like any other Soviet citizens. Their Nobel Prize money was confiscated as property of the state. From 1917 to 1920, like most residents of Petrograd, which would soon be called Leningrad, the Pavlovs struggled to feed themselves and to keep from freezing. It was nearly a full-time occupation; at least a third of Pavlov’s colleagues at the Russian Academy of Sciences died in those first post-revolutionary years. “Some starved to death in apartments just above or below his own in the Academy’s residence,” Todes writes. Pavlov grew potatoes and other vegetables right outside his lab, and when he was sick a colleague provided small amounts of firewood to burn at home.

In 1920, Pavlov wrote to Lenin’s secretary, Vladimir Bonch-Bruevich, seeking permission to emigrate, although, as Todes points out, it was probably not yet necessary to ask. Pavlov wanted to see if, as he suspected, universities in Europe or America would fund his research in circumstances that would prevent his dogs and lab workers from starving. Bonch-Bruevich turned the letter over to Lenin, who immediately grasped the public-relations repercussions of losing the country’s most celebrated scientist. He instructed Petrograd Party leaders to increase rations for Pavlov and his family, and to make sure his working conditions improved.

The Soviets came to regard Pavlov as a scientific version of Marx. The comparison could not entirely have pleased Pavlov, who rebelled at the “divine” authority accorded Marx (“that fool”) and denied that his own “approach represents pure materialism.” Indeed, where others thought that the notion of free will would come to be discarded once we had a full understanding of how the mind worked, Pavlov was, at least at times, inclined to think the opposite. “We would have freedom of the will in proportion to our knowledge of the brain,” he told Gantt in 1927, just as “we had passed from a position of slave to a lord of nature.”

That year, Stalin began a purge of intellectuals. Pavlov was outraged. At a time when looking at the wrong person in the wrong way was enough to send a man to the gulag, he wrote to Stalin saying that he was “ashamed to be called a Russian.” Nikolai Bukharin, who considered Pavlov indispensable, made the case for him: “I know that he does not sing the ‘Internationale,’ ” Bukharin wrote to Valerian Kuibyshev, the head of the state planning committee. “But . . . despite all his grumbling, ideologically (in his works, not in his speeches) he is working for us.”

Stalin agreed. Pavlov prospered even at the height of the Terror. By 1935-36, he was running three separate laboratories and overseeing the work of hundreds of scientists and technicians. He was permitted to collaborate with scholars in Europe and America. Still, his relationship with the government was never easy. Soviet leaders even engaged in a debate over whether to celebrate his eightieth birthday. “A new nonsensical letter from academician Pavlov,” Molotov wrote in the margin of a letter of complaint before it was passed to Stalin. Kuibyshev was deeply opposed to any state recognition. “Pavlov spits on the Soviets, declares himself an open enemy, yet Soviet power would for some reason honor him,” he grumbled. “Help him we must,” he said at the time, “but not honor him.” For a while, Kuibyshev prevailed, but in 1936, when Pavlov died, at eighty-six, a hundred thousand mourners, including Party officials, filed past his casket as he lay in state.

What Todes describes as Pavlov’s “grand quest”—to rely on saliva drops and carefully calibrated experiments to understand the mechanics of human psychology—lives on, in various forms. Classical conditioning remains a critical tool: it is widely used to treat psychiatric disorders, particularly phobias. But the greater pursuit is for a kind of unified field theory in which psychology and physiology—the subjective and the material realms—would finally be integrated.

And so we have entered the age of the brain. The United States and other countries have embarked upon brain-mapping initiatives, and Pavlov would have endorsed their principal goal: to create a dynamic picture of the brain that demonstrates, at the cellular level, how neural circuits interact. As Todes points out, while Pavlov examined saliva in his attempts to understand human psychology, today we use fMRIs in our heightened search for the function of every neuron. When he delivered his lectures on the “larger hemispheres of the brain,” Pavlov declared, “We will hope and patiently await the time when a precise and complete knowledge of our highest organ, the brain, will become our profound achievement and the main foundation of a durable human happiness.” We are still waiting, but less patiently than before. ♦

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How Pavlov’s bell teaches dogs to drool

You are free to share this article under the Attribution 4.0 International license.

A famous experiment left an unanswered question: What was happening in the brain cells of Pavlov’s dogs as they learned that a ringing bell meant it was time to eat?

Scientists have had a working hypothesis, but new research is helping to prove it.

Russian physiologist Igor Pavlov, working in the late 19th and early 20th centuries, showed that dogs can be taught—”conditioned”—to expect food (and therefore to salivate) when presented with a stimulus like a ringing bell.

But how does the brain begin to associate a very brief aural clue with the reward to come?

[Brain regions cooperate to put off reward]

“If you’re trying to train a dog to sit, the initial neural stimuli, the command, is gone almost instantly—it lasts as long as the word ‘Sit,'” says Alfredo Kirkwood, a neuroscientist at the Zanvyl Krieger Mind/Brain Institute at Johns Hopkins University.

“Before the reward comes, the dog’s brain has already turned to other things. The mystery was, ‘How does the brain link an action that’s over in a fraction of a second with a reward that doesn’t come until much later?'”

The working theory has been that invisible “eligibility traces” effectively tag brain cell synapses that are activated by a stimulus, such as Pavlov’s bell or Kirkwood’s “Sit!” With the eligibility trace in place, the hypothesis goes, true learning can be locked in with the eventual arrival of a reward.

For instance: When the dog sits and then gets a treat, neuromodulators like dopamine flood the dog’s brain with “good feelings.” Though the brain has long since processed the “Sit!” command, the eligibility traces left behind respond to the neuromodulators, prompting a lasting synaptic change. The dog has learned that obeying the command brings a reward.

[Odor ‘puffs’ spike neurons in trained locusts]

For the new study, published online in the journal Neuron , researchers were able to validate the hypothesis by isolating cells in the visual cortex of a mouse. When they stimulated the axon of one cell with an electrical impulse, they sparked a response in another cell.

By doing this repeatedly, they mimicked the synaptic response between two cells as they process a stimulus and create an eligibility trace. When the researchers later flooded the cells with neuromodulators, simulating the arrival of a delayed reward, the response between the cells strengthened or weakened, showing the cells had “learned” and were able to do so because of the eligibility trace.

“This is the basis of how we learn things through reward,” Kirkwood says, “a fundamental aspect of learning.”

In addition to a greater understanding of the mechanics of learning, the findings could help enhance teaching methods and lead to treatments for cognitive problems, researchers say.

Other researchers from Johns Hopkins, the University of California, Davis, and the University of Texas at Houston are coauthors of the study. The Science of Learning Institute at Johns Hopkins and the National Institutes of Health supported the work.

Source: Johns Hopkins University

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A dog's dilemma: Do canine's prefer praise or food?

Study explores canine reward preferences.

Given the choice, many dogs prefer praise from their owners over food, suggests a new study published in the journal Social, Cognitive and Affective Neuroscience . The study is one of the first to combine brain-imaging data with behavioral experiments to explore canine reward preferences.

"We are trying to understand the basis of the dog-human bond and whether it's mainly about food, or about the relationship itself," says Gregory Berns, a neuroscientist at Emory University and lead author of the research. "Out of the 13 dogs that completed the study, we found that most of them either preferred praise from their owners over food, or they appeared to like both equally. Only two of the dogs were real chowhounds, showing a strong preference for the food."

Dogs were at the center of the most famous experiments of classical conditioning, conducted by Ivan Pavlov in the early 1900s. Pavlov showed that if dogs are trained to associate a particular stimulus with food, the animals salivate in the mere presence of the stimulus, in anticipation of the food.

"One theory about dogs is that they are primarily Pavlovian machines: They just want food and their owners are simply the means to get it," Berns says. "Another, more current, view of their behavior is that dogs value human contact in and of itself."

Berns heads up the Dog Project in Emory's Department of Psychology, which is researching evolutionary questions surrounding man's best, and oldest friend. The project was the first to train dogs to voluntarily enter a functional magnetic resonance imaging (fMRI) scanner and remain motionless during scanning, without restraint or sedation. In previous research, the Dog Project identified the ventral caudate region of the canine brain as a reward center. It also showed how that region of a dog's brain responds more strongly to the scents of familiar humans than to the scents of other humans, or even to those of familiar dogs.

For the current experiment, the researchers began by training the dogs to associate three different objects with different outcomes. A pink toy truck signaled a food reward; a blue toy knight signaled verbal praise from the owner; and a hairbrush signaled no reward, to serve as a control.

The dogs then were tested on the three objects while in an fMRI machine. Each dog underwent 32 trials for each of the three objects as their neural activity was recorded.

All of the dogs showed a stronger neural activation for the reward stimuli compared to the stimulus that signaled no reward, and their responses covered a broad range. Four of the dogs showed a particularly strong activation for the stimulus that signaled praise from their owners. Nine of the dogs showed similar neural activation for both the praise stimulus and the food stimulus. And two of the dogs consistently showed more activation when shown the stimulus for food.

The dogs then underwent a behavioral experiment. Each dog was familiarized with a room that contained a simple Y-shaped maze constructed from baby gates: One path of the maze led to a bowl of food and the other path to the dog's owner. The owners sat with their backs toward their dogs. The dog was then repeatedly released into the room and allowed to choose one of the paths. If they came to the owner, the owner praised them.

"We found that the caudate response of each dog in the first experiment correlated with their choices in the second experiment," Berns says. "Dogs are individuals and their neurological profiles fit the behavioral choices they make. Most of the dogs alternated between food and owner, but the dogs with the strongest neural response to praise chose to go to their owners 80 to 90 percent of the time. It shows the importance of social reward and praise to dogs. It may be analogous to how we humans feel when someone praises us."

The experiments lay the groundwork for asking more complicated questions about the canine experience of the world. The Berns' lab is currently exploring the ability of dogs to process and understand human language.

"Dogs are hypersocial with humans," Berns says, "and their integration into human ecology makes dogs a unique model for studying cross-species social bonding."

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Story Source:

Materials provided by Emory University . Original written by Carol Clark. Note: Content may be edited for style and length.

Journal Reference :

• Peter F. Cook, Ashley Prichard, Mark Spivak, Gregory S. Berns. Awake canine fMRI predicts dogs’ preference for praisevsfood . Social Cognitive and Affective Neuroscience , 2016; nsw102 DOI: 10.1093/scan/nsw102

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Canine Food Preference Assessment of Animal and Vegetable Ingredient-Based Diets Using Single-Pan Tests and Behavioral Observation

Meghan c callon, cara cargo-froom, trevor j devries, anna k shoveller.

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Edited by: Laura Ann Boyle, Teagasc, The Irish Agriculture and Food Development Authority, Ireland

Reviewed by: Gráinne Michelle McCabe, Bristol Zoological Society, United Kingdom; Durga Chapagain, University of Veterinary Medicine Vienna, Austria

*Correspondence: Meghan C. Callon, [email protected] ; Cara Cargo-Froom, [email protected] ; Trevor J. DeVries, [email protected] ; Anna K. Shoveller, [email protected]

Specialty section: This article was submitted to Animal Behavior and Welfare, a section of the journal Frontiers in Veterinary Science

Received 2017 Apr 24; Accepted 2017 Sep 5; Collection date 2017.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Knowledge of canine food selection is critical for both the pet food industry and dog owners, since owners want quality foods that are palatable, while fulfilling their pet’s nutritional requirements. There are two common methods for assessing canine food preference: the two-pan test and the one-pan test. Neither test fully accounts for the complexity of the canine feeding experience nor do they provide applicable representations of canine feeding behavior in the home. The objectives of this study were to (1) determine whether dogs display a preference for animal ingredient-based diets when compared with vegetable ingredient-based diets and (2) examine whether dogs experience neophobia when presented with a novel diet. Eight adult Beagles (average age = 24 months, weighing 8–12 kg) were individually fed each of four novel diets in a 4 × 4 replicated Latin square design, with 10-d treatment periods and four dietary treatments. Data were analyzed using a mixed model with repeated measures and significance was declared when p  < 0.05. The diets were: animal and vegetable ingredient-based diets, and animal- and vegetable-based ingredients diluted with anhydrous α- d -glucose. The diluted diets were used for a larger study to determine true mineral digestibility. Dogs were fed twice per day (0800 and 1300 h). Behavioral observations were made by video on the first, and last 2 days of each 10-day treatment period of both a.m. and p.m. feedings. Time to consume feed, distraction, hesitation, level of anticipation pre-consumption, and interest post-consumption were recorded. Dogs experienced initial disruptive (neophobic) effects of a novel diet. Neophobia was demonstrated by a decreased (slower) rate of consumption, increased distraction during consumption of the diet, and increased hesitation on the first day of each new diet ( p  < 0.05). The level of interest post-consumption was highest when dogs consumed the animal-based ingredients diet ( p  < 0.05). This study presents insights into canine food preference assessment methods that may more accurately represent the dog owner’s experience. Further research is required to determine the minimum length of time necessary to eliminate neophobia to food. In addition, future research should also aim to establish whether interest post-consumption is due primarily to food preference or acute satiety.

Keywords: food preference, canine, animal-based protein, vegetable-based protein, single-pan, neophobia, pet food

Introduction

The study of canine food selection is crucial for both the pet food industry and dog owners. Pet owners want quality dog foods that fulfill their pet’s nutritional requirements, as well as being palatable and multiple approaches to assessing this have been reviewed ( 1 ). It is generally accepted by the industry that the top reasons for dog owners to switch food is: their dog disliked the previous food, price, and addressing a certain health outcome (i.e., skin and coat). The likelihood of consumption of a food source comes down to palatability, or the subjective preference of a food based on odor, texture, appearance, and taste ( 2 , 3 ). In dogs, food preference is influenced both by early-life experiences and genetics ( 4 ). Health status, age, and environmental conditions may all influence an animal’s perception of a food source ( 5 ). Together, these factors influence the perceived palatability of a food source and subsequent feeding behavior.

Since animals cannot directly communicate to indicate their food preferences, measurements of food preference are assessed by comparing relative acceptance of different diets. The two most common methods to assess food preference in dogs are the two-pan test and one-pan test ( 6 ). The two-pan, or split plate, test consists of presenting two different food sources to the animal and recording the amount consumed of each ( 6 ). The one-pan test often involves free-feeding one food source at a time, recording the amount of food consumed over a specified period, and then comparing that to one or more other feed types.

A one-pan test provides a more controlled method of assessing a dog’s initial reaction to a novel food source, as well as measuring any effects which occur due to a dietary change. It also eliminates any food interactions, where one may alter the palatability of the other, which may occur during a two-pan test ( 6 ). However, neither of the traditional one- or two-pan tests control for the effects of satiety. It is proposed that a one-pan test with controlled amounts of food may not only provide an accurate view of an animal’s food preference, but also be a more applicable representation of canine feeding behavior in the home. Using a one-pan test, with limited food availability, provides an opportunity to closely examine select behaviors that accompany the canine feeding experience. This is the first study to take this approach to examine dog feeding behavior; however, similar approaches have been utilized in other animals [cats ( 7 ); rats ( 8 ); human and non-human primates ( 9 )].

Another key concept that influences canine feeding behavior is that of neophobia. Stöwe et al. ( 10 ) describe neophobia as “the avoidance of an object or other aspect of the environment solely because it has never been experienced and is dissimilar from what has been experienced in the individual’s past.” Although dogs are considered to be naturally neophilic, which is a preference for novelty, neophobia has been frequently encountered with respect to novel food sources ( 11 ). Neophobic animals are often slow to investigate a novel object or food source and demonstrate reduced attentiveness to the task ( 12 ). In the wild, finding and eating nutritionally balanced foods are crucial, and this includes avoiding the potential hazards of consuming unfamiliar food sources ( 13 ). Kuo ( 14 ) demonstrated that when puppies eat the same food sources for their first 6 months of life they later rejected any novel food source. This was consistent even when the puppies were divested of any food ( 14 ). Cheney and Miller ( 15 ) also discovered that it often takes several days for an animal to overcome hesitation toward a novel food. Reluctance to consume a new food source is often encountered in the home environment, where owners may find their dog is hesitant when offered a new food type ( 16 , 17 ).

Domestic dogs are part of the order Carnivora , yet despite the name, they are considered omnivorous in terms of their nutrient metabolism ( 2 , 18 ). These abilities are thought to have come about during the domestication process, when dogs became adapted to a human-associated diet ( 19 ). In fact, many free-ranging dogs consume diets high in carbohydrates, and rarely hunt for protein-rich animal-based food sources ( 4 ). Omnivores may not only select their food based on its energy content (optimal foraging theory) but also on macronutrient balance ( 20 ). Macronutrient balance affects a multitude of variables that play a role in fitness, including growth, fecundity, and disease resistance ( 21 – 23 ). This ability to select a diet that is nutritionally balanced is especially crucial for omnivores, whose food sources can vary, especially when living in the wild ( 20 ).

Although vegetables can provide good sources of protein and energy, there is little empirical data concerning the digestibility of individual ingredients by domestic dogs. Vegetable-based ingredients in pet foods have a more consistent composition and macronutrient/micronutrient digestibility than animal-based ingredients ( 24 – 26 ). The use of vegetable-based protein may become more prominent in companion animal food for economic and sustainability reasons, increasing the need for a complete understanding of its food preference. This leads to the pursuit of alternative protein sources in dog food that meet the animal’s nutrient requirements, provide potential health benefits, while maintaining food preference ( 27 ).

The objectives of this study were to (1) determine whether dogs display a preference for animal ingredient-based diets when compared with vegetable ingredient-based diets and (2) examine whether dogs experience neophobia to animal ingredient- or vegetable ingredient-based diets. We hypothesized that dogs will demonstrate preference for animal-based protein over vegetable-based protein. Specifically, we predicted that dogs would show greater interest in the food before and after feeding, and feed at a faster rate without distraction. We also hypothesized that dogs will experience the initial effects of neophobia, with those effects declining with time. Specifically, we predicted that dogs will show longer periods of hesitation, reduced interest in the food before and after feeding, and feed at a slower rate with distraction when first introduced to a new diet.

Materials and Methods

All experiments and procedures were approved by the Animal Care Committee of the University of Guelph, Ontario (AUP# 3543). This behavioral study was part of a larger study focused on the apparent and true mineral digestibility of animal- and vegetable-based ingredient adult maintenance dog food. Dogs were fed two types diets, animal-based ingredient and vegetable-based ingredient, and two diets of different format with a 50% dilution by weight with anhydrous α- d -glucose. This dilution technique, known as the substitution method, allows for a more accurate assessment of the true digestibility of nutrients and accounts for endogenous losses ( 28 ).

Subjects and Facilities

Eight adult beagles ( n  = 8) were used in this experiment. The dogs included two intact males, and six spayed females of similar age (median = 15.2 months, range = 14–24 months) and ranging in body weight (median = 9.6 kg, range = 9.3–11.6 kg). Using G*Power (v. 3.1) ( 29 ) and basing effect size on other digestibility trials, where significant differences between digestibility of vegetable/legume and animal ingredient diets were present, we predicted that n  = 8 was a large enough sample size. Based on previous research and using G*Power, using a two tailed t test, an effect size of 3, an α = 0.05 and at different levels of power (1 − β err prob) including 0.8, 0.85, 0.9, an n of 8 is calculated, respectively. Client owned dogs outside of the University of Guelph were not included in this study due to the nature of the trial. Dogs were housed in the Central Animal Facility at the University of Guelph, Ontario. Dogs were housed in pairs, with each of the four kennels containing dogs of similar average body weight. The kennels were 121.9 cm × 190.5 cm kennels that were opened with sliding doors to allow for group housing for the majority of day, except during feeding. Kennels also had beds and spring boards located 76.2 cm high. All kennels were in the same environmentally controlled room, with a 12-h light:12-h dark cycle. Dogs were also provided enrichment within their kennels, which included beds and non-edible chew toys (Nylabone). Socialization included walks provided by the researcher and an employee at the Central Animal Facility. This socialization included walks in pairs each day, with walks lasting 20-min, 5 days per week, and 10-min, 2 days a week. This regime was kept consistent for each dog throughout the duration of the experiment.

Dogs were exposed to each of four diets in a replicated 4 × 4 Latin square design, with 10-d treatment periods. Ten day periods were selected based on a 6-day adjustment and 4-day collection period for the digestibility trial. There were four periods and four kennels for this design which ensured each dog/kennel received all diets, with each kennel consuming a different diet each period. The Latin square was replicated since two dogs were housed in each kennel and received the same diet. The four dietary treatment diets were (1) animal-based ingredient diet, (2) vegetable-based ingredient diet, (3) vegetable-based diet ingredient diet at a 50% dilution with anhydrous α- d -glucose on an “as is” basis (Sigma Aldrich, St. Louis, MO, USA), and (4) animal-based ingredient diet at a 50% dilution with anhydrous α- d -glucose on an as is basis (Sigma Aldrich, St. Louis, MO, USA) (Table 1 ).

Ingredients and nutrient predictions for animal- and vegetable-based diets.

a Calculated metabolizable energy based on Modified Atwater values .

b Analysis by Champion Pet Foods .

Diets were designed to be similar in terms of dryness, texture, kibble size, density, and fallout. Despite having similar macronutrient levels, the animal ingredient-based kibble contained more of its fat internally, while a greater amount of fat was provided externally for the vegetable ingredient-based kibble (2.5% for animal and 12% for the vegetable). The amount of diet provided to each dog (g/day) was determined based on the energy density of each diet and the maintenance energy requirements for individual dogs, which were determined using body weight at the beginning of the study, historical body weight (6-month records previous to study), and historical feeding amounts. Historical body weight values and feeding amounts were used to ensure dogs were consuming enough energy to maintain body weight and that body weight had not changed over the previous 6 months. To ensure equal novelty of the treatment diets, prior to the beginning of the study dogs were fed one commercial dog food of high quality to the same caloric intake as in the current study.

Dogs were fed 95% of their total maintenance energy requirements, in two meals per day, to ensure that there was total consumption of the diet. Dietary energy density was calculated using the Modified Atwater equation and the analyzed macronutrient content of both diets. Diets were extruded at Champion Pet Foods (Morinville, AB, Canada) and formulated to meet or exceed AAFCO nutrient standards. Nutrients were analyzed by near infrared spectroscopy and minerals by inductively coupled plasma analysis (Table 1 ). Prediction of nutrient content of other key AAFCO nutrients are presented in Table 1 , but were not analyzed for. For the diets that were diluted with d -glucose, d -glucose was added to diets on an iso-energetic basis to 50% of the daily caloric intake. Treatment diets were weighed and prepared [addition of glucose and titanium dioxide (Sigma Aldrich, St. Louis, MO, USA)] in advance for each 10-day treatment period. Titanium dioxide was added to each meal to act as an indigestible marker as part of the digestibility study. Warm deionized water was added to each of the fully prepared diets immediately before feeding to prevent the dogs from blowing out any glucose powder, and to ensure mixing and consumption of the titanium dioxide. Kibble was provided using two-cup round, translucent storage dishes (Pyrex, 26.7 cmL × 13.3 cmW × 19.1 cmH). Dogs were fed individually at 0800 and 1300 h each day and had ad libitum access to deionized water throughout all four treatments.

Feeding Behavior

Small camcorders (Sony HD “handycam,” HDR 3.1 megapixel) were set up approximately 60 cm away from kennel doors, and elevated using a 10 L bucket and small tripods to allow for a full view of the kennel. Dogs were acclimated to the cameras and feeding regime for 3-day prior to exposure to their first treatment diet. Dogs were then video recorded during both 0800 and 1300 h feedings, on days 0, 8, and 9 (first and last 2 days) of each treatment period. Thompson et al. ( 30 ) found that both shelter and pet owned dogs display consistent preference for food and was one reason that we did not video the feeding experience every day of each of the four periods of the study. Dogs were separated and fed individually with both dogs in each pen receiving a meal simultaneously. The order of feeding was kept consistent throughout the duration of the study. Recordings began approximately 10 s before the dogs were given their meal, and ended approximately 10 s after both dogs finished their meals (all kibble consumed). Videos were then coded for specific behaviors that may indicate their preference for each diet (Table 2 ). In addition, the duration of feeding was recorded, starting from the ingestion of the first kibble to the last. Rate of consumption was then calculated in seconds per gram for each dog on an as-fed basis. Hesitation prior to feeding was measured as the amount of time (seconds) before the dog took its first bite of food, after the dish was placed on the ground. Number of times dogs focused on other stimuli during consumption was also counted in each feeding bout.

Ethogram for the behaviors used to analyze the canine feeding experience.

Consumption, distraction, hesitation pre-consumption, anticipation pre-consumption, and interest post-consumption were recorded to determine preference for animal or vegetable ingredient-based diets, and the effects of neophobia. The specific behaviors were chosen as indicators of food preference or aversion. The presence of each of these behaviors was confirmed after analyzing the video recorded during the 3-day acclimation period .

a Presence (1) or absence (0) of behavior recorded. Anticipation calculated as sum of four behaviors .

b Level of interest recorded as one of the three levels (1, 2, or 3) .

Level of anticipation pre-consumption and level of interest post-consumption were scored per feeding bout. Level of anticipation pre-consumption (10 s before food was presented to the dog) was measured as the presence or absence of four specified behaviors prior to feeding. These behaviors include tail wagging, licking air/lips, pushing face through bars, and jumping at front of kennel. If one of the four behaviors was present, it was given a value of 1 (if absent, it was given a value of 0). Level of anticipation pre-consumption was then calculated as a sum of all four behaviors and given a score of “0 or 1.” Level of interest post-consumption was measured on a scale of 1–3 (1 being little to no interest, 3 being lots of interest). For example, if the dog immediately left the bowl after eating it was given a score of 1, but if it stayed and licked the bowl and/or ground until we stopped video recording then it received a score of 3. If the dog showed interest, but left the bowl before recording stopped it was given a score of 2. Diets which were diluted with 50% with anhydrous α- d -glucose were not included in the analysis of anticipation pre-consumption due to the variability of water added to each meal. However, these diets are essential for the digestibility trial and were included in Section “ Materials and Methods .”

All video analyses were completed by the same observer (Meghan C. Callon) who was blinded to the diets that the dogs were receiving. Furthermore, the single observer/coder was trained to code the videos and to improve reliability of the data.

Statistical Analysis

All statistical analyses were completed using the mixed procedure of SAS (SAS Institute, version. 9.4). Mixed effects repeated measures models were fit assuming the fixed effects of: dietary treatments, format (intact and diluted), day, and time of day. Day was treated as the repeated measure and a compound symmetry covariance structure. The statistical model for each dependent variable included the fixed effects and the interactions. Individual kennels and dog were used as random variables, with treatments being applied to the kennel. Dependent variables were rate of consumption (g/s), distraction (numbers of times the dog focuses elsewhere), hesitation (seconds), level of anticipation (sum of behaviours 1–4), and level of interest after consumption (presence of absence of behavior rating 1–3). When fixed effects were significant for a dependent variable, least square means were compared using the pdiff multiple comparison option. Alpha level of significance was set at 0.05. Differences were considered significant at p  < 0.05, and as tendencies at 0.05 <  p  < 0.10. Data were expressed as least square mean estimate ± SEM, except for age and BW which were expressed as median and range within tables and figures. Within the text, the differences between least square means, the t -value, and p -value are presented between contrasts.

There were no food refusals throughout this study.

For all analyses which included both the intact diets and diluted diets, there were no differences between the two ( p  > 0.10). Therefore, addition of d -glucose and water does not affect feeding behavior, and it is the type of food (animal vs. vegetable), day of feeding, or time of feeding that may have an effect.

Rate of Consumption

The type of diet (animal vs. vegetable) did not influence the rate of consumption (0.093 ± 0.08, t  = 1.19, p  = 0.27). Dogs consumed each diet slower on day 0 of each treatment period, when compared with days 8 (−0.35 ± 0.9, t  = −3.75, p  = 0.002) and 9 (−0.28 ± 0.09, t  = −2.83, p  = 0.01) (Figure 1 ). Dogs did not alter their rate of consumption based on the time of day fed (0800 vs. 1300 h; 0.08 ± 0.08, t  = 0.98, p  = 0.36).

Mean (±SEM) rate of consumption (g/s) for all dogs ( n  = 8) over time (days 0, 8, and 9). Data were pooled across both animal and vegetable diets, as well as a.m. and p.m. feedings. a,b Means with no common superscript differ ( p  < 0.05).

Distraction

The type of diet (animal vs. vegetable) did not influence the level of distraction (0.58 ± 0.45, t  = 1.30, p  = 0.24). The number of times the dogs focused on other stimuli throughout a feeding bout (level of distraction) was greater on day 0 when compared with days 8 (1.87 ± 0.54, t  = 3.48, p  = 0.003) and 9 (1.81 ± 0.56, t  = 3.22, p  = 0.006) (Figure 2 ). Dogs did not alter their level of distraction based on the time of day fed (0800 vs. 1300 h; 0.59 ± 0.45, t  = 1.31, p  = 0.23).

Mean (±SEM) level of distraction was measured as the number of times the dogs focused on other stimuli during the duration of a feeding bout. Data were pooled across both animal and vegetable diets, as well as a.m. and p.m. feedings. a,b Means with no common superscript differ ( p  < 0.05).

The type of diet (animal vs. vegetable) did not influence the amount of hesitation (−0.005 ± 0.70, t  = −0.01, p  = 0.99). There was no significant difference in hesitation on day 0, than on days 8 (1.48 ± 0.84, t  = 1.76, p  = 0.10) but there was a significant difference between day 0 and day 9 (1.91 ± 0.87, t  = 2.19, p  = 0.04). Finally, the dogs did not alter their hesitation based on the time of the day they were fed (0800 vs. 1300 h; 0.58 ± 0.70, t  = 0.83, p  = 0.43).

Level of Anticipation Pre-Consumption

The type of diet (animal vs. vegetable) did not influence the level of anticipation (−0.16 ± 0.09, t  = −1.83, p  = 0.12). Level of anticipation tended to be lower on day 9, than on days 0 (0.21 ± 0.11, t  = 1.88, p  = 0.08). Anticipation was significantly lower on day 9 when compared with day 8 (0.25 ± 0.11, t  = 2.31, p  = 0.04). Anticipation also tended to be higher prior to the p.m. feedings compared with the a.m. feedings (−0.18 ± 0.09, t  = −2.03, p  = 0.08).

Level of Interest after Consumption

Level of interest after consumption was greater when dogs were fed the animal diet when compared with the vegetable diet (0.24 ± 0.09, t  = 2.89, p  = 0.02) (Figure 3 ). Dogs tended to show higher interest (after consumption) when given the animal diet than the vegetable diet on day 8 (0.28 ± 0.14, t  = 2.02, p  = 0.06) and had significantly higher interest when given the animal diet than the vegetable diet on day 9 (0.48 ± 0.15, t  = 3.19, p  = 0.007) (Figure 4 ). Dogs showed greater interest in the animal diet on day 9 compared with the vegetable diet on day 8 (0.35 ± 0.14, t  = 2.46, p  = 0.027). Dogs also showed higher interest in the animal diet on day 8 compared with the vegetable diet on day 9 (0.41 ± 0.15, t  = 2.79, p  = 0.015). On day 0, there was no detected difference in level of interest between dogs fed the animal diets and vegetable diets (−0.04 ± 0.14, t  = −0.30, p  = 0.77). Finally, on day 0, dogs showed more interest in the vegetable diet compared with day 9 (0.31 ± 0.15, t  = 2.15, p  = 0.049). Time of day also did not alter level of interest after consumption (−0.09 ± 0.08, t  = −1.07, p  = 0.32).

Level of interest post-consumption (±SEM) was measured on a scale of 1−3, 1 being little to no interest, 3 being lots of interest. Data for format of food (water added for glucose dilution diets, vs. dry diets), time of day (a.m. vs. p.m.), and day fed (0, 8, and 9) were pooled. *Indicates a tendency.

Mean level of interest post-consumption (±SEM) was measured on a scale of 1–3, 1 being little to no interest, 3 being lots of interest. Both data on format and time fed were pooled. a–c Means with no common superscript differ ( p  < 0.05).

This study is the first to use several select canine feeding behaviors (rate of consumption, hesitation, level of interest before, and after consumption) to measure the perceived preference of a food source, and provide a good starting point to develop alternative food preference assessments. These types of behavioral observations are more applicable to the home environment and more accurately represent what consumers/pet owners might encounter when presenting their dogs with a novel food. Indicators of neophobia include longer periods of hesitation, reduced interest in the food pre- and post-consumption, and feeding at a slower rate with distraction when first introduced to a new diet. Overall, the dogs experienced neophobia at the beginning of each treatment period regardless of type of diet (animal vs. vegetable), with those effects declining by days 8 and 9. This suggests that dogs exhibited the disruptive effects of a change in diet. For rate of food consumption, distraction, and increased hesitation prior to eating on day 0, no difference was found between diet types, or in the time of day at which the dogs were fed. Rate of consumption was lower and distraction was highest on the first day of each diet, compared with the last 2 days. Dogs focused on other stimuli more frequently while consuming their meals on day 0. Hesitation was also highest on the first day of each new diet; the dogs took longer to begin eating when presented with each novel food. This suggests that pet owners should not be discouraged if their dog appears to dislike their new food during the first few days of feeding. It is apparent that several days are required for dogs to overcome neophobia. By day 9, the dog’s neophobic responses had diminished. However, due to the fact that feeding behaviors on days 2–7 were not recorded, it is possible that disruptive effects of a novel diet may have decreased sooner. Future research should measure these variables across each day following provision of a new diet to determine what amount of time is necessary for a dog to overcome neophobia.

Level of anticipation pre-consumption was higher on days 0 and 8, decreasing on day 9. This may have been a result of simple hunger. When dogs are awaiting their meals, they may demonstrate excitement, or anticipation, but once presented with the food, they become hesitant (demonstrating neophobia). These results may indicate that the dogs adjusted to the food by the day 9 on each diet, and were no longer anticipating a novel food source. The effect of the presence of cameras was eliminated by acclimating the dogs prior to the experiment. Therefore, anticipatory behaviors on day 9 were not due to the acclimation to cameras, and likely entirely due to dietary acclimation.

Anticipatory behaviors pre-consumption were found to be more frequent prior to the p.m. feeds compared with the a.m. feeds. This may be due to an increase in blood glucose concentrations in the early morning, and a subsequent drop in glucose levels prior to their afternoon meals. This rise and fall in blood sugar in dogs has been reported by Carciofi et al. ( 31 ) and is consistent with human research [e.g., Ref. ( 32 )], which found that blood glucose levels rise after 0530 h, and drop significantly 5 h after feeding (often below baseline levels) and this drop elicits hunger.

Since dogs are often considered as primarily meat-eaters, it was expected that they would demonstrate a preference for the diets with animal-based protein, despite more fat being applied to the outside of the vegetable-based kibble. Houpt et al. ( 33 ) found that meat-based diets were preferred over a diet composed of maize and soybean meal, suggesting that dogs prefer meat protein to high protein diets composed of non-meat products. Bhadra and Bhadra ( 4 ) found that adult Indian free-ranging dogs demonstrated a preference for meat when scavenging. It has also been suggested that dogs will likely find diets lacking any animal-based ingredients less palatable ( 34 ). In the present study, the dogs showed a higher interest in the animal-based diets after consumption, although there were no observed differences in feeding rate, level of distraction, hesitation, or anticipatory behaviors between the two diets. Interest post-consumption was evaluated based on the dog’s tendency to lick the ground or bowl after all kibble was consumed, signifying continued interest in their meal. This could imply one of two things: that the dogs found the animal diets more palatable and wanted more, or that they found the animal diets less satiating and were looking for more food. Future research should combine these behavioral measurements of the canine feeding experience with satiety hormone concentrations to determine the satiating effects of each diet. In doing so, one can establish whether interest post-consumption is due to acute satiety.

There is currently a lack of data comparing canine preference for animal and vegetable ingredient-based diets that are similar to commercial formulas and the interacting processing (i.e., level of cook, external application of fat or amino acids, etc.). Felix et al. ( 35 ) found that dogs demonstrated a preference for diets containing soybean meal, rather than diets containing poultry offal meal. This was determined using a two-pan test where they recorded which food the dogs approached first, and total consumption of the diet over a 30-min test period ( 35 ). The current results suggest that the dogs did not have preference for either the animal or vegetable ingredient-based diets with the understanding that more fat was applied to the outside of the vegetable-based kibble, a known palatability enhancement. These results, along with the opposing results by Felix et al. ( 35 ), may support the idea that satiation was the main driving force behind the interest post-consumption. This is also supported by Keller ( 36 ), who found that plant-based proteins have higher satiety ratings than animal-based proteins. Thus, the dogs may have found the vegetable-based ingredient diets more satiating than the animal-based ingredient diets.

Decreasing voluntary food intake can have a beneficial effect on both health and behavior. A decrease in voluntary food intake may provide a good mechanism to support weight maintenance, allowing dogs to consume fewer calories, while still feeling full. Furthermore, incessant feeding motivation between meals increases behavioral stereotypies, and occasionally even aggression, in dogs ( 37 ). Bosch et al. ( 37 ) concluded that feeding motivation can be decreased by altering sources and levels of dietary fiber in food, since these can affect both acute and prolonged food intake control. Legumes, such as soybeans, may also provide less variable macronutrient and micronutrient bioavailability and more consistent composition than animal-based ingredients. Indeed, a greater breadth of pulse crops should be investigated beyond the common soybean meal.

There may also be benefits to feeding animal-based protein diets. Based on the results for interest post-consumption, our results suggest that the dogs had a greater preference for the diet containing greater animal-based ingredients, even when there was more fat applied to the outside vs. inside of the vegetable-based kibble. This could be important when developing diets for dogs with more discriminating palates or greater energy requirements. Animal-based protein in the diet also prevents sports anemia in dogs ( 38 ). Furthermore, animal-based proteins may allow for higher digestibility of nutrients from the ingredients present, as ingredients in vegetable-based diets may be of poorer protein quality due to binding with other compounds, such as phytate, found in plants and legumes ( 39 ) or a poor amino acid balance.

Adding water to canine diets, commonly referred to as “baiting,” is anecdotally reported to increase palatability. However, no relationship was found in the present study between the addition of water in the diets that contained d -glucose and the perceived palatability of a meal. There was no subsequent increase in anticipation pre-consumption, distraction, hesitation, or interest post-consumption with water addition. In addition, research should evaluate the long-term effects of feeding a satiating diet on both feeding motivation and weight control.

This study provides a good starting point in developing alternative methods of assessing canine food preference that more accurately represent what the consumer might encounter in the home environment. The results of this study suggest that consumers should allow their dog a period of at least 9 days to test out a new diet, before determining whether or not their dog finds it acceptable. These results also suggest that dogs do not have an innate preference for animal or vegetable ingredient-based diets that mimic commercial formulas and that any difference in level of interest may be due to other factors, such as acute satiety, individual ingredients, or processing techniques employed to promote food intake. Further research is required to elucidate the complex variables that influence and predict food preference in dogs and how the owner perceives the feeding experience.

Ethics Statement

All experiments and procedures were approved by the Animal Care Committee at the University of Guelph, Ontario (AUP# 3543).

Author Contributions

MC, CC-F, and AS designed the research with major contributions from TD; MC and CC-F conducted the research. MC analyzed data, wrote the paper, and had primary responsibility for final content. All authors read and approved the final manuscript.

Conflict of Interest Statement

The authors declare that this study received funding from Champion Pet Foods. The funder was not involved in the study design, sample collection, sample analyses, statistical analyses, or interpretation of the data.

Acknowledgments

This research was funded by Champion Pet Foods, Alberta, Canada. The authors would like to thank the staff at the Central Animal Facility at the University of Guelph and the Clinical Nutrition Department at the Ontario Veterinary College for facilitating the research and resource sharing.

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