true lab experiment

Português do Brasil
2.1 Neutral Route
2.2 True Pacifist Route
2.3 Genocide Route
3.1 Entry Elevator to Power Room Door
3.2 Power Room Door to Red Key Slot
3.3 Red Key Door to Bedroom
3.4 Bedroom to Fan Room
3.5 Bedroom to DT Extraction Machine
3.6 DT Extraction Machine to Green Key Slot
3.7 Bedroom to Blue Key Slot
3.8 Power Room Door to Power Room
4 Lab Entries
5 VHS Tapes
7 References

Features [ ]

This area is the point of no return for the True Pacifist Route. Upon entering the True Lab, the True Pacifist Route can no longer be aborted, and most of the Underground becomes inaccessible until the epilogue .
The amalgamates are introduced, along with the details about Alphys's experiments with human SOULs in an attempt to find a way to destroy the Barrier .
It is also revealed that SOULs cannot be artificially created, contrary to what Catty and Bratty say Alphys told King Asgore [1] in order to get her job as a royal scientist.
A few of the screens also reveal how Flowey came to be.
This area also features a set of VHS tapes providing more information about the first fallen human and their relation with the Dreemurr family.

Main Story [ ]

Neutral route [ ].

When the protagonist first enters Hotland , they are led to believe that the elevator leading to the True Lab is a toilet, due to Alphys's dialogue.

In some Neutral endings, [2] it is implied Alphys commits suicide here.

In the near-genocide Neutral Route ending , Alphys talks for most of the post-credits phone call. She says that, despite having to reveal the truth about herself to everyone, people still treat her like a hero.

True Pacifist Route [ ]

Hey. Thanks for your help back there. You guys... Your support really means a lot to me. But... As difficult as it is to say this... You guys alone can't magically make my own problems go away. I want to be a better person. I don't want to be afraid anymore. And for that to happen, I have to be able to face my own mistakes. I'm going to start doing that now. I want to be clear. This isn't anyone else's problem but mine. But if you don't ever hear from me again... If you want to know "the truth." Enter the door to the north of this note. You all at least deserve to know what I did. Alphys's Note, before entering the True Lab

The entrance to the True Lab, initially disguised as a bathroom.

After the protagonist has completed the date with Alphys by giving her Undyne's Letter , Papyrus calls the protagonist and strongly recommends that they meet Alphys at her lab. When the protagonist arrives at the Lab, there is a note in front of the previously locked door, which now opens upon approaching.

Battle against Lemon Bread

After entering the door, the protagonist rides an elevator that malfunctions and crashes. Once the protagonist enters and opens the elevator door, they cannot return to the rest of the Underground as they are locked in the True Lab. The protagonist traverses the True Laboratory where they find several Lab Entries, Amalgamates, and four keys which give access to the power supply to restart the elevator.

In the True Lab, the protagonist learns about how Alphys experimented with determination, SOULs, fallen monsters, and Golden Flowers . It is here that the protagonist learns about the term "fallen down", which refers to a comatose state that monsters fall under before turning to dust (this term was previously mentioned in one of Mettaton's diaries in his house ). While working with Determination, Alphys resurrected monsters who had "fallen down" such as Shyren's sister and Snowdrake's Mother , who as a result soon melted into Amalgamates. The protagonist also discovers that Alphys attempted to create a soulless vessel from a Golden Flower; the vessel is heavily implied to be Flowey. Alphys's lab entries provide backstory on her experiments and are found throughout the True Lab.

The DT Extraction Machine

While exploring the Lab, the protagonist encounters a strange machine. This machine is the DT Extraction Machine , which Alphys used to extract determination from the six previously captured human SOULs . The protagonist also finds several VHS tapes that lack video motion but retain their audio. They document conversations between Toriel and Asgore, and Asriel and the first human. These tapes imply that the fallen human possessed darker tendencies: they attempted suicide as part of a plan to combine their SOUL with Asriel's to pass through the barrier, and that Asriel reluctantly helped them carry out their plan. The VHS TV in this room resembles the TV that projects Photoshop Flowey 's face.

The generator that powers the elevator up to New Home

The protagonist then restores power to the elevator. Moments later, Amalgamates (presumably Memoryheads , as their overworld sprites are similar) surround them. Alphys rushes into the room, saves the protagonist, and states that Amalgamates can get violent when not fed. After the Amalgamates leave the room, Alphys thanks the protagonist for the help and mentions that it is not the Amalgamates which would have made her "disappear" but instead something cowardly which she might do. This cowardly act may be suicide considering that some neutral endings tell of Alphys disappearing. [2]

As the protagonist makes their way to the elevator, the exit cuts off, and a voice is heard congratulating the protagonist. The elevator then leaves the protagonist in New Home , with the elevator down to the CORE sealed off with vines so that the protagonist cannot leave. This indicates that the requirements have been met for the True Pacifist Ending.

Genocide Route [ ]

Upon defeat, Undyne the Undying informs the protagonist that Alphys has evacuated the majority of the remaining monsters someplace safe, heavily implied to be the True Lab.

In the Genocide ending, the evacuation was pointless, as the first human destroys the entire world and ends the timeline.

Geography [ ]

A hallway in the True Lab

In contrast to the bright, sterile color scheme of the Lab, the True Lab is grimy, dark, and fog-filled. It has a dark green celeste color scheme and an unsettling atmosphere. Assorted objects fill the area, including beds, sinks, refrigerators, wall fans, mirrors, and Golden Flowers. There is a vending machine that dispenses Popato Chisps near the power room door.

There are four colored keys scattered throughout the True Lab. The slots that the keys are inserted into, save for the yellow key, are housed in small, square rooms. These rooms contain hints as to how to obtain the key that belongs in the slot.

Entry Elevator to Power Room Door [ ]

After exiting the elevator, the protagonist finds themself in a small room. After walking a short distance, the elevator door closes and is unable to be reopened. The room has a pathway to the right that leads to a horizontal hallway with entries 1, 2, 3, and 5 along the wall. The hallway veers upwards into the room with the power room door. The layout of this room is similar to that of the lobby of the CORE, with the power room door to the north and two upwards paths to the left and to the right. The left path leads to the slot for the red key, and the right path leads to a door that can only be unlocked by using the red key. The power room door is locked and can only be opened after all four keys are used. This room also contains two fake plants, a vending machine that dispenses Popato Chisps, and a partially readable note from Alphys stating the power room door must be opened to restore power to the elevator.

Power Room Door to Red Key Slot [ ]

The upwards path to the left veers to the left into a horizontal hallway that contains entry 6 and a foggy room that contains entry 9. In this room is a line of three operating tables that are revealed to be "sticky" upon inspection. Further into the room is a doorway leading to the red key slot, and next to the doorway is a line of three sinks. Turning on the three sinks (or turning one off and back on again) triggers an encounter with the Memoryheads . Upon defeat, the Memoryheads drop the red key, which is used to unlock the door to the right of the power room door.

Red Key Door to Bedroom [ ]

Entering through the red key door leads to a hallway that veers to the right. Entries 12 and 13 are along the wall. This hallway leads to the bedroom, which contains a dog food bowl, four fake plants, a broken clock, and nine beds. The bottom left bed can be slept in, and the middle right bed contains the yellow key. The northernmost part of the bedroom contains a doorway, a SAVE Point , and entry 14, and the eastern path leads to the blue key slot.

Bedroom to Fan Room [ ]

The doorway to the north of the bedroom leads to a long, horizontal hallway that spans to the left and right side of the pathway. Going to the right leads to the fan room, which contains entry 11. The area is initially clouded by fog, with white particles hovering above the floor. There is a switch at the end of the room that, when pressed, turns on the fans that blow the fog away, leaving behind the white particles. The white particles converge and form Endogeny , who slowly approaches the protagonist. The protagonist can walk to Endogeny to initiate the battle.

Bedroom to DT Extraction Machine [ ]

Along the wall to the left of the bedroom pathway are entries 15 and 16. Near the end of the hallway is a doorway leading to a vertical hallway with a bathtub. The bathtub is covered by a curtain, and the silhouette of an amalgamate can be seen behind it. Approaching the bathtub, the protagonist walks slower than normal, and the amalgamate moves faster the closer they get. Upon opening the curtain, the amalgamate disappears, and the green key is left behind. To the west is a large room containing the DT Extraction Machine, which is inactive. North of this room is a room with a TV and five VHS tapes, entry 4, and the yellow key slot. The pathway to the other side of the room with the DT Extraction Machine is blocked by a SAVE Point, which transforms into Lemon Bread upon inspection.

DT Extraction Machine to Green Key Slot [ ]

Past the DT Extraction Machine is a room containing entries 19, 20, and 21. This room contains five fridges spread evenly along the room. The fridges are either empty or contain samples of some sort. The third fridge shakes periodically, while the fifth fridge is revealed to be a disguise for Snowdrake's Mother upon inspection. If the fan switch has not been turned on, the room is shrouded in a thick fog which prevents the fridges from being seen, and their descriptions upon inspection are mere conjectures. Snowdrake's Mother drops the blue key upon defeat. In the adjoining room is the slot for the green key.

Bedroom to Blue Key Slot [ ]

Golden Flowers along a table in the room where Reaper Bird is fought

Returning to the bedroom and traveling through the right pathway, the protagonist enters a horizontal room with mirrors along the northern wall and a table with Golden Flowers along the southern wall. Between the first three mirrors are entries 7 and 10. While attempting to travel across the room, the protagonist is stopped by a random encounter indicator, which transforms into Reaper Bird . At the end of the room is a room with the blue key slot.

Power Room Door to Power Room [ ]

After collecting all four keys, the power room door is unlocked. Entering through the door leads to an elevator that is connected with a western pathway. Going through the pathway leads to a horizontal hallway with blank screens along the wall. At the end of this hallway is a doorway leading to the power room. The Power Room contains a generator which has a red, heart-shaped figure on its front. After turning on the power, several amalgamates approach and surround the protagonist, and Alphys rushes in and bails them out. The protagonist then leaves the room and travels back through the hallway. The blank screens on the wall turn on to reveal entries 8 and 18. After returning to the elevator, the western and southern pathways are cut off, and the protagonist is then thrust into New Home.

Lab Entries [ ]

Lab Entries can be found on the numerous panels that can be seen throughout the lab. The entries are numbered from 1 to 21, but there is no 17th entry. In the game data, there are two 17th lab entries, neither of which can be accessed in normal gameplay; one of them is completely in Wingdings and presumed to have been written by W. D. Gaster , [3] while the other would have appeared in the room with the DT Extraction Machine. The latter unused Entry Number 17 was removed in the v1.05 release, while the former was kept and even included in the Japanese localization. Most of the entries contain extensive information about Alphys's experimentation concerning SOULs, Determination, monsters, and Flowey.

This is it... Time to do what the King has asked me to do.
I will create the power to free us all.
(It seems to be turned off.) [Unused]
The barrier is locked by SOUL power..
Unfortunately, this power cannot be recreated artificially.
SOUL power can only be derived from what was once living.
So, to create more, we will have to use what we have now...
But extracting a SOUL from a living monster would require incredible power...
Besides being impractical, doing so would instantly destroy the SOUL's host.
And, unlike the persistent SOULs of humans...
The SOULs of most monsters disappear immediately upon death.
I've been researching humans to see if I can find any info about their SOULS.
I ended up snooping around the castle... And found these weird tapes.
I don't feel like ASGORE's watched them...
I've done it.
Using the blueprints, I've extracted it from the human SOULs.
I believe this is what gives their SOULs the strength to persist after death.
The will to keep living... The resolve to change fate.
Let's call this power...
ASGORE asked everyone outside the city for monsters that had "fallen down."
Their bodies came in today.
They're still comatose... And soon, they'll all turn into dust.
But what happens if I inject "determination" into them?
If their SOULS persist after they perish, then...
We'll need a vessel to wield the monster SOULs when the time comes.
After all, a monster cannot absorb the SOULs of other monsters.
Just as a human cannot absorb a human SOUL...
I've chosen a candidate.
I haven't told ASGORE yet, because I want to surprise him with it...
In the center of his garden , there's something special.
The first golden flower, that grew before all the others.
The flower from the outside world .
It appeared just before the queen left.
I wonder...
What happens when something without a SOUL gains the will to live?
things aren't going well.
none of the bodies have turned into dust, so I can't get the SOULs.
i told the families that i would give them the dust back for the funerals.
people are starting to ask me what's happening.
experiments on the vessel are a failure.
it doesn't seem to be any different from the control cases.
whatever. they're a hassle to work with anyway.
now that mettaton's made it big, he never talks to me anymore.
... except to ask when i'm going to finish his body.
but i'm afraid if i finish his body, he won't need me anymore...
then we'll never be friends ever again.
... not to mention, every time i try to work on it, i just get really sweaty...
nothing is happening. i don't know what to do.
i'll just keep injecting everything with "determination."
Everyone that had fallen down...
... has woken up.
They're all walking around and talking like nothing is wrong.
Seems like this research was a dead end...
But at least we got a happy ending out of it...?
I sent the SOULS back to ASGORE, returned the vessel to his garden....
And I called all of the families and told them everyone's alive.
monsters' physical forms can't handle "determination" like humans' can.
with too much determination, our bodies begin to break down.
DARK DARKER YET DARKER
THE DARKNESS KEEPS GROWING
THE SHADOWS CUTTING DEEPER
PHOTON READINGS NEGATIVE
THIS NEXT EXPERIMENT
INTERESTING
WHAT DO YOU TWO THINK
the flower's gone.
the families keep calling me to ask when everyone is coming home.
what am i supposed to say?
ASGORE left me five messages today.
four about everyone being angry
one about this cute teacup he found that looks like me
i spend all my time at the garbage dump now

VHS Tapes [ ]

The room with the TV, entry number 4, and the yellow-colored switch.

The five VHS tapes can be found in the room with the TV, which is north of the room with the DT Extraction Machine. Home (Music Box) plays at 80% speed over the first tape between Toriel and Asgore , the second through fourth tapes of the first human and Asriel play mus_birdnoise.ogg, and the last tape of the first human on their deathbed does not contain any music. They contain recordings of Asriel, his family and the Fallen Human interacting. However, these do not have any visual content.

[Toriel] Psssst. Gorey, wake up.
[Asgore] Mmm? What is it, dear?
[Asgore] ... err, and why do you have that video camera?
[Toriel] Shush! I want to get your reaction.
[Toriel] Gorey, dearest. What is my favorite vegetable?
[Asgore] Hmmm... Carrots, right?
[Toriel] No no no! My FAVORITE vegetable is...
[Toriel] Eda-MOM-e.
[Toriel] ... get it???
[Asgore] ...
[Asgore] Go back to bed, dear.
[Toriel] No no!! Not yet! Hee hee hee.
[Toriel] Now, If I were a dog, what breed of dog would I be?
[Asgore] Hmmm... I don't know, honey. What kind of dog would you be?
[Toriel] I would be...
[Toriel] A MOMERANIAN.
[Asgore] Hohoho!
[Asgore] You sure are excited to have this child.
[Asgore] You know, if you keep making jokes like this...
[Asgore] One day, you could be...
[Asgore] ... a famous MOMedian.
[Toriel] ...
[Toriel] Well, I am going to bed.
[Asgore] Hey! Come on, Tori! That one was funny!
[Toriel] Hahaha, I know. I am just teasing you.
[Toriel] Goodnight, dear.
[Asgore] Goodnight, honey.
[Toriel] Oh dear, perhaps it is too dark in here for the video to come out...
[Asriel] Okay, <Name>, are you ready?
[Asriel] Do your creepy face!
[Asriel] AHHHHH!! Hee hee hee!
[Asriel] Oh! Wait! I had the lens cap on...
[Asriel] What!? You're not gonna do it again...?
[Asriel] Come on, quit tricking me! Haha!
[Asriel] Howdy, <Name>! Smile for the camera!
[Asriel] Ha, this time I got YOU! I left the cap on... ON PURPOSE!
[Asriel] Now you're smiling for noooo reason! Hee hee hee!
[Asriel] What? Oh, yeah, I remember.
[Asriel] When we tried to make butterscotch pie for Dad, right?
[Asriel] The recipe asked for cups of butter...
[Asriel] But we accidentally put in buttercups instead.
[Asriel] Yeah! Those flowers got him really sick.
[Asriel] I felt so bad. We made Mom really upset.
[Asriel] I should have laughed it off, like you did...
[Asriel] Um, anyway, where are you going with this?
[Asriel] Huh? Turn off the camera...? OK.
[Asriel] I... I don't like this idea, <Name>.
[Asriel] Wh.. what? N-no, I'm not...
[Asriel] ... big kids don't cry.
[Asriel] Yeah, you're right.
[Asriel] No! I'd never doubt you, <Name>... Never!
[Asriel] Y... yeah! We'll be strong! We'll free everyone.
[Asriel] I'll go get the flowers.
[Toriel] <Name>... Can you hear me? We want you to wake up...
[Asgore] <Name>! You have to stay determined!
[Asgore] You can't give up... You are the future of humans and monsters...
[Asriel] ...
[Asriel] Psst... <Name>... Please... wake up...
[Asriel] I don't like this plan anymore.
[Asriel] I... I...
[Asriel] ... no, I said... I said I'd never doubt you.
[Asriel] Six, right? We just have to get six...
[Asriel] And we'll do it together, right?
The Cell Phone cannot be used to call Papyrus and Undyne , or Toriel in this area.
There is a known glitch in which the Blue Key cannot be seen after being dropped but can still be picked up.
The teacup mentioned in Entry Number 20 can be found in Alphys's lab, sitting on her desk.
The DT Extraction Machine also heavily resembles a Cervine (Deer) skull, the same way Sans 's Gaster Blasters resemble Canid (Dog) skulls, and Asriel's skull during the final battle resembles a Capra (Goat) skull.
In the room with the beds, laying down on the bottom left one for a short while will cause an amalgamate to appear and extend out an arm to pull up the cover over the protagonist, then pat their head before disappearing.

"There's something here... It feels like it's breathing."
"There's something here... It feels like a tree, ripe with delicious fruit."
"There's something here... Something in the shape of a man."
"There's something here... It feels warm, and moist."
The screens for Entry Numbers 8 and 18 display a red smile instead of green lines like the other entries, possibly because they tell of how Alphys created Flowey, and Flowey disguises his dark intentions with an innocent smile.
If the protagonist has Popato Chisps in their inventory, Alphys says in the power room Amalgamates probably smelled the chisps in their inventory.
It is speculated that the True Lab is where Alphys evacuates everybody to during the Genocide Route , as Alphys mentions during the Near Genocide Neutral ending that doing it would cause everyone to find out the truth about her. [4]
If the player's controller is disconnected in the Xbox version while in the True Lab, under the "No Controller Connected" message is a list of other human body parts that are said to not be connected. [5]
This is likely a conflation with fun events , which do appear under rare conditions.

References [ ]

↑ Bratty: So Alphys has always, like... Catty: Thought ASGORE is a SUPER cutie. Bratty: So, like, I'm pretty sure she... Catty: Made Mettaton to, like, totally impress him. Bratty: A robot with a SOUL... Catty: That's, like, SUPER relevant to his hobbies! - Bratty and Catty
↑ 2.0 2.1 Betrayed Undyne Ending (Mettaton dead) and the Mettaton Ending
↑ By changing your room number in both your save0 and your .ini file to 264, a set of wingdings will appear. - W.D Gaster: Undertale's Last Secret (Mistress Spitfire, September 18, 2015.) Steam Community .
↑ Even if it meant everybody would... Have to learn the truth about me. - Alphys
↑ I just find out that if you disconnect your controller in the "true laboratory" of alphys in the Xbox version, this shows up - u/MorsaRika on Reddit, March 18, 2021.
↑ Legends of Localization Book 3: UNDERTALE , page 232, ISBN 9781945908019
2 True Pacifist Route

Experimental Method In Psychology

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.

Learn about our Editorial Process

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.

On This Page:

The experimental method involves the manipulation of variables to establish cause-and-effect relationships. The key features are controlled methods and the random allocation of participants into controlled and experimental groups .

What is an Experiment?

An experiment is an investigation in which a hypothesis is scientifically tested. An independent variable (the cause) is manipulated in an experiment, and the dependent variable (the effect) is measured; any extraneous variables are controlled.

An advantage is that experiments should be objective. The researcher’s views and opinions should not affect a study’s results. This is good as it makes the data more valid and less biased.

There are three types of experiments you need to know:

1. Lab Experiment

A laboratory experiment in psychology is a research method in which the experimenter manipulates one or more independent variables and measures the effects on the dependent variable under controlled conditions.

A laboratory experiment is conducted under highly controlled conditions (not necessarily a laboratory) where accurate measurements are possible.

The researcher uses a standardized procedure to determine where the experiment will take place, at what time, with which participants, and in what circumstances.

Participants are randomly allocated to each independent variable group.

Examples are Milgram’s experiment on obedience and Loftus and Palmer’s car crash study .

Strength : It is easier to replicate (i.e., copy) a laboratory experiment. This is because a standardized procedure is used.
Strength : They allow for precise control of extraneous and independent variables. This allows a cause-and-effect relationship to be established.
Limitation : The artificiality of the setting may produce unnatural behavior that does not reflect real life, i.e., low ecological validity. This means it would not be possible to generalize the findings to a real-life setting.
Limitation : Demand characteristics or experimenter effects may bias the results and become confounding variables .

2. Field Experiment

A field experiment is a research method in psychology that takes place in a natural, real-world setting. It is similar to a laboratory experiment in that the experimenter manipulates one or more independent variables and measures the effects on the dependent variable.

However, in a field experiment, the participants are unaware they are being studied, and the experimenter has less control over the extraneous variables .

Field experiments are often used to study social phenomena, such as altruism, obedience, and persuasion. They are also used to test the effectiveness of interventions in real-world settings, such as educational programs and public health campaigns.

An example is Holfing’s hospital study on obedience .

Strength : behavior in a field experiment is more likely to reflect real life because of its natural setting, i.e., higher ecological validity than a lab experiment.
Strength : Demand characteristics are less likely to affect the results, as participants may not know they are being studied. This occurs when the study is covert.
Limitation : There is less control over extraneous variables that might bias the results. This makes it difficult for another researcher to replicate the study in exactly the same way.

3. Natural Experiment

A natural experiment in psychology is a research method in which the experimenter observes the effects of a naturally occurring event or situation on the dependent variable without manipulating any variables.

Natural experiments are conducted in the day (i.e., real life) environment of the participants, but here, the experimenter has no control over the independent variable as it occurs naturally in real life.

Natural experiments are often used to study psychological phenomena that would be difficult or unethical to study in a laboratory setting, such as the effects of natural disasters, policy changes, or social movements.

For example, Hodges and Tizard’s attachment research (1989) compared the long-term development of children who have been adopted, fostered, or returned to their mothers with a control group of children who had spent all their lives in their biological families.

Here is a fictional example of a natural experiment in psychology:

Researchers might compare academic achievement rates among students born before and after a major policy change that increased funding for education.

In this case, the independent variable is the timing of the policy change, and the dependent variable is academic achievement. The researchers would not be able to manipulate the independent variable, but they could observe its effects on the dependent variable.

Strength : behavior in a natural experiment is more likely to reflect real life because of its natural setting, i.e., very high ecological validity.
Strength : Demand characteristics are less likely to affect the results, as participants may not know they are being studied.
Strength : It can be used in situations in which it would be ethically unacceptable to manipulate the independent variable, e.g., researching stress .
Limitation : They may be more expensive and time-consuming than lab experiments.
Limitation : There is no control over extraneous variables that might bias the results. This makes it difficult for another researcher to replicate the study in exactly the same way.

Key Terminology

Ecological validity.

The degree to which an investigation represents real-life experiences.

Experimenter effects

These are the ways that the experimenter can accidentally influence the participant through their appearance or behavior.

Demand characteristics

The clues in an experiment lead the participants to think they know what the researcher is looking for (e.g., the experimenter’s body language).

Independent variable (IV)

The variable the experimenter manipulates (i.e., changes) is assumed to have a direct effect on the dependent variable.

Dependent variable (DV)

Variable the experimenter measures. This is the outcome (i.e., the result) of a study.

Extraneous variables (EV)

All variables which are not independent variables but could affect the results (DV) of the experiment. EVs should be controlled where possible.

Confounding variables

Variable(s) that have affected the results (DV), apart from the IV. A confounding variable could be an extraneous variable that has not been controlled.

Random Allocation

Randomly allocating participants to independent variable conditions means that all participants should have an equal chance of participating in each condition.

The principle of random allocation is to avoid bias in how the experiment is carried out and limit the effects of participant variables.

Order effects

Changes in participants’ performance due to their repeating the same or similar test more than once. Examples of order effects include:

(i) practice effect: an improvement in performance on a task due to repetition, for example, because of familiarity with the task;

(ii) fatigue effect: a decrease in performance of a task due to repetition, for example, because of boredom or tiredness.

What are “True” experiments in Psychology?

The true experiment is often thought of as a laboratory study. However, this is not always the case. A true experiment is defined as an experiment conducted where an effort is made to impose control over all other variables except the one under study. It is often easier to impose this sort of control in a laboratory setting. Thus, true experiments have often been erroneously identified as laboratory studies.

To understand the nature of the experiment, we must first define a few terms:

Experimental or treatment group – this is the group that receives the experimental treatment, manipulation, or is different from the control group on the variable under study.

Control group – this group is used to produce comparisons. The treatment of interest is deliberately withheld or manipulated to provide a baseline performance with which to compare the experimental or treatment group’s performance.

Independent variable – this is the variable that the experimenter manipulates in a study. It can be any aspect of the environment that is empirically investigated for the purpose of examining its influence on the dependent variable.

Dependent variable – the variable that is measured in a study. The experimenter does not control this variable.

Random assignment – in a study, each subject has an equal probability of being selected for either the treatment or control group. You can use sampling techniques such as opportunity sampling or stratified sampling from a larger target population, but once subjects are chosen they must be randomly assigned to treatment and subject groups. If you are unsure what this means, let me know.

Double blind – neither the subject nor the experimenter knows whether the subject is in the treatment of the control condition.

Now that we have these terms defined, we can examine further the structure of the true experiment. First, every experiment must have at least two groups: an experimental and a control group. Each group will receive a level of the independent variable. The dependent variable will be measured to determine if the independent variable has an effect. As stated previously, the control group will provide us with a baseline for comparison. All subjects should be randomly assigned to groups, be tested simultaneously as possible, and the experiment should be conducted double-blind.

M2024 IB Results

WASC Accreditation: Its Importance for Pamoja as a School

ManageBac and Pamoja at the IB Global Conference, Daegu 2024

Understanding True Experiments in Psychology: Principles and Applications

True experiments in psychology are a crucial method used by researchers to test hypotheses, establish cause and effect relationships, and advance scientific knowledge. In this article, we will delve into the principles of true experiments, such as random assignment and manipulation of variables.

We will also explore how true experiments differ from other types of studies, the ethical considerations involved, and the limitations researchers face. Stay tuned to discover how researchers can improve the validity of true experiments and their applications in the field of psychology.

Random assignment is a crucial principle in true experiments as it ensures that participants are assigned to groups without bias, increasing the validity of the study.
Manipulation of the independent variable and control group are key elements in establishing cause and effect relationships in true experiments.
True experiments have various applications such as testing hypotheses, identifying effective treatments, and advancing scientific knowledge in psychology.
1 What Are True Experiments in Psychology?
2.1 Random Assignment
2.2 Control Group
2.3 Manipulation of Independent Variable
2.4 Measurement of Dependent Variable
2.5 Elimination of Confounding Variables
3.1 Correlational Studies
3.2 Quasi-Experiments
3.3 Observational Studies
4.1 Testing Hypotheses
4.2 Establishing Cause and Effect Relationships
4.3 Replicating Previous Findings
4.4 Identifying Effective Treatments
4.5 Advancing Scientific Knowledge
5 What Are the Ethical Considerations in True Experiments?
6 What Are the Limitations of True Experiments?
7 How Can Researchers Improve the Validity of True Experiments?
8.1 What is a true experiment in psychology?
8.2 What are the principles of true experiments in psychology?
8.3 Why is random assignment important in true experiments?
8.4 How does manipulation of an independent variable work in true experiments?
8.5 How are extraneous variables controlled in true experiments?
8.6 What are some applications of true experiments in psychology?

What Are True Experiments in Psychology?

True experiments in psychology refer to research studies that involve the manipulation of an independent variable to observe the effects on a dependent variable within a controlled environment.

By manipulating the independent variable, researchers aim to determine causality relationships between variables, testing hypotheses and theories. This controlled setting ensures that any changes in the dependent variable are a direct result of the manipulated independent variable, helping to eliminate extraneous factors and increase the internal validity of the study.

Researchers carefully design these experiments, often using random assignment to assign participants to different conditions, minimizing the influence of individual differences. This rigorous methodology allows psychologists to draw reliable conclusions about human behavior and cognition.

What Are the Principles of True Experiments?

The principles of true experiments in psychology encompass key elements such as random assignment , control group implementation, and the manipulation of independent variables.

Random assignment is a crucial aspect of experimental design that involves assigning participants to different groups by chance to reduce biases and ensure that each participant has an equal chance of being in any group. This helps in establishing a cause-and-effect relationship between variables.

Control group practices involve creating a group that does not receive the experimental treatment to serve as a benchmark for comparison, allowing researchers to assess the impact of the treatment.

The manipulation of variables refers to intentionally changing one variable to observe its effect on another, allowing researchers to test hypotheses and draw conclusions based on the results.

Random Assignment

Random assignment is a crucial aspect of true experiments, ensuring that participants are assigned to groups without bias or influence.

By randomly assigning individuals to different experimental groups, researchers can be more confident that any differences observed in the outcomes are due to the manipulation of the independent variable rather than individual characteristics.

This process helps eliminate selection bias, where certain characteristics of participants may influence group allocation, ultimately leading to distorted results.

The importance of random assignment lies in its ability to create comparable groups, making the conclusions drawn from the study more credible and generalizable.

Control Group

The control group in true experiments serves as a baseline for comparison, allowing researchers to assess the impact of the independent variable.

By isolating the variable of interest and comparing it to a group that does not receive the treatment or intervention, researchers can determine whether the observed effects are truly due to the independent variable. This group provides a standard of reference against which the experimental group is measured, ensuring that any changes or outcomes can be attributed accurately. Control groups play a crucial role in reducing bias and ensuring the validity of study results, helping researchers draw meaningful conclusions from their experiments.

Manipulation of Independent Variable

Manipulating the independent variable is a core component of true experiments, enabling researchers to assess its causal impact on the dependent variable.

By systematically varying the independent variable, researchers can observe how changes in the manipulated factor lead to changes in the dependent variable, thereby establishing a cause-and-effect relationship. This manipulation allows for controlling and testing different conditions to study the direct influence of the independent variable on the outcome. Through this process, researchers can deduce the extent to which the independent variable influences the dependent variable, aiding in drawing valid conclusions about the relationship between the two variables.

Measurement of Dependent Variable

The measurement of the dependent variable in true experiments involves assessing the outcome or response that is influenced by the manipulation of the independent variable.

In research studies, the process of measuring the dependent variable plays a crucial role in determining the effectiveness of the experimental manipulation. Researchers use various techniques to quantify and record the responses of participants to different conditions. This measurement step is essential for comparing the outcomes across different groups and evaluating the impact of the independent variable on the dependent variable. Data collection tools such as surveys, questionnaires, observations, and physiological measurements are commonly employed to capture the relevant information accurately.

Elimination of Confounding Variables

Eliminating confounding variables is essential in true experiments to ensure that the observed effects are attributed to the manipulated variables rather than external influences.

To address confounding variables effectively, researchers employ various strategies to control and minimize the impact of extraneous factors.

One common approach is randomization, where participants are assigned to different experimental conditions randomly to distribute potential confounders evenly across groups.

Another method involves matching participants based on certain variables to ensure comparability between groups.

Researchers may use statistical techniques such as regression analysis to control for confounding variables during data analysis.

How Are True Experiments Different from Other Types of Studies?

True experiments in psychology differ from other types of studies such as correlational studies and quasi-experiments by their ability to establish causal relationships through controlled manipulation.

While correlational studies aim to identify relationships between variables without manipulating them, true experiments involve the deliberate manipulation of one or more factors to observe the effect on another variable. This manipulation allows researchers to assess causality effectively by controlling for confounding variables and random assignment of participants to experimental conditions.

With experimental designs, researchers can establish a cause-and-effect relationship, providing stronger evidence of the effect of an independent variable on a dependent variable. This rigorous approach helps in drawing more definitive conclusions compared to observational or correlational studies.

Correlational Studies

Correlational studies in psychology focus on identifying relationships between variables without manipulating them, offering insights into associations and predictive patterns.

These studies are significant in understanding how variables interact in the natural world, providing crucial data for researchers to analyze and draw conclusions from. By examining the relationship between variables, researchers can determine if changes in one variable correspond with changes in another, revealing potential predictive patterns. This type of research design is valuable when it is not possible or ethical to manipulate certain variables, allowing researchers to observe and interpret connections without intervening. Through statistical analysis, correlational studies help establish the strength and direction of relationships between different factors, contributing to a deeper understanding of complex phenomena.

Quasi-Experiments

Quasi-experiments in psychology resemble true experiments but lack random assignment or full control over variables, often utilized when strict experimental conditions are challenging to implement.

This type of research design shares many similarities with traditional experiments, such as having a treatment group and a control group to analyze the effects of an independent variable. Without random assignment, researchers cannot ensure that participants are equally distributed between groups based on relevant factors, potentially impacting the internal validity of the study. The limitation in control and randomization in quasi-experiments leads to difficulties in establishing a cause-and-effect relationship definitively.

Observational Studies

Observational studies in psychology involve the systematic observation of behaviors, perceptions, or phenomena without intervention or manipulation, providing valuable insights into natural settings.

In these studies, researchers carefully examine how people interact with their environment and how certain stimuli influence their actions and reactions. Behavioral analysis plays a crucial role in understanding human nature and decision-making processes. By closely monitoring individuals in their everyday routines and environments, psychologists can uncover patterns, trends, and subconscious influences that might not be apparent in experimental settings.

What Are the Applications of True Experiments in Psychology?

True experiments play a vital role in psychology by testing hypotheses, establishing cause-and-effect relationships, replicating findings, and advancing scientific knowledge through systematic procedures.

One of the key elements of true experiments is hypothesis testing , where researchers formulate a clear statement to be tested through experimentation. This process allows them to investigate and validate theories in a controlled environment.

These experiments are essential for assessing causality , as they help determine if changes in one variable directly cause changes in another. This ability to establish cause-and-effect relationships is crucial for understanding the intricacies of human behavior and mental processes.

By focusing on these rigorous methods, psychologists can push the boundaries of scientific advancement and contribute valuable insights to the field.

Testing Hypotheses

One of the primary applications of true experiments in psychology is testing hypotheses by manipulating variables and analyzing the resulting data for empirical support.

Formulating a hypothesis is the initial step in this process. Researchers conceptualize a testable statement that predicts the relationship between variables. For instance, in a study examining the impact of music on concentration, the hypothesis could be that participants exposed to classical music will perform better on a cognitive task compared to those in a silent environment.

After establishing the hypothesis, the experiment is designed to manipulate the independent variable (in this case, music exposure) and measure the dependent variable (concentration level). Data collection methods, such as observation or surveys, are then employed to gather information.

Establishing Cause and Effect Relationships

True experiments excel in establishing cause-and-effect relationships, particularly in cognitive processing studies, by systematically manipulating variables to determine their impact on outcomes.

In cognitive psychology, researchers use true experiments to delve into the intricate mechanisms of cognitive processes, such as memory, attention, and perception. By carefully manipulating independent variables and observing changes in dependent variables, they can infer causal relationships and better understand the underlying cognitive mechanisms. This method allows researchers to draw reliable conclusions about how specific variables influence mental processes, contributing valuable insights to the field.

Replicating Previous Findings

True experiments contribute to replicating previous findings in psychology, especially in memory research, by confirming the reliability and validity of established results through rigorous experimentation.

In memory-related studies, replicating research findings becomes crucial to strengthen the scientific foundation and ensure the credibility of existing knowledge in cognitive processes. Through meticulous experimental design and methodological precision, researchers aim to validate the consistency of outcomes, providing a solid basis for generalizing findings to broader populations or contexts.

Result validation processes often involve conducting multiple trials, controlling for confounding variables, and utilizing statistical analyses to determine the robustness and significance of the obtained results. By meticulously following these steps, scientists can enhance the overall understanding of memory mechanisms and contribute to the advancement of psychological theories.

Identifying Effective Treatments

True experiments aid in identifying effective treatments and interventions in psychology, enabling researchers to evaluate the efficacy of therapeutic approaches or behavioral modifications through controlled studies.

By establishing control over variables and random assignment of participants, true experiments establish a cause-and-effect relationship between the intervention and outcomes. These experiments often involve an experimental group receiving the treatment and a control group that does not, allowing researchers to compare results objectively.

The results obtained from true experiments provide valuable insights into the effectiveness of different therapeutic techniques and help psychologists tailor interventions to suit individual client needs. This evidence-based approach ensures that psychological interventions are not only well-founded but also have a higher chance of success.

Advancing Scientific Knowledge

True experiments are pivotal in advancing scientific knowledge in psychology, with EEG data studies exemplifying how controlled experimentation enhances our understanding of cognitive processes and brain functions.

Through true experiments, researchers are able to systematically manipulate variables to establish cause-and-effect relationships in their studies, providing valuable insights into complex neural mechanisms. The meticulous process of EEG data analysis in experimental settings allows scientists to observe real-time brain activity, monitor cognitive responses, and pinpoint specific brain regions involved in various tasks.

The applications of cognitive research are vast and impactful, ranging from exploring memory formation, attentional processes, language comprehension, to investigating neurological disorders such as Alzheimer’s disease and schizophrenia. Understanding the intricacies of the brain through empirical research is crucial for developing effective interventions and treatments for cognitive impairments.

What Are the Ethical Considerations in True Experiments?

Ethical considerations in true experiments involve ensuring the well-being and rights of participants, obtaining informed consent, maintaining confidentiality, and adhering to ethical guidelines set by psychological associations.

Central to the ethical framework of true experiments is the fundamental principle of beneficence, where researchers must prioritize the welfare and best interests of those participating in the study. This encompasses not only physical health but also psychological and emotional aspects to ensure a holistic approach to participant protection. Informed consent plays a pivotal role, granting individuals the autonomy to make voluntary decisions regarding their involvement after being provided with all pertinent information. This transparent exchange is crucial for fostering trust and respect.

What Are the Limitations of True Experiments?

The limitations of true experiments in psychology include challenges related to controlling extraneous variables , generalizing findings to real-world scenarios, and addressing ethical constraints in experimental designs.

Extraneous variables, also known as confounding variables, can significantly impact the results of an experiment by introducing unintended influences that distort the relationships being studied. These variables are crucial to be managed effectively to ensure the internal validity of the study. Complete control over all extraneous variables is often impractical, especially in complex human behaviors where numerous factors can interact. This limitation highlights the need for researchers to carefully design experiments and utilize statistical techniques to minimize their effects.

How Can Researchers Improve the Validity of True Experiments?

Researchers can enhance the validity of true experiments in psychology by implementing rigorous scientific methods, conducting thorough data analysis, ensuring result reliability, and adhering to established research protocols.

One of the key strategies for enhancing experiment validity is to prioritize random assignment of participants to experimental groups, which helps control for confounding variables and increases the likelihood of establishing cause and effect relationships.

Researchers should carefully design control conditions to accurately measure the impact of the independent variable. Data validation processes such as peer review and replication studies play a vital role in confirming the robustness of experimental findings.

Frequently Asked Questions

What is a true experiment in psychology.

A true experiment in psychology is a research method in which an independent variable is manipulated to determine its effect on a dependent variable, while controlling for other variables that may influence the results.

What are the principles of true experiments in psychology?

The three main principles of true experiments in psychology are random assignment, manipulation of an independent variable, and control of extraneous variables.

Why is random assignment important in true experiments?

Random assignment helps to ensure that participants are assigned to different experimental groups by chance, reducing the likelihood of pre-existing differences between the groups that could affect the results.

How does manipulation of an independent variable work in true experiments?

The independent variable, often referred to as the treatment, is manipulated by the researcher to observe its effects on the dependent variable. This allows for the establishment of cause-and-effect relationships.

How are extraneous variables controlled in true experiments?

Extraneous variables, which are factors that may influence the results but are not the focus of the study, are controlled through various methods such as random assignment, use of control groups, and experimental design.

What are some applications of true experiments in psychology?

True experiments are commonly used in psychology to study the effects of various interventions or treatments on behavior or mental processes. They can also be used to test theories and hypotheses, and to determine the effectiveness of different strategies or programs.

Dr. Emily Tan is a researcher in the field of psychological assessment and testing. Her expertise includes the development and validation of psychological measures, with a particular interest in personality assessment. Dr. Tan’s work aims to improve the accuracy and ethical application of psychological tests in various settings, from clinical diagnostics to organizational hiring processes.

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Psychology Sorted

Psychology for all, experimental methods explained.

The easiest one to define is the true experiment.

Often called a ‘laboratory/lab’ experiment, this does not have to take place in a lab, but can be conducted in a classroom, office, waiting room, or even outside, providing it meets the criteria. These are that allocation of participants to the two or more experimental (or experimental and control) groups or conditions is random and that the independent variable (IV) is manipulated by the researcher in order to measure the effect on the dependent variable (DV). Other variables are carefully controlled, such as location, temperature, time of day, time taken for experiment, materials used, etc. This should result in a cause and effect relationship between the IV and the DV. Examples are randomised controlled drug trials or many of the cognitive experiments into memory, such as Glanzer and Cunitz_1966.

A field experiment is similar, in that individuals are usually randomly assigned to groups, where this is possible, and the IV is manipulated by the researcher. However, as this takes place in the participants’ natural surroundings, the extraneous variables that could confound the findings of the research are somewhat more difficult to control. The implications for causation depend on how well these variables are controlled, and on the random allocation of participants. Examples are bystander effect studies, and also research into the effect of digital technology on learning, such as that conducted by Hembrooke and Gay_2003 .

A quasi-experiment is similar to either or both of the above, but the participants are not randomly allocated to groups. Instead they are allocated on the basis of self-selection as male/female; left or right-handed; preference for coffee or tea; young/old, etc. or researcher selection as scoring above or below and certain level on a pre-test; measured socio-economic status; psychology student or biology student, etc. These are therefore, non-equivalent groups. The IV is often manipulated and the DV measured as before, but the nature of the groups is a potential confounding variable. If testing the effect of a new reading scheme on the reading ages of 11 year olds, a quasi-experimental design would allocate one class of 11 year olds to read using the scheme, and another to continue with the old scheme (control group), and then measure reading ages after a set period of time. But there may have been other differences between the groups that mean a cause and effect relationship cannot be reliably established: those in the first class may also have already been better readers, or several months older, than those in the control group. Baseline pre-testing is one way around this, in which the students’ improvement is measured against their own earlier reading age, in a pre-test/post-test design. In some quasi-experiments, the allocation to groups by certain criteria itself forms the IV, and the effects of gender, age or handedness on memory, for example, are measured. Examples are research into the efficacy of anti-depressants, when some participants are taking one anti-depressant and some another, or Caspi et al._2003 , who investigated whether a polymorphism on the serotonin transporter gene is linked to a higher or lower risk of individual depression in the face of different levels of perceived stress.

Finally, natural experiments are those in which there is no manipulation of the IV, because it is a naturally-occurring variable. It may be an earthquake (IV) and measurement of people’s fear levels (DV) at living on a fault line before and after the event, or an increase in unemployment as a large factory closes (IV) and measurement of depression levels amongst adults of working age before and after the factory closure (DV). As with field experiments, many of the extraneous variables are difficult to control as the research takes place in people’s natural environment. A good example of a natural experiment is Charlton (1975) research into the effect of the introduction of television to the remote island of St. Helena.

The differences between quasi experiments and correlational research, and between natural experiments and case studies are sometimes hard to determine, so I would always encourage students to explain exactly why they are designating something as one or the other. We can’t always trust the original article either – Bartlett was happy to describe his studies as experiments, which they were not! Here’s hoping these examples have helped. The following texts are super-useful, and were referred to while writing this post.:

Campbell, D.T. & Stanley J.C . (1963). Experimental and Quasi-Experimental Designs for Research. Boston: Houghton Mifflin (ISBN 9780528614002)

Coolican, H. (2009, 5th ed.). Research Methods and Statistics in Psychology. UK: Hodder (ISBN 9780340983447)

Shadish, W.R., Cook, T.D. & Campbell, D.T. (2001, 2nd ed.). Experimental and Quasi-experimental Designs for Generalized Causal Inference. UK: Wadsworth (ISBN 9780395615560)

True, Natural and Field Experiments An easy lesson idea for learning about experiments.

Travis Dixon September 29, 2016 Research Methodology

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There is a difference between a “true experiment” a “field experiment” and a “natural experiment”. These separate experimental methods are commonly used in psychological research and they each have their strengths and limitations.

True Experiments

Berry’s classic study compared two cultures in order to understand how economics, parenting and cultural values can influence behaviour. But what type of method would we call this?

A true experiment is one where:

have randomly assigned participants to a condition (if using independent samples)

Repeated measures designs don’t need random allocation because there is no allocation as all participants do both conditions.

One potential issue in laboratory experiments is that they are conducted in environments that are not natural for the participants, so the behaviour might not reflect what happens in real life.

Field Experiments

A field experiment is one where:

the researcher conducts an experiment by manipulating an IV,
…and measuring the effects on the DV in a natural environment.

They still try to minimize the effects of other variables and to control for these, but it’s just happening in a natural environment: the field.

Natural Experiment

A natural experiment is one where:

the independent variable is naturally occurring. i.e. it hasn’t been manipulated by the researcher.

There are many instances where naturally occurring events or phenomenon may interest researchers. The issue with natural experiments is that it can’t be guaranteed that it is the independent variable that is having an effect on the dependent variable.

Quantitative Research Methods Glossary
Let’s STOP the research methods madness!
What makes an experiment “quasi”?

Activity Idea

Students can work with a partner to decide if the following are true, field or natural experiments.

If you cant’ decide, what other information do you need?

Berry’s cross-cultural study on conformity ( Key Study: Conformity Across Cultures (Berry, 1967)
Bandura’s bobo doll study ( Key Study: Bandura’s Bobo Doll (1963)
Rosenzweig’s rat study ( Key Study: Animal research on neuroplasticity (Rosenzweig and Bennett, 1961)

Let’s make it a bit trickier:

Key Study: London Taxi Drivers vs. Bus Drivers (Maguire, 2006)
Key Study: Evolution of Gender Differences in Sexual Behaviour (Clark and Hatfield, 1989)
Key Study: Serotonin, tryptophan and the brain (Passamonti et al., 2012)
Saint Helena Study : television was introduced on the island of Saint Helena in the Atlantic ocean and the researchers measured the behaviour of the kids before and after TV was introduced.
Light Therapy : the researchers randomly assigned patients with depression into three different groups. The three groups received different forms of light therapy to treat depression (red light, bright light, soft light). The lights were installed in the participants’ bedrooms and were timed to come on naturally. The effects on depression were measured via interviews.

What are the strengths and limitations of:

True Experiment
Field Experiment

Travis Dixon is an IB Psychology teacher, author, workshop leader, examiner and IA moderator.

What are “True” experiments in Psychology?

To understand the nature of the experiment, we must first define a few terms:

Experimental or treatment group – this is the group that receives the experimental treatment, manipulation, or is different from the control group on the variable under study.

Dependent variable – the variable that is measured in a study. The experimenter does not control this variable.

Double blind – neither the subject nor the experimenter knows whether the subject is in the treatment of the control condition.

Last updated 3 years ago

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How to Conduct a True Experiment

Last Updated: February 2, 2024 References

This article was co-authored by Bess Ruff, MA . Bess Ruff is a Geography PhD student at Florida State University. She received her MA in Environmental Science and Management from the University of California, Santa Barbara in 2016. She has conducted survey work for marine spatial planning projects in the Caribbean and provided research support as a graduate fellow for the Sustainable Fisheries Group. There are 14 references cited in this article, which can be found at the bottom of the page. This article has been viewed 149,742 times.

Experiments are vital to the advancement of science. One important type of experiment is known as the true experiment. A true experiment is one in which the experimenter has worked to control all of the variables except the one that is being studied. In order to accomplish this, true experiments make use of random test groups. [1] X Trustworthy Source PubMed Central Journal archive from the U.S. National Institutes of Health Go to source True experiments are useful for exploring cause and effect relationships such as: is a particular treatment effective for a medical condition? Or, does exposure to a particular substance cause a certain disease? However, because they take place in controlled circumstances, they don’t always fully reflect what will happen in the real world.

Designing the Experiment

Step 1 Formulate the question you would like to answer.

For example, if you want to know if listening to punk music makes you sleep less, the dependent variable will be the numbers of hours slept.
A dependent variable must be measurable.

Step 3 Identify the independent variable.

In your cause-and-effect question, it is the term that comes before "cause": does better nutrition cause higher test scores? Better nutrition is the independent variable, and higher test scores is the dependent variable.
In the example about punk music, listening to punk music is the independent variable.

Step 4 Identify the relevant population.

Random selection ensures that your subjects have a diverse set of characteristics that reflects the population in general. This helps you to avoid introducing unintended variables. If education level is significant to your study, for example, and your population includes people with very little education as well as people with Ph.D.s, you don’t want a subject group composed only of college freshmen.
There are several methods of randomly selecting subjects. For a relatively small population, you could assign each member a number and then use a random number generator to select members. For a larger population, you could take a systematic sample (for example, the second name on each page of a directory) and then use the random number method just described with that smaller subset. [5] X Research source
Additionally, large populations can be randomly sampled through stratified sampling methods, which divide the population into homogeneous "strata" and then select individuals from each group to generate a random sample population. [6] X Research source
Select a group large enough to produce statistically useful data. The ideal size will vary greatly depending on factors such as the size of the underlying population and the expected size of the effect. [7] X Trustworthy Source PubMed Central Journal archive from the U.S. National Institutes of Health Go to source You may use a sample size calculator to aid in determining a target size.

Running the Experiment

Step 1 Randomly assign subjects into two groups.

Use a random number generator to assign a number to each subject. Then place them in the two groups by number. For instance, assign the lower half of the random numbers to the control group.
The control group will not be given the treatment or intervention. This will allow you to measure the effect of the intervention.

Step 2 Ensure that subjects do not know which group they are in.

Have different people in charge of assigning subjects to a group, administering treatment, and evaluating subjects after treatment.

A pretest is not a required feature of the true experiment. However, it increases the ability of your experiment to demonstrate cause and effect. [10] X Research source In order to say that A causes B, you want to show that A happened before B, which can only be done through the use of a pretest.
For example, if you are conducting an experiment on how listening to punk music affects sleep, you’d want to gather data on how long each participant typically sleeps at night when they haven’t listened to punk music.

Step 5 Administer the treatment to the experimental group.

In a clinical trial, this often means that a placebo is administered to the control group. A placebo resembles the real treatment as closely as possible, but is in fact designed to have no effect. For example, in a study on the effect of a medicine, both groups would come to the same room and receive an identical-looking pill. The only difference would be that one pill would contain the medicine, while the other would be an inert “sugar pill.”
In other kinds of experiments, keeping the two experiences equivalent will take other forms. Take the example of the effect of playing the trumpet on academic performance. You might want to offer the control group another kind of lesson or opportunity for socialization, to be sure that it’s really the trumpet-playing in specific and not getting a music lesson in general that is causing the effect. [11] X Research source

Analyzing Your Results

Step 1 Calculate descriptive statistics.

What is the central tendency of the data? Central tendency is measured using mean (average), median, or mode. For example, in a study on the effects of caffeine on sleep, you will want to calculate the mean number of hours slept by members of the control and experimental groups.
What is the distribution of the data? Again, there are many different ways to measure how the data are distributed, including range, variance, and standard deviation.

Step 2 Compare the post-test results produced by the experimental and control groups.

A t-test is a common test of significance. A t-test compares the difference between the means of two sets of data in relation to the variation within the data. [15] X Research source You can calculate a t-test by hand or by using statistical software such as Microsoft Excel.

Community Q&A

Combine true experiments with other types of experiments in order to gain a fuller picture. Observational studies will provide information about how a given treatment, for example, works in real life. Thanks Helpful 1 Not Helpful 1
True experiments are often conducted in a laboratory. But they don’t have to be, as long as control is imposed over possible extraneous factors. Thanks Helpful 0 Not Helpful 1
Be sure to take ethics into consideration when conducting this type of study. Never administer anything that may be harmful to a subject. Always stop the study if adverse effects occur. Never withhold treatments knowing that they will improve a subject's health. Follow the guidelines of your school, university, lab, or company in handling human or animal subjects. Thanks Helpful 0 Not Helpful 0
Be aware of how research design affects results. Bias in how you select subjects or how you control the environment of the experiment can introduce hidden effects on your results. Thanks Helpful 0 Not Helpful 0

↑ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3505292/
↑ https://nces.ed.gov/nceskids/help/user_guide/graph/variables.asp
↑ http://linguistics.byu.edu/faculty/henrichsenl/ResearchMethods/RM_2_08.html
↑ http://allpsych.com/researchmethods/selectingsubjects/
↑ http://www.stat.yale.edu/Courses/1997-98/101/sample.htm
↑ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2876926/
↑ http://www.bmj.com/rapid-response/2011/10/31/what-single-blind-trial
↑ https://www.verywellmind.com/what-is-a-double-blind-study-2795103
↑ http://web.csulb.edu/~msaintg/ppa696/696exper.htm
↑ http://allpsych.com/researchmethods/trueexperimentaldesign/
↑ https://statistics.laerd.com/statistical-guides/descriptive-inferential-statistics.php
↑ https://www.stat.cmu.edu/~hseltman/309/Book/Book.pdf
↑ http://www.stat.yale.edu/Courses/1997-98/101/sigtest.htm
↑ http://archive.bio.ed.ac.uk/jdeacon/statistics/tress4a.html

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Lab Experiment

What do you think of when you hear the word "laboratory"? Do you picture people in white coats and goggles and gloves standing over a table with beakers and tubes? Well, that picture is pretty close to reality in some cases. In others, laboratory experiments, especially in psychology, focus more on observing behaviours in highly controlled settings to establish causal conclusions. Let's explore lab experiments further.

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The aim of lab experiments is to identify if observed changes in the are caused by the .

Is it difficult to generalise results from lab experiments to real-life settings?

Demand characteristics lower the of the research.

True or false: there is more likelihood of demand characteristics influencing lab experiments than field experiments.

A researcher wanted to explore how driving conditions affected speeding. Which type of experimental method is the researcher more likely to use?

A researcher wanted to explore if sleep deprivation affected cognitive abilities. Which type of experimental method is the researcher more likely to use?

Are lab experiments easy to replicate?

True or false: Participants are aware that they are taking part in the lab experiment and sometimes may not know the aim of the investigation.

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We are going to delve into the topic of lab experiments in the context of psychology.
We will start by looking at the lab experiment definition and how lab experiments are used in psychology.
Moving on from this, we will look at how lab experiment examples in psychology and cognitive lab experiments may be conducted.
And to finish off, we will also explore the strengths and weaknesses of lab experiments.

Lab Experiment Psychology Definition

You can probably guess from the name that lab experiments occur in lab settings. Although this is not always the case, they can sometimes occur in other controlled environments. The purpose of lab experiments is to identify the cause and effect of a phenomenon through experimentation.

A lab experiment is an experiment that uses a carefully controlled setting and standardised procedure to accurately measure how changes in the independent variable (IV; variable that changes) affects the dependent variable (DV; variable measured).

In lab experiments, the IV is what the researcher predicts as the cause of a phenomenon, and the dependent variable is what the researcher predicts as the effect of a phenomenon.

Lab Experiment: P sychology

Lab experiments in psychology are used when trying to establish causal relationships between variables . For example, a researcher would use a lab experiment if they were investigating how sleep affects memory recall.

The majority of psychologists think of psychology as a form of science. Therefore, they argue that the protocol used in psychological research should resemble those used in the natural sciences. For research to be established as scientific , three essential features should be considered:

Empiricism - the findings should be observable via the five senses.
Reliability - if the study was replicated, similar results should be found.
Validity - the investigation should accurately measure what it intends to.

But do lab experiments fulfil these requirements of natural sciences research? If done correctly, then yes. Lab experiments are empirical as they involve the researcher observing changes occurring in the DV. Reliability is established by using a standardised procedure in lab experiments .

A standardised procedure is a protocol that states how the experiment will be carried out. This allows the researcher to ensure the same protocol is used for each participant, increasing the study's internal reliability.

Standardised procedures are also used to help other researchers replicate the study to identify if they measure similar results.

Dissimilar results reflect low reliability.

Validity is another feature of a lab experiment considered. Lab experiments are conducted in a carefully controlled setting where the researcher has the most control compared to other experiments to prevent extraneous variables from affecting the DV .

Extraneous variables are factors other than the IV that affect the DV; as these are variables that the researcher is not interested in investigating, these reduce the validity of the research.

There are issues of validity in lab experiments, which we'll get into a bit later!

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Lab Experiment Examples: Asch's Conformity Study

The Asch (1951) conformity study is an example of a lab experiment. The investigation aimed to identify if the presence and influence of others would pressure participants to change their response to a straightforward question. Participants were given two pieces of paper, one depicting a 'target line' and another three, one of which resembled the 'target line' and the others of different lengths.

The participants were put in groups of eight. Unknown to the participants, the other seven were confederates (participants who were secretly part of the research team) who were instructed to give the wrong answer. If the actual participant changed their answer in response, this would be an example of conformity .

Asch controlled the location where the investigation took place, constructed a contrived scenario and even controlled the confederates who would affect the behaviour of the actual participants to measure the DV.

Some other famous examples of research that are lab experiment examples include research conducted by Milgram (the obedience study) and Loftus and Palmer's eyewitness testimony accuracy study . These researchers likely used this method because of some of their strengths , e.g., their high level of control .

Lab Experiment Examples: Cognitive Lab Experiments

Let's look at what a cognitive lab experiment may entail. Suppose a researcher is interested in investigating how sleep affects memory scores using the MMSE test. In the theoretical study , an equal number of participants were randomly allocated into two groups; sleep-deprived versus well-rested. Both groups completed the memory test after a whole night of sleep or staying awake all night.

In this research scenario , the DV can be identified as memory test scores and the IV as whether participants were sleep-deprived or well-rested.

Some examples of extraneous variables the study controlled include researchers ensuring participants did not fall asleep, the participants took the test at the same time, and participants in the well-rested group slept for the same time.

Lab Experiment Advantages and Disadvantages

It's important to consider the advantages and disadvantages of laboratory experiments . Advantages include the highly controlled setting of lab experiments, the standardised procedures and causal conclusions that can be drawn. Disadvantages include the low ecological validity of lab experiments and demand characteristics participants may present.

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Strengths of Lab Experiments: Highly Controlled

Laboratory experiments are conducted in a well-controlled setting. All the variables, including extraneous and confounding variables , are rigidly controlled in the investigation. Therefore, the risk of experimental findings being affected by extraneous or confounding variables is reduced . As a result, the well-controlled design of laboratory experiments implies the research has high internal validity .

Internal validity means the study uses measures and protocols that measure exactly what it intends to, i.e. how only the changes in the IV affect the DV.

Strengths of Lab Experiments: Standardised Procedures

Laboratory experiments have standardised procedures, which means the experiments are replicable , and all participants are tested under the same conditions. T herefore, standardised procedures allow others to replicate the study to identify whether the research is reliable and that the findings are not a one-off result. As a result, the replicability of laboratory experiments allows researchers to verify the study's reliability .

Strengths of Lab Experiments: Causal Conclusions

A well-designed laboratory experiment can draw causal conclusions. Ideally, a laboratory experiment can rigidly control all the variables , including extraneous and confounding variables. Therefore, laboratory experiments provide great confidence to researchers that the IV causes any observed changes in DV.

Weaknesses of Lab Experiments

In the following, we will present the disadvantages of laboratory experiments. This discusses ecological validity and demand characteristics.

Weaknesses of Lab Experiments: Low Ecological Validity

Laboratory experiments have low ecological validity because they are conducted in an artificial study that does not reflect a real-life setting . As a result, findings generated in laboratory experiments can be difficult to generalise to real life due to the low mundane realism. Mundane realism reflects the extent to which lab experiment materials are similar to real-life events.

Weaknesses of Lab Experiments: Demand Characteristics

A disadvantage of laboratory experiments is that the research setting may lead to demand characteristics .

Demand characteristics are the cues that make participants aware of what the experimenter expects to find or how participants are expected to behave.

The participants are aware they are involved in an experiment. So, participants may have some ideas of what is expected of them in the investigation, which may influence their behaviours. As a result, the demand characteristics presented in laboratory experiments can arguably change the research outcome , reducing the findings' validity .

Lab Experiment - Key takeaways

The lab experiment definition is an experiment that uses a carefully controlled setting and standardised procedure to establish how changes in the independent variable (IV; variable that changes) affect the dependent variable (DV; variable measured).

Psychologists aim to ensure that lab experiments are scientific and must be empirical, reliable and valid.

The advantages of lab experiments are high internal validity, standardised procedures and the ability to draw causal conclusions.

The disadvantages of lab experiments are low ecological validity and demand characteristics.

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Frequently Asked Questions about Lab Experiment

What is a lab experiment?

A lab experiment is an experiment that uses a carefully controlled setting and standardised procedure to establish how changes in the independent variable (IV; variable that changes) affects the dependent variable (DV; variable measured).

What is the purpose of lab experiments?

Lab experiments investigate cause-and-effect. They aim to determine the effect of changes in the independent variable on the dependent variable.

What is a lab experiment and field experiment?

A field experiment is an experiment conducted in a natural, everyday setting. The experimenter still controls the IV; however, extraneous and confounding variables may be difficult to control due to the natural setting.

Similar, to filed experiments researchers, can control the IV and extraneous variables. However, this takes place in an artificial setting such as a lab.

Why would a psychologist use a laboratory experiment?

A psychologist may use a lab experiment when trying to establish the causal relationships between variables to explain a phenomenon.

Why is lab experience important?

Lab experience allows researchers to scientifically determine whether a hypothesis/ theory should be accepted or rejected.

What is a lab experiment example?

The research conducted by Loftus and Palmer (accuracy of eyewitness testimony) and Milgram (obedience) used a lab experiment design. These experimental designs give the researcher high control, allowing them to control extraneous and independent variables.

Test your knowledge with multiple choice flashcards

The aim of lab experiments is to identify if observed changes in the are caused by the .

Demand characteristics lower the of the research.

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UNDERTALE is an indie RPG created by developer Toby Fox about a child, who falls into an underground world filled with monsters. Their only weapon being their DETERMINATION as they try to FIGHT or ACT their way out. Will you show monsters standing in your way MERCY, or slaughter them all?

True Lab- All Entries and Tapes transcribed

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Undertale - True Laboratory explored: How to beat Memoryheads, Endogeny, Lemon Bread, Snowdrake's Mom and Reaper Bird

True Laboratory is filled with new secrets in Undertale - here's how to explore it.

True Laboratory is an optional area in Undertale , following the boss battle with Asgore and completing the requirements of a Pacifist playthrough.

Our complete Pacifist guide tells you how to get here, but in short, you need to go through the entire game without killing anything to unlock this bonus dungeon.

Most other endings follow the exact same route and only differ in small ways, and our wider Undertale walkthrough delves into other areas of the game.

How to access the True Laboratory

If you made it to the end without killing any monsters (apart from Flowey) and befriended Papyrus and Undyne along the way then the story's not quite over yet, and there's more to discover.

Head back to MTT Resort and Undyne will call with a favour to ask. Get the ferry from Hotlands to Snowdin Village and go to Papyrus's house, and Undyne will give you a letter to deliver to Alphys.

Take the ferry back to Hotlands and slide the note under the door, and after a brief and awkward conversation you'll end up on a date with Alphys.

During the date it makes no difference which answers you give to any of the questions. Undyne will show up, things will get even more awkward, and you'll find yourself back in the sewer.

As you leave Papyrus will call and suggest you go and speak to Alphys again, so head back to the Laboratory.

True Laboratory

When you arrive the place is deserted, and you'll find a note on the floor. Read it, then head through the door to the north and ride the elevator down to the bottom.

It's dark and eerie down here, but you have no choice other than exploring so head east - the panels on the wall will provide some clues as to what's going on.

When you reach the lobby at the end of the corridor you'll encounter a locked door; there are four keys needed to open it, so start by heading through the exit in the top left and follow the corridor to the end. Use the three taps to summon some Memoryheads.

Memoryheads boss battle

As with all the fights in this area, they're designed more to be creepy rather than dangerous. Call the Memoryheads on your phone by selecting Cell from the Act menu, then Refuse when they ask you to join them.

Their attacks are very easy to avoid - just stay away from the dots that appear in the combat box.

Once you've Spared them collect the red key they leave behind and head through the door to the north. Use the key in the panel on the wall, retrace your steps to the lobby, and head out through the exit in the top right.

Follow the passageway east until you come to a room with several beds in it. Examine the rightmost bed in the middle row to find the yellow key, use the save point in the corner, and then exit to the north.

Head right into the foggy room and use the switch at the end to clear the air, and Endogeny will appear.

Endogeny boss battle

This fight is very similar to Greater Dog. Start by Beckoning it towards you, Pet it, Play with it, then Pet it twice more to Spare it.

Head back out into the corridor and head west. When you come to the door in the north wall head inside and examine the bathtub at the far end to find the green key, then return to the corridor and head west again.

You'll come to a room with a rather odd looking structure in the middle of it. Head into the room immediately to the north and use your yellow key.

The room contains some video tapes that answer some questions but pose just as many; once you've watched them head back out into the main room and use the save point.

Lemon Bread boss battle

This creature is a combination of Shyren, Moldbygg, and Aaron. Start by Humming to it, then Unhug it, and finally give it a Flex, and when it attacks stand in the gap between its teeth to avoid taking damage.

Head west and you'll end up in a room full of fridges. Look at them all, and then head for the door at the far end.

Snowdrake's Mom boss battle

She won't attack you - just tell her three Jokes and the fight is over.

Pick up the blue key she drops, head through the door to the north and use your green key, then return to the room with the beds in it and exit to the east. As you walk past the mirrors Reaper Bird will attack.

Playing Undertale? Our complete Undertale walkthrough and Pacifist guide will explain how to finish the game while sparing everyone, covering all areas including the Ruins , Snowdin , Waterfall , Hotlands and The Core and more. You can also learn about how to unlock every Undertale ending and all Undertale Trophies , access hard mode and play the game in the most evil way possible with a Genocide run .

Reaper Bird boss battle

Pick On the bird first, then Pray, and finally Mystify it. Her attacks vary each round, but are all easy to dodge.

Head to the room at the end of the corridor and use the blue key, then return to the lobby - the large door will now be unlocked, so head inside.

The elevator doesn't have power, so leave through the door to the left and follow the corridor. As you approach the switch in the room at the end more creatures will attack, but Alphys will call them off. Restore the power, then return to the elevator and you'll be returned to New Home.

Head back to the throne room where you first fought Asgore. There's quite a lot of story to take in, but the pieces should all start falling into place as it builds towards the encounter with the final boss and the true ending . Very best of luck!

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How to Conduct a Psychology Experiment

Conducting your first psychology experiment can be a long, complicated, and sometimes intimidating process. It can be especially confusing if you are not quite sure where to begin or which steps to take.

Like other sciences, psychology utilizes the scientific method and bases conclusions upon empirical evidence. When conducting an experiment, it is important to follow the seven basic steps of the scientific method:

Ask a testable question
Define your variables
Conduct background research
Design your experiment
Perform the experiment
Collect and analyze the data
Draw conclusions
Share the results with the scientific community

At a Glance

It's important to know the steps of the scientific method if you are conducting an experiment in psychology or other fields. The processes encompasses finding a problem you want to explore, learning what has already been discovered about the topic, determining your variables, and finally designing and performing your experiment. But the process doesn't end there! Once you've collected your data, it's time to analyze the numbers, determine what they mean, and share what you've found.

Find a Research Problem or Question

Picking a research problem can be one of the most challenging steps when you are conducting an experiment. After all, there are so many different topics you might choose to investigate.

Are you stuck for an idea? Consider some of the following:

Investigate a Commonly Held Belief

Folk knowledge is a good source of questions that can serve as the basis for psychological research. For example, many people believe that staying up all night to cram for a big exam can actually hurt test performance.

You could conduct a study to compare the test scores of students who stayed up all night with the scores of students who got a full night's sleep before the exam.

Review Psychology Literature

Published studies are a great source of unanswered research questions. In many cases, the authors will even note the need for further research. Find a published study that you find intriguing, and then come up with some questions that require further exploration.

Think About Everyday Problems

There are many practical applications for psychology research. Explore various problems that you or others face each day, and then consider how you could research potential solutions. For example, you might investigate different memorization strategies to determine which methods are most effective.

Define Your Variables

Variables are anything that might impact the outcome of your study. An operational definition describes exactly what the variables are and how they are measured within the context of your study.

For example, if you were doing a study on the impact of sleep deprivation on driving performance, you would need to operationally define sleep deprivation and driving performance .

An operational definition refers to a precise way that an abstract concept will be measured. For example, you cannot directly observe and measure something like test anxiety . You can, however, use an anxiety scale and assign values based on how many anxiety symptoms a person is experiencing.

In this example, you might define sleep deprivation as getting less than seven hours of sleep at night. You might define driving performance as how well a participant does on a driving test.

What is the purpose of operationally defining variables? The main purpose is control. By understanding what you are measuring, you can control for it by holding the variable constant between all groups or manipulating it as an independent variable .

Develop a Hypothesis

The next step is to develop a testable hypothesis that predicts how the operationally defined variables are related. In the recent example, the hypothesis might be: "Students who are sleep-deprived will perform worse than students who are not sleep-deprived on a test of driving performance."

Null Hypothesis

In order to determine if the results of the study are significant, it is essential to also have a null hypothesis. The null hypothesis is the prediction that one variable will have no association to the other variable.

In other words, the null hypothesis assumes that there will be no difference in the effects of the two treatments in our experimental and control groups .

The null hypothesis is assumed to be valid unless contradicted by the results. The experimenters can either reject the null hypothesis in favor of the alternative hypothesis or not reject the null hypothesis.

It is important to remember that not rejecting the null hypothesis does not mean that you are accepting the null hypothesis. To say that you are accepting the null hypothesis is to suggest that something is true simply because you did not find any evidence against it. This represents a logical fallacy that should be avoided in scientific research.

Conduct Background Research

Once you have developed a testable hypothesis, it is important to spend some time doing some background research. What do researchers already know about your topic? What questions remain unanswered?

You can learn about previous research on your topic by exploring books, journal articles, online databases, newspapers, and websites devoted to your subject.

Reading previous research helps you gain a better understanding of what you will encounter when conducting an experiment. Understanding the background of your topic provides a better basis for your own hypothesis.

After conducting a thorough review of the literature, you might choose to alter your own hypothesis. Background research also allows you to explain why you chose to investigate your particular hypothesis and articulate why the topic merits further exploration.

As you research the history of your topic, take careful notes and create a working bibliography of your sources. This information will be valuable when you begin to write up your experiment results.

Select an Experimental Design

After conducting background research and finalizing your hypothesis, your next step is to develop an experimental design. There are three basic types of designs that you might utilize. Each has its own strengths and weaknesses:

Pre-Experimental Design

A single group of participants is studied, and there is no comparison between a treatment group and a control group. Examples of pre-experimental designs include case studies (one group is given a treatment and the results are measured) and pre-test/post-test studies (one group is tested, given a treatment, and then retested).

Quasi-Experimental Design

This type of experimental design does include a control group but does not include randomization. This type of design is often used if it is not feasible or ethical to perform a randomized controlled trial.

True Experimental Design

A true experimental design, also known as a randomized controlled trial, includes both of the elements that pre-experimental designs and quasi-experimental designs lack—control groups and random assignment to groups.

Standardize Your Procedures

In order to arrive at legitimate conclusions, it is essential to compare apples to apples.

Each participant in each group must receive the same treatment under the same conditions.

For example, in our hypothetical study on the effects of sleep deprivation on driving performance, the driving test must be administered to each participant in the same way. The driving course must be the same, the obstacles faced must be the same, and the time given must be the same.

Choose Your Participants

In addition to making sure that the testing conditions are standardized, it is also essential to ensure that your pool of participants is the same.

If the individuals in your control group (those who are not sleep deprived) all happen to be amateur race car drivers while your experimental group (those that are sleep deprived) are all people who just recently earned their driver's licenses, your experiment will lack standardization.

When choosing subjects, there are some different techniques you can use.

Simple Random Sample

In a simple random sample, the participants are randomly selected from a group. A simple random sample can be used to represent the entire population from which the representative sample is drawn.

Drawing a simple random sample can be helpful when you don't know a lot about the characteristics of the population.

Stratified Random Sample

Participants must be randomly selected from different subsets of the population. These subsets might include characteristics such as geographic location, age, sex, race, or socioeconomic status.

Stratified random samples are more complex to carry out. However, you might opt for this method if there are key characteristics about the population that you want to explore in your research.

Conduct Tests and Collect Data

After you have selected participants, the next steps are to conduct your tests and collect the data. Before doing any testing, however, there are a few important concerns that need to be addressed.

Address Ethical Concerns

First, you need to be sure that your testing procedures are ethical . Generally, you will need to gain permission to conduct any type of testing with human participants by submitting the details of your experiment to your school's Institutional Review Board (IRB), sometimes referred to as the Human Subjects Committee.

Obtain Informed Consent

After you have gained approval from your institution's IRB, you will need to present informed consent forms to each participant. This form offers information on the study, the data that will be gathered, and how the results will be used. The form also gives participants the option to withdraw from the study at any point in time.

Once this step has been completed, you can begin administering your testing procedures and collecting the data.

Analyze the Results

After collecting your data, it is time to analyze the results of your experiment. Researchers use statistics to determine if the results of the study support the original hypothesis and if the results are statistically significant.

Statistical significance means that the study's results are unlikely to have occurred simply by chance.

The types of statistical methods you use to analyze your data depend largely on the type of data that you collected. If you are using a random sample of a larger population, you will need to utilize inferential statistics.

These statistical methods make inferences about how the results relate to the population at large.

Because you are making inferences based on a sample, it has to be assumed that there will be a certain margin of error. This refers to the amount of error in your results. A large margin of error means that there will be less confidence in your results, while a small margin of error means that you are more confident that your results are an accurate reflection of what exists in that population.

Share Your Results After Conducting an Experiment

Your final task in conducting an experiment is to communicate your results. By sharing your experiment with the scientific community, you are contributing to the knowledge base on that particular topic.

One of the most common ways to share research results is to publish the study in a peer-reviewed professional journal. Other methods include sharing results at conferences, in book chapters, or academic presentations.

In your case, it is likely that your class instructor will expect a formal write-up of your experiment in the same format required in a professional journal article or lab report :

Introduction
Tables and figures

What This Means For You

Designing and conducting a psychology experiment can be quite intimidating, but breaking the process down step-by-step can help. No matter what type of experiment you decide to perform, always check with your instructor and your school's institutional review board for permission before you begin.

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Serdar CC, Cihan M, Yücel D, Serdar MA. Sample size, power and effect size revisited: simplified and practical approaches in pre-clinical, clinical and laboratory studies . Biochem Med (Zagreb) . 2021;31(1):010502. doi:10.11613/BM.2021.010502

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

Child Care and Early Education Research Connections

Experiments and quasi-experiments.

This page includes an explanation of the types, key components, validity, ethics, and advantages and disadvantages of experimental design.

An experiment is a study in which the researcher manipulates the level of some independent variable and then measures the outcome. Experiments are powerful techniques for evaluating cause-and-effect relationships. Many researchers consider experiments the "gold standard" against which all other research designs should be judged. Experiments are conducted both in the laboratory and in real life situations.

Types of Experimental Design

There are two basic types of research design:

True experiments
Quasi-experiments

The purpose of both is to examine the cause of certain phenomena.

True experiments, in which all the important factors that might affect the phenomena of interest are completely controlled, are the preferred design. Often, however, it is not possible or practical to control all the key factors, so it becomes necessary to implement a quasi-experimental research design.

Similarities between true and quasi-experiments:

Study participants are subjected to some type of treatment or condition
Some outcome of interest is measured
The researchers test whether differences in this outcome are related to the treatment

Differences between true experiments and quasi-experiments:

In a true experiment, participants are randomly assigned to either the treatment or the control group, whereas they are not assigned randomly in a quasi-experiment
In a quasi-experiment, the control and treatment groups differ not only in terms of the experimental treatment they receive, but also in other, often unknown or unknowable, ways. Thus, the researcher must try to statistically control for as many of these differences as possible
Because control is lacking in quasi-experiments, there may be several "rival hypotheses" competing with the experimental manipulation as explanations for observed results

Key Components of Experimental Research Design

The manipulation of predictor variables.

In an experiment, the researcher manipulates the factor that is hypothesized to affect the outcome of interest. The factor that is being manipulated is typically referred to as the treatment or intervention. The researcher may manipulate whether research subjects receive a treatment (e.g., antidepressant medicine: yes or no) and the level of treatment (e.g., 50 mg, 75 mg, 100 mg, and 125 mg).

Suppose, for example, a group of researchers was interested in the causes of maternal employment. They might hypothesize that the provision of government-subsidized child care would promote such employment. They could then design an experiment in which some subjects would be provided the option of government-funded child care subsidies and others would not. The researchers might also manipulate the value of the child care subsidies in order to determine if higher subsidy values might result in different levels of maternal employment.

Random Assignment

Study participants are randomly assigned to different treatment groups
All participants have the same chance of being in a given condition
Participants are assigned to either the group that receives the treatment, known as the "experimental group" or "treatment group," or to the group which does not receive the treatment, referred to as the "control group"
Random assignment neutralizes factors other than the independent and dependent variables, making it possible to directly infer cause and effect

Random Sampling

Traditionally, experimental researchers have used convenience sampling to select study participants. However, as research methods have become more rigorous, and the problems with generalizing from a convenience sample to the larger population have become more apparent, experimental researchers are increasingly turning to random sampling. In experimental policy research studies, participants are often randomly selected from program administrative databases and randomly assigned to the control or treatment groups.

Validity of Results

The two types of validity of experiments are internal and external. It is often difficult to achieve both in social science research experiments.

Internal Validity

When an experiment is internally valid, we are certain that the independent variable (e.g., child care subsidies) caused the outcome of the study (e.g., maternal employment)
When subjects are randomly assigned to treatment or control groups, we can assume that the independent variable caused the observed outcomes because the two groups should not have differed from one another at the start of the experiment
For example, take the child care subsidy example above. Since research subjects were randomly assigned to the treatment (child care subsidies available) and control (no child care subsidies available) groups, the two groups should not have differed at the outset of the study. If, after the intervention, mothers in the treatment group were more likely to be working, we can assume that the availability of child care subsidies promoted maternal employment

One potential threat to internal validity in experiments occurs when participants either drop out of the study or refuse to participate in the study. If particular types of individuals drop out or refuse to participate more often than individuals with other characteristics, this is called differential attrition. For example, suppose an experiment was conducted to assess the effects of a new reading curriculum. If the new curriculum was so tough that many of the slowest readers dropped out of school, the school with the new curriculum would experience an increase in the average reading scores. The reason they experienced an increase in reading scores, however, is because the worst readers left the school, not because the new curriculum improved students' reading skills.

External Validity

External validity is also of particular concern in social science experiments
It can be very difficult to generalize experimental results to groups that were not included in the study
Studies that randomly select participants from the most diverse and representative populations are more likely to have external validity
The use of random sampling techniques makes it easier to generalize the results of studies to other groups

For example, a research study shows that a new curriculum improved reading comprehension of third-grade children in Iowa. To assess the study's external validity, you would ask whether this new curriculum would also be effective with third graders in New York or with children in other elementary grades.

Glossary terms related to validity:

internal validity
external validity
differential attrition

It is particularly important in experimental research to follow ethical guidelines. Protecting the health and safety of research subjects is imperative. In order to assure subject safety, all researchers should have their project reviewed by the Institutional Review Boards (IRBS). The National Institutes of Health supplies strict guidelines for project approval. Many of these guidelines are based on the Belmont Report (pdf).

The basic ethical principles:

Respect for persons -- requires that research subjects are not coerced into participating in a study and requires the protection of research subjects who have diminished autonomy
Beneficence -- requires that experiments do not harm research subjects, and that researchers minimize the risks for subjects while maximizing the benefits for them
Justice -- requires that all forms of differential treatment among research subjects be justified

Advantages and Disadvantages of Experimental Design

The environment in which the research takes place can often be carefully controlled. Consequently, it is easier to estimate the true effect of the variable of interest on the outcome of interest.

Disadvantages

It is often difficult to assure the external validity of the experiment, due to the frequently nonrandom selection processes and the artificial nature of the experimental context.

16 Advantages and Disadvantages of Experimental Research

How do you make sure that a new product, theory, or idea has validity? There are multiple ways to test them, with one of the most common being the use of experimental research. When there is complete control over one variable, the other variables can be manipulated to determine the value or validity that has been proposed.

Then, through a process of monitoring and administration, the true effects of what is being studied can be determined. This creates an accurate outcome so conclusions about the final value potential. It is an efficient process, but one that can also be easily manipulated to meet specific metrics if oversight is not properly performed.

Here are the advantages and disadvantages of experimental research to consider.

What Are the Advantages of Experimental Research?

1. It provides researchers with a high level of control. By being able to isolate specific variables, it becomes possible to determine if a potential outcome is viable. Each variable can be controlled on its own or in different combinations to study what possible outcomes are available for a product, theory, or idea as well. This provides a tremendous advantage in an ability to find accurate results.

2. There is no limit to the subject matter or industry involved. Experimental research is not limited to a specific industry or type of idea. It can be used in a wide variety of situations. Teachers might use experimental research to determine if a new method of teaching or a new curriculum is better than an older system. Pharmaceutical companies use experimental research to determine the viability of a new product.

3. Experimental research provides conclusions that are specific. Because experimental research provides such a high level of control, it can produce results that are specific and relevant with consistency. It is possible to determine success or failure, making it possible to understand the validity of a product, theory, or idea in a much shorter amount of time compared to other verification methods. You know the outcome of the research because you bring the variable to its conclusion.

4. The results of experimental research can be duplicated. Experimental research is straightforward, basic form of research that allows for its duplication when the same variables are controlled by others. This helps to promote the validity of a concept for products, ideas, and theories. This allows anyone to be able to check and verify published results, which often allows for better results to be achieved, because the exact steps can produce the exact results.

5. Natural settings can be replicated with faster speeds. When conducting research within a laboratory environment, it becomes possible to replicate conditions that could take a long time so that the variables can be tested appropriately. This allows researchers to have a greater control of the extraneous variables which may exist as well, limiting the unpredictability of nature as each variable is being carefully studied.

6. Experimental research allows cause and effect to be determined. The manipulation of variables allows for researchers to be able to look at various cause-and-effect relationships that a product, theory, or idea can produce. It is a process which allows researchers to dig deeper into what is possible, showing how the various variable relationships can provide specific benefits. In return, a greater understanding of the specifics within the research can be understood, even if an understanding of why that relationship is present isn’t presented to the researcher.

7. It can be combined with other research methods. This allows experimental research to be able to provide the scientific rigor that may be needed for the results to stand on their own. It provides the possibility of determining what may be best for a specific demographic or population while also offering a better transference than anecdotal research can typically provide.

What Are the Disadvantages of Experimental Research?

1. Results are highly subjective due to the possibility of human error. Because experimental research requires specific levels of variable control, it is at a high risk of experiencing human error at some point during the research. Any error, whether it is systemic or random, can reveal information about the other variables and that would eliminate the validity of the experiment and research being conducted.

2. Experimental research can create situations that are not realistic. The variables of a product, theory, or idea are under such tight controls that the data being produced can be corrupted or inaccurate, but still seem like it is authentic. This can work in two negative ways for the researcher. First, the variables can be controlled in such a way that it skews the data toward a favorable or desired result. Secondly, the data can be corrupted to seem like it is positive, but because the real-life environment is so different from the controlled environment, the positive results could never be achieved outside of the experimental research.

3. It is a time-consuming process. For it to be done properly, experimental research must isolate each variable and conduct testing on it. Then combinations of variables must also be considered. This process can be lengthy and require a large amount of financial and personnel resources. Those costs may never be offset by consumer sales if the product or idea never makes it to market. If what is being tested is a theory, it can lead to a false sense of validity that may change how others approach their own research.

4. There may be ethical or practical problems with variable control. It might seem like a good idea to test new pharmaceuticals on animals before humans to see if they will work, but what happens if the animal dies because of the experimental research? Or what about human trials that fail and cause injury or death? Experimental research might be effective, but sometimes the approach has ethical or practical complications that cannot be ignored. Sometimes there are variables that cannot be manipulated as it should be so that results can be obtained.

5. Experimental research does not provide an actual explanation. Experimental research is an opportunity to answer a Yes or No question. It will either show you that it will work or it will not work as intended. One could argue that partial results could be achieved, but that would still fit into the “No” category because the desired results were not fully achieved. The answer is nice to have, but there is no explanation as to how you got to that answer. Experimental research is unable to answer the question of “Why” when looking at outcomes.

6. Extraneous variables cannot always be controlled. Although laboratory settings can control extraneous variables, natural environments provide certain challenges. Some studies need to be completed in a natural setting to be accurate. It may not always be possible to control the extraneous variables because of the unpredictability of Mother Nature. Even if the variables are controlled, the outcome may ensure internal validity, but do so at the expense of external validity. Either way, applying the results to the general population can be quite challenging in either scenario.

7. Participants can be influenced by their current situation. Human error isn’t just confined to the researchers. Participants in an experimental research study can also be influenced by extraneous variables. There could be something in the environment, such an allergy, that creates a distraction. In a conversation with a researcher, there may be a physical attraction that changes the responses of the participant. Even internal triggers, such as a fear of enclosed spaces, could influence the results that are obtained. It is also very common for participants to “go along” with what they think a researcher wants to see instead of providing an honest response.

8. Manipulating variables isn’t necessarily an objective standpoint. For research to be effective, it must be objective. Being able to manipulate variables reduces that objectivity. Although there are benefits to observing the consequences of such manipulation, those benefits may not provide realistic results that can be used in the future. Taking a sample is reflective of that sample and the results may not translate over to the general population.

9. Human responses in experimental research can be difficult to measure. There are many pressures that can be placed on people, from political to personal, and everything in-between. Different life experiences can cause people to react to the same situation in different ways. Not only does this mean that groups may not be comparable in experimental research, but it also makes it difficult to measure the human responses that are obtained or observed.

The advantages and disadvantages of experimental research show that it is a useful system to use, but it must be tightly controlled in order to be beneficial. It produces results that can be replicated, but it can also be easily influenced by internal or external influences that may alter the outcomes being achieved. By taking these key points into account, it will become possible to see if this research process is appropriate for your next product, theory, or idea.

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Laboratory Experiments

Last updated 22 Mar 2021

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Experiments look for the effect that manipulated variables (independent variables, or IVs) have on measured variables (dependent variables, or DVs), i.e. causal effects.

Laboratory experiments pay particular attention to eliminating the effects of other, extraneous variables, by controlling them (i.e. removing or keeping them constant) in an artificial environment. This makes it more likely for researchers to find a causal effect, having confidence that no variables other than changes in an IV can affect a resulting DV. Laboratory experiments are the most heavily controlled form of experimental research.

Participants can also be randomly allocated to experimental conditions, to avoid experimenter bias (i.e. the experimenter cannot be accused of choosing who will be in each experimental condition, which could affect the results).

Evaluation of laboratory experiments:

- High control over extraneous variables means that they cannot confound the results, so a ‘cause and effect’ relationship between the IV and DV is often assumed.

- Results of laboratory experiments tend to be reliable, as the conditions created (and thus results produced) can be replicated.

- Variables can be measured accurately with the tools made available in a laboratory setting, which may otherwise be impossible for experiments conducted ‘in the field’ (field experiments).

- Data collected may lack ecological validity, as the artificial nature of laboratory experiments can cast doubt over whether the results reflect the nature of real life scenarios.

- There is a high risk of demand characteristics, i.e. participants may alter their behaviour based on their interpretation of the purpose of the experiment.

- There is also a risk of experimenter bias, e.g. researchers’ expectations may affect how they interact with participants (affecting participants’ behaviour), or alter their interpretation of the results.

Laboratory Experiment

Emergence of psychology as a science: the laboratory experiment, learning approaches - the behaviourist approach, similarities and differences between classical and operant conditioning, learning approaches - social learning theory, differences between behaviourism and social learning theory, research methods in the social learning theory, example answers for research methods: a level psychology, paper 2, june 2018 (aqa).

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How to write a lab report

How To Write A Lab Report | Step-by-Step Guide & Examples

Published on May 20, 2021 by Pritha Bhandari . Revised on July 23, 2023.

A lab report conveys the aim, methods, results, and conclusions of a scientific experiment. The main purpose of a lab report is to demonstrate your understanding of the scientific method by performing and evaluating a hands-on lab experiment. This type of assignment is usually shorter than a research paper .

Lab reports are commonly used in science, technology, engineering, and mathematics (STEM) fields. This article focuses on how to structure and write a lab report.

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Structuring a lab report, introduction, other interesting articles, frequently asked questions about lab reports.

The sections of a lab report can vary between scientific fields and course requirements, but they usually contain the purpose, methods, and findings of a lab experiment .

Each section of a lab report has its own purpose.

Title: expresses the topic of your study
Abstract : summarizes your research aims, methods, results, and conclusions
Introduction: establishes the context needed to understand the topic
Method: describes the materials and procedures used in the experiment
Results: reports all descriptive and inferential statistical analyses
Discussion: interprets and evaluates results and identifies limitations
Conclusion: sums up the main findings of your experiment
References: list of all sources cited using a specific style (e.g. APA )
Appendices : contains lengthy materials, procedures, tables or figures

Although most lab reports contain these sections, some sections can be omitted or combined with others. For example, some lab reports contain a brief section on research aims instead of an introduction, and a separate conclusion is not always required.

If you’re not sure, it’s best to check your lab report requirements with your instructor.

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Your title provides the first impression of your lab report – effective titles communicate the topic and/or the findings of your study in specific terms.

Create a title that directly conveys the main focus or purpose of your study. It doesn’t need to be creative or thought-provoking, but it should be informative.

The effects of varying nitrogen levels on tomato plant height.
Testing the universality of the McGurk effect.
Comparing the viscosity of common liquids found in kitchens.

An abstract condenses a lab report into a brief overview of about 150–300 words. It should provide readers with a compact version of the research aims, the methods and materials used, the main results, and the final conclusion.

Think of it as a way of giving readers a preview of your full lab report. Write the abstract last, in the past tense, after you’ve drafted all the other sections of your report, so you’ll be able to succinctly summarize each section.

To write a lab report abstract, use these guiding questions:

What is the wider context of your study?
What research question were you trying to answer?
How did you perform the experiment?
What did your results show?
How did you interpret your results?
What is the importance of your findings?

Nitrogen is a necessary nutrient for high quality plants. Tomatoes, one of the most consumed fruits worldwide, rely on nitrogen for healthy leaves and stems to grow fruit. This experiment tested whether nitrogen levels affected tomato plant height in a controlled setting. It was expected that higher levels of nitrogen fertilizer would yield taller tomato plants.

Levels of nitrogen fertilizer were varied between three groups of tomato plants. The control group did not receive any nitrogen fertilizer, while one experimental group received low levels of nitrogen fertilizer, and a second experimental group received high levels of nitrogen fertilizer. All plants were grown from seeds, and heights were measured 50 days into the experiment.

The effects of nitrogen levels on plant height were tested between groups using an ANOVA. The plants with the highest level of nitrogen fertilizer were the tallest, while the plants with low levels of nitrogen exceeded the control group plants in height. In line with expectations and previous findings, the effects of nitrogen levels on plant height were statistically significant. This study strengthens the importance of nitrogen for tomato plants.

Your lab report introduction should set the scene for your experiment. One way to write your introduction is with a funnel (an inverted triangle) structure:

Start with the broad, general research topic
Narrow your topic down your specific study focus
End with a clear research question

Begin by providing background information on your research topic and explaining why it’s important in a broad real-world or theoretical context. Describe relevant previous research on your topic and note how your study may confirm it or expand it, or fill a gap in the research field.

This lab experiment builds on previous research from Haque, Paul, and Sarker (2011), who demonstrated that tomato plant yield increased at higher levels of nitrogen. However, the present research focuses on plant height as a growth indicator and uses a lab-controlled setting instead.

Next, go into detail on the theoretical basis for your study and describe any directly relevant laws or equations that you’ll be using. State your main research aims and expectations by outlining your hypotheses .

Based on the importance of nitrogen for tomato plants, the primary hypothesis was that the plants with the high levels of nitrogen would grow the tallest. The secondary hypothesis was that plants with low levels of nitrogen would grow taller than plants with no nitrogen.

Your introduction doesn’t need to be long, but you may need to organize it into a few paragraphs or with subheadings such as “Research Context” or “Research Aims.”

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A lab report Method section details the steps you took to gather and analyze data. Give enough detail so that others can follow or evaluate your procedures. Write this section in the past tense. If you need to include any long lists of procedural steps or materials, place them in the Appendices section but refer to them in the text here.

You should describe your experimental design, your subjects, materials, and specific procedures used for data collection and analysis.

Experimental design

Briefly note whether your experiment is a within-subjects or between-subjects design, and describe how your sample units were assigned to conditions if relevant.

A between-subjects design with three groups of tomato plants was used. The control group did not receive any nitrogen fertilizer. The first experimental group received a low level of nitrogen fertilizer, while the second experimental group received a high level of nitrogen fertilizer.

Describe human subjects in terms of demographic characteristics, and animal or plant subjects in terms of genetic background. Note the total number of subjects as well as the number of subjects per condition or per group. You should also state how you recruited subjects for your study.

List the equipment or materials you used to gather data and state the model names for any specialized equipment.

List of materials

35 Tomato seeds

15 plant pots (15 cm tall)

Light lamps (50,000 lux)

Nitrogen fertilizer

Measuring tape

Describe your experimental settings and conditions in detail. You can provide labelled diagrams or images of the exact set-up necessary for experimental equipment. State how extraneous variables were controlled through restriction or by fixing them at a certain level (e.g., keeping the lab at room temperature).

Light levels were fixed throughout the experiment, and the plants were exposed to 12 hours of light a day. Temperature was restricted to between 23 and 25℃. The pH and carbon levels of the soil were also held constant throughout the experiment as these variables could influence plant height. The plants were grown in rooms free of insects or other pests, and they were spaced out adequately.

Your experimental procedure should describe the exact steps you took to gather data in chronological order. You’ll need to provide enough information so that someone else can replicate your procedure, but you should also be concise. Place detailed information in the appendices where appropriate.

In a lab experiment, you’ll often closely follow a lab manual to gather data. Some instructors will allow you to simply reference the manual and state whether you changed any steps based on practical considerations. Other instructors may want you to rewrite the lab manual procedures as complete sentences in coherent paragraphs, while noting any changes to the steps that you applied in practice.

If you’re performing extensive data analysis, be sure to state your planned analysis methods as well. This includes the types of tests you’ll perform and any programs or software you’ll use for calculations (if relevant).

First, tomato seeds were sown in wooden flats containing soil about 2 cm below the surface. Each seed was kept 3-5 cm apart. The flats were covered to keep the soil moist until germination. The seedlings were removed and transplanted to pots 8 days later, with a maximum of 2 plants to a pot. Each pot was watered once a day to keep the soil moist.

The nitrogen fertilizer treatment was applied to the plant pots 12 days after transplantation. The control group received no treatment, while the first experimental group received a low concentration, and the second experimental group received a high concentration. There were 5 pots in each group, and each plant pot was labelled to indicate the group the plants belonged to.

50 days after the start of the experiment, plant height was measured for all plants. A measuring tape was used to record the length of the plant from ground level to the top of the tallest leaf.

In your results section, you should report the results of any statistical analysis procedures that you undertook. You should clearly state how the results of statistical tests support or refute your initial hypotheses.

The main results to report include:

any descriptive statistics
statistical test results
the significance of the test results
estimates of standard error or confidence intervals

The mean heights of the plants in the control group, low nitrogen group, and high nitrogen groups were 20.3, 25.1, and 29.6 cm respectively. A one-way ANOVA was applied to calculate the effect of nitrogen fertilizer level on plant height. The results demonstrated statistically significant ( p = .03) height differences between groups.

Next, post-hoc tests were performed to assess the primary and secondary hypotheses. In support of the primary hypothesis, the high nitrogen group plants were significantly taller than the low nitrogen group and the control group plants. Similarly, the results supported the secondary hypothesis: the low nitrogen plants were taller than the control group plants.

These results can be reported in the text or in tables and figures. Use text for highlighting a few key results, but present large sets of numbers in tables, or show relationships between variables with graphs.

You should also include sample calculations in the Results section for complex experiments. For each sample calculation, provide a brief description of what it does and use clear symbols. Present your raw data in the Appendices section and refer to it to highlight any outliers or trends.

The Discussion section will help demonstrate your understanding of the experimental process and your critical thinking skills.

In this section, you can:

Interpret your results
Compare your findings with your expectations
Identify any sources of experimental error
Explain any unexpected results
Suggest possible improvements for further studies

Interpreting your results involves clarifying how your results help you answer your main research question. Report whether your results support your hypotheses.

Did you measure what you sought out to measure?
Were your analysis procedures appropriate for this type of data?

Compare your findings with other research and explain any key differences in findings.

Are your results in line with those from previous studies or your classmates’ results? Why or why not?

An effective Discussion section will also highlight the strengths and limitations of a study.

Did you have high internal validity or reliability?
How did you establish these aspects of your study?

When describing limitations, use specific examples. For example, if random error contributed substantially to the measurements in your study, state the particular sources of error (e.g., imprecise apparatus) and explain ways to improve them.

The results support the hypothesis that nitrogen levels affect plant height, with increasing levels producing taller plants. These statistically significant results are taken together with previous research to support the importance of nitrogen as a nutrient for tomato plant growth.

However, unlike previous studies, this study focused on plant height as an indicator of plant growth in the present experiment. Importantly, plant height may not always reflect plant health or fruit yield, so measuring other indicators would have strengthened the study findings.

Another limitation of the study is the plant height measurement technique, as the measuring tape was not suitable for plants with extreme curvature. Future studies may focus on measuring plant height in different ways.

The main strengths of this study were the controls for extraneous variables, such as pH and carbon levels of the soil. All other factors that could affect plant height were tightly controlled to isolate the effects of nitrogen levels, resulting in high internal validity for this study.

Your conclusion should be the final section of your lab report. Here, you’ll summarize the findings of your experiment, with a brief overview of the strengths and limitations, and implications of your study for further research.

Some lab reports may omit a Conclusion section because it overlaps with the Discussion section, but you should check with your instructor before doing so.

If you want to know more about AI for academic writing, AI tools, or fallacies make sure to check out some of our other articles with explanations and examples or go directly to our tools!

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A lab report conveys the aim, methods, results, and conclusions of a scientific experiment . Lab reports are commonly assigned in science, technology, engineering, and mathematics (STEM) fields.

The purpose of a lab report is to demonstrate your understanding of the scientific method with a hands-on lab experiment. Course instructors will often provide you with an experimental design and procedure. Your task is to write up how you actually performed the experiment and evaluate the outcome.

In contrast, a research paper requires you to independently develop an original argument. It involves more in-depth research and interpretation of sources and data.

A lab report is usually shorter than a research paper.

The sections of a lab report can vary between scientific fields and course requirements, but it usually contains the following:

Abstract: summarizes your research aims, methods, results, and conclusions
References: list of all sources cited using a specific style (e.g. APA)
Appendices: contains lengthy materials, procedures, tables or figures

The results chapter or section simply and objectively reports what you found, without speculating on why you found these results. The discussion interprets the meaning of the results, puts them in context, and explains why they matter.

In qualitative research , results and discussion are sometimes combined. But in quantitative research , it’s considered important to separate the objective results from your interpretation of them.

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Guide to Experimental Design
Table of contents. Step 1: Define your variables. Step 2: Write your hypothesis. Step 3: Design your experimental treatments. Step 4: Assign your subjects to treatment groups. Step 5: Measure your dependent variable. Other interesting articles. Frequently asked questions about experiments.
Conducting an Experiment in Psychology
When conducting an experiment, it is important to follow the seven basic steps of the scientific method: Ask a testable question. Define your variables. Conduct background research. Design your experiment. Perform the experiment. Collect and analyze the data. Draw conclusions.
Experiments and Quasi-Experiments
Experiments and Quasi-Experiments
16 Advantages and Disadvantages of Experimental Research
6. Experimental research allows cause and effect to be determined. The manipulation of variables allows for researchers to be able to look at various cause-and-effect relationships that a product, theory, or idea can produce. It is a process which allows researchers to dig deeper into what is possible, showing how the various variable ...
APA Dictionary of Psychology
true experiment. Share button. Updated on 04/19/2018. a study in which participants are assigned at random to two or more experimentally manipulated treatment conditions or to a treatment group and a control group. This type of experiment is in contrast to quasi-experimental designs, ...
Laboratory Experiments
Laboratory Experiments | Reference Library | Psychology
Pacifist
updated Oct 9, 2018. This page tells you how to get through the True Laboratory section in Undertale which is only accessible on a true Pacifist run after completing New Home. It seems you've ...
How To Write A Lab Report
Introduction. Your lab report introduction should set the scene for your experiment. One way to write your introduction is with a funnel (an inverted triangle) structure: Start with the broad, general research topic. Narrow your topic down your specific study focus. End with a clear research question.

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Experimental Method In Psychology

What is an Experiment?

1. Lab Experiment

2. Field Experiment

3. Natural Experiment

Key Terminology

Experimenter effects

Demand characteristics

Independent variable (IV)

Dependent variable (DV)

Extraneous variables (EV)

Confounding variables

Random Allocation

Order effects

What are “True” experiments in Psychology?

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Understanding True Experiments in Psychology: Principles and Applications

What Are True Experiments in Psychology?

What Are the Principles of True Experiments?

Random Assignment

Control Group

Manipulation of Independent Variable

Measurement of Dependent Variable

Elimination of Confounding Variables

How Are True Experiments Different from Other Types of Studies?

Correlational Studies

Quasi-Experiments

Observational Studies

What Are the Applications of True Experiments in Psychology?

Testing Hypotheses

Establishing Cause and Effect Relationships

Replicating Previous Findings

Identifying Effective Treatments

Advancing Scientific Knowledge

What Are the Ethical Considerations in True Experiments?

What Are the Limitations of True Experiments?

How Can Researchers Improve the Validity of True Experiments?

Frequently Asked Questions

What are the principles of true experiments in psychology?

Why is random assignment important in true experiments?

How does manipulation of an independent variable work in true experiments?

How are extraneous variables controlled in true experiments?

What are some applications of true experiments in psychology?

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Psychology Sorted

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True, Natural and Field Experiments An easy lesson idea for learning about experiments.

True Experiments

Field Experiments

Activity Idea

What are “True” experiments in Psychology?

How to Conduct a True Experiment

Designing the Experiment

Running the Experiment

Analyzing Your Results