What's the IA all about?

The Internal Assessment (IA) is your chance to carry out an experiment in Psychology!   You will no longer just be reading about other people's research studies - you will be carrying out your own.  In doing so, you will experience what it is like to be a Psychological scientist.  You will face many of the same challenges that Psychology researchers encounter on a daily basis:  like how to ensure the ethical treatment of participants, design and carry out an effective experimental procedure, and draw out conclusions from raw data.

Your IA will involve a replication of an existing study.  That means you won't have to come up with a completely original research idea yourself; rather, you will be repeating a study which has already been published.  Replication has become a hot button issue in Psychology over the past few years, as many famous studies have been difficult to replicate with the same findings.  Your IA will attempt to confirm the findings of an original study, and in doing so, help establish the study's reliability.  You will need to consider how to adapt the original study so that it is easily replicated in the context of your local community, while keeping the spirit of the study as close to the original as possible. 

Your IA is worth 25% of your final grade if you are studying Psychology at Standard Level, and 20% if you are studying Psychology at Higher Level.  While getting an excellent grade will require a fair bit of work, it is certainly achievable if you understand the requirements of the IA and follow them carefully.  This guide will show you how.

Think Critically

Before you begin your IA, it is important to understand the role that replication plays in Psychology.  This understanding will help you realize that your IA is not just another meaningless school project - it is the real work of Psychology.

Read the article titled " More social science studies failed to replicate.  Here's why this is good" and consider the following discussion questions:

  • Why is replication important in the social sciences?

  • What is the "replication crisis" in Psychology?  What are the key events of the crisis to date?

  • If a study fails to replicate, what are some possible reasons why?
Step 1: Choose your team!

You are required to complete your IA in a group of two to four people.  Your group will choose an experiment to replicate, design a procedure, and collect data from participants.  Once the experiment has been carried out and the data collected, however, you will then each work individually to write your own final IA reports.

Working in a group can reduce the time each person must spend in carrying out the experiment.  For instance, if you work in a group of four, and aim to collect data from twenty participants, each group member could recruit and collect data from just five participants.  The data could then be pooled from all the participants, for instance, using a shared Google spreadsheet.  On the other hand, you will have to closely co-ordinate your group to make sure that each group member is following the exact same experimental procedure.

In choosing your group members, it is best to work with people who are reliable and trustworthy!  The success of your experiment depends on it.

Step 2: Choose a study

The IB sets particular guidelines for what kinds of studies are acceptable for your IA.  Some of these are due to ethical concerns, while others are due to methodological issues.  It is very important to make sure that your chosen study is suitable for replication - otherwise, you could instantly fail your IA.

To ensure your IA meets the ethical requirements of the IB, it cannot involve experimentation on animals, young children, or the use of any kind of substance.  It is best to use participants aged 16 and over - although you are allowed to use participants aged 12-16, consent from parents must be obtained for any participant under the age of 16.  Finally, your experiment cannot involve obedience or conformity, as these could be psychologically distressing to participants.

Your study must be a true experiment - in other words, there must be an independent variable that is manipulated, and a dependent variable that is measured.  To keep things simple, it is easiest to have two groups of participants, with each group assigned to one "level" of the independent variable.  The independent variable must be a variable that you can manipulate - comparing groups of participants (like males vs. females, or older students vs. younger students) is not a true experiment, and hence is not suitable for your IA.  The dependent variable must be something that you can measure with a number, like number of words remembered or estimated speed.

While there may seem to be many restrictions on what kind of experiment you can replicate, there are still many great options (Hint: most of them come from the Cognitive level of analysis).  For four suggested alternatives, see the next page in this guide.

Step 3: Design a procedure

Once you have chosen a study to replicate, you then need to plan exactly how you will carry out the replication.  First, you need to select between two basic study designs.  In an independent samples design, participants will be randomly assigned to one of two groups, and each group will get a different "level" of the independent variable.  For example, in Loftus and Palmer's experiment on memory, participants were randomly assigned to be asked slightly different questions about a car crash - some were asked "How fast were the cars going when they bumped each other?" while others were asked "How fast were the cars going when they smashed each other?"  On the other hand, in a repeated measures design, all participants are exposed to each level of the independent variable.  For example, in the famous STROOP experiment, all participants first name the colors when the words and colors are in sync, and then again when the words and colors are out of sync.

After choosing a basic study design, you will then need to decide how to recruit participants.  Will you send out an e-mail asking for volunteers, ask people in front of the cafeteria during lunchtime, or ask your family members to take part?  All of these sampling methods have strengths and limitations, and you should have good reasons for choosing a particular method.  Review the page on sampling methods for more guidance.

Finally, you now have to plan - in minute by minute detail - exactly how your experiment will be carried out.  Where will the experiment take place - and when?  What will you say to participants at each stage of the experiment?  What variables need to be controlled?  Your goal is to ensure that each participant has the exact same experience - except for the change in the independent variable.  Think carefully about any external factors that might affect participants - like the time of day, level of fatigue, whether the participant has just eaten or not, the level of noise in the surroundings, and so on.  Try to keep as many of these factors constant for all participants.

Think Critically

Watch the video below on the still face experiment and consider the following:

  • What is the independent variable?

  • What is the dependent variable?

  • Is this an independent design or repeated measures experiment? Explain why

  • Would it be suitable to replicate this study for your IA?  Explain why or why not.
Step 4: Collect and Analyze Data

Once you have carried out your experiment and collected your data, you then will apply statistical methods to interpret your findings.  If you used an independent samples design, you should have data from at least 20 participants - ten participants from each group.  If you used a repeated measures design, you are only required to have ten participants, since each participant is measured twice.  There are two types of statistics you will use to interpret your data:  descriptive and inferential.

  • Descriptive statistics involve summarizing the data you have collected.  You should calculate the mean and standard deviation of the dependent variable for each group of participants (or level of the independent variable).  Bar charts are helpful in comparing the mean and standard deviations.

  • Inferential statistics involve applying a statistical test to determine if the results are significant.  Let's say you found a difference in the mean between the two groups in your experiment.  This difference might be due to chance, or it might actually be caused by the independent variable.  Inferential statistics can help you determine which is more likely.

Step 5: Write your final report

The final step in the IA process is to write up and submit your final research report.  This is modeled on the format that Psychologists use when they submit their research papers to academic journals for publication.  More detail on each section is included on the rest of this website, but here is a brief overview of the required format:

  • Cover page and table of contents

  • Introduction - Explain the aim of your experiment, the theory upon which your experiment is based, the independent and dependent variables, and the hypothesis you are making

  • Procedure - Explain your experimental design, the sampling method, the characteristics of your sample, the variables that you controlled, and any materials you used

  • Findings - Results of the descriptive statistics (mean and standard deviation), a graph of the results, results of the inferential statistical test, and an interpretation of the findings in answering the hypothesis

  • Discussion - Interpret the findings with respect to the background theory you discussed in the introduction.  Explain strengths and limitations of the design, sample and procedure, and suggest how a future attempt at replication could be modified to address these limitations.

  • Appendices - Include the raw data you collected, and all materials you used in the experiment (such as the consent form, standardized briefing and debriefing instructions, and so forth)

  • References - Including the citation for the original study your IA is based upon, references that explain the background theory, and any online tools used in calculations

Quiz Yourself!

1.  Which group size is not acceptable for your IA?

(a) One

(b) Two

(c) Three

(d) Four

2.  Which part of the following tasks in your IA must be done individually?

(a) Designing the experimental procedure

(b) Selecting the independent and dependent variables

(c) Collecting data from participants

(d) Calculating descriptive and inferential statistics

3.  All of the following topics are not acceptable for your IA, except for one:

(a) Memory

(b) Compliance

(c) Conformity

(d) Animal research

4.  What is the minimum age for participants, for which no parental consent is required?

(a) 14

(b) 16

(c) 18

(d) 20

5.  Only one of the following hypotheses is acceptable for your IA.  Which one?

(a) The relationship between gender and spatial navigation ability

(b) The effects of a delay in recall on memory

(c) The correlation between age and intelligence

(d) A comparison of memory ability between IB and A-level students

6.  In a repeated measures design....

(a) Each participant is given each level of the independent variable

(b) There will be at least two groups of participants

(c) A minimum of 20 participants is required

(d) Results are only correlational

7.  Which statement is true about inferential statistics?

(a) Can only be applied for independent samples design

(b) Requires a minimum of 20 participants

(c) Can best be summarized with a bar chart

(d) Involves applying findings from the sample back to the general population

8.  Which is not required in your IA?

(a) A table of contents

(b) A description of the theory behind the study

(c) A brief description of 2-3 related studies

(d) A table of raw data


​1 - A, 2- D, 3 - A, 4 - B, 5 - B, 6 - A, 7 - D, 8 - C