Internally-assessed simple experiment

In IB Diploma Psychology jargon this is the “IA” and the report of this experiment is worth 25% of your grade if you are an SL student and 20% if you are studying Psychology at HL. So it is worth doing well!  

The main rule, whether you are conducting your IA at the SL or HL, is Keep It Simple.  Here is feedback from the May 2013 exam report regarding the IA.


HL – Favourite experiments were, as usual, levels of processing, the Stroop effect, reconstructive memory and experiments related to schema theory and imagery vs rehearsal (Pavio). Other good IAs were based on availability heuristics and social loafing. A few candidates performed experiments with several conditions although a simple experiment with only two conditions is recommended in the guide.

Mistakes that were made:

In general, the weaker reports shared the following characteristics:

  • Weak and imprecise explanation of background research in the introduction. The hypotheses were not clearly justified and operationalized, that is, made measurable.
  • For the descriptive statistics, the results were not stated in words, the use of descriptive statistics was not explained, and/or there was no relevant graph and/or table. For the inferential statistics, tests were absent or not justified.
  • Discussions were superficial with no discussion of the IA results in the light of background research and/or no reference to statistics. This was often due to the limited relevant research and/or theories presented in the introduction. Identification of limitations of own procedure was not linked to suggestions for modification.
  • The referencing was poorly done.

It should be noted that it is not required to make an exact replication of an experiment. A partial replication is adequate but the candidate’s experiment should be closely linked to an actual experiment.

SL – Most studies conducted were simple classic experiments suitable for the purpose of the internal assessment (IA). They involved manipulation of a clearly identified independent variable to determine its effect on the dependent variable. The vast majority of reports allowed candidates the opportunity to access all the available marks. The most popular topics came from cognitive psychology such as Stroop effect and Loftus and Palmer replications on reconstructive memory. Some interesting works were presented on short-term memory, the effect of priming on perception of ambiguous figures and some variations on the halo effect. The majority of candidates were well aware of ethical issues and most candidates with a full report included a copy of informed consent in the appendices.

Mistakes that were made:

  • Non-experimental works (for example, comparing performance of female versus male participants in a Stroop effect study). 
  • Studies which were not conducted in accordance with ethical guidelines, such as replications of Asch’s conformity research or studies with very young children as participants. 
  • Some schools seem to have encouraged candidates to present hypotheses although this is not needed for standard level and in a few schools candidates had applied inferential statistical tests which again is not needed for standard level.


IA quick tips

Choose a simple experimental study that will allow you to conduct the required statistical analysis – descriptive at SL and descriptive and inferential at HL.ood teamwork

Keep to your school’s deadlines.

Work in a group if allowed by your teacher, but write up separately.  See here for an example of good teamwork – everyone supporting each other to make something that is truly beautiful.


Finally – make your draft as near-perfect as you can, and act on any feedback you are given. Good Luck!

1 Comment
  • Toby Frazier
    December 4, 2013

    The results of these two experiments present fairly clear evidence for the hypothesis that biologically significant stimuli such as angry faces are detected more efficiently than positively toned “happy” faces. However, given the variability of results in previous studies (e.g. Hansen & Hansen, 1988 ; Nothdurft, 1993 ; Purcell et al., 1996 ; Suzuki & Cavanagh, 1992 ; White, 1995 ) we were concerned that the present results might be due to some factor other than the emotional expression on the faces. In particular, some studies have noted that visual confounds such as inadvertent shading can lead to “pop-out” regardless of emotional expressions ( Purcell et al., 1996 ). Indeed, as discussed in the Introduction this was the main reason for using schematic faces in the current research, on the assumption that what we lost in terms of realism we made up for in terms of equivalence between the “angry” and “happy” faces. Nevertheless, we thought it was worth checking to ensure that some low level feature of the angry faces (e.g. the angle of the brow) was not producing the effects. To examine this possibility, we conducted a third experiment in which the facial displays were presented upside down. It is well established that inversion of faces destroys holistic processing ( Tanaka & Farah, 1993 ) and therefore if the emotional expressions were the critical factor in producing the more efficient detection of anger then this result should not appear when the faces are inverted. In contrast, if detection of an isolated feature was responsible for the results then the same pattern should emerge with inverted faces since all of the same features were present. These two alternatives were tested in Experiment 3.

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