Inhibition Of Return (IOR) is a phenomenon first described by Michael Posner and Yoav Cohen in 1984.

People are slower in detecting relevant stimuli at positions that have been attended shortly before to view an uninformative cue (time between uninformative cue and target has to be at least 300 ms).

The effect is, absolutely speaking, relatively small. The response time difference between detecting relevant stimuli at locations that were cued before and locations that were not cued before is around 20 ms. The effect size depends strongly on the interval between cue and stimulus. At shorter times between cue and target, people respond faster to locations that were previously cued.

About this implementation

In this example, you need to respond to a green stimulus "GO". In each trial, you need to ignore the "X" stimulus. The "X" functions here as an uninformative cue. It is "uninformative" because the location of the "X" is randomly chosen. The time between the "cue" and the "target" stimulus in this example is 1 second. At the end, you will see how fast your responded in cued and uncued locations.

The demo takes less than 5 minutes to complete (100 trials).

Run the demo

Stimulus-response associations

Use the following keys for your response:

  • a go signal on the left

  • l go signal on the right


If you have a PsyToolkit account, you can upload the zipfile directly to your PsyToolkit account. Watch a video on how to do that. If you want to upload the zipfile into your PsyToolkit account, make sure the file is not automatically uncompressed (some browsers, especially Mac Safari, by default uncompress zip files). Read here how to easily deal with this.

Data output file

In PsyToolkit, the data output file is simply a textfile. The save line of the PsyToolkit experiment script determines what is being saved in the data output file. Typically, for each experimental trial, you would have exactly one line in your text file, and each number/word on that line gives you the information you need for your data analysis, such as the condition, response speed, and whether an error was made.

Meaning of the columns in the output datafile. You need this information for your data analysis.

Colum Meaning


cue position (left or right)


target position (left or right)


cue validity (cued/valid, uncued/invalid)


same as column 3, cued as a number 0=cued, 1=uncued


Response time (milliseconds)


Status (1=correct, 2=wrong, 3=timeout)

Further reading

  • Abrams, R. A., & Dobkin, R. S. (1994). The gap effect and inhibition of return: Interactive effects on eye movement latencies. Experimental Brain Research, 98, 483-487.

  • Abrams, R. A., & Dobkin, R. S. (1994). Inhibition of return: Effects of attentional cuing on eye movement latencies. Journal of Experimental Psychology: Human Perception and Performance, 20, 467-477.

  • Klein, R. M. (2000). Inhibition of return. Trends in Cognitive Sciences, 4, 138-146.

  • Posner, M.I. & Cohen, Y.P.C. (1984). Components of visual ori- enting. In H. Bouma & D. Bouwhuis (Eds.), Attention and per- formance X: Control of language processes (pp. 531–556). London: Lawrence Erlbaum.

  • Pratt, J., & Abrams, R. A. (1999). Inhibition of return in discrimination tasks. Journal of Experimental Psychology: Human Perception and Performance, 25, 229-242.