Introduction

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

PsyToolkit code

Click to expand the PsyToolkit script code (part of zip file below)
# every line starting with # is comment

options
  bitmapdir stimuli    # the folder that contains the stimuli bitmaps
  escape

# the following section defines the bitmaps.  the default format for
# bitmaps is "png" if you use png files, you do not need to use the
# extension.

bitmaps
  cuesignal # this refers to the file cuesignal.png
  gosignal
  fixpoint1 # small
  fixpoint2 # medium
  fixpoint3 # large
  box
  instruction
  afterwords
  mistakefeedback

fonts
  arial 20

# the table section contains 4 rows, one for each of the four
# conditions the stuff in quatation marks is human readable
# information, the program doesn't really need it.

table iortable
  "cueleft  targetleft  cued   0" -200 -200  1
  "cueleft  targetright uncued 1" -200  200  2
  "cueright targetleft  uncued 1"  200 -200  1
  "cueright targetright cued   0"  200  200  2

# the task describes exactly one trial. On each each trial, one of the
# rows of the cue table is chosen at random

task iortask
  table iortable
  keys a l
  delay 500 # time between trials
  show bitmap fixpoint1
  show bitmap box -200 0
  show bitmap box  200 0
  delay 75
  show bitmap fixpoint2
  delay 75
  show bitmap fixpoint3
  delay 75
  clear 4 5
  show bitmap fixpoint2
  delay 75
  clear 6
  show bitmap fixpoint1
  delay 200
  show bitmap cuesignal @2 0 # now show the cue
  delay 200
  clear -1
  delay 800
  show bitmap gosignal @3 0 # show target (go) 700 ms later
  readkey @4 1500
  clear -1
  if STATUS != CORRECT
    show bitmap mistakefeedback 0 200
    delay 2000
    clear -1
  fi
  save @1 RT STATUS # this saves the data to an output file

block iorblock
  bitmap instruction
  wait_for_key
  tasklist
    iortask 100 # do the task 100 times
  end
  bitmap afterwords
  wait_for_key
  feedback
    set &RTcued   mean c5 ; prefix "Cued conditions:" ; select c6 == 1 && c4 == 0
    set &RTuncued mean c5 ; prefix "Uncued conditions:" ; select c6 == 1 && c4 == 1
    set &IOReffect expression &RTcued - &RTuncued
    text 0 0 "Response time (ms)"
    text 0 50 &RTcued     ; prefix "Cued conditions: " ; postfix " ms"
    text 0 100 &RTuncued  ; prefix "Uncued conditions:" ; postfix " ms"
    text 0 150 &IOReffect ; prefix "IOR effect (cued - uncued):"  ; postfix " ms"
    text 0 250 "Press space bar to continue"
  end

Download

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

1

cue position (left or right)

2

target position (left or right)

3

cue validity (cued/valid, uncued/invalid)

4

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

5

Response time (milliseconds)

6

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.