Introduction

This is a touchscreen friendly version of the Simon task.

The Simon task and the Simon effect are named after J. R. Simon. Together with his colleague, he first described this effect in 1963. In essence, it shows that people respond faster and more accurately if there is a match between stimulus and response features (e.g., location, when for example stimulus and response are both located on the left side of one’s body).

The effect is also known as a stimulus-response compatibility effect. There are many variants of the stimulus-response compatibility available. Like the Stroop effect, it is easy to notice consciously how difficult a mismatch between a stimulus and response can be.

About this implementation

This runs well on mobile phones too, in particular Android phones. It was originally developed for a Samsung J5, which has a 1280x720 screen resolution. Because in fully screen, it is always scaled so that the resolution is actually 640x360, that is what you have in the options line of the code as well.

Run the demo

In this task, you always see two circles, one colored and one white. The colored one is red or green. If it is red, you need to touch/click the left circle. If it is green, you need to touch/click the right circle.

The demo takes less than 2 minutes to complete.

Click here to run a demo of the Simon task

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 only if you use this experiment for your research project.

Colum Meaning

1

Name of block

2

Congruent or incongruent (as a word)

3

Color (red or green)

4

Congruent or incongruent (as a number, 1=congruent or 2=incongruent)

5

Table row chosen

5

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

6

Response Time (ms)

7

X-position of where stimulus was clicked/touched

8

Y-position of where stimulus was clicked/touched

PsyToolkit code

Click to expand the PsyToolkit script code (part of zip file below) 
## Samsung J5 has 1280x720 resolution. In fullscreen it will still be
## 640x360, that is what images are scaled to.

options
  resolution 640 360
  mouse on
  fullscreen
  
bitmaps
  cover
  i1
  i2
  i3
  i4
  i5
  i6
  i7
  mistake
  
fonts
  arial 18
  
table simontasktable
  "congruent   red "  1 1  255   0   0   255 255 255 #red
  "incongruent red "  1 2  255 255 255   255   0   0 #red
  "congruent   green" 2 1  255 255 255     0 255   0 #green
  "incongruent green" 2 2  0   255   0   255 255 255 #green

task simon
  table simontasktable # the table that describes conditions 
  show circle -200 0 50   @4 @5 @6
  show circle  200 0 50   @7 @8 @9
  readmouse l @2 5000
  set $XX MOUSE_X
  set $YY MOUSE_Y
  clear 1 2
  # if STATUS != CORRECT
  if STATUS = 2 || STATUS = 3
    show bitmap mistake 
    delay 1200
    clear -1
  fi
  delay 500                              
  save BLOCKNAME @1 @3 TABLEROW STATUS RT $XX $YY

block test
  message cover mouse
  message i1 mouse
  message i2 mouse
  message i3 mouse
  message i4 mouse
  message i5 mouse
  message i6 mouse
  message i7 mouse
  tasklist
    simon 30
  end
  feedback
    text align left
    set &Con mean c7 ; select c4 == 1
    set &Inc mean c7 ; select c4 == 2
    set &SimonEffect expression &Inc - &Con
    text -200 -150 "Your personal Simon task results"
    text -200  -50 &Con ; prefix "Congruent: " ; postfix " ms"
    text -200   50 &Inc ; prefix "Incongruent: " ; postfix " ms"    
    text -200  150 &SimonEffect ; prefix "Simon effect: " ; postfix " ms"    
    wait_for_key mouse
  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.

Further reading

Simon, J.R. and Wolf, J.D. (1963). Choice reaction times as a function of angular stimulus-response correspondence and age. Ergonomics, 6, 99-105.

Hommel, B. (1993). Inverting the Simon effect by intention: Determinants of direction and extent of effects of irrelevant spatial information. Psychological Research, 55, 270-279.

Prinz, W. & Hommel, B. (2002). Common mechanisms in perception and action: Attention and Performance, Vol. XIX. Oxford: Oxford University Press.