Cognition Laboratory Experiments

John H. Krantz, Hanover College,






Mental Imagery


Decision Making


Statistical Concepts

Hanover College
Psychology Department

Instructions for the Stroop Experiment


Having problems, try the new HTML5 version with improved results reporting.

When you click on the link below, you will be presented with the experiment setup screen.  On this screen will be the variables you can set to define your condition.  Here is a list of the variables and their settings

Variable Settings
  • Congruent Words (color and word same)
  • Incongruent Words (color and word different)
  • XXXX Colored (string of X's colored)
  • Word White
  • Congruent Reversed (color and word same but word backward)
  • Incongruent Reversed (color and word different but word backward)
  • Beginning Congruent (first two letters of the color word then x's in congruent color)
  • Beginning Incongruent (first two letters of the color word then x's in an incongruent color)
  • End Congruent (two x's then last letters of word in congruent color)
  • End Incongruent (two x's then last letters of word in incongruent color)
  • Middle Random Congruent (first and last letter in correct position, the middle in random order in congruent color)
  • Middle Random Incongruent (same as above but in an incongruent color)
  • End Random Congruent (first letter in correct position, rest of letters in random position, in congruent color)
  • End Random Incongruent (same as above but in an incongruent color)
  • Beginning Random Congruent (last letter incorrect position, the rest in random position, in congruent color)
  • Beginning Random Incongruent (same as above but in an incongruent color)
  • Word In Black Background Congruent
  • Word in Black Background Incongruent.
Colors to Use Click on the check boxes to have the colors and the corresponding words used in your experiment.
Respond to What? Whether the participant is to respond to the color or the word.  (Set automatically and not available in conditions XXXColored, for partial words, and when the words are not colored).
Number of Words in Condition The number of words that will be displayed, from 20 to 200.
Font Size The size of the words, from 12 point to 64 point.
Location of the word Center, Left, or Right.  If the words are not centered, there is a fixation mark shown and the words are oriented vertically.
Distance from Center If the words are not centered, this is the distance of the word from the center measured as a proportion of the distance from the center to the edge of the screen. (0nly visible when location is other than center).
Size of Background Region If using a background color the size of the total experimental screen that is colored.  (only visible in proper conditions)
Use Prime Flash A set of parameters that allow a colored flash to be presented prior to the word.  The flash can be congruent or incongruent to the color of the word or string.  You can also set the duration of the flash.

After you have finished making your settings, press the Done button at the bottom of the screen.  The Stroop experiment screen will then be presented.  Press the button at the top of the page or the space bar to begin the experiment.  First a fixation mark in the middle of the screen will be presented.  It will be removed if the words are presented in the center.  When the word or string of X'x is presented, indicate the color of the stimulus.  You can do this three ways:

  1. press the relevant button at the bottom of the screen.
  2. press the following keys: r for red, g for green, b for blue, y for yellow
  3. press the following keys: a for red, f for green, j for blue and ; for yellow.

The stimuli are randomly selected so you might see the same stimulus twice in a row - there is no break so you might not see it reappear.  Just press the proper key again.

At the end of the experiment, your results will be presented, both average reaction time and your accuracy.  You can also get your trial by trial results.  Closing your results window(s) will take you back to the setup window so you can run another experiment.

Click here to start the experiment.



  • The priming flash is the idea of Dana Newton, Becky Nixon, and Sarah Pollom of Hanover College.
  • The idea to display words backwards comes from Cole Wyatt, Alexis Rose and Matt Moore of Hanover College.
  • The idea to use background colors on black words comes from Angela DiGeronimo, Dwayne Guenther, and Amber Adkins of Hanover College
  • The use of random letter positions and the selection of different colors is inspired by Matt Moore and Sarah Pollom of Hanover College