The Stroop Effect

Exploring the Stroop Effect

Overview
Mental operations can come into conflict with each other. For example, it is exceedingly difficult to both remember a list of 15 words and count backwards from 500 in multiples of 7. This is because distinct mental processes (remembering, computing a number) can share mental resources. This lesson explores a similar kind of mental conflict directly, by replicating a famous psychological effect discovered by John Ridley Stroop.

Focus Question
Are all colors processed in the same way by the human eye and visual system?

Objectives
Through this lesson, students will:
Predict how quickly they can read a given list of words.
Perform an experiment to establish relationships between naming a color and automatically reading a presented word.

Background
The Stroop effect was first described in 1935 by John Ridley Stroop. Generally, the Stroop effect refers to the difficulty observers have in eliminating meaningful but conflicting information from a task, even when that information is irrelevant or counterproductive in that task. The Stroop effect can manifest as either interference, that is, when one mental operation degrades the performance of another, or as facilitation, that is, when one mental operation enhances the performance of another. The focus of this lesson is exploring conditions under which both interference and facilitation can occur.
Materials
Choose 3 people (including yourself to participate in this exercise) They may be other class members or individuals you know outside of class.
1 timing devices (phone, watch, stopwatch, etc.)
3 lists of words per group (congruent, incongruent, control)
1 Data sheet per group

Preparation
In this experiment, every group member will be tested on all of the word lists twice (right side up and upside down). Make sure that the current group member being tested doesnt know which list will be shown to him/her (and whether the list will be presented right-side up or upside down).

Procedure
1. Have one group member be in charge of timing the current group member being tested while the other member presents the current word list to the current subject.
2. Notify the member being tested that his/her task is to name the color that the words are written in as quickly as possible without making any mistakes.
3. Present the subject with one of the lists and immediately begin timing.
4. Record their time and note whether any mistakes in naming were made.
5. Continue in the same way with all other word lists and across other subjects. Make sure that word lists have been presented in the correct orientation (right side up) and upside down to all group members.
6. Students should then first calculate mean color naming times from all the raw data for each of the three lists. These means can then be combined in different ways to investigate whether facilitation and interference occurred.
7. To calculate Stroop Interference:
Stroop Interference(right side up) = RTincongruent(right side up) RTControl(right side up)

8. To calculate Stroop Facilitation:
Stroop Facilitation(right side up) = RTCongruent(right side up) RTControl(right side up)

9. You can also determine whether the Stroop effect is made smaller by making the words difficult to read:
Stroop Interference(upside down) = RTIncongruent(upside down) Rtcontrol(upside down) Stroop Facilitation(upside down)= RTCongruent(upside down) RTControl(upside down)

10. Now you can determine whether the effect decreases when you interfere with the automatic reading of words (Is the second group of numbers smaller than the first?)

Additional Information
The classic demonstration of the Stroop effect is produced when one tries to name the color of the ink in which a word is printed when the word itself is the name of a color other than that of the ink. Typically, one is slower in this situation than if the word is not a color term. This form of Stroop interference is thought to be evidence for the automatic nature of reading. Automatic in this context refers to an activity, such as reading, that is so well learned that it is occurs even when one attempts to suppress it. The interference probably arises when different words in the mental lexicon representing the color terms are activated by both the words and the ink color and compete with one another, slowing the overt response
Answers MUST be highlighted or change font color) for credit. Failure to do so will result in only a max of half credit.

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