Pay Attention! A Parametric Study of the Stroop Effect

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Updated on Jan 13, 2014

Grade Level: Middle School; Type: Social Science, Life Science


  • To learn about our cognitive capacity of attention
  • To learn about factors that influence attention

Research Questions:

  • What is semantic interference?
  • What is semantic facilitation?
  • What is your hypothesis concerning the mixed color stimulus set?

How easily distracted are we? In this study, you will have subjects read aloud three different sets of words that describe numbers; for one set, the word will be written in the same color ink as the word names, for another the word will be written with the first and last letter of the word written in the same color ink as the word names and the middle letters will be written in a different color ink, and in the last set, the entire word will be written in a different color ink than the color the word names. The number of errors made and the time it takes to read each set aloud will be recorded. The average number of errors made for each set and the average time it takes subjects to read each set aloud will be calculated and the results graphed as bar graphs, and the results discussed.


  • Poster board
  • Colored felt tip pens (with at least six different colors)
  • Stopwatch
  • Paper and pen
  • (Stopwatch can be found at sporting goods stores; all other materials are available at an office supply store.)

Experimental Procedure

  1. Create stimuli for three sets of test cards: Cut the poster board in three equal pieces with a scissors. On the first piece, write the names of six different colors in the matching color felt tip pen; on the second piece write the names of the six colors with the first and last letter in the matching color and the letters in between in a single color other than the color spelled by the word; on the third piece, write the names of the six colors in a single mismatching color.
  2. Create a sample stimulus by writing the name of a color on a piece of poster board or paper with ink of a different color.
  3. Create a data sheet by making 4 vertical columns. Label the first column “Student #”, the next one, “Matching”, then “Partial Mismatch”, then “Mismatch”. Under the Matching column create two sub-columns and label the first “# of errors” and the second “Time”; do the same for the “Partial Mismatch” and the “Mismatch” column.
  4. Write the numbers “1, 2, 3”, “2, 3, 1”, “3, 1, 2”, “3, 2, 1”, “2, 1, 3”, “1, 3, 2” on pieces of paper, fold them in half and put them in a jar or hat; the subjects will each choose a piece of paper before doing the experiment and the number will determine the order in which the sets are presented.
  5. Test subjects one at a time. Have them pick a piece of paper to determine the order in which you will present the sets of stimuli. Show the subject the sample stimulus. Tell the subject that s/he will be seeing a series of words that describe different colors and that sometimes the words will be written in the same color ink as the word describes, sometimes they’ll be written in a different color - as in the sample shown - and sometimes they will be written in a combination of the same and different colors. Their task is to name the color of the INK that each word is written in as quickly as possible. For each set, start the stopwatch when the set is first presented, note the number of errors that the subject makes, and stop the watch when the subject has finished reading the set. Record the errors and time. Follow the same procedure when you present the second and third sets.
  6. Average the errors made as well as the times for reading each set. Create a bar graph with the results.
  7. Discuss the results in terms of interference of attentional processing as a result of the semantic meaning of the word.

Terms/Concepts: Reaction time; Semantic interference; Semantic facilitation; Interference theory


Dr. LaCerra is an evolutionary neuroscientist, author of "The Origin of Minds" (with co-author, Roger Bingham, Harmony, 2002) and a columnist and contributing editor at "Spirituality & Health" Magazine.

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