In 1935, John Ridley Stroop described an unusual phenomenon of competing attention that has since come to bear his name: the Stroop phenomenon. What Stroop found is that when humans are faced with a task that can require attention to one of several possible task features, some tasks can overrun the others. Specifically, reading appears to be so well-trained in us educated humans that we will pay attention to that component of a task, even if it is not the particular aspect of a tast we are being asked to do.

The task of selecting an appropriate response from among conflicting conditions has been tentatively located in a part of the brain called the anterior cingulate. This brain region lies between the right and left cortical hemispheres at the front of the brain, and is involved in a wide range of thought and emotional processes. Although the functions of the anterior cingulate are vast and complex, broadly speaking it serves as a conduit between the raw emotional responses of the limbic system and the more rational responses of the frontal cortex. It has been speculated that it is this area of the brain that is involved in producing the Stroop effect.

Ready for the test? Here we go!

Decide who on your team is going to be the subject first. Test one subject on all components of the test before swapping roles as subject and experimenter. Get a copy of the Stroop data sheet here or from your instructor.

Below you will see a list of words arranged in 4 columns of 5 words each. Your first task is to read through the list of words as quickly as you can. When your experimenter says "go!," start reading the words out loud. Experimenters should start their stopwatches when they say "go!" and stop when the subject reads out the last word.

Color Words Test 1:

Enter the amount of time it took your subject to read through this list (List 1) on the appropriate place on the data sheet you received in class.

Then, go on to list 2. For this list, the task is the same. Read through the words as quickly as you can. The experimenter on the team should time how long it takes the subject to do this task

Color Words Test 2:

Record the time it took for the subject to complete this task, and add that datum to the appropriate place on your data sheet.

Now, the final test. This time, instead of reading out loud the word you see, say out loud the color of the ink in which the word is printed. The experimenter should time how long it takes the subject to complete this task, and record the results on your data sheet.

Color Words Test 3:

How did your subject do? Take turns being experimenters and subjects until you have tested all of the people in your group. If the instructor asks you, enter your teammates' data into the class spreadsheet using the computer at the front of the classroom or the handheld data entry pads you received at the start of class. Take a few minutes to brainstorm with your team about what factors might influence the Stroop phenomenon. Write these down on your team data sheet, and turn it in at the end of class. Only one data sheet is needed per team.

Keep these ideas in mind as you test your own subjects later on for your research summary. For your summary, you should test 3 different subjects. Compare the results of the first and second task in each test with the last task. Did one task seem more difficult for your subjects than another? Why do you think that might be? What do your results suggest to you about how humans think about numbers and counting? Make these speculations in the discussion section of your research summary.

Below are links to the stimuli you will use for that study, and to a data sheet you can use to record your results. Be sure to attach your data sheet to your completed summary. Summaries without data sheets will be returned ungraded.

Stroop Test with Numbers

Stroop Summary Data Sheet