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The Split-Brain Student
Edward J. Morris, Ph.D.
Owensboro Community College
Purpose:
- The purpose of this exercise is to allow students an opportunity to experience the frustrations and deficits of patients who have had the split-brain operation. During the demonstration, participants explore the interesting limitations caused by the procedure known as the commissurotomy, giving them insight into the functioning of the hemispheres of the brain in a way impossible through reading and lecture alone.
Materials:
- Materials are simple. Collect blindfolds, a shoe with a shoelace, a few coins, a pen or a pencil and some toy blocks.
Instructions:
- Have your students sit together as close as can be arranged (in the same chair, if possible). They then interlock their inside arms and put their outside arms behind them. With their inside arms together, it will be as if they are one person, one of the pair using their left hand and the other using their right. Instruct the student on the left that he/she must be the voice for the pair. The student on their right is not allowed to speak from this point on. The student on their right communicates through non-verbal means.
- While they are in this configuration, have the students tie the shoelace. They will have some difficulty with this, but will eventually accomplish it. Then repeat the task with both students blindfolded. They will find this to be very difficult and the left student who is using his/her right hand may spontaneously talk the other through the task.
- With the students still blindfolded, place one of the objects in the left hand and ask if they are able to identify the object. The "left-brain" student will say no while the "right-brain" student will possibly nod "their" head affirmatively. While the voice of the pair will be unable to correctly identify the object, the left hand will be able to correctly select the object from several placed before him/her when the blindfolds are removed. When asked why a correct response could not be produced before the blindfolds were removed, the "voice' will come up with interesting rationalizations such as "I can't feel what is in my left hand".
- You may also place other objects in the pair's hands in different combinations to demonstrate how a correct response is possible under certain conditions. If a retractable ballpoint pen is used, a correct response may be forthcoming if the left hand clicks the mechanism on the pen allowing the other side to hear the sound of it.
- The differences in the abilities of the two hands may be demonstrated by having the students use the blocks to reproduce a pattern in a picture or a model created by you. Handedness may play a part in how well they are able to do this task.
- The manner in which the right and left visual fields are processed by the hemispheres is demonstrated by having the students in the pair fix their gazes in opposite directions. In this situation, each "hemisphere" is only aware of what happens in his/her sight and will be unable to answer questions about objects displayed in the other "hemisphere's" visual field.
Discussion:
- After the demonstration, students can be lead in a discussion about the localization of language in the left hemisphere in most people, as well as how vision and hearing are processed by the brain. Students can be encouraged to think about the conditions under which this operation would be worth the difficulties it causes.
References:
- Gazzaniga, M.S. (1967). The split brain in man. Scientific American, 217, 24-29.
Gazzaniga, M.S. (1987). Perceptual and attentional processes following callosal section in humans. Neuropsychologia, 25, 119-133.
Hay, J.C. (1985). Psychworld. New York: McGraw-Hill.
Nebes, R.D., & Sperry, R.W. (1971). Hemispheric deconnection syndrome with cerebral birth injury in the dominant arm area. Neuropsychologia, 9, 247-259.NOTE:
- A similar article appeared previously in Teaching of Psychology, Vol. 18, No. 4, December 1991. Used by permission of Lawrence Erlbaum Associates, Inc., Hillsdale, NJ.
The above activity was originally published in the Jan/Feb 1995 issue of The Psychology Teacher Network. The activity is reprinted here with the permission of the Education Directorate of the APA. Further publication of the activity is not permitted without the express written consent of the Education Directorate.
For information on subscribing to The Psychology Teacher Network, write to:
Psychology Teacher Network
Education Directorate
APA
750 First Street, NE,
Washington, DC 20002-4242.
