Mirror

Mirror-Image Tracing Experiment

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Introduction
Design
Data Analysis
References

Introduction

Are there asymmetries in the functions of the two cerebral hemispheres? A great deal of evidence has accumulated in recent years suggesting that the left brain and the right brain are not identical in their capabilities. This experiment is designed to demonstrate that for right-handed people, who comprise over 90% of the population, the right hemisphere performs visual spatial tasks better than the left hemisphere. For most right-handers, whereas the left hemisphere excels in verbal and analytical tasks, the right hemisphere specializes in emotional, nonverbal, and visual-spatial tasks.

The mirror-image tracing experiment requires that the participant use the mouse to trace the star (see figure below), first with one hand, and then with the other hand. Because mirror- image tracing is primarily a visual-spatial task, and each half of the brain controls the contralateral side of the body, it is expected that right-handed participants will take longer to complete the task with their right hand (controlled by the left hemisphere) compared to their left hand ( controlled by the right hemisphere). Please note that this prediction may not necessarily hold for left-handed participants, because their brains are more bilateral.
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Design

The experiment has a within-participant design with one independent variable, i.e., the hand used to do the tracing. There are two levels to the independent variable: the left vs. the right hand. The dependent variable is the time it takes the participant to complete the tracing.
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Data Analysis

Sample data for the experiment are shown in the bar graph below. The X -axis represents the hand used to do the tracing, and the y -axis represents the mean response time. A paired t-test can be conducted to see if the reaction times of the two conditions (the left-hand condition vs. the right-hand condition) are significantly different.
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References

Gazzaniga, M. S. (1970). The bisected brain. New York: Appleton-Century-Crofts.

Gazzaniga, M. S., Bogen, J. E., & Sperry, R. W. (1965). Observations on visual perception after disconnection of the cerebral hemispheres in man. Brain, 88,221-236.

Nass, R. D., & Gazzaniga, M. S. (1987). Lateralization and specialization in human central nervous system. In Handbook of Physiology Sec. 1., The Nervious System. Vol. 5, parts 1 and 2, Higher Functions of the Brain. F. Plum, ed. Bethesda, Md.: The American Physiological society, 701- 761.

Springer,S.P.,& Deutsch,G. (1989). Left brain, right brain. (3rd edition) New York: W. H. Freeman and Company.
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Last revised:June 03, 2003 11:46:57 AM
Copyright© 1995 The University of Mississippi. All rights reserved.
Questions about this page?PsychExps



Mirror-Image Tracing Experiment

Back to Instructor's Page
Introduction Design Data Analysis References
Introduction
Are there asymmetries in the functions of the two cerebral hemispheres? A great deal of evidence has accumulated in recent years suggesting that the left brain and the right brain are not identical in their capabilities. This experiment is designed to demonstrate that for right-handed people, who comprise over 90% of the population, the right hemisphere performs visual spatial tasks better than the left hemisphere. For most right-handers, whereas the left hemisphere excels in verbal and analytical tasks, the right hemisphere specializes in emotional, nonverbal, and visual-spatial tasks. The mirror-image tracing experiment requires that the participant use the mouse to trace the star (see figure below), first with one hand, and then with the other hand. Because mirror- image tracing is primarily a visual-spatial task, and each half of the brain controls the contralateral side of the body, it is expected that right-handed participants will take longer to complete the task with their right hand (controlled by the left hemisphere) compared to their left hand ( controlled by the right hemisphere). Please note that this prediction may not necessarily hold for left-handed participants, because their brains are more bilateral. « Return to Top»
Design
The experiment has a within-participant design with one independent variable, i.e., the hand used to do the tracing. There are two levels to the independent variable: the left vs. the right hand. The dependent variable is the time it takes the participant to complete the tracing. « Return to Top»
Data Analysis
Sample data for the experiment are shown in the bar graph below. The X -axis represents the hand used to do the tracing, and the y -axis represents the mean response time. A paired t-test can be conducted to see if the reaction times of the two conditions (the left-hand condition vs. the right-hand condition) are significantly different. « Return to Top»
References
Gazzaniga, M. S. (1970). The bisected brain. New York: Appleton-Century-Crofts. Gazzaniga, M. S., Bogen, J. E., & Sperry, R. W. (1965). Observations on visual perception after disconnection of the cerebral hemispheres in man. Brain, 88,221-236. Nass, R. D., & Gazzaniga, M. S. (1987). Lateralization and specialization in human central nervous system. In Handbook of Physiology Sec. 1., The Nervious System. Vol. 5, parts 1 and 2, Higher Functions of the Brain. F. Plum, ed. Bethesda, Md.: The American Physiological society, 701- 761. Springer,S.P.,& Deutsch,G. (1989). Left brain, right brain. (3rd edition) New York: W. H. Freeman and Company. « Return to Top»

Last revised:June 03, 2003 11:46:57 AM Copyright© 1995 The University of Mississippi. All rights reserved. Questions about this page?PsychExps