Curriculum Resources/Demonstrations

Light-Dark Sensory Adaptation

By Martin Anderson, Ph.D.
San Gabriel High School
San Gabriel, California

Concept:

This activity clearly demonstrates the process of light-dark sensory adaptation and provides students with an excellent opportunity to learn about this phenomenon through their own individual experience.

Materials Needed:

The student will need to fashion something that will serve as an eyepatch to wear over one eye for a period of at least 20 minutes.

Instructions:

This activity is best conducted in an environment in which the light can be reduced quickly to a lower level where vision can still occur after dark adaptation. I suggest that my students do this at home at night. Have the student place the patch over one eye, then go about his/her regular activities (e.g., studying, reading, watching TV, etc.) for about twenty minutes in a well-lit room. At the end of this time, the student is to turn off the lights, then remove the eyepatch. Looking at various objects in the room, the student will notice marked differences in visual ability between the light-adapted and dark-adapted eyes. While this difference is still apparent, have the student turn on the lights and observe at what speed the eyes become equal in their light adaptation.

Discussion:

This experience should prepare the students for a discussion of light-dark adaptation. What was the difference between light adaptation and dark adaptation? What are some possible explanations for the time difference between light adaptation and dark adaptation? Where does light-dark adaptation take place? In the retina or in the brain? What observations support your answer?

The above activity was originally published in the Nov/Dec 1994 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.