What Affects the Appearance of Afterimages? (page 2)

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Author: Selby, Grade 6




I observed that subjects who didn't wear glasses saw the after-image in half the time. Subjects who were older took longer most times, whereas young subjects typically saw an after-image quicker. Females saw an image a second sooner than most males. I noticed that people in the same light typically saw an image at the same time.

Often subjects would say "neat" or "cool" when seeing the after-image. Many subjects were doubtful of seeing the image and were extremely amazed when they did.


My experiment indicates that there is a relationship between the age of a subject and the time it took to see an after-image. The older subjects generally took longer to see an after-image, whereas younger subjects saw the after-image sooner. Although there were some exceptions and people who did not see an after-image.

I think it took older subjects longer to see an after-image because their rods and cones are worn and don't react as fast as a younger person's does. I accept the hypothesis. I feel that a larger sampling of people would prove my hypothesis even more.

I found it very interesting that twenty percent of subjects saw no after-image. This could be explained if subjects didn't understand my instructions. Also I believe that subjects who mentally decided that this was impossible did not see an after-image because they didn't want to.

A major factor (according to the graphs) was vision. Subjects who didn't wear glasses saw the after-image in half the time it took subjects with glasses. I think that this because most of the subjects tested wore glasses. Most people who wear glasses are old, and as I stated above older subjects took longer to see and after-image.

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