Madison Welsh Academy of Notre Dame

Question Does eye color affect one’s ability to identify colors in dark and dim levels of light?

Background Research The eye’s iris controls pupil size. Pupils expand in dim light and contract in bright light. Humans can perceive light wavelengths ranging from nanometers. The stimulation from light wavelengths produces the color spectrum. Eyes use cells called rods and cones to detect the intensity of photons, the smallest unit of light.

Background Research Eyes process information when objects release photons towards eyes and when objects deflect photons towards eyes. Once photons are deflected or emitted into eyes, the cornea and crystalline lenses focus the light into the retina, which contains the rods and cones. These cells send signals into the brain after they are stimulated by light. Rods cannot distinguish between colors besides black and white and have very poor resolution. Cones are responsible for fine resolution and they discriminate between colors. Cones control photopic vision, the ability to see in high levels of light.

Background Research Humans need time for their eyes to adjust from a high luminance setting to a low luminance setting (called dark adaptation.) Rods and cones contain light-sensitive chemicals called photopigments. When they are exposed to light, a chemical reaction occurs that converts light energy to electrical activity. People with lighter colored eyes have a heightened sensitivity to light.

Hypothesis If someone has lighter colored eyes, then their ability to perceive colors will be the same as their darker colored counterparts in medium light, enhanced in low light, and decreased in bright levels of light.

Materials Light meter Nine colored index cards Blinds Walk-in Closet Twenty-one subjects

Procedure The light meter was used to measure the amount of light in the closet (.1 FC), the amount of light in a dim room (.48 FC), the amount of light in a naturally lit room (1.2 FC) and the amount of light in a room with bright sunlight (175 FC). A subject was then asked to name the colors of the nine index cards in each level of light. The results and eye color of the subject were recorded. The light meter was used to measure the FC’s of each level of light before the next subject participated. This procedure was repeated twenty times.

Variables Independent Variable- the subject’s eye color Dependent Variable- the number of colors the subjects correctly identified Constants- the amount of light in each level, the cards, and the rooms in which the tests were given Control- there is no control group for this project since everyone has pigment in their eyes, however the medium light level functions effectively

Data: Dark Level of Light.1 FC Subject Number Brown EyesBlue EyesGreen Eyes 18 correct7 correct5 correct 29 correct8 correct7 correct 36 correct 7 correct 4 6 correct8 correct 5 7 correct6 correct 68 correct7 correct6 correct 79 correct8 correct5 correct Average7.9 correct7 correct6.3 correct

Data: Dim Level of Light.48 FC Subject Number Brown EyesBlue EyesGreen Eyes 19 correct correct 48 correct 7 correct 59 correct7 correct8 correct 6 9 correct 7 8 correct Average8.7 correct8.3 correct8.1 correct

Data: Medium Level of Light 1.2 FC Subject Number Brown EyesBlue EyesGreen Eyes 19 correct correct 79 correct Average9 correct 8.7 correct

Data: Bright Level of Light 175 FC Subject Number Brown EyesBlue EyesGreen Eyes 17 correct9 correct correct 59 correct 6 7 Average8.7 correct9 correct8.8 correct

Graph

Conclusion The hypothesis of this experiment was rejected. There was no substantial difference in the results of the subjects with different eye colors in bright and medium light. Brown eyed participants had better vision than green and blue eyed subjects in dark and dim light, while the hypothesis predicted the opposite.

Sources of Error One brown eyed subject had trouble identifying colors in the control (medium light) and may have been color blind. The bright level of light may not have been bright enough to show the difference of sight between subjects with light eyes and those with dark eyes.

Continuation This experiment could be taken further by asking subjects to identify shapes, print, and other objects in the different levels of light.

Works Cited Arida, M., & Butterworth, P. (2005, December 1). How Our Eyes See Light. Retrieved October 5, 2010, from Nasa website: Cook, R. G. (n.d.). Visual Perception. Retrieved October 6, 2010, from Tufts University website: Dubow, B. (2010, June). Eye Color- How It Develops? Why Does It Change? In All About Vision. Retrieved October 5, 2010, from The Eye and Night Vision. (n.d.). Retrieved October 6, 2010, from American Optometric Association website: Lee, J., Bailey, G., & Thompson, V. (2009, January). Photophobia (Light Sensitivity). Retrieved October 6, 2010, from