Arizona high school graduate makes the USA Today’s 2007 All-USA academic team

Veronica Shi, a new graduate of Corona del Sol High School, has been working in the laboratory of Dr. Susana Martinez-Conde at the Barrow Neurological Institute for the last three years, where she has made a new discovery of great importance. She has discovered that the brightness of an object’s surface depends on the size of the surface’s image on the retina of the eye. This outstanding discovery, which propelled her into the USA Today’s 2007 All-USA High School Academic Team, and into the 2007 freshman class at Harvard University, has major implications for how we see, and could be used, in part, as a method to increase visibility in the partially blind.

The project has been a three year study on human volunteers to measure how perceived brightness varies as a function of the size of an object’s surface on the retina. The neural cells of the retina are sensitive to light and each cell is sensitive to a specific area of the visual field, called a receptive field. The hypothesis of the project is that the apparent brightness of an object’s surface should increase when the size of the surface matches the size of the retinal cells’ receptive fields. The subjects viewed grayscale visual stimuli presented on a computer monitor. The subjects, who did not know the purpose of the study, indicated whether a surface was brighter or darker than a standard stimulus of known luminance. The experimenters varied the size of the surfaces and found that, when the surface size matched the size of retinal receptive fields, the apparent brightness increased, thus verifying the hypothesis. This result has far reaching implications for improving the visibility of visual objects for the partially blind, and also has important implications for how the brain processes information about object luminance.

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