In the mind's eye: how the brain makes a whole out of parts
Part 3: Why do pictures look the same from different angles?

When you look at a picture, there is only one viewing position—the picture's centre of projection—that yields a correct image at your eye. For example, there is but one place in the movie theatre where the film creates the same image at your eye as the original scene. Viewing from other places causes distortion of the image at your eye. Why, then, don't moviegoers rush to the correct position? Indeed, do they even know where that position is?

A team of scientists from the University of California at Berkley and RIT have released new findings that solve a key mystery of our visual perception. Martin S. Banks, Professor of Optometry and Vision Science at the University of California at Berkeley, Dhanraj Vishwanath, Assistant Professor of Psychology at Rochester Institute of Technology, and Ahna Girshick, a PhD student at UC Berkeley, have developed a new scientific model of the processes underlying these phenomena.

Using a series of psychophysical experiments, the researchers were able to show that the human visual system flexibly adjusts to viewing position so that sitting at the right place is not required. The brain makes small adjustments to the image the eyes receive, such that the picture appears the way it is supposed to—even when people look at it from different locations.

This work has implications for designing better devices that display 3D pictures, and also for creating more realistic computer-graphic images. It will also increase our understanding of how the eyes and brain work, providing insight for both medical and psychological use. The results of this finding were published in the September 2005 issue of Nature Neuroscience .

In this connection, Vishwanath states that “T he human visual system automatically corrects distortions, but until now research had not been able to pinpoint how this correction occurs … Visual perception of displayed images is a key factor in human decision making. Properly describing how humans view and perceive images will provide a better understanding of why people respond positively to some images and negatively to others.”

The full results of this research study are available in Nature Neuroscience at nature.com/neuro.

Monika

Monika Bhatia
Project Manager and Editor, Quality4life
10 March 2006