Hearing and Vision Closely Linked, Scientists Say

When audiophiles speak of "imaging," they may not be using the term metaphorically. Recent research at the University of California at San Diego's School of Medicine indicates that hearing and vision are more closely related than had been previously thought.

Experiments described in the journal Nature seem to prove what stage directors and filmmakers have long known: that sounds can enhance the ability to see things clearly. "We found that what people hear significantly influences what they see," said lead researcher John McDonald. His team investigated the responses of 33 volunteers, who were asked to indicate when a dim light appeared after they had heard a sound, either from the same side or from the opposite side.

When the two stimuli came from the same direction, the light was detected with greater accuracy, lending credence to the theory that hearing is an animal's "early warning system" in the wild. "Our results suggest that you will see an object or event more clearly if it makes a sound before you see it." said researcher Steven Hillyard. "In this study, we found that paying attention to a sudden sound enhances our ability to see visual stimuli that appear at the same location." McDonald added.

During the experiments, the researchers recorded brain responses both to the light and the sound to see how focusing on the sound affects the brain's visual cortex. They are hoping to gain insight into learning problems such as attention deficit disorder by understanding how the two senses interact and enhance each other. Interestingly, some home theater fans have noted a seemingly inexplicable phenomenon: that better sound systems seem to improve the picture. Research such as that at UCSD may eventually explain the mystery.