Sound improves sight

The research could improve design in warning systems

Scientists have uncovered evidence that the perception of sight and sound are inextricably linked.

Neuroscientists from the University of California, San Diego, have discovered that when attention is drawn to a sound it also enhances the ability to see.

They believe the discovery could provide some clues as to how the brain makes sense of the environment, and ultimately lead to new treatments for neurological disorders such as attention deficit disorder and schizophrenia.

Our results suggest that you will see an object or event more clearly if it makes a sound before you see it

Professor Steven Hillyard, University of California, San Diego

It may also prove to be significant for the design of warning systems and man-machine interfaces where attention is crucial.

Researcher Professor Steven Hillyard said: "These studies show a stronger linkage between sight and hearing than previously demonstrated.

"Our results suggest that you will see an object or event more clearly if it makes a sound before you see it."

The researchers carried out two experiments with 33 volunteers.

The subjects were told to indicate whether a dim, obscured light appeared soon after a sound was presented.

The sound and light appeared either on the same side, or on opposite sides of the subject's direction of gaze.

Mathematical model

Using a mathematical model called signal detection theory to weed out guesses by the volunteers, researchers found that the light was detected more accurately when it appeared on the same side as the sound.

Researchers have long known that the brain integrates information received from multiple stimuli in the environment.

But the procedures that enable us to selectively pay attention to information coming in from the different senses has been poorly understood.

Lead researcher Dr John McDonald said: "What people hear significantly influences what they see.

"We found that paying attention to a sudden sound enhances our ability to see visual stimuli that appear at the same location."

Dr McDonald said that the more information that could be collected about how the normal brain perceived the external environment, the more it would help to pinpoint differences present in abnormal conditions.

The research is published in the journal Nature.