Turn up da noise


We usually think of noise as a bad thing -- like the background sound of street traffic that makes it hard to hear a conversation or your favorite CD. Researchers know that such extraneous stimuli exist for other senses, too: Noise can affect your ability not only to hear, but also to see and feel.

But it's not always a bad thing, it turns out. Researchers from the University of British Columbia recently showed that noise can at times help, rather than hinder, people's ability to sense things. Researcher Lawrence M. Ward said that "although counterintuitive ... noise can actually help us to see, hear or feel weak signals that would otherwise be imperceptible."

Researchers Cari Wells, Lawrence M. Ward, Romeo Chua, and J. Timothy Inglis presented their findings in the study, "Touch Noise Increases Vibrotactile Sensitivity in Old and Young," in the April 2005 issue of Psychological Science, a journal of the American Psychological Society.

The researchers tested the effects of tactile noise on touch sensation by applying weak vibrations to the soles of people's feet. By themselves the vibrations were undetectable, or below-threshold, to the participants. But when the researchers added random vibrations -- noise, that is -- people were able to detect the frequency of the weak, original vibrations. However, the noise had to be "just the right amount to raise it above a sensory threshold so it can be perceived. Too little noise isn't enough, and too much noise just hides the signal," Ward said.

"This is especially important for people whose sensory thresholds have been elevated, such as the elderly or people who have sustained damage to their visual, auditory or touch systems through accident or disease. Adding noise to signals that are below such elevated thresholds might make the signals perceptible again."

The authors believe that this effect could be useful in designing prosthetics to help the elderly avoid the painful falls that too often lead to immobility or death. The authors note that, "it has already been shown that facilitation of other types of foot sensation can be helpful in the elderly by improving the effectiveness of stabilizing reactions and by improving balance control while standing."

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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