|October 19, 2000
Media Contact: Sue Pondrom
Find That Attention to Sound Influences Ability to See
Study Has Implications for the Role of Attention in Brain Disorders
and the Work Environment
In studies of how people process sound and sight together to make
sense of the complex world around them, neuroscientists at the UCSD
School of Medicine have found that attention drawn to a sound also
enhances an individual's ability to see.
Published in the Oct. 19,
2000 issue of Nature, the study provides important insights into
normal brain activities, and may lead to better understanding of the
role attention plays in dysfunctional neurological conditions such as
attention deficit disorder and schizophrenia. Another potential
application is in the workplace for design of warning systems and
man-machine interfaces where attention is crucial.
The study's lead author is
John J. McDonald, Ph.D., a post-doctoral fellow in the lab of Steven
Hillyard, Ph.D., UCSD professor of neurosciences and study co-author
along with UCSD assistant project scientist Wolfgang A.
"These studies show a
stronger linkage between sight and hearing than previously
demonstrated," Hillyard said. "Our results suggest that you
will see an object or event more clearly if it makes a sound before
you see it."
McDonald noted that the
majority of past studies looked at only one sense, such as vision or
sound or touch. In order to study the role of attention in more
realistic situations and the specific connection between sound and
sight, the UCSD researchers conducted 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. 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.
"We found that what
people hear significantly influences what they see," McDonald
said. "Researchers have known for many years that the brain
integrates information received from multiple stimuli in the
environment, and ignores nonessential information. What we haven't
understood are the processes that enable us to selectively pay
attention to events occurring in different modalities. 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."
"As we continue to learn
how individuals perceive the multiple stimuli taking place around
them, we'll have data from normal brain function to compare with and
help us understand abnormal conditions, such as attention deficit
disorder, " McDonald said.
Teder-Sälejärvi added that
the findings also hold promise for the "ergonomic design of
warning systems in assembly lines and for other high-risk work
environments such as radar operation. Studies like ours also may help
in the design of man-machine interfaces where focussing of attention
on a primary task is mandatory."
While the results reported in
Nature covered the behavioral performance of subjects, the researchers
also recorded the brain's responses to sound and light stimuli to see
whether paying attention to sound influences neural activity in visual
areas of the brain.
"We're now compiling
this data to give us a precise measurement of the moment to moment
changes in the visual cortex that arise from paying attention to
sound," McDonald said.
Next steps in the research
include more studies of normal brain function involving different
senses and comparisons to individuals with abnormal brain function.