LISTENING to music while you drive can improve your reaction time and
ability to avoid hazards, according to Australian psychologists. But turning
your car stereo up to full volume could turn you into a liability on the
roads.
The performance of complex tasks can be impaired if people are subjected to
high-intensity noise. The experience of pulling up at traffic lights alongside
cars throbbing with heavy bass prompted Helen Beh and Richard Hirst of the
University of Sydney to investigate whether loud music interferes with
driving.
The researchers recruited 60 men and women aged between 20 and 28 and tested
them on simulated driving tasks under three noise conditions: silence, rock
music played at a gentle 55 decibels, and the same music blaring out at 85
decibels.
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For 10 minutes the recruits sat in front of a monitor operating a steering
wheel and foot pedals representing brake and accelerator. They had to track a
moving disk on screen, respond to traffic signals changing colour, and brake in
response to arrows that appeared without warning.
On the tracking task, there was no difference in performance under the three
noise conditions. But under both the loud and quiet music conditions, the
volunteers 鈥渂raked鈥� at a red light about 50 milliseconds sooner than they did
when there was no rock music at all. That could mean a reduction in braking
distance of a couple of metres鈥攑otentially, the difference between life
and death for a pedestrian.
When it came to the arrows that appeared across the visual field, Beh and
Hirst found that when the music was quiet, people responded faster to objects in
their central field of vision by about 50 milliseconds. For the people listening
at 85 decibels, response times dropped by a further 50 milliseconds鈥攁
whole tenth of a second faster than those 鈥渄riving鈥� with no music.
鈥淏ut there鈥檚 a trade-off,鈥� Beh told the European Congress of Psychology.
鈥淭hey lose the ability to scan the environment effectively.鈥� In responding to
objects intruding on their peripheral vision, people subjected to 85-decibel
rock music were around 100 milliseconds slower than both the other groups. Since
some hazards鈥攕uch as children running into the road鈥攅merge from the
periphery, drivers listening to loud music must be less safe as a result.
The beneficial effect of quiet music on attentiveness while driving is
probably related to the boost in arousal induced by the 鈥渕uzak鈥� played at
conversational level in many shops鈥攁nd which is thought to make customers
pull more products off the shelves.