STARING at ROAD INTERFERES with DRIVER'S ABILITY
to SAFELY PASS OTHER VEHICLES
By Rob Gray, Ph.D. & David Regan, Ph.D.
Overtaking and passing other cars is considered one of the more dangerous situations
facing drivers. New research based on driving simulations suggests that
staring at the road while driving at a high-speed may put drivers at
greater risk for rear-end collisions when they attempt to overtake and
pass another car.
Focusing on the road in front of your car for
too long can be hazardous say psychologist and lead author Rob Gray,
Ph.D., of Nissan Cambridge Basic Research and co-author psychologist
David Regan, Ph.D., of York University. "Motion adaptation - which is
a change in the motion-detecting cells in your brain produced by prolonged
viewing of moving objects - can occur when driving on a straight empty
road. This can have detrimental effects on visually guided motor actions
such as overtaking another car and can lead to a fatal error."
is not uncommon during highway driving that we are exposed to the type
of repetitive motion that can produce motion adaptation," said Dr. Gray.
"For example, when driving straight ahead on an empty highway, a driver's
visual image continuously expands and objects such as the road markings
and trees continually move past our eyes. As the driver continues to
drive and gets closer to the trees, the image of the trees keep getting
bigger and bigger. The trees actually move from the center of the driver's
windshield towards the edge of the windshield until they disappear out
of view. When we look at something that always moves in the same way
it causes the motion-detecting cells in our brain to adapt to that motion,"
explains Dr. Gray.
In our study, we examined the effects of motion
adaptation -produced by driving on a virtual highway - on overtaking
maneuvers in a driving simulator. Eighteen 19 to 36 year old experienced
drivers participated, said Dr. Gray. The driving simulator consisted
of the frontal two-thirds of a Nissan 240SX convertible and a wide-field-of-view
(60 degrees horizontal X 40 degrees vertical) display of a simulated
driving scene. It provided realistic feedback through the torque in
the steering wheel and audio feedback consisting of engine noise that
increased with faster car speeds, according to the study.
five minutes of driving on a straight empty highway, drivers initiated
overtaking of other vehicles substantially later (by 0.2-0.5 seconds)
than comparable maneuvers made following five minutes of driving on
a winding country road, said the authors. "This delay in the initiation
of overtaking appears to be caused by an overestimation of the time
to collision with the lead vehicle (i.e. the driver has the illusion
that she/he has more time before a collision will occur) caused by motion
adaptation. To make matters worse, we also found that motion adaptation
caused our participants to drive considerably faster (by 5 mph on average)."
changes in driving behavior resulting from motion adaptation substantially
reduce the margin for error and place the driver at a much higher risk
for a rear-end collision, said Dr. Gray. If a driver delays the initiation
of overtaking, it increases the chance that they will clip the rear
corner of a car when trying to pass. Motion adaptation it also dangerous
because it occurs without the driver being aware that it is happening.
Drivers in our experiments did not know that they were driving faster
and initiating overtaking later.
Motion adaptation can also cause
problems when a driver exits a highway and enters an off-ramp, said
Dr. Gray. The increase in driving speed resulting from motion adaptation
can cause drivers to lose control when going around a sharply curved
off-ramp. Unequally spaced white stripes painted across the road leading
up to an off-ramp have been used to create an illusion that counteracts
motion adaptation and reduces driving speed.
has been reported to reduce the number of accidents and is now commonly
used on roundabouts and off-ramps. However, it does not solve the problems
associated with overtaking and passing. "We are currently exploring
strategies for reducing the build-up of these dangerous aftereffects
during driving. For example, dashboard displays which elicit eye movements
and prevent the driver from staring straight ahead," said the authors.
"Risky Driving Behavior: A Consequence of Motion Adaptation for Visually
Guided Motor Action," Rob Gray, Ph.D., Nissan Cambridge Basic Research
and David Regan, Ph.D.; Journal of Experimental Psychology:
Human Perception and Performance, Vol. 26, No. 6.
The American Psychological Association (APA), in
Washington, DC, is the largest scientific and professional organization representing
psychology in the United States and is the world's largest association of psychologists.
APA's membership includes more than 159,000 researchers, educators, clinicians,
consultants and students. Through its divisions in 50 subfields of psychology
and affiliations with 58 state, territorial and Canadian provincial associations,
APA works to advance psychology as a science, as a profession and as a means
of promoting human welfare.