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 In experiments using a driving simulator, drivers distracted by
complex or emotional questions constantly compensated for erroneous
steering reactions. But the same adaptability did not kick in for
drivers distracted by texting, the study found.
“Our working hypothesis was that pure emotional and cognitive
distractions were about the same with pure physical (i.e.,
sensorimotor) distractions,” but according to these results, they
are not, said lead author Ioannis Pavlidis of the Computational
Physiology Laboratory at the University of Houston in Texas.
The researchers studied 59 subjects who completed several test
drives in the simulator. For the first few, participants focused on
relaxing and getting familiar with the machine while sensors
recorded perspiration levels on their faces as a measure of the
state of their sympathetic nervous system, which governs the
unconscious “fight or flight” response.
The simulator measured steering angle and lane departures to the
left or right while the subjects were driving the course. The
subjects drove the course four times under stress: once with
cognitive stress coming from a researcher posing the driver
challenging questions, and another under emotional stress, where the
questions were emotionally charged. One simulated drive had the
driver sending text messages, representing “sensorimotor stress,”
and a fourth time there were mixed stressors.
Steering became more jittery than normal in all four conditions, but
lane deviations only became “unsafe” while drivers were texting.
In the mentally and emotionally challenging conditions where drivers
still had their eyes forward, their driving trajectories were
actually straighter than under normal conditions, hinting at a kind
of coping mechanism that pays extra attention to the task of driving
when the brain is busy, the study team speculates in Scientific
Reports.
“The driver’s sympathetic system is already loaded, as driving
itself is a task that needs psychophysiological resources,” Pavlidis
told Reuters Health by email. “Atop of that, if you add another
stressor (cognitive, emotional, or physical), it arouses the
sympathetic system even further, as it antagonizes for some of the
same resources needed for the driving task.”
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“Jittery” steering may come from latent fight-or-flight energy, he
said.
These distractions are “potentially dangerous, if they are instantly
corrected, which is the case with the pure emotional and cognitive
stressors,” Pavlidis said. “They are immediately dangerous if they
are left occasionally uncorrected (as is the case with texting),
because they lead to significant left or right lane deviations.”
Texting undoes the “auto-pilot” mechanism we have to deal with
driving and other routine tasks, he said, because to text you must
look away from the road and disrupt the eye-hand feedback loop.
“Vehicle control requires hands on the wheel so a distraction such
as holding a phone could impact stabilization and make it a bit more
'jittery'," said Despina Stavrinos of the University of Alabama at
Birmingham, who was not part of the new study. “When driver’s eyes
are off the road they may also overcorrect in steering when they
shift attention to driving.”
Drivers can drift into emotional or mental distraction without
realizing it, Pavlidis said.
“The best thing to do is to not drive at all when angry or upset –
take a few moments to settle down before returning to the road,”
Stavrinos told Reuters Health by email.
“In the case of texting it is hard because smartphones are addictive
and this is the case not only in driving but in all aspects of life,
as we sadly see all around us everyday,” Pavlidis said.
SOURCE: http://bit.ly/27ETaD0 Scientific Reports, online May 12,
2016.
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