One factor that promotes overconfidence in one’s ability to “safely” multitask while driving is the idea that we cannot often correctly monitor our own level of vigilance.
A CAR’S judgement on the driver’s levels of alertness could be more reliable than the driver’s own perception of it.
So say Eike Schmidt of car manufacturer Daimler in Böblingen, Germany, and his team, after tests on volunteers during a 4-hour drive along the autobahn. To make the drive as boring as possible, the drivers were asked not to chat or listen to the radio.
Every 20 minutes, the team asked the volunteers how attentive they were feeling. They also tested the volunteers’ reaction times by asking them to push a button attached to their thumbs every time they heard a certain tone. Each driver’s heart rate and brainwave frequency, which are indicators of attentiveness, were also recorded during these tasks.
The team found that while all measures of alertness declined over the 4-hour period, in the final hour the drivers reported feeling more vigilant than the physiological tests suggested.
This relates to a point I tried to raise in Traffic — that drivers are not only distracted, but unaware of their level of distraction.
William Horrey and colleagues found a similar result in a study that looked at drivers on mobile devices on a closed track. As other studies have found, their were “performance decrements” while using a hand-held and hands-free device versus “baseline driving,” but what was interesting here is that subjects’ estimates of how distracted they were had little to do with the actual level of distraction:
[I]n some cases, the subjective measure of distraction was in the opposite direction of the actual distraction effect. That is, drivers that estimated the smallest (or no) distraction effects exhibited the largest ones. In general, a disconnect between performance and awareness was consistent across driving measure and phone type.
Interestingly, in this study, the researchers suggested it was not overconfidence per se, but a “failure of perception,” underpinning the disconnect. Just as a fatigued driver does not quite know the point at which his fatigue will become deadly, nor does the distracted driver know the exact tipping point moment where they will miss something they might have otherwise detected.