Memory failures aren’t only a consequence of disease and brain injury; all of us experience periods when our memories aren’t quite up to par because we’re distracted. Working memory, the memory system that holds and manages the information we need to perform the task at hand, has limited capacity – meaning it can only hold a few items at once. When distracted, working memory may be diverted to deal with the distraction, often at the expense of what we were previously doing.
There are times when such distraction can have serious consequences, such as when we’re driving a car. The statistics are clear: car accidents are much more likely if drivers are distracted, such as by talking on a cell phone. Now research is beginning to show us why.
A recent study examined the performance of drivers using a computerized driving simulator, while those drivers were conversing either with in-car passengers (who could see the same driving simulator), or via cell phones. As several prior studies have shown, drivers’ performance suffered during cell phone conversations compared to in-car conversations; the cell-phone-using drivers showed slowed reaction times (such as speed of braking responses) and poorer avoidance of road and traffic hazards. One reason appeared to be “conversation suppression”: in-car passengers tended to slow their rates of conversation as the driver approached a hazard. This could free up attention and other brain resources, allowing the driver to focus with the hazards of the road. In contrast, cell-phone conversants (who could not see the road, and thus could not judge approaching hazards) did not tend to suppress conversation at those critical moments.
Importantly, this particular study considered hands-free phone usage. Several states in the US now ban or restrict drivers from using handheld cell phones, but allow hands-free phones. But many studies now suggest the real issue isn’t whether the driver is physically holding the phone; the real issue is that a conversant who is not in the same car as the driver doesn’t suppress conversation when a road hazard appears.
The bottom line from a growing body of studies seems to be a consistent warning that cell phone usage (whether handheld or hands-free) while driving can seriously impair a driver’s performance. The good news: talking to an in-car passenger may actually improve driver performance, because passengers often spontaneously provide alerting comments, helping the driver notice and attend to looming hazards or changes in road conditions.
Further reading:
S. G. Charlton (2009) Driving while conversing: Cell phones that distract and passengers who react. Accident Analysis and Prevention, vol. 41, pp. 160-173.
Y. Ishigami and R. M. Klein (2009) Is a hands-free phone safer than a handheld phone? Journal of Safety Research, vol. 40, pp. 157-164.
Tags: attention, cell phone, distraction, driving, working memory
