Thursday, March 1, 2012

Are there supertaskers? Please don’t try this at home

When I’m driving and someone is doing something strange on the road, it is virtually guaranteed that they are talking on the cell phone.  I have seen people driving far too slowly on the highway, weaving across lanes, and braking quickly to avoid hitting a car in front of them.  Earlier this summer, I had to lean on my horn as someone talking on the phone blissfully drove within a few feet of my car exiting a parking lot while talking animatedly to a friend.

It shouldn’t be surprising that talking on the cell phone (even with a hands-free device) impairs your driving ability.  Driving is a moderately difficult thing to do.  You have to watch out for other drivers, for bicycles, for pedestrians, and you have to keep control of a large and heavy vehicle.  You need to anticipate what is going to happen, because your car will not stop or change direction immediately. 

Having a conversation also requires some effort.  You have to listen to what someone else is saying.  You have to think about what you are going to say next.  You have to keep in mind what you want to say when your conversation partner is finishing up. 

Psychologists have spent years demonstrating that performing two tasks at once almost always makes you worse at both tasks than you would be if you did the two tasks alone.  In particular, doing effortful things like driving are made worse by doing something else at the same time.

A paper by Jason Watson and David Strayer in the August, 2010 issue of Psychonomic Bulletin and Review suggests that some people may not be affected by doing two tasks at once.  They had 200 people perform a realistic driving simulation in a lab.  They had to drive on a simulated highway behind a car that would sometimes step on the brakes.  They had to follow the car at an appropriate distance and brake when necessary.  Sometimes, people did the driving alone.  At other times, they did it while performing a complicated task while talking on a hands-free cell phone device.  This second complex task is called the OSPAN, and it involves remembering words and doing math problems.  People also did the OSPAN without driving.

Almost everyone in the experiment was worse at both driving and the OSPAN when they did them together compared to when they did them alone.  However, they found 5 people whose performance on the two tasks was completely unimpaired when they did them together.  That is, these people did just as well when driving and doing the OSPAN as when they were just driving.  These people were all ones who had done quite well in the driving task alone, so it wasn’t just that they were distracted by something else when they were driving, and then were distracted again when they had to do the OSPAN.

Watson and Strayer called these people supertaskers, and they did some statistical analyses to show that there were more than you would expect just by chance.

Before you go trying this at home, though, there are a few reasons to want to treat these results with some care.

First, let’s assume that about 2.5% of the population really can do two things at once without suffering on either task.  That still means that there is a 97.5% chance that you are not one of them.  So, you should still assume that talking on the cell phone makes you worse at driving.

Second, you are the worst judge of your own performance.  Most people recognize that other people’s driving is made worse by talking on the cell phone, but still believe that their own performance is not.  There are a few reasons for that.  For one, the difficulties you have doing two things at once also make it less likely that you will notice your own driving errors.  For another, most of the errors you make when driving are (thankfully) not catastrophic.  So, you may not notice that you were a little to close to the car in front of you or that you braked a little too later.  It is only when a series of things go wrong that you end up in an accident, and at that point it is too late.

Third, there is some reason to treat the results of this study with some caution.  In this experiment, people were tested in one session.  That means that 2.5% of the people in this study demonstrated “supertasking.”  That is, these people did well on both tasks.  But, without bringing these people back a few times, we don’t know where they are “supertaskers.”  So, we don’t know whether they will always be good at both tasks.  Maybe there are circumstances that lead people to perform well, but they affect different people at different times.  If we brought all 200 people from this study to the lab a few times, it is possible that about 2.5% of people will perform well when given two tasks to do at once, but it would be a different 2.5% of the people each time. 

Ultimately, it is worth cutting back on the amount of time you spend on the cell phone while driving.  Even if there are supertaskers and you happen to be one, you set a better example for everyone else by paying attention to the road.