Daydreaming and driving – an unsafe combination?

Sometimes while I’m driving I notice that for some minutes previously I have been daydreaming. My own personal daydreams can verge from the sublime - dreaming about scoring a winning goal at Wembley - to the mundane – dreaming about what kind of sandwich I will have for lunch. Usually cheese salad. You probably have your own regular daydreams too. The pop psychology notion of being “lost in a daydream” raises an intriguing question: how unsafe is it to daydream while driving?

How psychologists might go about researching this is not at first obvious. Usually an experiment is set up where psychologists arrange for participants to do something in one condition and not in another, and then differences in the behaviour or performance of the participants across the conditions are examined. But how can you get people to daydream to order and how could you measure that while they are driving?

Jino He and colleagues at the University of Illinois had access to a fully immersive high fidelity driving simulator. This consisted of a real car (the Saturn SL, at one time the most stolen car in America) with computer controlled steering wheel and pedals, housed in a laboratory and surrounded by a 360 degree screen on which computer generated roads to drive along are projected. I have used a simulator much like this at TRL in Surrey. It is uncannily like driving a real car.

To invoke daydreaming the 18 participants were asked to undertake a boring drive for one hour along straight roads with no oncoming traffic. There was always a car up ahead, behind which participants were instructed to maintain a safe headway distance. A following vehicle was added to encourage regular mirror checks. Occasional simulated crosswinds broke the tedium. Participants were asked to press a button on the steering wheel whenever they found their minds wandering (i.e. daydreaming). Psychologists, being the kinds of people we are, felt it necessary to define exactly what was meant by mind wandering: thinking about task unrelated images and thoughts, planning a schedule, having recollections of childhood, or simply having a blank mind.

There were, on average, 5.7 daydreaming episodes - roughly one daydream every 10 minutes. This was slightly reduced during cross-winds, suggesting we daydream less when conditions place heavier demands on attention. Nobody crashed showing that participants were taking the simulation seriously rather than embarking on a Grand Theft Auto style rampage through the simulated roadscape (!) To assess whether daydreaming affects car control, driving performance in the 9 second window before and after each button press were compared. A few seconds were allowed either side of pressing the button to avoid picking up disruptive effects of carrying out the action of moving to press the button.

Daydreaming did not affect chosen speed, safe following distance in relation to the car in front or lane positioning. However, daydreaming did increase the length of time participants would tend to stay at one speed rather then slowing down and speeding up. Also, most importantly, while daydreaming, participants tended more often to look straight ahead rather than checking their side mirrors.

The conclusion from these observations was that daydreaming while driving does pose a safety risk. The authors of the article suggest that the tendency to look straight ahead while in the middle of a daydream entails a failure to scan or monitor the environment such that a daydreaming driver becomes less aware of the other vehicles around them on the road, which could contribute to increased risk of crashing.

Of course, driving a simulator is not the same as driving a real car on the road. Despite increasingly realistic graphics depicting the environment and a real vehicle for the driver to occupy and control, bumps and acceleration and deceleration forces are difficult to simulate. From my own experience of using a driving simulator braking seems particularly difficult to reproduce convincingly. Not only that but the knowledge that one is not really driving and so could crash without damage or injury must alter the driving task in subtle ways. On the other hand driving a simulator can be a very immersive experience. I once accidentally reached the end of the computer generated environment while in a simulator and had the very unnerving experience of driving off the end of the road into a vast white nothingness. I stopped, got out and stood looking back watching various simulated cars and lorries heading towards me until, at the point where the road ended and the white void began, they simply vanished into thin air.

Overall I find these results quite convincing and admire what is, for me, a very cool psychology paper. Why? Well, for a start, daydreaming is such an inherently human and easy to relate to activity that researching what happens during a daydream seems a very interesting and cool undertaking. As a car-fan I find driving simulators very cool and fun and would recommend you have a go on one if you ever get the chance. This study is also cool in my book because the findings are so easy to interpret and so readily applicable to everyday life. Thanks to this study we know that the rate of daydreaming while driving is around once every 10 minutes, and we also know that getting lost in a daydream doesn’t affect that much of the driving task apart from a tendency to forget to monitor other vehicles around us. Which is useful, because that gives us a concrete suggestion as to what should be the first thing we do when we snap out of a driving daydream – check mirrors!

Finally, like most cool psychology research, this study was not funded by a mainstream research funding agency. The paper mentions no acknowledgments.

If you are interested, the full reference for the original research paper is below. A pdf copy of the paper is not available to download for free but you may be able to obtain a copy through your university library subscription. Otherwise, you could try e-mailing the corresponding author, Jason S. McCarley. Cite the full reference below and be sure to ask very politely!

He, J, Becic, E, Lee, Y, McCarley, JS (2011). Mind Wandering Behind the Wheel: Performance and Oculomotor Correlates. Human Factors, 53, 13-21. doi:10.1177/0018720810391530