Attitudes on wheels

Delta, 18 March 2010

Young drivers are four times more likely to be involved in a crash than their middle-aged parents. In her PhD-thesis, titled ‘The X-factor’, dr. Saskia de Craen pursues the question of how experience reduces crash risk over time.

In the Netherlands over hundred young people each year die in car crashes involving a novice driver behind the wheel, which often also involve groups of people and occur at night. Statistics show that crash rates are highest in the first months after a person receives a driving license, and then drop substantially over the first two years of driving, with the sharpest decline occurring during the first six months or 5,000 kilometres.
There are several known factors in youngsters contributing to the risk, such as underdeveloped executive functions concerning planning, impulse control and reasoning. And, for some specific sub-groups, intentional risk taking, sensation seeking and peer pressure put them even more at risk. One could argue that young drivers just need to acquire experience, so that driving becomes automated, reducing the mental workload. But Dr Saskia de Craen counters this argument, stating that mental load doesn’t seem to be the issue here. Firstly, any driver can reduce the mental work load of driving by simply reducing speed – but young drivers seldom do – and secondly young drivers typically engage in secondary behaviour, like making a telephone call, which increases mental pressure instead of decreasing it.
De Craen is a psychologist working at the Dutch Institute for Road Safety Research (Swov) in Leidschendam. She performed her study of young drivers acquiring driving experience under the supervision of professor Karel Brookhuis, of TU Delft’s faculty of Technology, Policy and Management. The concept most used in such studies is called calibration. Calibration is the complex process of matching up a complex traffic situation against one’s own impression of one’s driving skills, and then adapting your driving behaviour accordingly.
De Craen has put the concept of calibration to the test in two-year, longitudinal study involving over 500 novice drivers: Does poor calibration indeed mean a higher crash risk? And how can calibration be measured and how does it change over time?
Young drivers were recruited directly after they passed their examination. “They’re so exhilarated, they’d say yes to anything”, De Craen says. Over a period of two years, the new drivers were, at four month intervals, presented with a questionnaire on skills and self-confidence, a driving diary (in which they reported remarkable incidents over the past three week) and a newly developed adaptation test for measuring their degree of calibration. In addition to the self-reported behaviour, the driving behaviour of a group of drivers was additionally judged in an on-road driving assessment. An older group of experienced drivers was enrolled as well as a control group.
The findings partly support the role of calibration in gaining driving experience, but not entirely. As expected, the results showed that young drivers overestimate their driving skills more than experienced drivers do. What’s worse, the drivers who drove so unsafe that they failed the on-road driving assessment reported the same confidence level as their peers who performed best. In other words: the worst young drivers have the highest self-esteem. Results also showed that such overestimation of skills resulted in more crashes.
The problem with calibration lies in its lack of measured development. It is indeed strange that although crash rates diminish quickly over the first six months of driving, De Craen has found no correlated improvement in calibration. She offers a number of possible explanations for this awkward fact, but concludes that the search for the X-factor in gaining driving experience has not yet been found.
However, the good news is that, despite the lack of full theoretical understanding, some practical recommendations can be made. Accompanied driving, for example, might well work. It entails that 17-year-olds who have passed their driving tests may – up to their 18th birthdays – only drive in the company of a more experienced driver. This might be a safer way for the novice driver to gain experience in those first few dangerous months. In Germany, accompanied driving has reduced the number of accidents by people from the programme by thirty percent. The programme is expected to be introduced in the Netherlands later this year.
Saskia de Craen, ‘The X-factor – A longitudinal study of calibration in young novice drivers’, 16 March 2010, PhD supervisor professor Karel Brookhuis

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