Dynamic traffic management on a familiar road: Failing to detect changes in variable speed limits

Variable speed limits (VSL) are used more commonly around the globe lately. Although on a macroscopic level positive effects of VSLs have been reported, the caveat is that the impact of VSLs is very sensitive to the level of driver compliance. Thus far it is unknown whether all individual drivers are actually able to notice when a speed limit changes into another speed limit; a prerequisite for purposeful speed limit compliance in the first place. To simulate regular driving conditions, twenty-four participants were familiarised with a particular route by driving the same route in a driving simulator nineteen times on five separate days. Part of the route consisted of a motorway where VSL signs were regularly displayed above every driving lane. At drive nineteen, speed limits changed from 80 km/h to 100 km/h on four out of eight consecutive signs. After passing all signs, one expects 6.25% of the participants still to be unaware that the speed limit had increased (based on chance), while the results showed most participants had failed to notice the speed limit change (58.3%). Instead, they saw what they expected to see: a speed limit of 80 km/h. If the speed change had been vice versa, in other words from 100 km/h to 80 km/h, this would immediately result in speed offences, though not deliberately at all.     

From riskier to safer driving decisions: The role of feedback and the experiential automatic processing system

Decision making in risky driving contexts is mainly guided by automatic processes. This requires the previous learning of cognitive rules and heuristics. The acquisition of safer cognitive heuristics depends on previous experience and adequate feedback to our responses. The first aim of this research was to analyze the effect of negative feedback on risk evaluation and decision processes in dangerous and harmless driving contexts. The second aim was to demonstrate the influence of prior experience upon the process of decision-making and feedback, comparing individuals with and without driving experience. One hundred and three participants (with and without driving license) were required to evaluate a set of 120 driving images with respect to the risk level of the situations and decide whether to brake or not. Half of the participants received negative feedback. The results showed that decisions were faster and more accurate than evaluations, and both were improved by the effect of feedback and previous experience in risk situations. However, the same feedback resulted in inaccurate risk evaluations and decisions in harmless situations. The cognitive processes underlying these effects point to a response bias rather than to discriminative factors. These results clarify the effect of negative feedback and previous experience on different phases of the decision-making process, showing the importance of these factors for the automatic processes and cognitive heuristics implied in driving. Our findings have potentially important applied value in the promotion of safe driving practices.