Distracted by familiarity:Implications of ‘autopilot’ as a default cognitive mode

Most trips are made, and most travel is done on roads and paths well-known. To provide insight in the cognitive processes involved in visual information processing of familiar traffic environments this paper considers a series of four consecutive empirical studies. The aim of this paper is 1) to discuss the implications of these insights on research methodologies used to measure driver attention and distraction and 2) to provide recommendations for policymaking, road design and vehicle design. This line of work consists of three studies on car driver behaviour (two driving simulator studies and a video-based study) and an observational study on pedestrian behaviour. The recurring theme in the results of these studies is that the progressive exposure to the same traffic environment enables participants to automatise their behavioural performance in traffic up to the point that it could be executed at skill-based level. As a result, attention is easily diverted away from traffic participation, while participating in traffic. Participants could act without thinking about it, so they didn't always even remember what they had done. People get used to familiar traffic environments so much that they don't have to think about walking or driving with much conscious focus. Hence, when studying road user behaviour and particularly driver distraction, it is crucial to mimic these natural circumstances as closely as possible. It is therefore proposed that within driver distraction research, route familiarity should be regarded as a context that enables distraction. What is more, is that the results point in the direction of a familiarity paradox: deviating from what is very familiar likely results in involuntary distraction, but being very familiar may lead to underload resulting in (voluntarily) diverting attention elsewhere.</p

Traffic management:assessing various countermeasures to improve detection failure of changes in speed limit signals

Under certain circumstances, drivers fail to notice changes in electronic speed limits. A video-based study was performed to reveal which countermeasures would improve drivers’ ability to detect changes in electronic speed limits. Countermeasures included leaving electronic signs blank prior to a speed limit change and adding motion signals by means of flashing amber lights or a wave. A video representing a motorway was shown repeatedly to 255 participants. They were instructed to press the space bar when detecting a change. The video was viewed 13 times before the speed limit changed. Results showed that leaving signs blank prior to the change instead of displaying speed limits continuously did not alter change detection, whereas flashers and waves eroded detection of the changed speed limit. This suggests that using flashers and waves to attract attention to electronic signs in fact decreases people's ability to process the information contained in the signs

Don’t shoot the messenger:traffic-irrelevant messages on variable message signs (VMSs) might not interfere with traffic management

Road authorities struggle with the question whether variable message signs (VMSs) should exclusively be used for traffic management or could also be used to display traffic-irrelevant messages, such as mottos or commercial advertisements. The current study assesses behavioural responses to a critical route instruction displayed on the same VMS that previously displayed a variety of traffic-irrelevant messages. For this, thirty-two participants were divided between a control group and an experimental group (the advertisements group). In a driving simulator, all were familiarised with the same route by driving a VMS-equipped motorway nine times. For the advertisements group, up to drive 8, this VMS displayed various advertisements. Whereas for the control group it was blank. In the 9th drive, the VMS displayed a critical detour message for all participants. This critical route instruction – informing drivers to take the nearest exit – resulted in compliant driver behaviour in the advertisements group. In addition, they only reduced speed marginally to increase the time to process the VMS text. The control group, on the contrary, displayed a much sharper speed reduction; though the instruction only moderately altered motorway exit behaviour. What is more, the 31% (n = 4) of the advertisements group who complied with the critical route instruction subsequently failed to recall this message (recalling an advertisement instead). In conclusion, this study provides evidence that displaying traffic-irrelevant messages on VMSs might not interfere with traffic management; provided the format of said messages is in accordance with ergonomic VMS guidelines as used in this study. It is proposed that due to repeated exposure to various VMS texts, reading the sign has been practised to the extent that little to no conscious deliberation was required. As a result, recall of what was seen, proved to be an inadequate proxy for assessing driver behaviour. This study shows that conscious attention might not be a prerequisite for compliance. Furthermore, it suggests that continuous variability in objects in the traffic environment may become part of a subconscious monitoring process, as long as they have been sufficiently practised