The comparative Situation Awareness performance of older (to younger) drivers

The overall aim of this thesis is to corroborate whether the Situation Awareness (SA) of older drivers is deficient to that of younger driving groups, due to the onset of age-related cognitive decrements. This is important to ascertain due to a presumed linkage between the concept and accident causation. In addition, the research undertaken to date to investigate this linkage has exclusively utilised rather artificial driving simulators and simulations. Thus there is a need for data from more ecologically valid methods. The research studies reported here have sought to preference on-road assessments (of different complexity), and to capture what information was selectively perceived, comprehended and reacted to; rather than, as in previous work, what was recalled. To achieve this, a Think aloud methodology was chosen to produce narratives of a driver s thoughts. This method was advantageously unobtrusiveness, but also flexible - it could additionally be used to compare an individual's SA to a driving performance measure, Hazard Perception. The driving-based studies undertaken found that for a relatively non-taxing route, an older driver group could produce cohesive awareness in parity with a younger driver group. However, the concepts from which that awareness was based upon drew more on general, direction based, concepts, in contrast to the younger group s focus on more specific, action based, concepts, and rearward and safety-related cues. For a more cognitively taxing route, the younger group produced significantly higher (p<0.024) individual SA-related scores than their older counterparts. But the concepts/cues both groups relied upon remained similar - particularly in regards to the ratio of those indicative of a rearward and/or a safety-related focus. In a video-based study, however, and in contrast, the older driver group s SA scores improved sufficient to outperform a younger group, but, despite this, not for video-based scores indicative of Hazard Perception (HP). In this latter regard, age-related decrements appeared to be more influential, as the older group felt they were under time pressure during a HP test. However, the difficulty this presented appeared to advantageously bring more attention and effort to the task, which were argued as important factors for the uplift in their SA scoring. The thesis also showed that older groups judgement of the actual complexity of a driving task could potentially be deficient to that of younger driver groups. This could cause problems as incorrect perceptions could deflate the relevance and cohesiveness of information being processing. In contrast, the perceived complexity of a task could bring a rise or fall in SA score for both groups. Such results raised questions as to the impact of cognitive decrements, relative to task difficulty and related effort whilst driving. It also provided evidence that Situation Awareness, rather than being uniformly good or bad, could, like any other psychological construct, be prone to change. These aspects were drawn together in a proposed model of driving SA.