Advancing Knowledge on Situation Comprehension in Dynamic Traffic Situations by Studying Eye Movements to Empty Spatial Locations

Objective: This study used the looking-at-nothing phenomenon to explore situation awareness (SA) and the effects of working memory (WM) load in driving situations. Background: While driving, people develop a mental representation of the environment. Since errors in retrieving information from this representation can have fatal consequences, it is essential for road safety to investigate this process. During retrieval, people tend to fixate spatial positions of visually encoded information, even if it is no longer available at that location. Previous research has shown that this "looking-at-nothing" behavior can be used to trace retrieval processes. Method: In a video-based laboratory experiment with 2 (WM) x 3 (SA level) within-subjects design, participants (N = 33) viewed a reduced screen and evaluated auditory statements relating to different SA levels on previously seen dynamic traffic scenarios while eye movements were recorded. Results: When retrieving information, subjects more frequently fixated emptied spatial locations associated with the information relevant for the probed SA level. The retrieval of anticipations (SA level 3) in contrast to the other SA level information resulted in more frequent gaze transitions that corresponded to the spatial dynamics of future driving behavior. Conclusion: The results support the idea that people build a visual-spatial mental image of a driving situation. Different gaze patterns when retrieving level-specific information indicate divergent retrieval processes. Application: Potential applications include developing new methodologies to assess the mental representation and SA of drivers objectively

Driving with Foresight - Evaluating the Effect of Cognitive Distraction and Experience on Anticipating Events in Traffic

Driving with foresight is essential for road safety. Anticipating upcoming events and intended maneuvers of other traffic participants requires the perception and processing of meaningful and valid cues. To provide insights into the cognitive mechanisms of anticipation, we investigated the effect of cognitive load, experience and cue characteristic on the anticipation of upcoming lane changes in urban driving scenarios. A two-step reaction method gathered low and high certainty anticipatory reactions of student and ambulance drivers. Results indicated that different anticipatory cues affected anticipatory performance. Target cues highly associated with the intended behavior of another traffic participant increased while context cues in the surrounding environment seemed to hamper anticipatory reactions. Furthermore, high cognitive load prolonged the latencies of low certainty anticipation but did not affect the performance quality. This initial intuition of an upcoming lane change was indicated earlier by experienced than by inexperienced drivers. These findings enhance the understanding of the human process of anticipation in dynamic uncritical traffic situations

Real Autonomous Driving from a Passenger’s Perspective: Two Experimental Investigations Using Gaze Behaviour and Trust Ratings in Field and Simulator

Trusting autonomous vehicles is seen as crucial for their dissemination. However, research on autonomous driving so far is restricted by using closed training courses or simulators and by comparing behaviour and evaluation while driving oneself (a manual car) with being driven (by an autonomous car). In the current study, we investigated passengers’ eye movements, categorized as safety-relevant or not safety-relevant, and trust ratings while being driven, once manually and once by an autonomous car, in real traffic as well as in a simulator. As some of the effects observed in the field experiment might have been caused by driving style, driving style was additionally varied in the simulator. Fixations in safety-relevant regions (e.g., on the road and steering wheel) were observed more frequently during safety critical driving situations than during regular driving. More safety-relevant fixations for the autonomous compared to the manual driving mode were observed particularly in the field. Trust ratings were affected by driving mode mainly in the simulator: Here, being driven autonomously led to a lower reported trust than believing to be driven by a human driver. Driving style showed to affect trust ratings, but not gaze behaviour in the simulator experiment. Correlations between gazing into safety relevant regions and trust ratings were of smaller descriptive size than in recent investigations on drivers, suggesting that gazing into safety-relevant regions as objective alternative to trust ratings may not be as exhaustive for passengers as for drivers