Driving with hemianopia: IV. Head scanning and detection at intersections in a simulator.

Investigative Ophthalmology & Visual Science

PubMedID: 24474265

Bowers AR, Ananyev E, Mandel AJ, Goldstein RB, Peli E. Driving with hemianopia: IV. Head scanning and detection at intersections in a simulator. Invest Ophthalmol Vis Sci. 2014;55(3):1540-8.
Purpose. Using a driving simulator, we examined the effects of homonymous hemianopia (HH) on head scanning behaviors at intersections and evaluated the role of inadequate head scanning in detection failures. Methods. Fourteen people with complete HH and without cognitive decline or visual neglect and 12 normally sighted (NV) current drivers participated. They drove in an urban environment following predetermined routes, which included multiple intersections. Head-scanning behaviors were quantified at T-intersections (n = 32) with a stop or yield sign. Participants also performed a pedestrian detection task. The relationship between head scanning and detection was examined at 10 intersections. Results. For HH drivers, the first scan was more likely to be toward the blind than the seeing hemifield. They also made a greater proportion of head scans overall to the blind side than the NV drivers to the corresponding side (P = 0.003). However, head scans magnitudes of HH drivers were smaller than those of the NV group (P < 0.001). HH drivers had impaired detection of blind side pedestrians either due to not scanning in the direction of the pedestrian or an insufficient scan magnitude (left HH detected only 46% and right HH 8% at the extreme left and right of the intersection, respectively). Conclusions. HH drivers demonstrated compensatory head scan patterns, but not scan magnitudes. Inadequate scanning resulted in blind side detection failures, which might place HH drivers at increased risk for collisions at intersections. Scanning training tailored to specific problem areas identified in this study might be beneficial.