Abstract
Purpose :
Drivers with homonymous visual field loss (HVFL) may have delayed responses to hazards from the blind side. Warnings that indicate hazard direction may be helpful for directing gaze to blind-side hazards. Using a driving simulator, we tested the hypothesis that responses to blind-side hazards would be faster with directional than non-directional warnings.
Methods :
Sixteen subjects with HVFL (25-82y) completed 2 drives with directional warnings, 2 with non-directional warnings, and 2 without warnings. Per drive, 10 realistic pedestrian hazards appeared midblock from the left or right and crossed the road in front of the driver's vehicle, requiring a braking response to avoid a collision. If the situation started to become dangerous (time to contact < 3s) in drives with warnings, motors embedded in the seat vibrated to give either a directional warning (vibration on left/right for a hazard on left/right) or a non-directional warning (vibrated simultaneously on both sides). Gaze position and driving metrics were recorded for analysis. Traffic, pedestrians, and crowds populated the virtual city environment.
Results :
Participants received warnings in about 36% of pedestrian events, with no effects of event side or warning type. After a blind-side hazard warning, participants made their first scan toward the blind side in 39% of events for directional and 34% for non-directional warnings. They usually fixated blind-side hazards before braking; however, rates of fixating first were lower (p<0.05) for non-directional warnings (72%) than directional (87%) and no warnings (86%). For seeing side events, rates of fixating first (about 80%) did not differ across warning modalities. For blind side events, participants fixated significantly faster on the hazard for directional (1.48s) than non-directional (2.42s, p<0.001) and no warning drives (2.56s, p<0.001), with no difference across the conditions for seeing side events (1.3s). Warnings significantly reduced blind side collision rates (0% directional, 0.7% non-directional vs. 15.7% without warnings). Most participants (94%) preferred directional over non-directional warnings.
Conclusions :
Although both warning modalities substantially reduced the number of blind side collisions, participants fixated significantly faster on blind side pedestrians with directional than non-directional warnings and preferred directional over non-directional warnings.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.