Abstract
Purpose :
Individuals with hemianopic field loss (HFL) are permitted to drive in many states. To see potential hazards on the blind side, drivers with HFL need to scan (look) toward that side. However, in scanning from side to side, the blind hemifield obscures and disrupts vision of the scene. Such disruptions can cause failures of awareness called change blindness, a failure to notice an obvious change that occurs when vision is disrupted by an eye movement or a scene cut in a video. We used a novel driving simulator paradigm to test the hypothesis that individuals with HFL would be more susceptible to change blindness than individuals with normal visual fields.
Methods :
To date, 10 individuals with complete HFL and 5 controls with normal visual fields have driven through 2 routes in a virtual city while their eyes and head were tracked. They were instructed to obey traffic rules and press a button whenever they detected a pedestrian who changed location. Pedestrians changed locations equally on the left and right. The majority of the changes (n = 16) were triggered to occur only during a scan in the opposite direction from the side of the change. The remaining changes (n = 8) were triggered when the driver was a predetermined distance from the pedestrian and thus always occurred. To reduce anticipation of events, the city included traffic, distractor pedestrians and pedestrian crowds.
Results :
There were similar proportions of triggered changes for the HFL and control groups [70% v 64%, p = .11]. Those with HFL experienced more change blindness than controls [18% v 7% of all triggered events, p < .005]. Those with HFL experienced change blindness on 28% of the events on the blind side and 15% on the seeing side, which was significantly different [p < .05].
Conclusions :
We found change blindness in both individuals with HFL and controls and in both the blind and seeing side for those with HFL. Change blindness occurred more frequently in the blind than seeing side, which may reflect the increased cognitive demands to accurately represent information on the blind side. These results suggest that individuals with HFL may be more susceptible to failures of awareness, such as change blindness, than individuals with normal vision. Increased risk for failures of awareness may result in motor vehicle crashes where the driver fails to notice the other road user (looked-but-failed-to-see incidents).
This is a 2020 ARVO Annual Meeting abstract.