How People with a Visual Field Defect Scan their Environment: An Eye-Tracking Study

Abstract

The scanning behavior of people with a Visual Field Defect (VFD) is still relatively unexplored, although a VFD can have great impact on the person concerned with it. This study examined the scanning behavior of people with a VFD in a mobility situation by the means of an Eye-Tracker. Participants were asked to watch a video of everyday mobility situations, showing both walking and biking sequences from first person perspective. They were asked to imagine being that person in the video and look around naturally. In the video, 33 objects were defined as regions of interest (ROIs), as they are important to detect in order to walk or bike safely. The Eye-Tracker recorded when and where the participants looked. It was expected, that people with a visual field defect (VIPs) need more time to fixate on relevant ROIs for the first time, detect less ROIs in total, do not look at them as long as sighted people do and fixate more often on the ROIs. The results confirmed that VIPs detect less ROIs and spend less time looking at them. Contrary to what was expected, the results also showed that sighted people fixate more on the ROIs than VIPs. An additional analysis showed that the time until an ROI is first looked at, is significantly shorter for sighted people. These findings showed that there are indeed differences in scanning behavior and they could be used to help VIPs counterbalance their decreased visual field.