The relative importance of foveal vision in visual search in 3D dynamic scenes

Adam C. Clayden, Robert B. Fisher
University of Edinburgh, United Kingdom
s1475487@sms.ed.ac.uk

Search performance when finding targets within static naturalistic-scenes has been demonstrated to
be similar with and without foveal vision (Nuthmann, 2014). However, detection of objects during
self-motion has been shown to rely on optical flow (Warren & Rushton, 2008). Participants in our
study were required to search for context free targets within 3D, simulated self-motion scenes, made
with the Unity Game Engine. As the targets were non-moving, they conformed with the optical flow.s
movement, and so blended with the flow field. We investigated: 1) Does the inclusion of optical flow
produce costs to search performance with foveal vision loss? 2) If there is a cost, can we improve
search performance by manipulating optic flow trajectory and target placement? Results show that 1)
localising targets while moving without foveal vision produces a significant cost to performance. 2)
Manipulating the path of self-motion and varying target location did not eliminate the cost of foveal
impairment. As target motion blended with the flow field, observers needed to fixate near the target
for detection, utilising their high acuity vision. We suggest that the optical flow interfered with the
target localisation process, which results in an increased reliance on high acuity vision.