The effects of simulated central and peripheral vision loss on naturalistic search.

Worldwide, millions of people experience central or peripheral vision loss. The consequences on daily visual functioning are not completely known, in particular because previous studies lacked real-life representativeness. Our aim was to examine the effects of simulated central or peripheral impairment on a range of measures underlying performance in a naturalistic visual search task in a three-dimensional (3D) environment. The task was performed in a 3D virtual reality (VR) supermarket environment while being seated in a swivel chair. We used gaze-contingent masks to simulate vision loss. Participants were allocated to one of three conditions: full vision, central vision loss (a 6° mask), or peripheral vision loss (a 6° aperture) in a between-subject design. Each participant performed four search sequences, each consisting of four target products from a memorized shopping list, under varying contrast levels. Besides search time and accuracy, we tracked navigational, oculomotor, head and torso movements to assess which cognitive and motor components contributed to performance differences. Results showed increased task completion times with simulated central and peripheral vision loss, but more so with peripheral loss. With central vision loss, navigation was less efficient and it took longer to verify targets. Furthermore, participants made more and shorter fixations. With peripheral vision loss, navigation was even less efficient, and it took longer to find and verify a target. Additionally, saccadic amplitudes were reduced. Low contrast particularly affected search with peripheral vision loss. Memory failure, indicating cognitive load, did not differ between conditions. Thus we demonstrate that simulations of central and peripheral vision loss lead to differential search profiles in a naturalistic 3D environment.