The perception of depth induced by texture gradient can partly control vergence.
56.512, Tuesday, May 14, 2:45 - 6:45 pm, Vista Ballroom
Kristin Osk Ingvarsdottir1; 1Lund University Cognitive Science, Sweden
Traditionally, vergence eye movements are considered to be elicited by binocular depth cues. Nevertheless, studies have revealed similar eye movements at some degree when perceiving monocular depth cues during monocular viewing (Ringach, et al. 1996. Vision Res, 36: 1479-1492) and binocular viewing (Ringach, et al. 2011. J. Neurosci, 31: 17069-17073). The aim of current study was to see whether previous results could be generalized to texture gradient viewed in a binocular condition. A Hi-Speed tower-mounted eye tracker was used to binocularly measure eye movements of 7 subjects participating in a visual-search task. The task was to search for a dot presented in various locations on a background that either had texture gradient or no depth cue at all. It was assumed that the vergence would be in line with the depth provided by the texture gradient. Thus the eyes would converge when looking at a dot appearing closer to the viewer, and diverge when appearing further away, despite the fact that the physical distance was always the same. In contrast to previous results I found that the perception of texture gradient could only partly generate vergence response and that effect was weak and disappeared quickly. I conclude that, in binocular viewing, the perception of texture gradient does not manage to override the binocular cues completely. Nevertheless, the thought of seeing depth is enough to generate mild vergence response. My findings are discussed in terms of conflicting theories on vergence control and depth perception, where it is debated whether vergence are only elicited by the properties of the visual input, or if they are also emitted by the perception of the input.