Roles of perspective and pursuit cues in the disambiguation of depth from motion parallax
53.325, Tuesday, May 14, 8:30 am - 12:30 pm, Royal Ballroom 6-8
Marcus Mahar1, Gregory DeAngelis2, Mark Nawrot1; 1Center for Visual and Cognitive Neuroscience, Department of Psychology, North Dakota State University, 2Department of Brain and Cognitive Sciences, Center for Visual Science, University of Rochester, NY
While there is abundant psychophysical and neurophysiological evidence for an extra-retinal pursuit signal that disambiguates perception of depth from motion parallax (MP), we investigated the possible role of perspective information in disambiguating MP, both alone and in combination with pursuit. Dynamic perspective cues were generated with a random-dot plane that rotated (CW or CCW) about the vertical meridian, into or out of the screen. Such a dynamic-perspective stimulus could provide information about change in eye orientation relative to the scene, a variable needed to compute depth from MP (Nawrot & Stroyan, 2009). Can this dynamic perspective disambiguate the perceived depth-phase of an ambiguous MP stimulus? Which cue determines perceived depth when perspective and pursuit are in competition? Observers maintained fixation at the center of a MP stimulus surrounded by the perspective plane and reported perceived depth-phase of the MP stimulus. In Condition 1, rotation of a square perspective plane, with visible edges, disambiguated depth for most observers (average performance = 85%), although there was considerable variation across observers. In Condition 2, rotation of a large perspective plane that filled the screen, obscuring the planes edges, had a substantially weaker disambiguating effect (average = 65%, range 50-80%). These results suggest that dynamic perspective can disambiguate depth for some observers. The difference between conditions 1 and 2 suggests that the transforming edges of the perspective plane play a larger role than the relative motion of dots within. In Condition 3, when perspective and pursuit were combined congruently, perceived depth was in near perfect agreement with these cues. When perspective and pursuit were in conflict, some observers percepts were dominated by pursuit, but other observers showed an asymmetry depending on the direction of pursuit. Together, these findings demonstrate that both perspective and pursuit can contribute to perception of depth from MP.