Abstract
In natural conditions, a given object property is often specified by multiple sources of visual information, so the sources of information must be integrated during perception. Recent results suggest that the visual system combines information in an optimal manner, with cues being weighted according to their reliability. But the reliability of information from a given source surely changes over time, as sensory measurements accumulate and as computations that use them progress, and there is no reason to believe that the time course would be the same for all cues. Van Ee and Erkelens (1996) found that the influence of stereo on perceived slant continues to accumulate over a period of many seconds. Greenwald, Knill and Saunders (VSS 04) perturbed stereo and texture cues during reaching movements, and observed an early influence of stereo, followed by a later influence of texture. We tested how the contributions of stereo and texture change over time for a slant judgment task, using briefly presented stimuli in order to track changes during the critical first moments of perceptual processing. Stimuli were binocular images of textured planar surfaces displayed for a limited time, followed by a binocular noise mask. The display duration had values between 30 and 4000 ms, tested in separate blocks. On each trial, subjects judged the sign of slant relative to frontal. Stimuli contained a ±10 deg conflict between the slants indicated by stereo and texture cues, respectively, and we used the differences in observed PSEs for the different conflict conditions to infer the relative weights given to stereo and texture. The weight given to stereo increased with display duration, and some observers gave weight to stereo even at the very briefest durations.