Abstract
It has been well known that spatial properties of vertical disparity processing are different from those of horizontal disparity processing for slant perception. Regarding the temporal properties, we showed, in a previous study, that vertical size disparities are temporally integrated within a certain period although horizontal size disparity processes in a short period for slant perception produced by a stimulus having oscillating size disparities. In this study, we aimed to show temporal properties of vertical and horizontal disparity processing in more detail. We investigated how these disparities are temporally summed from the onset of the stimulus. We measured the effects of stimulus duration and preceding disparity on the perceived slant for vertical- or horizontal-size disparities with short duration. Random dot stimulus having vertical or horizontal size disparity was presented with a variable duration following a preceding stimulus having the different magnitude and same type of disparity. The duration of stimulus, the presence or absence and the magnitude of preceding disparity were manipulated. Subjects responded the magnitude of slant perceived just before the stimulus disappeared. The results showed that the perceived slant for the stimulus gradually increased or decreased from the perceived slant for preceding disparity to the perceived slant for the same stimuli with infinite duration as the duration increased. The increase or decrease lasted longer period for vertical disparity than for horizontal disparity. These results suggest that the slant perception for stimulus with short duration is affected by the preceding disparity, and the effect of preceding vertical disparity remains for longer period than that of preceding horizontal disparity.