Abstract
The simultaneous lightness contrast (SLC) has been mainly explained by the lateral inhibition in the retinal level of visual information processing. Agostini and Profitt (1993) have reported that the belongingness of target rather than the lateral inhibition could affect the SLC. In addition to common fate and figural alignment which Agostini and Profitt examined, the 3D depth of target and background might work as a critical factor in perceptual belongingness and affect the SLC. We examined this possibility. More importantly, we were interested in how common fate and 3D depth affected the SLC when both provided inconsistent perceptual belongingness information and how the perceptual belongingness interacted with the lateral inhibition in the SLC. In the experiments, the perceived belongingness of the target and the possible effect of lateral inhibition were manipulated independently. Four different conditions were examined; common fate only condition (i.e., perceptual belongingness was defined only by common fate), 3D depth only condition, consistent condition (i.e., both common fate and 3D depth defined consistent perceptual belongingness) and inconsistent condition. The amount of the SLC was measured with the method of constant stimuli. In general, the effect of perceptual belongingness on the SLC depended on the intensity of lateral inhibition. Specifically, the SLC was observed in the 3D depth only condition as well as in the common fate only condition. In the consistent condition, the SLC was perceptually most distinct. Moreover, the lightness contrast was mostly determined by 3D depth rather than by common fate in the inconsistent condition. These results imply that 3D depth is more critical factor than common fate in determining perceptual belongingness to affect the SLC and that lightness is still processed even at the late level of visual information processing, e.g. after 3D depth information is processed.
Supported by M103KV010021-04K2201-02140 from BRC, 21st Century Frontier Research Program