Abstract
We investigated the effects of perceptual grouping by colour and shape similarity on flash-induced perceptual fading. This flash-induced fading effect (Kanai et al, 2003 Journal of Cognitive Neuroscience 15 664 - 672) is considered as a time-locked variant of the Troxler effect. In the original experiment by Kanai, a short circular flash surrounding an object in the peripheral visual field causes the object to temporarily disappear from visual awareness. In the present study, two objects (which could either be similar or different both in colour and in shape) were presented at an eccentricity of 2.6 deg from a fixation cross. After 2 s, a short flash (40 ms) was presented around one of the objects. The two objects remained on the screen for 2.5 s after the flash. Participants were instructed to report which objects disappeared from awareness for a short period after the flash. Significant effects of both colour similarity and shape similarity were found. For colour as well as for shape the percentage of mutual disappearance was higher in trials containing similar objects as compared to those containing dissimilar objects. The results suggest that the flash-induced perceptual fading effect is influenced by grouping by colour and shape similarity.
