Abstract
In long-range apparent motion, when a static object is presented at two different locations successively, one perceives its motion across these locations. When the objects presented at the two locations differ in shape, observers perceive a gradual shape change across the locations. In contrast, the interpolated color along the motion path abruptly changes from the color of the first stimulus into that of the second, suggesting no gradual feature updating for color during apparent motion (Hidaka et al., 2011; Kolers & von Grunau, 1976; Souto & Johnston, 2012). Here we report that a color, categorically distinct from the colors at the initial and terminal positions of apparent motion, can be interpolated as the intermediate percept on the path of apparent motion. Two blue (at the initial position) and green (at the terminal position) Gaussian blobs were repeatedly presented in a bistable quartet sequence. Perception of horizontal or vertical motion is possible at any given moment, and subjects were cued to see only one of the two possible directions in each trial. A colored target was briefly presented at the mid-point of either the left or right vertical motion paths within the final motion cycle and subjects reported on which motion path the target appeared. The results showed that subjects’ target detection was impaired when the color of the target was "in-between" the initial and terminal stimulus color (cyan) as well as when it was the color of the terminal stimulus (green). This selective impairment disappeared when horizontal motion was seen, therefore the target was no longer on the path of apparent motion. This suggests that color may be also gradually updated during apparent motion, consistent with the previous findings using shape.
Meeting abstract presented at VSS 2013