Color-motion feature misbinding without color

Abstract

PURPOSE. Previous experiments reveal that color-motion misbinding occurs in the periphery when central and peripheral objects share the same color, but move in opposite directions (Wu et al., 2004): The perceived illusory direction of peripheral objects is the same as the physical direction of central objects. This study tested whether color is necessary to elicit the illusory motion direction in the periphery, or whether shape-motion misbinding occurs without color. METHODS. The stimulus had moving objects in a central visual region and in adjacent peripheral regions. The objects were 0.3 deg long lines, half oriented vertically and half horizontally. In the central region, vertical lines moved in one vertical direction (say, upward) and horizontal lines in the opposite direction (downward). In peripheral regions, horizontal and vertical lines moved in the opposite directions (say, vertical lines moved downward, horizontal lines upward). All of the objects were either achromatic (metameric to EES 'white') or, in separate sessions, chromatic. In the chromatic condition, vertical lines were (say) red and horizontal lines green. In both conditions, observers fixated on a small cross in the center and judged the direction of motion of vertical lines in the periphery during a 20-second trial. The proportion of time with peripheral illusory motion in the chromatic condition was compared with the proportion in the achromatic condition. RESULTS & DISCUSSION. The proportion of time with illusory motion, and thus feature-binding errors, was greater in the achromatic condition than the chromatic condition (p<0.01 for each of three observers). Although introducing color increased the number of shared features between central and peripheral objects, feature misbinding was more likely without color. This shows that color is not necessary for motion misbinding, and that shape-motion misbinding in the periphery is at least as common as color-motion misbinding. Meeting abstract presented at VSS 2014