Abstract
Previous studies show that segmentation of a center from its surround by either a physical or illusory contour attenuates the perceived chromatic fluctuation within the center (Elliott & Shevell, 2013). This is consistent with form-cue invariance, which holds that the neural representation of the edge of an object is equivalent whether due to a physical luminance edge or an illusory (Kanizsa) contour. It is not clear, however, whether form-cue invariance extends to integrated subparts of an object or applies to only a whole object composed entirely from physical or illusory contours. A combination of illusory and physical contours was used to create the percept of a square centered in the central 2 deg area of a larger 6 deg surround. Specifically, 0, 1, 2, 3 or 4 sides of the square had "pac-men" located to invoke the percept of an illusory-contour side. The remaining sides of the square were formed by a physical luminance edge. The central test, its surround, and a separate matching disk were modulated in luminance, all in-phase at 2 Hz. Observers adjusted the Michelson contrast of the matching disk to equal the perceived modulation depth within the central test. Results indicated that regardless of how the square was defined, perceived modulation within it was attenuated. This result is consistent with form-cue invariance for the individual integrated subparts of an object.
Meeting abstract presented at VSS 2016