Abstract
Previous studies on perceptual filling-in occurring in peripheral vision have been adopted filling-in time to evaluate the facilitation of filling-in. Filling-in time is not a suitable criterion for representing facilitation of filling-in because filling-in time does not distinguish among cases: filling-in is rapidly induced by a certain mechanism and a filling-in target area is essentially difficult to distinguish from its surrounding. From this viewpoint, we focus on a filling-in occurred in the following condition: a small homogeneous area (filling-in target), surrounded by spatio-temporal frequency limited random-dot dynamic textures, is presented to an observer's peripheral vision. We first introduced a new criterion - the attenuation factor of distinguishability of a filling-in target from its surroundings - to represent facilitation of filling-in. We then propose a model to express the filling-in process.
In order to examine spatio-temporal frequency characteristics of filling-in facilitation, the present study measured time to filling-in for various spatio-temporal frequencies of target-surrounding dynamic textures. Spatio-temporal frequency sensitivity in the eccentricity where filling-in target is located was also estimated. These results are applied to the proposed model. The results revealed that attenuation factor is high when the dynamic texture has spatio-temporal frequency of high-sensitivity corresponding to the frequency characteristic in the M-channel in LGN. In contrast, it is low where the P-channel sensitivity is high. We infer that filling-in is facilitated in the M-channel pathway, but inhibited in the P-channel one.
Supported by a Grant-in-Aid for Scientific Research (C) 2005, No.15500332 from JSPS in Japan.