A Temporal Factor Affecting Field Facilitation : Latency for Depolarization of the Opponent-color System

抄録

Field facilitation refers to the phenomenon in which thresholds for a test stimulus obtained on an adapting field, F_1, tends to decrease when the second field, F_2, is superimposed on F_1, if their colors are opponent to each other. This has often been ascribed to "depolarization" of an opponent-color system. In the present study, detection thresholds for a red test stimulus of a 200 ms-duration and 40'-dia were obtained on a steady red adapting field of a fixed intensity, on which a green second field of various intensities was superimposed. The green field was presented for 3s, and the stimulus onset asynchrony (SOA) between this field and the test stimulus was varied systematically. The results of two subjects show that field facilitation critically depends on SOA, i.e. it vanishes at the SOAs shorter than about 100ms. Those results suggest that the opponentcolor system, r-g system here, should take approximately 100ms for depolarization in the present stimulus condition.