低照度レベルにおける周辺視野でのカテゴリカル色知覚の特性

Abstract

We measured the characteristics of categorical color perception in the peripheral visual field under low illumination conditions and compared with those under 2000 lx illuminance in our previous study [J. Illum. Engng. Inst. Jpn. 83 (1999)]. OSA color chips, simulated by the LCD projector, were presented at the fovea (0 deg), at eccentricities of 30 and 50 deg in the nasal visual field, and at 30, 50, 70, and 80 deg in the temporal visual field. A large gray surrounding field, made with a hemisphere, was illuminated by D65 fluorescent lamps at 5 or 0.1 lx. The stimulus was subtended 4 deg and presented for 3 s. The observer reported the color appearance of the stimulus with 1 of 11 basic color terms. The response of color categories at the fovea showed almost no difference to the 50 deg temporal under 5 lx illuminance. Beyond the 30 deg nasal and the 70 deg temporal, the response of achromatic categories increased, and that of green, purple, and pink categories decreased. Under 0.1 lx the response of achromatic categories dominated. Our results show that categorical color perception in the central visual field is constant across a large visual area under a wide range of illumination conditions.