- 一般社団法人 照明学会
- 照明学会誌 (ISSN:00192341)
- vol.83, no.11, pp.860-868, 1999-11-01 (Released:2011-07-19)
We can perceive small color differences, and we can also perceive color as a group of many different colors (categorical color perception). Visual performances based on small color differences are known to be better in the central visual field than in the periphery. We have clarified the characteristics of categorical color perception in the peripheral visual field. Observers were shown color chips of the OSA Uniform Color Scales set in the central or the peripheral visual field. The chip, which subtended 4deg, was presented at the fovea (Odeg), eccentricities of 30, 50, and 60 deg in the nasal visual field and of 30, 50, 70, 80, and 90 deg in the temporal visual field. A large gray surrounding field was made with a hemisphere and illuminated at a moderate intensity of D65 lights (yielding 2000 scotopic td) to suppress rod activity. The observers reported color appearance of the stimulus with one of the eleven basic color terms. The distributions of the color categories on the xy chromaticity diagram varied little between stimulus locations from 30 deg to the nasal and 70 deg to the temporal visual field. The results of eccentricities greater than nasal 50 deg and temporal 80 deg were remarkable different from those in the locations closer to the fovea. Our results suggest that categorical color perception in the central visual field is maintained across a wide area of the peripheral visual field.