The foveal color-match-area effect.

Rayleigh matches for foveal, temporally alternating fields showed only a small increase in the log green/red matching ratio (0.03--average of 10 observers) as the field was decreased from 116 to 19 min arc. This is consistent with only a small, 10%, change in photopigment density or lengthening of the cone outer segments in the central fovea. The change in matches with field size is considerably less than reported in several previous studies.