Critical flicker frequency of equiluminous red-green alternation across the human visual field

Abstract

Luminous critical flicker frequency (OFF) becomes independent of visual field location1 when (1) the stimulus is enlarged with increasing eccentricity in inverse proportion to the sampling density of ganglion-cell receptive fields across the human retina (M-scaling) and (2) stimulus luminance is reduced toward the retinal periphery in inverse proportion to photopic Ricco’s area (F-scaling). Using two low-frequency oscillators and a panel consisting of 256 red and 256 green light-emitting diodes we generated sinusoidal chromatic flicker. The diodes flickered in counterphase. The panel was covered with a white diffusion screen. Its average luminance was 60 cd m−2, and CIE 1931 chromaticity coordinates (x, y) were (0.68, 0.32). Luminance modulations in red and green light were both 20%. Chromaticity coordinates varied between (0.61, 0.39) and (0.72, 0.28). CFF of equiluminous red-green alternation was measured in the temporal visual field. When stimulus size and luminance were constant, CFF first increased and then decreased with increasing eccentricity. However, CFF increased monotonically with eccentricity when the stimulus size was M-scaled but decreased monotonically when the stimulus luminance was F-scaled. In addition, CFF became independent of visual field location when stimulus size and luminance were MF-scaled.