Spatial frequency phase effects in human vision

Abstract

Color aftereffects (McCollough effects) were generated specific to each member of a pair of vertical gratings which had identical frequency spectra but which differed in the phase angles between their frequency components. The pairs of gratings were either left- and rightfacing sawooth gratings or gratings comprised of the sum of two harmonics—first and second, first and third, or first and fourth. Color aftereffects were readily obtained with sawtooth gratings (which had sharp edges) and with patterns comprised of first and second harmonics; the effects were very weak with the first and third harmonic patterns and almost absent with the first and fourth harmonic patterns. The results suggest that there are phase-sensitive broadband mechanisms within the visual system and that each “spatial frequency channel” cannot be simply represented by a single, symmetric line spread function.