A phase-specific adaptation effect of the square-wave grating.

The existence of wide-band, phase-specific channels in the human visual system has been suggested in recent investigations. We used a number of adapting gratings to test for phase-specific adaptation effects. Observers were asked to discriminate between a simple 3 cpd sine-wave grating, (3), and a complex grating composed of this (3) plus a 9 cpd grating combined in one of two phases: peaks-subtract, (3,9:0), or peaks-add, (3,9:pi). The results show a significant phase-specific adaptation effect. That is, following adaptation to a square-wave grating, discrimination performance for (3,9:0) vs. (3) deteriorated significantly more than for (3,9:pi) vs. (3). Adaptation to the first two harmonics of the square-wave, (3,9:0), or a 3 cpd triangle-wave grating failed to produce phase-specific adaptation effects that reached significance.