Classification and perceived similarity of compound gratings that differ in relative spatial phase

Discrimination studies suggest that two, and only two, channels encode relative spatial phase shifts in compound gratings (Bennett & Banks, 1991 ; Field & Nachmias, 1984). The more sensitive channel consists of even-symmetric filters and responds best to cosine phase shifts (e.g., 0°–180°); the other consists of odd-symmetric filters and responds best to sine phase shifts (e.g., 90°–270°). The present experiments investigated whether the …