Adaptation to square‐wave gratings: inhibition between spatial frequency channels in the human visual system

1. The observation that the detection threshold for a square‐wave grating depends only on that of its fundamental was confirmed by showing that adapting to the fundamental spatial frequency caused elevation of the square‐wave threshold, to the same extent as the fundamental threshold was elevated by the same adapting pattern. Adapting to the third harmonic frequency had no effect on the square‐wave threshold.