Independence of black and white: Phase-specific adaptation

Abstract

Following adaptation to a black/white rectangular-wave grating, the black and white bars of a square wave of the same period no longer appear equal. Black bars are shifted in apparent width away from the width of the black adaptation bars, and white bars appear to be shifted away from the width of the white adaptation bars. Tests with single adaptation and test bars (rather than gratings) confirm the contrast specificity of the effect—i.e. white test bars are reliably affected only by white adaptation bars. This suggests separate processing of black and white size-specific information, or phase specificity of spatial frequency channels.