ORIENTATION-TUNED SPATIAL FILTERS FOR TEXTURE-DEFINED FORM

Detection threshold for an orientation-texture-defined (OTD) test grat ing was elevated after adapting to an OTD grating of high orientation contrast. Threshold elevation was greatest for a test grating parallel to the adapting grating, and fell to zero for a test grating perpendi cular to the adapting grating. We conclude that the human visual syste m contains an orientation-tuned neural mechanism sensitive to OTD form , and propose a model for this mechanism. We further propose that orie ntation discrimination for OTD bars and gratings is determined by the relative activity of these filters for OTD form. (C) 1998 Elsevier Sci ence Ltd. All rights reserved.