Perceptual adaptation to combinations of stimulus motion, color, form, and orientation suggests the operation of specialized receptive units in man of the kind which have been identifed in cat and monkey. Some aspects of such adaptation, however, seem to resemble a conditioning process rather than a strictly sensory one. Failure of an established adaptation to dissipate over a period of neutral stimulation may be one of these aspects. It is planned to study simultaneous adaptation to different combinations of stimulus motion, color, and form and to measure the dissipation of the adaptation over increasing periods of exposure to homogeneous stimulation. Control of the experimental apparatus requires online interfacing with a computer. Suitable facilities were not available, and the project was held in abeyance this year.