Abstract
The spatial selectivity of contrast adaptation found psychophysically has generally been taken as evidence for its cortical origin, and physiological studies have confirmed that adaptation occurs in many simple and complex cells. However, recent work in LGN shows substantial contrast adaptation in at least one of the pathways leaving the retina, and the characteristics of this adaptation are unlike those of adaptation in cortex. To complicate the picture further, adaptation in many neurons in V1 is often much less selective than earlier work would have led us to expect, and provides a less compelling account of psychophysical observations. The perceptual adaptation probably reflects changes occurring at several levels of the visual pathway, including some beyond V1.