Adaptation and the Phenomenology of Perception

This chapter considers how the nature of subjective experience is constrained by the processes of sensory adaptation. Adaptation adjusts visual sensitivity according to the set of stimuli an observer is exposed to. Such adjustments are a built-in feature of visual coding and probably regulate most if not all aspects of visual perception. Indeed, adaptation may represent a fundamental "law" of cognition and behavior, a point most forcefully argued by Helson (1964). This chapter focuses on how specific presumed properties of visual adaptation might be expected to influence visual phenomenology. Studies of adaptation aftereffects have shown that changes in the state of adaptation have dramatic consequences for how the world appears. The states of adaptation may therefore play a fundamental role in determining whether the world looks the same or different to others.