CCN Colloquium: "Perceptual adaptation: What it is, what it isn't, and what it reveals about the mind and brain"

In 1834, Robert Adams reported a "peculiar optical phenomenon" upon viewing the Falls of Foyers in Scotland. "Having steadfastly looked" at the falls for a moment, he found that a stationary rocky face briefly appeared "as if in motion upwards, and with an apparent velocity equal to that of the descending water". Unbeknownst to him at the time, Adams was experiencing what we now think of as a canonical case of perceptual adaptation. These days, however, cases of adaptation like this one have become more than a "peculiar phenomenon". Adaptation is a construct of great theoretical importance: It is seen by many to be one of the key factors, if not the key factor, which helps us to distinguish between that which is perceived (i.e., as we see the color red) and that which is conceived (i.e., as we think about kinds of fruits). It is, in other words, said to be a tool that allows us to carve nature at its joints. In this talk, I'm going to argue that perceptual adaptation is not the unified phenomenon that many take it to be and that, therefore, it may not be a very useful 'theoretical scalpel' after all. I'll focus on two cases studies of perceptual adaptation - visual number adaptation and visual size adaptation - and show how these cases pose challenges for the broader understanding of adaptation. I argue, ultimately, that we should be skeptical not only about the putative link between adaptation and perception, but about the meaning of adaptation in sensory systems in general.