I study mental representation and (with greater trepidation) consciousness from an empirically informed philosophical perspective. Most of my current research clusters around three issues.

The format of mental representation

Are mental representations analog or digital? Conceptual or nonconceptual? A good deal of my work has focused on representations of magnitudes such as numerosity, duration, rate, distance, and size. In a series of articles I have argued that magnitude representations have an analog format, nonconceptual contents, and are sometimes cognitive rather than merely perceptual. I have also argued that they illustrate how sophisticated behavior can be explained in representational and computational terms without being explained in conceptual or linguistic terms. More generally, I’m interested in how the format of nonhuman animal cognition may differ from the format of human cognition. Recently, I have also been investigating whether sensory experience has an analog format.

The perception–cognition boundary

How should we understand the difference between perceptual states (e.g. seeing a body as red or hearing a sound to one’s left) and cognitive states (e.g. imagining a red body or believing that justice is fairness)? I have been developing an account that draws on the concept of stimulus-dependence. Very roughly: perceptual states are dependent on proximal stimulation in a way that cognitive states are not.

How consciousness and representation interrelate

Do changes in consciousness always coincide with changes in representation? If so, can consciousness be explained in terms of representation? I have argued that work on attention suggests that consciousness and representation come apart. Attention alters the salience of perceived stimuli but does not change the properties that they are represented to have.