Abstract
The perceived duration of a stimulus can be modulated by novelty and repetition (Pariyadath & Eagleman, 2007, 2008; Eagleman and Pariyadath, 2009). For example, in a repeated presentation of auditory or visual stimuli, an oddball stimulus of equivalent physical duration appears to last longer, a phenomenon known as the oddball effect. We have proposed that this duration illusion is a reflection of the neural phenomenon of repetition suppression – the diminishment of the neural response to a stimulus that is repeated – suggesting that the illusion reflects not a subjective expansion of the oddball, but rather a contraction of the repeated stimuli. In support of this hypothesis, we show that patient populations with impaired repetition responses, such as in schizophrenia, perceive duration illusions differently from healthy controls. We further present neuroimaging data indicating that repetition suppression in stimulus-specific cortical areas influences subjective duration. Results from our lab and several scattered findings in the literature can be compiled to demonstrate that, in general, any stimulus manipulation that increases response magnitude (such as increasing stimulus size, brightness or predictability) leads to a concurrent increase in the perceived duration of the stimulus (Eagleman and Pariyadath, 2009). We propose the novel hypothesis that the experience of duration is a signature of the amount of energy expended in representing a stimulus–that is, the coding efficiency.