Modelling perceptual discrimination

Accounts of perceptual decision making, such as evidence accrual models, represent mental states as noisy numerical vectors describing the stimuli. As such, these are not biological models. An alternative scheme is presented in which mental states are represented as functions. This generalises an analogue coding scheme for numbers, and might be biologically implemented as functions of cortical activity. Some properties of this representation are illustrated in modelling accuracy and response time patterns observed in a classic experiment into perceptual processes