The tactile perception of roughness depends on lateral movement between the skin and the surface, yet studies of the stimulus variables relevant to roughness perception have failed to find substantial evidence for temporal factors. This project asks whether the temporal frequency of a textured stimulus affects roughness perception. The hypothesis that tactile roughness perception depends partially on temporal factors will be investigated using three approaches. First, normal human volunteers will perform either of two psychophysical tasks as temporal frequency is manipulated as an independent variable. Next, the representation of stimulus frequency in somatosensory cortical neurons will be investigated. Finally, numerous studies have linked dyslexia to a mufti- modal sensory deficit specific for high-frequency information. In light of this evidence, volunteers with dyslexia will perform a psychophysical discrimination task using textured stimuli of varying frequencies. This project will contribute not only to the understanding of tactile coding of texture, but also to the understanding of sensory differences in dyslexia.
