Autobiographical accounts of autism often emphasize difficulties with sensory input from the environment. Some reports also indicate a reduced ability to coherently merge sensory signals from two or more senses, resulting in a confusing, fragmented perceptual world and the impetus for social withdrawal. These studies importantly assess sensory functioning within the natural environment, but are limited by their subjective nature, which makes the findings difficult to link to underlying brain mechanisms. A natural complement to previous approaches is psychophysics, that is, the objective quantitative measurement of sensation and perception that can be linked to brain mechanisms. In this study, Dr. Essik will use psychophysical techniques to study sensory processing both within a sensory system (the system for touch) and between the touch and visual systems. He will assess sensory sensitivity in groups of adults with and without autism for several types of stimuli. To understand the neural bases of these findings, the brain's responses to these stimuli will be studied using functional magnetic resonance imaging (fMRI). Stimuli will be presented either alone or simultaneously in order to detect their interactions. Based on pilot work, the researchers predict that sensitivity to the diverse forms of stimuli and their brain responses will be altered in autism. What this means for people with autism: Characterization of altered sensory perception and sensory interactions is key to understanding the difficulties autistic individuals experience. It is also the first step toward the identification of novel therapeutic approaches from a sensory perspective.