Though researchers understand integrative processes such as center-surround inhibition in relatively early stages of visual processing, the neurophysiological mechanisms that underlie higher-level contextual integration are not well understood. This dissertation investigates the cognitive correlates and neurological underpinnings of visuospatial contextual processing ability. Participants performed tasks in which contextual information caused a misperception of the target object (i.e. visual illusions) in order to better understand how the brain integrates contextual information under non-illusory conditions every day. In one task, participants were asked to indicate whether a small target was located to their left or right. When a large, shifted frame was presented simultaneously with the target, participants made systematic judgment errors dependent on the direction of the frame shift (with targets reported further to the right in the context of a left-shifted frame and vice versa—the induced Roelofs effect). These errors appear to be caused by a distortion of the observer's egocentric reference frame; that is, the observer's perceived midline is pulled in the direction of the offset frame. Intriguingly, individual susceptibility to the Roelofs effect is correlated with the ability to find a target shape within a more complex object (e.g. in the Hidden Figures Task; HFT), suggesting that individual differences in visuospatial ability may operate over a range of seemingly dissimilar tasks. This dissertation provides evidence that behavioral performance on visuospatial processing tasks (such as Roelofs and HFT) is correlated with a tendency to systemize (as measured by the Systemizing Quotient) which has been proposed as one of the core features underlying the autism spectrum disorders. In addition, functional neuroimaging evidence is reported demonstrating localized, bilateral activations in posterior parietal cortex that appear to be responsible for processing the contextual cues that lead to the Roelofs effect. A similar network of parietal areas was activated during the HFT in a second neuroimaging study with the same participants, suggesting that these brain regions are specifically involved in processing visuospatial contextual information. Combined with behavioral and imaging work in other labs, the pattern of results suggests that a processing difference in parietal cortex may be a hallmark of autism.