The ability to imagine objects undergoing rotation (mental rotation) improves markedly with practice, but an explanation of this plasticity remains controversial. Some researchers propose that practice speeds up the rate of a general-purpose rotation algorithm. Others maintain that performance improvements arise through the adoption of a new cognitive strategy—repeated exposure leads to rapid retrieval from memory of the required response to familiar mental rotation stimuli. In two experiments we provide support for an integrated explanation of practice effects in mental rotation (...) by combining behavioral and EEG measures in a way that provides more rigorous inference than is available from either measure alone. Before practice, participants displayed two well-established signatures of mental rotation: Both response time and EEG negativity increased linearly with rotation angle. After extensive practice with a small set of stimuli, both signatures of mental rotation had all but disappeared. In contrast, after the same amount of practice with a much larger set both signatures remained, even though performance improved markedly. Taken together, these results constitute a reversed association, which cannot arise from variation in a single cause, and so they provide compelling evidence for the existence of two routes to expertise in mental rotation. We also found novel evidence that practice with the large but not the small stimulus set increased the magnitude of an early visual evoked potential, suggesting increased rotation speed is enabled by improved efficiency in extracting three-dimensional information from two-dimensional stimuli. (shrink)

In this paper a theoretical framework is proposed for how the brain processes the information necessary for us to achieve the understanding of others that we experience in our social worlds. Our framework attempts to expand several previous approaches to more fully account for the various data on interpersonal understanding and to respond to theoretical critiques in this area. Specifically, we propose that social understanding must be achieved by at least two mechanisms in the brain that are capable of parallel (...) information processing. The first mechanism, based on research into mirror matching systems in the brain, suggests that representations of others are mapped onto an observer's representations of these same schemas in order to understand them. The second mechanism requires semantic analysis of a given social situation in order to understand the actions of others and most likely involves conscious processes. We suggest that experimental correlates of these systems should be dissociable using both behavioral and neuroimaging techniques. (shrink)