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Olav Krigolson, Heather Gallant, Cameron Hassall; More Blobs: A Training Study Examining the Role of Medial-Frontal Cortex in the Development of Perceptual Expertise. Journal of Vision 2013;13(9):663. doi: 10.1167/13.9.663.
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In a recent study, Krigolson and colleagues (2009) demonstrated that a reinforcement learning system within medial-frontal cortex plays a key role in the development of perceptual expertise. Specifically, Krigolson et al. found that when participants learned to discriminate between two families of "blobs" feedback processing elicited an error-related negativity (fERN) – a component of the human event-related brain potential (ERP) evoked by performance feedback. Further, Krigolson et al. observed increases in ERP components associated with object recognition (N250) and response error evaluation (rERN) in participants who demonstrated behavioral learning improvements as gauged by task performance. Here, we utilized the same task at Krigolson et al. but extended training over five days so participants were exposed to 5000 learning trials. In line with the predictions of reinforcement learning theory, the amplitude of the fERN diminished with learning, and somewhat interestingly demonstrated restart costs that align with the observations of traditional learning theory. Further, and novelly, our data also provide unique insight into the N250 (object familiarity) and N170 (object expertise) visual ERP components. Specifically, we propose that the N250 is not a learned effect per se, but instead is a measure of familiarity with a basis in short term memory as we found that N250 amplitude "resets" daily dependent upon object exposure. Further, we find found that the amplitude of the N170 diminished with day-to-day learning, a result counter to studies that have examined its amplitude on a single exposure basis.
Meeting abstract presented at VSS 2013
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