Abstract
In a recent study involving visual expertise training with birds, we identified two distinct ERP components, the N170 and the N250, that are correlated with the acquisition of perceptual expertise (Scott, et al., in press). Whereas the N170 is sensitive to the encoding of basic level, shape information, the N250 is modulated by the more fine grain perceptual detail required for subordinate level identification. The goal of this study was to further our understanding of these components. Subjects were either exposed to or learned to classify three categories of cars (sedans, SUVs, antique) at either the basic or subordinate level. ERPs were recorded before, immediately after, and 1-week after training. Behavioral results showed that compared to the basic level and exposure-only learning conditions, subordinate level training led to better discrimination of trained cars and this ability was retained a week after training. However, unlike the previous bird study, discrimination did not transfer to novel exemplars or novel categories of subordinate level cars. The ERP results showed an equivalent increase in the N170 across all three training conditions whereas the N250 was only enhanced in response to the cars trained at the subordinate level. In contrast to the behavioral results, the N250 generalized to novel exemplars and novel cars in the subordinate level condition. The current results suggest that an increased N170 is related to the amount of exposure to objects within the expert category. On the other hand, the enhanced N250 reflects subordinate level access to these objects.