Perceptual Learning Leads to Category Selectivity 100ms after Stimulus Onset T C Kietzmann1, B Ehinger1, D Porada1, A Engel2, P König1 |
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1Institute of Cognitive Science, University of Osnabrück, Germany |
| Categorizing visual input is one of the most essential challenges faced by our visual system. Despite its importance, however, the debate on the cortical origin and the timing of category-specific effects remains unsettled. This is in part due to potential low-level confounds arising from the use of naturally occurring visual categories. Here we circumvent such problems by combining extensive training of two artificial visual categories with EEG and MEG adaptation. This approach allowed us to investigate category effects arising purely from category training, while ruling out alternative explanations based on low-level stimulus properties. Prior to category training, no differences in the visually evoked potentials were observed, demonstrating a successful control for low-level stimulus properties. After training, however, we find significant category-selective differences in the early P100 (EEG, peak latency 108ms, p<0.05 two-tailed t-test) and M100 (MEG, peak latency 118ms, p<0.05 two-tailed t-test) components. Importantly, significant differences were only found for correct trials and not for incorrect ones, illustrating the behavioral relevance of the investigated process. The timing and topography of the found effects render feedback from frontal areas unlikely and suggest rather that the origin of category selective representations is in the ventral stream. |
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