PT - JOURNAL ARTICLE AU - Edward F. Ester AU - Thomas C. Sprague AU - John T. Serences TI - Category learning biases sensory representations in human visual cortex AID - 10.1101/170845 DP - 2017 Jan 01 TA - bioRxiv PG - 170845 4099 - http://biorxiv.org/content/early/2017/08/01/170845.short 4100 - http://biorxiv.org/content/early/2017/08/01/170845.full AB - Category learning distorts perceptual space by enhancing the discriminability of physically similar yet categorically distinct exemplars. These distortions could in part reflect changes in how sensory neural populations selective for category-defining features encode information. Here, we tested this possibility by using fMRI and EEG to quantify the feature-selective information content of signals measured in early visual cortical areas after participants learned to classify a set of oriented stimuli into discrete categories. Reconstructed representations of orientation in early visual areas were systematically biased by category membership. These biases were strongest for orientations near the category boundary, predicted category discrimination performance, and emerged rapidly after stimulus onset, suggesting that category learning can produce significant changes in how neural populations in early visual areas respond to incoming sensory signals.