Neurophysiological correlates of perceptual learning in the human brain.

Rapid learning processes are crucial for human object recognition. We report here on the alterations in neurophysiological activity in the human brain induced by repeated presentation of visual stimuli. In psychophysical experiments the percentage of correct responses increased significantly within less than 30 minutes in untrained observers. This stimulus-specific improvement was not carried over to differently oriented stimuli. Similar learning effects were observed in component latencies of evoked potential field distributions. The occurrence of specific potential field configurations reflected perceptual learning. A spatio-temporal activation pattern with steep gradients over the primary visual cortex appeared to be correlated with plasticity in the human visual system.