An event-related potential study on perceptual learning in grating orientation discrimination

This study aims to investigate the neural mechanism of visual perceptual learning in grating orientation discrimination. We recorded event-related potentials of human adults when they were trained with a grating orientation discrimination task. Although psychophysical thresholds decreased significantly across training sessions, event-related potentials showed larger P2 and P3 amplitudes and smaller NI amplitudes over the parietal/occipital areas with more practice. In line with the psychophysical thresholds, the training effect on the P2 and P3 were specific to stimulus orientation. The NI effect, however, was generalized over differently oriented gratings. Our findings show that several stages of visual processing are involved in perceptual learning and provide an illustration of the temporal relationship between specific and generalized perceptual learning in human adults.