An event-related potential study on visual perceptual learning under short-term and long-term training conditions

The present study investigated learning-induced changes of event-related potentials in a visual discrimination task, focusing on making a comparison between short-term and long-term learning perceptual processes. Event-related potentials were recorded from two groups of human adults. One group (short-term training group) was given 1.5 h of training in a single day, and another group (long-term training group) was given the same training procedure (1.5 hour of training) on each of 3 consecutive days. The results demonstrated that for short-term training group, along with the reduction of reaction times, the amplitudes of N1 and N2 negativities over the central/parietal areas decreased during the training. For long-term training group, however, after long-term training, the N2 effect disappeared and the N1 effect occurred over the posterior areas. In addition, the amplitudes of N2 for long-term training group were less than those for short-term training group. Our results suggest that neural activity depends not only on perceptual mechanisms and on the parameters of the physical stimuli but also on the extent of the observer's previous learning.