Individual differences in working memory on event-related potentials (ERP)

The effects of individual differences in working memory on the semantic facilitation of words were investigated by measuring event-related potentials (ERP). There were three conditions consisting of three types of prime-target pairs: related pairs, unrelated pairs and controls. Individual differences in working memory were measured by a reading span test (RST). Twenty students participated in the experiment. They were divided into two groups based on the working memory capacities. ERP was recorded from 12 positions and topographical mapping was measured at each condition. A large negative shift that peaked at about 400 ms (N400) appeared in the unrelated condition. N400 appeared mostly around the frontal positions. Moreover, there were individual differences of N400 amplitude in positional differences. For high-capacity subjects, a large amplitude of N400 appeared mostly in the frontal region. For low-capacity subjects, however, only small or ambiguous peaks were observed. These results suggested that semantic facilitation of word meaning was related to the working memory efficiency and its locus in the brain was the frontal area.