Learning effects on event-related brain potentials

This study investigates whether learning can manifest itself in EEG changes without explicit awareness of the acquired knowledge and without any motor requirement (to rule out acquisition of motor skills). Subjects passively heard particular stimulus combinations interspersed with random combination s. Immediately after this, stimulus combinations were presented which conta ined violations of the previously learned regular sequences. These violatio ns elicited two frontally distributed negative waves peaked at about 250 ms and 500 ms, respectively. None of the participants could detect any regula rity of the stimulation. No significant difference between regular vs rando m stimulus combinations was found during acquisition. These findings indica te that learning without explicit knowledge does not require motor activity (i.e. is independent of learning response sequences) and does not depend o n stimulus probabilities. NeuroReport 11:3327-3331 (C) 2000 Lippincott Will iams & Wilkins.