P300 stimulus sequence effects in children and adults.

Immediate memory capability for 12 children (8 years) and 12 adults (21 years) was assessed electrophysiologically by using P300 event-related brain potential (ERP) stimulus sequences. These were derived from an auditory discrimination paradigm in which participants detected target stimuli in a series of target (T) and standard (S) tones that were varied by randomly presenting one of four sequence patterns (SSSS, TTTT, TTTS, SSST). Short-term memory capability was assessed behaviorally by recall performance of a 20-word list. Children and adults showed virtually identical P300 amplitude sequence patterns, such that for both groups component size increased systematically as the discrepancy between standard and target stimuli increased across sequence patterns. P300 latency evinced similar, albeit weaker, stimulus sequence effects, with children having longer component peak latencies. Memory recall performance was substantially weaker for the children than for adult participants, especially for recency effects. The findings suggest that immediate memory for stimulus sequences is fully developed in young children, although long-term memory is not.