Event-related brain potentials (ERPs) will be recorded from children, adolescents and adults using experimental designs that assess the effect of encoding activity on pictures and words during on-line processing as well as delayed memory tasks. The main thrust of the proposal is to study performance on explicit and implicit memory tasks in carefully controlled designs, in which encoding task and stimulus form (i.e., pictures/words) are manipulated so that all subjects are engaged in the same kind of processing during encoding, and stimulus form can be varied within and between study and test phases. The proposal asks the general question how do people of different ages differ (behaviorally and with respect to ERPs) in the ways in which they process pictorial and verbal input on-line, and the ways in which they remember and retrieve such input during delayed memory tasks. Behavioral evidence suggests an increase in encoding efficiency as development unfolds, and that information processing of pictorial and visually presented verbal material may undergo developmental change. There is some evidence of age-related differences in ERPs as a function of stimulus form, and that ERP activity predictive of subsequent memory performance changes as a function of age. This ERP activity may reflect elaboration, a memory strategy whose use is known to increase with age. Thus, ERP activity elicited by items during study that is predictive of subsequent recognition is expected to differ among age groups as a function of such developmental differences in memory function. It is also expected that N400 amplitude will reflect the magnitude of priming during on-line and delayed memory tasks, and may change systematically across the age range studied with the congruence between stimulus modality (pictures or words) at study and test. ERPs will be recorded from several scalp placements in order to determine whether scalp distributions and, by implication, their intracranial generators, differ systematically with age. The data will be relevant to the developmental course of semantic processing and memory function, and their physiological underpinnings.
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