ERPs (62 channels) will be recorded from 4 age groups, 5-7, 9-11. 14-16 and young adults during tasks that tap implicit and explicit memory. One goal of the proposal is to study direct memory performance using tasks for which performance has been demonstrated to depend upon the media temporal (item or fact memory) and frontal (memory for source) lobes. The extant neuropsychological data suggest long maturational courses for the frontal lobes, whereas the medial temporal lobes do not appear to undergo such developmental trajectories. These data lead to the prediction that item memory should be relatively mature in the youngest subjects under investigation while source memory function is still developing. Hence, in the first phase of this proposal, study phases comprised of pictorial stimuli will be followed by inclusion (yes/no recognition) and exclusion (target class/other) memory effects using environmental sound stimuli, which appear to be organized in memory in similar fashion to words and pictures. Further, some evidence indicates that the left and right hemispheres are differentially engaged by environmental sounds and their verbal referants during cross-form semantic priming tasks. However, little is known about the developmental dynamics of memory for environmental sounds or of the maturational aspects of how the cerebral hemispheres interact in retrieving these kinds of stimuli. Hence, in the second phase of this proposal, we will assess sound-sound repetition priming of brief environmental sounds (using a behavioral anchor, reaction time), as well as within (e.g., word-word) and cross-form (e.g., word-sound) priming of longer-duration environmental sounds and their verbal referents. Both of these on-line priming series will be followed by recognition testing. It is expected that within- and cross-form priming effects will reflect the magnitude of priming during the on-line and delayed memory tasks, and may change systematically across the age range studied. In the first phase of the proposal, ERP and reaction time (RT) old/new effects will be compared between item and source memory tasks from a developmental vantage point. In the second, ERP and RT within-form as well as cross-form priming effects will be compared between the priming series and the delayed recognition tests. The resulting data will be relevant to the developmental course of implicit and explicit memory, item and source memory, repetition and semantic priming, and their physiological underpinnings.
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