Neural Correlates of Rapid Word Learning in 19- to 24-month-olds

Abstract:
Abstract: By late infancy, children learn word-referent associations under conditions of minimal exposure. This phenomenon is sometimes called "fast mapping." Our goal was to characterize the neural systems underlying this impressive ability, especially as they differ from those required for processing a) familiar word-sound patterns, and b) well-known words. Using a 64-channel montage, we compared event-related potentials (ERPs) elicited by words that were presented in training under two different social conditions: Comprehension - where a nonce word was presented 4 times by a speaker looking at a referent, and Familiarization - same as Comprehension but no referent was provided. ERPs to well-known and completely novel words were also recorded. ERPs for trained Comprehension and Familiarization words showed characteristic differences both early (250-300ms) and late (400-700ms) in the recording epoch. The ERPs for trained Comprehension words were similar to those elicited by well-known familiar words; however, a direct comparison between these two conditions revealed important differences in both the topography and latency of their characteristic components. These findings suggest a dissociation of the neural systems responsible for processing recently "fast mapped" words versus well-known words.