The Structure of Semantic Memory in School-Age Children: An ERP Study

The current study uses event-related potentials (ERPs) to examine how school-age children (5-8- years-old) organize lexical-semantic information in long-term memory. N400 amplitudes were examined as participants saw a picture and heard a word that either matched the picture (match), shared a majority of features with the picture (near violation), shared fewer features with the picture (far violation), or shared no features with the picture (between-category violation). Featural similarity modulated the amplitude of the N400 response, such that words sharing more features with the picture elicited smaller N400 amplitudes and words sharing fewer features with the picture elicited larger N400 amplitudes. N400 amplitudes showed a graded effect based on featural similarity in posterior regions early in semantic processing (200-400 ms), and this graded response became more broadly distributed in the mid-latency time window (400-600 ms). Previous research shows that late in processing, concepts that are not the target are suppressed and this was reflected in the current study. Indeed, from 600-800 ms all violation conditions displayed significant N400 effects, however, there was no difference between near, far, and between-category violations. These results demonstrate that like adults, school-age children organize semantic information based on subtle differences in featural similarity. These results are in line with theories of semantic memory that suggest activation spreads across featurally similar concepts.