Tracking the acquisition and retention of novel word representations: an ERP study

The event-related N400 provides a measure of lexical-semantic processing, indexing the encoding strength of newly learned words. We examined N400 modulations following associative learning of novel written words paired with novel object pictures from early to later stages of acquisition. During the initial learning session, novel picture-word pairs accompanied by semantic attributes were presented as stimuli for learning at multiple timepoints. Following learning at each of these timepoints, we examined behavioural and neural effects for recognition of familiar and novel words, as well as at a follow-up session several days later. Rapid behavioural learning was accompanied by N400 congruity effects for novel words, displaying a similar neurophysiological profile to familiar words. These behavioural and neural effects were largely sustained several days later in the follow-up session. Our findings indicate that explicit learning of novel object-word associations leads to the rapid formation and longer-term retention of new word memory traces.