Since when or how often? Dissociating the roles of age of acquisition (AoA) and lexical frequency in early visual word processing.

The aim of the study was to investigate the effect of both word age of acquisition (AoA) and frequency of occurrence on the timing and topographical distribution of ERP components. The processing of early- versus late-acquired words was compared with that of high-frequency versus low-frequency words. Participants were asked to perform an orthographic task while EEG was recorded from 128 sites. RTs showed an effect of both word AoA and lexical frequency. ERPs revealed a neuro-functional dissociation between AoA and frequency effects in early word processing. AoA modulated the amplitude of left occipito-temporal selection-negativity, suggesting an effect of AoA on early orthographic and lexical access and revealing the crucial role of AoA in determining how words are neurally represented in the ventral pathway. Lexical frequency modulated the amplitude of left anterior negativity, providing evidence for the involvement of the left inferior frontal cortex in the processing of low-frequency words.