The Impact of Age of Acquisition on Semantic Representations: An EEG Study

Abstract

The age of acquisition (AOA) of a word has a significant impact on how it is processed; words acquired earlier in life are processed more quickly and accurately than words acquired later. Previous behavioural research has also independently established that AOA affects semantic processing, and that electroencephalography (EEG) can be used to examine AOA effects. However, no study has examined AOA and semantic processing in tandem, nor have potential confounds between AOA and word frequency been considered. To disentangle these effects, the current study employs EEG to examine the interaction between AOA and concreteness, whilst controlling for and investigating word frequency. Data was obtained from 28 participants completing a lexical decision task. The results revealed a significant effect of concreteness on the N400 component of the event-related potential (ERP) when controlling for AOA. The impact of AOA on the N400 supports a relationship with semantic processing. Importantly, there was also an interaction between concreteness and AOA; however, only earlier acquired concrete words displayed an AA effect. The ERPs for word frequency after controlling for AOA showed a similar pattern of differences to previous research, although no comparisons reached significance. This suggests the AOA results were not likely to be confounded by frequency. These findings contribute to the understanding of semantic processing and suggest that AOA and concreteness each have distinct effects on processing and also provide insight into how the lexical system is organised. Notably, the findings suggest that abstract and concrete words are learned differently early in life, but not later in life. These results assist in further specifying previous theories where differences between abstract and concrete words were hypothesised, but interactions across the lifespan were not considered. Keywords: age of acquisition, semantic processing, electroencephalography study