Semantic richness, concreteness, and object domain: an electrophysiological study

Results from previous event-related potential (ERP) studies of semantic richness and concreteness effects have been mixed. Feature production norms have been used to derive one measure of semantic richness, the number of listed semantic features (NOF) for a given concept. Whereas some ERP studies have found evidence for a semantic richness continuum from abstract concepts, to concrete concepts with few features, to concrete concepts with several features, other studies have not. The present study assessed the effects of NOF (within concrete concepts) and concreteness (concrete vs. abstract concepts), on ERP amplitudes and behavioural decision latencies during a concrete/abstract decision task. It is important we also manipulated object domain, which has been found to influence ERP amplitude and topography. High and low NOF concepts were selected from animal and nonliving thing categories and all four conditions were matched on several potential confounds. We show that although decision latencies support a semantic richness continuum, electrophysiological activity does not. Whereas concrete concepts produce a larger negativity than abstract concepts, low NOF concepts are associated with larger negativities than high NOF concepts. We also replicate an increased posterior positivity for processing animal concepts, and report an interaction between object domain and semantic richness such that the NOF effect is larger within animal concepts.