On processing BEASTS and BIRDS: an event-related potential study on the representation of taxonomic structure

In two event-related potential (ERP) studies it was investigated whether concrete nouns of different taxonomic level (basic level terms, e.g., BIRD, and superordinate terms, e.g., BEAST) are processed differentially under conditions where no processing of taxonomic relations is required. The first experiment, a lexical decision task with taxonomic terms serving as no-go trials, revealed no differences in ERP waveforms to basic level as compared to superordinate terms. The second experiment, a modified oddball paradigm, revealed a consistent pattern of ERP differences: Superordinate deviants elicited a prolonged early positivity as compared to standard items, possibly a P3a component, while basic level deviants elicited an enlarged N400 compared to standard items. Additionally, taxonomic items presented only once in a recognition test elicited different ERPs depending on their respective taxonomic level. Moreover, study- as well as recognition-ERP patterns differed depending on whether Subjects were confronted with basic level terms or with superordinates as standards. It was concluded that representations of basic level terms form a distinct conceptual class, while representations of superordinate terms probably do not.