Functional magnetic resonance imaging of taxonomic and thematic processing of abstract and concrete word pairs

This study used fMRI to examine the effect that the abstract-concrete dimension may have on the thematic-taxonomic distinction. The dual hub theory (DHT) posits that left angular gyrus supports thematic relationships and left temporal pole supports taxonomic relationships; however, the DHT is largely based on evidence from concrete words. It is important that theories of semantic organization include abstract words as they are ubiquitous in everyday discourse (Lupyan & Winter, Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 2018, 373, 20170137). Additionally, there is reason to believe that there may bean interaction between the abstract-concrete dimension and the thematic-taxonomic distinction, based on the different representational frameworks (DRF) hypothesis, which posits that abstract concepts are primarily organized by association/theme, and that concrete concepts are primarily organized by similarity/taxonomy. However, there appears to be a mismatch among the DHT, predictions of the DRF hypothesis for brain activation, and existing neuroimaging data for the concreteness effect. Thus, we sought to include abstract words in a test of the DHT and determine whether any interactions exist between the abstract-concrete dimension and the thematic-taxonomic distinction. While we replicated the localization of abstract and concrete word processing, we did not extend the DHT to include abstract words, nor did we find an interaction that would support the DRF hypothesis. Rather, our results align more closely with the hub-and-spoke model (Patterson et al., Nature Reviews Neuroscience, 2007, 8, 976).