Abstract
The advent of brain reading techniques has enabled new approaches to the study of concept representation, based on the analysis of multivoxel activation patterns evoked by the contemplation of individual concepts such as animal concepts. The present fMRI study characterized the representation of 30 animal concepts. Dimensionality reduction of the multivoxel activation patterns underlying the individual animal concepts indicated that the semantic building blocks of the brain's representations of the animals corresponded to intrinsic animal properties (e.g. fierceness, intelligence, size). These findings were compared to behavioral studies of concept representation, which have typically collected pairwise similarity ratings between two concepts (e.g. Henley, 1969). Behavioral similarity judgments, by contrast, indicated that the animals were organized into taxonomically defined groups (e.g. canine, feline, equine). The difference in the results between the brain reading and behavioral approaches might derive from differences in cognitive processing during judging similarities versus contemplating one animal at a time. Brain reading approaches may have an advantage in describing thoughts about an individual concept, owing to the ability to decode brain activation patterns elicited by the brief consideration of a single concept (e.g. word reading) without a complex cognitive or behavioral task (e.g. similarity judgments). On the other hand, some behavioral tasks may tend to evoke a concept from numerous perspectives, yielding a representation of the breadth and sophistication of the concept knowledge. These results suggest that neural and behavioral measures offer complementary perspectives that together characterize the content and structure of concept representations.