How do blind people represent rainbows? Disentangling components of conceptual representations.

Abstract

How do we represent information that has no sensory features? How are abstract concepts like \"freedom\", devoid of external perceptible referents, represented in the brain? To address the role of sensory information in the neural representation of concepts, we investigated how people born blind process concepts whose referents are imperceptible to them because of their visual nature (e.g. \"rainbow\", or \"red\"). We find that the left dorsal anterior temporal lobe (ATL) shows preference both to typical abstract concepts (\"freedom\") and to concepts whose referents are not sensorially-available to the blind (\"rainbow\"), as compared to partially sensorially-perceptible referents (e.g. \"rain\"). Activation pattern similarity in dorsal ATL is related to the sensorial-accessibility ratings of the concepts in the blind. Parts of inferior-lateral aspects of ATL and the temporal pole responded preferentially to abstract concepts devoid of any external referents (\"freedom\") relative to imperceptible objects, in effect distinguishing between object and non-object concepts. The medial ATL showed a preference for concrete concepts (\"cup\"), along with a preference for partly perceptible items to the blind (\"rain\", as compared with \"rainbow\"), indicating this regions role in representing concepts with sensory referents beyond vision. The findings point to a new division of labor among medial, dorsal and lateral aspects of ATL in representing different properties of object and non-object concepts.