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When Abstract Becomes Concrete: Naturalistic Encoding of Concepts in the Brain

Language is acquired and processed in complex and dynamic naturalistic contexts, involving simultaneous processing of connected speech, faces, bodies, objects, etc. How words and their associated concepts are encoded in the brain during real-world processing is still unknown. Here, the representational structure of concrete and abstract concepts was investigated during movie watching to address the extent to which brain responses dynamically change depending on contextual information. First, averaging across contexts, concrete and abstract concepts are shown to encode different experience-based information in separable sets of brain regions. However, these differences reduce when multimodal context is considered. Specifically, the response profile of abstract words becomes more concrete-like when these are processed in visual scenes highly related to their meaning. Conversely, when the visual context is unrelated to a given concrete word, the activation pattern resembles more that of abstract conceptual processing. These results suggest that while concepts encode habitual experiences on average, the underlying neurobiological organization is not fixed but depends dynamically on available contextual information. Significance Statement The capability of extracting and representing meaningful concepts from words is a unique function of human cognition. It allows us to think, communicate, and behave in goal-directed ways. Previous studies have used isolated sentences or words to study the underlying neurobiological mechanisms. However, humans learn and process language in rich, multimodal, and dynamic contexts how does this information affect conceptual processing? We used functional MRI (fMRI) to analyze patterns of brain activity corresponding to concepts processed in naturalistic context. We found that multimodal contextual information can alter the organization of conceptual representation in the brain, suggesting that the underlying neurobiology is context dependent and organized in a distributed way.