Cortical Representations of Concrete and Abstract Concepts in Language Combine Visual and Linguistic Representations

The human semantic system stores knowledge acquired through both perception and language. To study how semantic representations in cortex integrate perceptual and linguistic information, we created semantic word embedding spaces that combine models of visual and linguistic processing. We then used these visually-grounded semantic spaces to fit voxelwise encoding models to fMRI data collected while subjects listened to hours of narrative stories. We found that cortical regions near the visual system represent concepts by combining visual and linguistic information, while regions near the language system represent concepts using mostly linguistic information. Assessing individual representations near visual cortex, we found that more concrete concepts contain more visual information, while even abstract concepts contain some amount of visual information from associated concrete concepts. Finally we found that these visual grounding effects are localized near visual cortex, suggesting that semantic representations specifically reflect the modality of adjacent perceptual systems. Our results provide a computational account of how visual and linguistic information are combined to represent concrete and abstract concepts across cortex.