How do we understand the meaning of words? Neuroscientists have long debated about the role of perceptual and motor experience in language processing. Embodied Semantics (ES) suggests that the meaning of a word is instantiated in sensorimotor areas of the brain: We use the visual cortex to extract the meaning of the word “red” and the motor cortex to understand the word “grasp”. Meaning is the product of on-line perceptual and motor simulations. Conversely, Amodal Semantics (AS) suggests that meaning emerges from the connection between symbolic units in a semantic network. These symbols are neither perceptual nor motoric; and sensorimotor activity may be a consequence of linguistic processing, but not part of the meaning itself.
Both theories fall short in accounting for all aspects of word meaning: available data suggest that semantics can’t be completely unrelated to sensorimotor information, but neither can be entirely embodied. We need to specify how symbolic and sensorimotor knowledge are instantiated in the brain, what is their specific contribution to lexical semantics, and how they get integrated in the construction of meaning.
We seek to move toward an integrated theory of word meaning by investigating semantic processing in early blind individuals. The visually deprived brain provides a unique model to study how the lack of a perceptual modality influences the format of conceptual knowledge, allowing for a straightforward test of Embodied Semantics: If meaning is based on perceptual simulations, different perceptual experience should lead to different semantics. In our experiments the role of the visual perceptual system will be contrasted, at first, and then integrated, with an account of symbolic semantics based on language statistics. Crucially, since blind and sighted individuals have a different perceptual experience, but are exposed to the same language statistics, we will be able to make contrasting predictions between these two models of semantics.
This research was conceived and is now carried out together with Olivier Collignon (Université de Louvain, Belgium and CIMeC, University of Trento, Italy) and our post–doc Roberto Bottini. Part of the group is detached to CIMeC, Trento, where we carry out the neuroimaging part of the project. We also collaborate on this line of research with several associations for blind people (Unione Italiana dei Ciechi e degli Ipovedenti in several Itailan cities, Istituto dei Ciechi di Milano). Roberto and the CIMeC team have also created a website entirely dedicated to this research project, the Semanticat; please go take a look if you're interested.