Phd in CLINICAL EXPERIMENTAL NEUROSCIENCE AND PSYCHIATRY

Thesis title: Interoception and its role in shaping words meaning: behavioral and electrophysiological explorative evidence on the concreteness of Abstract concepts

According to Embodied theories of language, sensorimotor systems are actively involved in the processing of words meaning. Different studies support this theoretical proposition, showing that modality-specific sensorimotor representations built on actual experiences are reenacted during words processing. While Concrete concepts are thought to rely on reactivation of experiences in exteroceptive modalities; Abstract concepts are thought to reactivate bodily sensations through the interoceptive modality. The main aim of the current thesis is to provide evidence advocating for the prominent role of interoception in embodiment of Abstract concepts, providing additional insight on the body-language coupling adopting behavioral and electrophysiological techniques. In Experiment 1, we compared perceptual strength ratings across languages, explored the importance of interoception in defining Abstract concepts, and addressed its implication for trait measures of empathy and interoceptive sensitivity. Moreover, cluster analysis was conducted with the aim of examining whether perceptual strength ratings could provide a reliable way of distinguishing conceptual categories. In detail, we explored perceptual strength ratings of 40 Abstract and 40 Concrete concepts in Italian, Hebrew, and English native speakers. As far as we are aware of, no previous studies directly compared different languages combining perceptual strength ratings, trait measurements, and clustering analysis. We observed high consistencies between languages for what concerns: 1) pattern of perceptual ratings for Abstract and Concrete concepts for each modality; 2) the importance of interoception in embodiment of Abstract concepts; and 3) the perceptual-based distinction in conceptual categories. In addition, some cross-linguistic differences emerged in relation to the levels in which interoceptive components of concepts influence empathy. In addition, to understand better the contribution of bodily states and interoception to word processing, we further examined the effects of being immersed in a perceptual deprivation chamber aimed at increasing saliency of bodily and internal states on electrophysiological correlates of word processing. To the best of our knowledge no previous studies explored the effect of this kind of manipulation on word processing. Consequently, in Experiment 2, we collected ERPs related to the processing of Abstract and Concrete words, focusing on the N400 and a late N700-like negativity. We hypothesized that the immersion in the perceptual deprivation chamber would reduce the differences between ERPs’ amplitudes for Abstract and Concrete words as an effect of increased interoceptive and decreased exteroceptive saliency. In line with our hypothesis, we observed that: 1) the N400 difference between Abstract and Concrete concepts was reduced in the perceptual deprivation chamber; and 2) Abstract concepts elicited stronger late N700-like negativity in the perceptual deprivation chamber. We suggest that increased attentional focus on internal states would reduce the retrieval of sensorimotor components during Concrete concepts processing and facilitate multimodal imagery processes during Abstract words’ processing. Taken together, the current thesis supports the bidirectional relationship between bodily states and language processing in which words act as cue to the retrieval of perceptual experiences (language-to-body) and the bodily state facilitate the retrieval of multimodal situated representations (body-to-language). Furthermore, the importance of directing attention towards bodily and internal states and the implications of our results on the Abstract-Concrete distinction are discussed. In conclusion, bodily states appear to be involved in word processing even more than previously thought. Future studies aimed at providing deeper understanding of the body-language coupling including additional physiological measures are recommended.