Somatic and visceral effects of word valence, arousal and concreteness in a continuum lexical space

Although affective and semantic word properties are known to independently influence our sensorimotor system, less is known about their interaction. We investigated this issue applying a data-driven mixed-effects regression approach, evaluating the impact of lexical-semantic properties on electrophysiological parameters, namely facial muscles activity (left corrugator supercilii, zygomaticus major, levator labii superioris) and heartbeat, during word processing. 500 Italian words were acoustically presented to 20 native-speakers, while electrophysiological signals were continuously recorded. Stimuli varied for affective properties, namely valence (the degree of word positivity), arousal (the amount of emotional activation brought by the word), and semantic ones, namely concreteness. Results showed that the three variables interacted in predicting both heartbeat and muscular activity. Specifically, valence influenced activation for lower levels of arousal. This pattern was further modulated by concreteness: the lower the word concreteness, the larger affective-variable impact. Taken together, our results provide evidence for bodily responses during word comprehension. Crucially, such responses were found not only for voluntary muscles, but also for the heartbeat, providing evidence to the idea of a common emotional motor system. The higher impact of affective properties for abstract words supports proposals suggesting that emotions play a central role in the grounding of abstract concepts.