The influence of finger-strategies on number processing is documented by several findings which suggest that finger-based embodied representations could constitute a potential bridge between the innate number sense and the development of symbolic numerical abilities. Recent studies show evidence of hand muscle activation during passive observation of Arabic digits, as well as priming on the processing of Arabic stimuli if preceded by pictures of culturally-appropriate canonical finger-numeral configurations. However, little is known about how the sensory-motor and visual systems interact in the adulthood cognition and about the particulars of numerical processing grounding in the brain hemispheres. To fill this gap, a cross-modal priming study was designed, in which participants had to identify lateralized Arabic digits (2-3-4) while performing covert canonical or non-canonical finger-numeral configurations with their hemisphere-matching or hemisphere-mismatching hand. Results showed that responses to a visual target (e.g., 3) were faster when participants’ hand was fixed in canonical configuration compared to arbitrary finger position, particularly when bodily-hand information and visual stimuli were projected simultaneously into the left hemisphere. This cross-modal priming effect can be taken as evidence of the numerical cognitive-facilitation supported by integrative processing of multiple sensorial information, and as an indication of specialized hemispheric involvement in the semantic processing of number information.
