The interplay between tonal synchrony and social engagement in mother-infant interaction

This study explores the relationship between tonal synchrony and maternal-infant social engagement based on free-play recordings of 15 mothers and their 3-month-old infants in a laboratory-setting. Moment-by-moment analyses on a micro-level were used to study social engagement and vocal interaction. We analysed and categorized 854 vocalization periods (Mother-Only Vocalizations (MOV), Tonal Interaction Periods (TIP), non-Tonal Interaction Periods (nTIP), and mutual Silence (SIL)). Tonal synchrony was analysed in terms of harmonic and pentatonic series based on pitch frequency-analyses. Social engagement was micro-analysed in terms of matched and mismatched engagement states. ANOVA-repeated measures revealed, most importantly, a significant relationship between TIPs and social interaction repair, which indicates the importance of tonal synchrony in the flow of social engagement in mother-infant dyads. Other significant relationships were found between a) nTIPs/mismatch-mismatch, and, b) MOV/affect loss. As mentioned in the discussion, the findings are suggestive for clinical applications (e.g., music therapy) and warrant further research.