Maternal voice contingency affects tactile habituation in full-term newborns

Multisensory interactions are central to early development, yet their influence on newborns' tactile processing remains unclear. In particular, it is unknown whether auditory input interferes with or modulates tactile habituation, and how this depends on voice familiarity and temporal contingency. This study investigated these questions in 96 full-term newborns using a manual habituation-discrimination paradigm across four auditory conditions: silence, recorded stranger voice, recorded maternal voice, and live maternal voice contingent on the infant's object-holding behavior. Infants explored a smooth object until habituation, after which they were presented with a novel shape to assess discrimination. The presence of a voice generally reduced the proportion of infants reaching habituation compared to silence, with an apparent gradient from stranger to maternal to live contingent maternal voice; pairwise comparisons were significant only between silence and live contingent maternal conditions. Among infants who habituated, total holding time was significantly longer in the live contingent maternal voice condition, whereas initial holding times did not differ across conditions. No evidence of tactile discrimination was observed, likely reflecting the small number of infants completing the test phase. These findings indicate that auditory input, particularly when contingent on the infant's actions, strongly engages newborns' attention and behavior. Rather than merely interfering with tactile learning, live contingent maternal vocalizations may promote socio-emotional engagement and operant-like associations, redirecting attention toward salient cues. Overall, the results underscore the attentional salience of maternal vocal input and indicate that temporally contingent maternal speech can modulate newborns' engagement during tactile exploration, suggesting a potential influence on attentional and learning processes.