InCHORRRuS: Infant-Directed Communication Highlights and Organizes Repetition and Redundancy Through Rhythmic Structure.

Learning to successfully participate in social interactions is a monumental task for infants, whose perceptual systems are immature and communicative signals complex and hard to parse. To support their infants, caregivers naturally modify their communicative behaviors to be more repetitive, redundant, and rhythmic, thus engaging infants' perceptual biases. In this paper, we present the InCHORRRuS framework: which considers the role of rhythm in organizing caregivers' communicative behaviors across modalities to scaffold communication and dyadic coordination in early social interactions. We argue rhythm's role in infant-directed (ID) communication is particularly highlighted in ID singing, in which metrically structured beat-based rhythms make the multimodal redundancy and repetition in ID communication also temporally predictable, thus "supercharging" the cues' communicative value. Additionally, the repetition in songs, across verses and over time, offers caregivers a natural way of leveraging predictability and familiarity at the local level and at longer interactional timescales alike, increasing the impact of the enriched communicative signal. We review the current literature on timing and rhythm, redundancy, and repetition in ID signals; discuss the evidence on the confluence of redundancy and repetition in rhythmic contexts; and consider open questions and future directions our framework inspires.