Sensory-motor dynamics of mother-infant-object interactions: Longitudinal changes in micro-behavioral patterns across the first year

Summary form only given. Infants rapidly develop the skills to coordinate attention to objects and people. In particular, the period 9-12 months is thought to bring a new ability to coordinate with and to share the objects of another persons\´ attention-like following the gaze of the mother or playing a ball tossing game together. This has been termed “triadic” or “you-me-it” attention and is thought to be the basis for future learning, including early language. The development of triadic attention was investigated in a longitudinal sample of 26 mother-infant dyads interacting with objects in a naturalistic setting. Video recordings of sessions when the infants were four, six, nine, and twelve months of age were analyzed frame-by-frame, coding multiple dimensions of mother and infant sensory-motor contact as they attended to one another and to a set of shared objects. Specifically, we coded targets of gaze and manual contact of both participants, noting all changes occurring at 10Hz. Additionally, we coded salient macro level features of the interaction, such as moments of imitation and games. Databases detailing the micro behaviors of the interaction are only beginning to be coded in developmental psychology. Our dataset is the first of its kind to be created in a naturalistic home environment with infants younger than a year. Previous accounts code at the level of the triad (e.g. jointly attending to a toy vs. infant solo toy play). This has led to the conclusion that the development of triadic attention is the result of a sudden, qualitative leap in infant cognitive abilities. By contrast, our analyses of changes in sensory motor dynamics of attending indicate that gradual shifts in sensory motor coordination lead to continuous changes in mother-infant-object interactions over the first year. Our analyses indicate that at four months, infants converged all modalities (gaze and two hands) to a single target. Across individual infan- s, such sensory-motor coupling decreased gradually over the first year of life. This change fundamentally alters the dyadic social interaction. Specifically, we found that the degree of decoupling was related to the infant\´s responses to mother\´s actions on toys. Young infants transitioned all of their modalities to toys manipulated by mom. Over the course of the first year, infants increasingly distributed their attention between toys manipulated by mother and toys in their own possession. This allows the infant to observe manipulations made by mom on one set of objects while simultaneously maintaining a high degree of sensory motor contact on with another object, upon which they can practice performing those same manipulations. We confirmed these relations quantitatively by first creating an index of “total modality time” spent attending to "already-available" versus "maternal bid" objects. This was a temporal summation of all infant modalities directed towards both kinds of objects, after the mother presented a new object. We modeled session by session changes in the distribution of attending with a beta model, indicating a gradual shift in relative proportions of attending across the first year. Split halves analyses indicated that within a single session, infants who showed higher proportions of sensory-motor coupling showed less mature patterns of responding to the maternal bids, whereas those who decoupled more resembled the profiles of older infants. Overall, our results indicate that triadic attention emerges not as a novel form of social-cognition, but as a continuous product of sensory-motor maturation . In particular, infants changing abilities to distribute attention between multiple targets allows for increasing complexity of mother-infant-object manipulations.