Infants' object interactions are long and complex during everyday joint engagement

As infants interact with the object world, they generate rich information about object properties and functions. Much of infant learning unfolds in the presence of caregivers, who talk about and act on the objects of infant play. Does mother joint engagement correspond to real-time changes in the complexity and duration of infant object interactions? We observed thirty-eight mothers and their first-born infants (cross-sectional, 13, 18, and 23 months) during 2 hours of everyday activity as infants freely navigated their home environments. Behavioral coding explored thousands of infant object interactions within and outside mother joint engagement. Object interactions involving exclusively simple play were shorter than complex play bouts. Critically, mothers' multimodal input (i.e., touching/gesturing toward and talking about the focal object) corresponded with more complex and longer play bouts than when mothers provided no input. Bouts involving complex play and multimodal input lasted 7.5 times longer than simple play bouts absent mother input. Moreover, "action-orienting talk" (e.g., "Twist it", "Feed dolly"), rather than talk per se, corresponded with longer bout duration and complexity. Notably, the association between joint engagement and play duration was not a function of mothers having more time to join. Analyses that eliminated short infant bouts and considered the timing of mothers' behaviors confirmed that mother input "extended" the duration of play bouts. As infants actively explore their environments, their object interactions change moment to moment in the presence of mothers' multimodal engagement. RESEARCH HIGHLIGHTS Mothers and infants were videorecorded for 2 hours at home; researchers coded infants' object interactions and mothers' behaviors (verbal, manual) toward the focal object. Mothers' multimodal joint engagement (i.e., coordinated manual and verbal input) was associated with long and complex infant object interactions. The pragmatics of mothers' talk-namely action-orienting language-related to the duration and complexity of infant object bouts beyond talk per se. Infants' object interactions change in complexity and duration in line with maternal joint engagement, indicating potential mechanisms of real-time learning. This article is protected by copyright. All rights reserved.

The role of social signals in segmenting observed actions in 18-month-old children

Learning about actions requires children to identify the boundaries of an action and its units. Whereas some action units are easily identified, parents can support children's action learning by adjusting the presentation and using social signals. However, currently, little is understood regarding how children use these signals to learn actions. In the current study, we investigate the possibility that communicative signals are a particularly suitable cue for segmenting events. We investigated this hypothesis by presenting 18-month-old children (N = 60) with short action sequences consisting of toy animals either hopping or sliding across a board into a house, but interrupting this two-step sequence either (a) using an ostensive signal as a segmentation cue, (b) using a non-ostensive segmentation cue and (c) without additional segmentation information between the actions. Marking the boundary using communicative signals increased children's imitation of the less salient sliding action. Imitation of the hopping action remained unaffected. Crucially, marking the boundary of both actions using a non-communicative control condition did not increase imitation of either action. Communicative signals might be particularly suitable in segmenting non-salient actions that would otherwise be perceived as part of another action or as non-intentional. These results provide evidence of the importance of ostensive signals at event boundaries in scaffolding children's learning.

Motion tracking of parents' infant- versus adult-directed actions reveals general and action-specific modulations

Parents tend to modulate their movements when demonstrating actions to their infants. Thus far, these modulations have primarily been quantified by human raters and for entire interactions, thereby possibly overlooking the intricacy of such demonstrations. Using optical motion tracking, the precise modulations of parents' infant-directed actions were quantified and compared to adult-directed actions and between action types. Parents demonstrated four novel objects to their 14-month-old infants and adult confederates. Each object required a specific action to produce a unique effect (e.g. rattling). Parents were asked to demonstrate an object at least once before passing it to their demonstration partner, and they were subsequently free to exchange the object as often as desired. Infants' success at producing the objects' action-effects was coded during the demonstration session and their memory of the action-effects was tested after a several-minute delay. Indicating general modulations across actions, parents repeated demonstrations more often, performed the actions in closer proximity and demonstrated action-effects for longer when interacting with their infant compared to the adults. Meanwhile, modulations of movement size and velocity were specific to certain action-effect pairs. Furthermore, a 'just right' modulation of proximity was detected, since infants' learning, memory, and parents' prior evaluations of their infants' motor abilities, were related to demonstrations that were performed neither too far from nor too close to the infants. Together, these findings indicate that infant-directed action modulations are not solely overall exaggerations but are dependent upon the characteristics of the to-be learned actions, their effects, and the infant learners.