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Previous accounts of the development of triadic attention identify a ‘‘curious'' shift around nine to twelve months. We introduce a novel approach inspired by distributed and embodied cognition frameworks. In a longitudinal study of five mother-infant dyads, videos of home play interactions were recorded over the infants' first year. We scrutinized the real-time organization of mother-infant sensorimotor activity, including the targets of hands, gaze, and mouth, as the dyad members attended to one another and to toys. We identified a pervasive developmental pattern: At four months, infants converged all sensory modalities on objects introduced by the mother. From six to twelve months, infants showed increasing decoupling of hands and eyes and increasingly elaborate sequences in multi-object play. Concurrently, dyads engaged in increasingly elaborate social exchanges (e.g., turn-taking) as mothers adapted to infants' sensorimotor skills. We therefore theorize that triadic attention emerges not as a novel form of social cognition but as a continuous product of sensorimotor development, scaffolded by parents' expanding social actions.

Previous developmental accounts of joint object activity identify a qualitative “shift” around 9–12 months. In a longitudinal study of 26 dyads, videos of joint object interactions at 4, 6, 9, and 12 months were coded for all targets of gaze and manual activity (at 10 Hz). At 12 months, infants distribute their sensorimotor modalities between objects handled by the parent and others controlled by the infant. Analyses reveal novel trajectories in distributed joint object activity across the 1st year. At 4 months, infants predominantly look at and manipulate a single object, typically held by their mothers. Between 6 and 9 months, infants increasingly decouple their visual and haptic modalities and distribute their attention between objects held by their mothers and by themselves. These previously unreported developments in the distribution of multimodal object activity might “bridge the gap” to coordinated joint activity between 6 and 12 months.

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Decades after key modifiable risk factors were identified, cardiovascular disease remains the leading cause of preventable death, and only one quarter of persons with high cholesterol levels have attained recommended levels of control. Cholesterol control efforts have focused on consumer education and medical treatment. A powerful, complementary approach is to change the makeup of food, a route the New York City Department of Health and Mental Hygiene took when it restricted artificial trans fat--a contributor to coronary heart disease--in restaurants. The Department first undertook a voluntary campaign, but this effort did not decrease the proportion of restaurants that used artificial trans fat. In December 2006, the Board of Health required that artificial trans fat be phased out of restaurant food. To support implementation, the Department provided technical assistance to restaurants. By November 2008, the restriction was in full effect in all New York City restaurants and estimated restaurant use of artificial trans fat for frying, baking, or cooking or in spreads had decreased from 50% to less than 2%. Preliminary analyses suggest that replacement of artificial trans fat has resulted in products with more healthful fatty acid profiles. For example, in major restaurant chains, total saturated fat plus trans fat in French fries decreased by more than 50%. At 2 years, dozens of national chains had removed artificial trans fat, and 13 jurisdictions, including California, had adopted similar laws. Public health efforts that change food content to make default choices healthier enable consumers to more successfully meet dietary recommendations and reduce their cardiovascular risk.