Measuring naturalistic proximity as a window into caregiver-child interaction patterns.

The interactions most supportive of positive child development take place in moments of close contact with others. In the earliest years of life, a child's caregivers are the primary partners in these important interactions. Little is known about the patterns of real-life physical interactions between children and their caregivers, in part due to an inability to measure these interactions as they occur in real time. We have developed a wearable, infrastructure-free device (TotTag) used to dynamically and unobtrusively measure physical proximity between children and caregivers in real time. We present a case-study illustration of the TotTag with data collected over two (12-hour) days each from two families: a family of four (30-month-old son, 61-month-old daughter, 37-year-old father, 37-year-old mother), and a family of three (12-month-old daughter, 35-year-old-father, 33-year-old mother). We explored patterns of proximity within each parent-child dyad and whether close proximity would indicate periods in which increased opportunity for developmentally critical interactions occur. Each child also wore a widely used wearable audio recording device (LENA) to collect time-synced linguistic input. Descriptive analyses reveal wide variability in caregiver-child proximity both within and across dyads, and that the amount of time spent in close proximity with a caregiver is associated with the number of adult words and conversational turns to which a child was exposed. This suggests that variations in proximity are linked to-though, critically, not synonymous with-the quantity of a child's exposure to adult language. Potential implications for deepening the understanding of early caregiver-child interactions are discussed.