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, 61month-old daughter, 37-year-old father, 37-year-old mother), and a family of three (12-monthold 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 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, quantity of a child's exposure to adult language. Potential implications for deepening understanding of early caregiver-child interactions are discussed.

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Testbeds for wireless IoT devices facilitate testing and validation of distributed target nodes. A testbed usually provides methods to control, observe, and log the execution of the software. However, most of the methods used for tracing the execution require code instrumentation and change essential properties of the observed system. Methods that are non-intrusive are typically not applicable in a distributed fashion due to a lack of time synchronization or necessary hardware/software support. In this article, we present a tracing system for validating time-critical software running on multiple distributed wireless devices that does not require code instrumentation, is non-intrusive and is designed to trace the distributed state of an entire network. For this purpose, we make use of the on-chip debug and trace hardware that is part of most modern microcontrollers. We introduce a testbed architecture as well as models and methods that accurately synchronize the timestamps of observations collected by distributed observers. In a case study, we demonstrate how the tracing system can be applied to observe the distributed state of a flooding-based low-power communication protocol for wireless sensor networks. The presented non-intrusive tracing system is implemented as a service of the publicly accessible open source FlockLab 2 testbed.

The types of interactions that we believe to be most supportive of positive child development (e.g., joint attention, physical touch) take place in moments of close contact with others, and in the earliest years of life a child’s caregivers are the primary partners in these important interactions. However, we know little about the patterns of real-life interactions between children and their caregivers. To address this gap, we have developed a wearable, infrastructure-free device (TotTag) used to dynamically and unobtrusively measure real-time physical proximity between children and caregivers throughout the day. The present study examines the TotTag validity and reliability with data collected over two days from a family of four (30-month-old son, 61-month-old daughter, 37-year-old father, 37-year-old mother), including information about their patterns of interaction as well as how the children’s experiences might differ depending on proximity to their caregivers. We explored patterns of proximity across the day within each parent–child dyad and whether measurements corresponding to close proximity between child and caregiver 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 analysis of the TotTag data reveal wide variability in caregiver–child proximity over the course of the recordings. Further, results suggest that the amount of time spent in close proximity with a caregiver is associated with the quantity of a child’s exposure to adult language, suggesting that variations in proximity are linked to, though not synonymous with, the experience of adult speech. Potential implications for deepening understanding of early caregiver–child interactions are discussed.