Caregiver-child proximity as a dimension of early experience

A social science trust taxonomy with emergent vectors and symmetry

Introduction

Trust is foundational to all social science domains, but to date, there is no unifying theory or consistent measurement basis spanning the social sciences. This research hypothesized that trust forms the basis of an ontology that could unify the social science domains. The proposed ontology comprises a Cartesian plane with axes self-trust and other-trust. Self-trust manifests in dominant behaviors, and other-trust manifests in cooperative behaviors. Both axes are divided into five discrete categories, creating a matrix of 25 cells. All words in the lexicon are allocated into one of these 25 cells.

Methods

This research started with an existing 14,000-word lexicon of dominance and affiliation. The lexicon was extended by manually identifying and including socially descriptive words with information regarding self-trust, other-trust, dominance, and cooperation. The taxonomy was optimized using the Gradient Descent machine learning algorithm and commercially curated synonyms and antonyms. The t-test was employed as the objective (or loss) function for Gradient Descent optimization. Word vectors were identified using groups of four words related as synonyms and antonyms.

Results

Over 30,000 words were identified and included in the lexicon. The optimization process yielded a t-score of over 1,000. Over 226,000 vectors were identified, such as malevolent-mean-gentle-benevolent. A new form of symmetry was identified between adjectives and verbs with a common root; for example, the words reject and rejected are horizontally reflected.

Discussion

The word vectors can create a metrologically compliant basis for psychometric testing. The symmetries provide insight into causes (verbs) and effects (adjectives) in social interactions. These vectors and symmetries offer the social sciences a basis of commonality with natural sciences, enabling unprecedented accuracy and precision in social science measurement.

The impact of daily affective touch on cortisol levels in institutionalized & fostered children

Institutionalized children are often deprived of affective touch. Such tactile deprivation often leads to constant stress, as measured by the levels of salivary cortisol. We report here the impact of an affective touch program, optimized to activate a specific population of unmyelinated mechanosensitive nerves in the skin called c-tactile afferents (CT) on stress resistance. Two populations of children (age 4-10) were recruited: (i) a cohort living in an orphanage and (ii) a fostered cohort. Both groups received the affective touch program daily for 10-15 min for 5-6 weeks. A cohort of age-matched children living in a family environment acted as a control group and did not receive any instructions for tactile stimulation. Salivary cortisol was collected at the beginning (T1) and at the end (T2) of the study in all three groups. For institutionalized and fostered children there was a significant improvement in the level of cortisol (p < 0.0001) between T1 and T2, which is manifested in the balancing cortisol levels: a decrease where it was elevated and an increase, where the critically low level testified to the distress of the child. Balancing cortisol levels is a process of recovery to normal values, which indicates the restoration of neurohumoral mechanisms of stress regulation. The effect of balancing cortisol levels was more pronounced in the group of fostered children compared to the group of orphanage children (p = 0.0326). The children in the control group had no significant differences.

Caregiving relationships are a cornerstone of developmental psychopathology

The interdisciplinary field of developmental psychopathology has made great strides by including context into theoretical and empirical approaches to studying risk and resilience. Perhaps no context is more important to the developing child than their relationships with their caregivers (typically a child's parents), as caregivers are a key source of stimulation and nurturance to young children. Coupled with the high degree of brain plasticity in the earliest years of life, these caregiving relationships have an immense influence on shaping behavioral outcomes relevant to developmental psychopathology. In this article, we discuss three areas within caregiving relationships: (1) caregiver-child interactions in everyday, naturalistic settings; (2) caregivers' social cognitions about their child; and (3) caregivers' broader social and cultural context. For each area, we provide an overview of its significance to the field, identify existing knowledge gaps, and offer potential approaches for bridging these gaps to foster growth in the field. Lastly, given that one value of a scientific discipline is its ability to produce research useful in guiding real-world decisions related to policy and practice, we encourage developmental psychopathology to consider that a focus on caregiving, a modifiable target, supports this mission.

Within arms reach: Physical proximity shapes mother-infant language exchanges in real-time

During everyday interactions, mothers and infants achieve behavioral synchrony at multiple levels. The ebb-and-flow of mother-infant physical proximity may be a central type of synchrony that establishes a common ground for infant-mother interaction. However, the role of proximity in language exchanges is relatively unstudied, perhaps because structured tasks-the common setup for observing infant-caregiver interactions-establish proximity by design. We videorecorded 100 mothers (U.S. Hispanic N = 50, U.S. Non-Hispanic N = 50) and their 13- to 23-month-old infants during natural activity at home (1-to-2 h per dyad), transcribed mother and infant speech, and coded proximity continuously (i.e., infants and mother within arms reach). In both samples, dyads entered proximity in a bursty temporal pattern, with bouts of proximity interspersed with bouts of physical distance. As hypothesized, Non-Hispanic and Hispanic mothers produced more words and a greater variety of words when within arms reach than out of arms reach. Similarly, infants produced more utterances that contained words when close to mother than when not. However, infants babbled equally often regardless of proximity, generating abundant opportunities to play with sounds. Physical proximity expands opportunities for language exchanges and infants' communicative word use, although babies accumulate massive practice babbling even when caregivers are not proximal.

Direct and Observed Joint Attention Modulate 9-Month-Old Infants' Object Encoding

Sharing joint visual attention to an object with another person biases infants to encode qualitatively different object properties compared to a parallel attention situation lacking interpersonal sharedness. This study investigated whether merely observing joint attention amongst others shows the same effect. In Experiment 1 (first-party replication experiment), N = 36 9-month-old German infants were presented with a violation-of-expectation task during which they saw an adult looking either in the direction of the infant (eye contact) or to the side (no eye contact) before and after looking at an object. Following an occlusion phase, infants saw one of three different outcomes: the same object reappeared at the same screen position (no change), the same object reappeared at a novel position (location change), or a novel object appeared at the same position (identity change). We found that infants looked longer at identity change outcomes (vs. no changes) in the "eye contact" condition compared to the "no eye contact" condition. In contrast, infants' response to location changes was not influenced by the presence of eye contact. In Experiment 2, we found the same result pattern in a matched third-party design, in which another sample of N = 36 9-month-old German infants saw two adults establishing eye contact (or no eye contact) before alternating their gaze between an object and their partner without ever looking at the infant. These findings indicate that infants learn similarly from interacting with others and observing others interact, suggesting that infant cultural learning extends beyond infant-directed interactions.

Caregiver monitoring, but not caregiver warmth, is associated with general cognition in two large sub-samples of youth

Individual differences in cognitive abilities emerge early during development, and children with poorer cognition are at increased risk for adverse outcomes as they enter adolescence. Caregiving plays an important role in supporting cognitive development, yet it remains unclear how specific types of caregiving behaviors may shape cognition, highlighting the need for large-scale studies. In the present study, we characterized replicable yet specific associations between caregiving behaviors and cognition in two large sub-samples of children ages 9-10 years old from the Adolescent Brain Cognitive Development Study® (ABCD). Across both discovery and replication sub-samples, we found that child reports of caregiver monitoring (supervision or regular knowledge of the child's whereabouts) were positively associated with general cognition abilities, after covarying for age, sex, household income, neighborhood deprivation, and parental education. This association was specific to the type of caregiving behavior (caregiver monitoring, but not caregiver warmth), and was most strongly associated with a broad domain of general cognition (but not executive function or learning/memory). Additionally, we found that caregiver monitoring partially mediated the association between household income and cognition, furthering our understanding of how socioeconomic disparities may contribute to disadvantages in cognitive development. Together, these findings underscore the influence of differences in caregiving behavior in shaping youth cognition. RESEARCH HIGHLIGHTS: Caregiver monitoring, but not caregiver warmth, is associated with cognitive performance in youth Caregiver monitoring partially mediates the association between household income and cognition Results replicated across two large matched samples from the Adolescent Brain Cognitive Development Study® (ABCD).

Observational measures of caregiver's touch behavior in infancy: A systematic review

The caregiver's touch behavior during early infancy is linked to multiple developmental outcomes. However, social touch remains a challenging construct to operationalize, and although observational tools have been a gold standard for measuring touch in caregiver-infant interactions, no systematic review has been conducted before. We followed the PRISMA guidelines and reviewed the literature to describe and classify the main characteristics of the available observational instruments. Of the 3042 publications found, we selected 45 that included an observational measure, and from those we identified 12 instruments. Most of the studies were of infants younger than six months of age and assessed touch in two laboratory tasks: face-to-face interaction and still-face procedure. We identified three approaches for evaluating the caregiver's touch behavior: strictly observational (the observable touch behavior), functional (the functional role of the touch behavior), or mixed (a combination of the previous two). Half of the instruments were classified as functional, 25% as strictly observational, and 25% as mixed. The lack of conceptual and operational uniformity and consistency between instruments is discussed.

Interpersonal synchronization of spontaneously generated body movements

Interpersonal movement synchrony (IMS) is central to social behavior in several species. In humans, IMS is typically studied using structured tasks requiring participants to produce specific body movements. Instead, spontaneously generated (i.e., not instructed) movements have received less attention. To test whether spontaneous movements synchronize interpersonally, we recorded full-body kinematics from dyads of participants who were only asked to sit face-to-face and to look at each other. We manipulated interpersonal (i) visual contact and (ii) spatial proximity. We found that spontaneous movements synchronized across participants only when they could see each other and regardless of interpersonal spatial proximity. This synchronization emerged very rapidly and did not selectively entail homologous body parts (as in mimicry); rather, the synchrony generalized to nearly all possible combinations of body parts. Hence, spontaneous behavior alone can lead to IMS. More generally, our results highlight that IMS can be studied under natural and unconstrained conditions.

Oxytocin but not naturally occurring variation in caregiver touch associates with infant social orienting

Caregiver touch is crucial for infants' healthy development, but its role in shaping infant cognition has been relatively understudied. In particular, despite strong premises to hypothesize its function in directing infant attention to social information, little empirical evidence exists on the topic. In this study, we investigated the associations between naturally occurring variation in caregiver touch and infant social attention in a group of 6- to 13-month-old infants (n = 71). Additionally, we measured infant salivary oxytocin as a possible mediator of the effects of touch on infant social attention. The hypothesized effects were investigated both short term, with respect to touch observed during parent-infant interactions in the lab, and long term, with respect to parent-reported patterns of everyday touching behaviors. We did not find evidence that caregiver touch predicts infant social attention or salivary oxytocin levels, short term or long term. However, we found that salivary oxytocin predicted infant preferential attention to faces relative to nonsocial objects, measured in an eye-tracking task. Our findings confirm the involvement of oxytocin in social orienting in infancy, but raise questions regarding the possible environmental factors influencing the infant oxytocin system.