Vagal tone during infant contingency learning and its disruption

A quarter century of research on infant contingency learning: Current and future directions

Although traditional learning paradigms provided a substantial base for the emergence of the field of infant studies from the 1960s through the 1990s, research on contingency (operant) learning in infancy has not attracted much attention over the last 25 years. While the reasons for such neglect are unclear, learning protocols offer valuable contributions to the field of infant studies, spanning basic research, translational work, and application. An examination of the literature over the last quarter century shows operant learning concepts in use with respect to the development of agency, goal blockage reactivity, clinical cross-group comparisons, and developmental interventions. Building upon the foundation that infants are capable of contingency learning, research has explored underlying mechanisms, including coordinated movement dynamics and psychobiological correlates. Methodological innovations-such as novel paradigms and cutting-edge techniques like motion capture, eye-tracking, and computational modeling-have further refined our understanding of these processes. Efforts have also focused on identifying conditions that promote learning and factors contributing to data loss. An overarching question remains whether infants demonstrate agency during contingency learning. Additionally, recent research has shifted from a primarily experimental group approach to considering individual differences in early learning. However, it is unclear whether traditional learning metrics effectively capture nonmonotonic behavioral change and variability in learning patterns. The review offers cogent rationales for reintegrating these paradigms into the field of infant studies, discusses gaps in the literature that should be addressed for this goal to be realized, and proposes future directions for advancing the field.

Anticipatory regulation of cardiovascular system on the emergence of auditory-motor interaction in young infants

Humans develop auditory-motor interaction to produce a variety of rhythmic sounds using body movements, which are often produced and amplified with tools, such as drumming. The extended production of sounds allows us to express a wide range of emotions, accompanied by physiological changes. According to previous studies, even young infants enhance movements in response to auditory feedback. However, their exhibition of physiological adaptation on the emergence of auditory-motor interaction is unclear. We investigated the movement and cardiac changes associated with auditory feedback to spontaneous limb movements in 3-month-old infants. The results showed that infants increased the frequency of limb movements inducing auditory feedback, while they exhibited a more regular rhythm of the limb movements. Furthermore, heart rate increase associated with the limb movement was first inhibited immediately after the timing of the auditory feedback, which may reflect sustained attention to the auditory stimuli. Then, through auditory-motor experience, the heart rate increase was inhibited even prior to the auditory feedback, leading to suppression of the peak intensity of the heart rate increase. These findings suggest that young infants regulate the cardiovascular system as well as limb movements in anticipation of the auditory feedback. The anticipatory regulation associated with movement and attentional changes may contribute to reduced cardiovascular stress in auditory-motor interaction, and provide a developmental basis for more sophisticated goal-directed behavior of producing rhythmic sounds.

Characterizing change in vagal tone during the first three years of life: A systematic review and empirical examination across two longitudinal samples

Functioning of the parasympathetic nervous system (PNS), most often indexed by respiratory sinus arrhythmia (RSA), influences the volitional, cognitively-mediated forms of self-regulation across development. However, despite its clear relevance to children's self-regulation, and its utility as a transdiagnostic biomarker of emotion dysregulation and psychopathology, the ontogeny of vagal tone under conditions of homeostasis across infancy and early childhood is not well understood. The current research is comprised of two complementary studies. The first aims to address this gap by conducting a systematic review of the literature which has assessed resting RSA in the first three years of life. The second study uses data from two diverse, longitudinal datasets (n = 203 and n = 370) to model change in RSA from infancy to toddlerhood. Results from a systematic review of 62 studies meeting inclusion criteria suggest that measures of resting RSA increase over time and demonstrate moderate stability across infancy, toddlerhood, and preschool ages. Results from a series of models fit to longitudinal data in study two suggest that baseline RSA is characterized by stable increases across infancy and early childhood. Moreover, although there was equivocal evidence for individual variability in trajectories of RSA, the findings suggest that the individual differences in resting RSA may become entrenched in early life based on observed significant variance in growth model intercepts. In all, the current study contributes to our understanding of the developmental trajectories of baseline RSA across infancy and early childhood and should support future research examining links between children's parasympathetic regulation and their adjustment in early life.

Anger, sad, and blended expressions to contingency disruption in young infants

Three studies elicited young infants' (aged 17-23 weeks) anger and sad facial expressions during brief contingency disruptions to explore their potential organization over time as a biphasic process. Study 1 examined partial correlations among anger, sad, blended anger/sad, and neutral expressions during extinction in three extant, independently recruited samples. Across samples, all three negative expressions were inversely related to neutral expressions, but anger and sad expressions were not significantly correlated when anger/sad blends were controlled. Study 2 compared expressions during contingency and disruption minutes in two groups: one in which the disruption was an extinction phase (the absence of the formerly contingent event), or one in which the disruption was noncontingent presentations of the stimuli. Study 3 examined expression trajectories over time in two contingency and extinction sessions. Independent trajectories of anger and sad expressions occurred over time in Studies 2 and 3. Extinction and noncontingency differed in sad expression. The relation between expressions and blends also varied over time.

Cardiac vagal regulation in infancy predicts executive function and social competence in preschool: Indirect effects through language

Parasympathetic nervous system functioning in infancy may serve a foundational role in the development of cognitive and socioemotional skills (Calkins, 2007). In this study (N = 297), we investigated the potential indirect effects of cardiac vagal regulation in infancy on children's executive functioning and social competence in preschool via expressive and receptive language in toddlerhood. Vagal regulation was assessed at 10 months during two attention conditions (social, nonsocial) via task-related changes in respiratory sinus arrhythmia (RSA). A path analysis revealed that decreased RSA from baseline in the nonsocial condition and increased RSA in the social condition were related to larger vocabularies in toddlerhood. Additionally, children's vocabulary sizes were positively related to their executive function and social competence in preschool. Indirect effects from vagal regulation in both contexts to both 4-year outcomes were significant, suggesting that early advances in language may represent a mechanism through which biological functioning in infancy impacts social and cognitive functioning in childhood.