Oscillatory entrainment to our early social or physical environment and the emergence of volitional control

An individual’s early interactions with their environment are thought to be largely passive; through the early years, the capacity for volitional control develops. Here, we consider: how is the emergence of volitional control characterised by changes in the entrainment observed between internal activity (behaviour, physiology and brain activity) and the sights and sounds in our everyday environment (physical and social)? We differentiate between contingent responsiveness (entrainment driven by evoked responses to external events) and oscillatory entrainment (driven by internal oscillators becoming temporally aligned with external oscillators). We conclude that ample evidence suggests that children show behavioural, physiological and neural entrainment to their physical and social environment, irrespective of volitional attention control; however, evidence for oscillatory entrainment beyond contingent responsiveness is currently lacking. Evidence for how oscillatory entrainment changes over developmental time is also lacking. Finally, we suggest a mechanism through which periodic environmental rhythms might facilitate both sensory processing and the development of volitional control even in the absence of oscillatory entrainment

Form-function relationship in the amplitude and frequency modulations of infant - directed speech: A predictive processing perspective

Infants prefer infant-directed speech (IDS) over adult-directed speech (ADS). IDS is thought to serve specific functions compared to ADS: - Attracting infant attention to the speech signal - Conveying clear opportunities for easier word segmentation. Two independent domains of complexity that are embedded in the speech stream: - Amplitude complexity: Lower amplitude complexity associates with greater ease in identifying word boundaries ​ - ​Frequency complexity: Higher fre q uency complexity associates with more attention eliciting speech attention by inducing uncertaint

Developing through relationships with the physical and social environment: disentangling the transition from co-regulation to self-regulation

The present thesis centres its attention on early regulatory skills of physiological arousal and attention. These abilities play a central role during early infancy and are crucial for achieving autonomy and establishing the foundation for later social, behavioural, and cognitive development. Early in development, infant’s self-regulatory capacities are thought to be immature, poorly coordinated, and limited. Because of this, co-regulation with the caregiver is particularly important. Much of the infant/ child research emphasizes the developmental increase in self-regulation and highlights a gradual transition from co-regulation (where regulatory processes are shared between child and caregiver) to self-regulation. Research on this transition, however, is scarce and complex and remarkably little is known on how these co-regulatory dynamics between infant-caregiver change and evolve over time. Taking a novel, multi-method approach that integrates neural, physiological, and behavioural techniques and uses a mixture of home- and naturalistic lab-based research, the present thesis examines the development of self- and co- regulatory processes in infancy. More specifically, it explores whether infants’ physiological and attentional states gradually become less dependent on others as they get better at self-regulation over developmental time. Evidence is presented showing developmental changes in the way environmental factors (both physical and social) influence infants’ regulation of physiological arousal and attention. Evidence also shows that, contrary to our hypothesis, dyadic strategies, rather than being phased out or replaced, seem to continue to play an important role. Discussion is focused on the contribution of the findings to theories of the development of dyadic regulatory process, and in identifying new and more naturalistic ways to study them

The Sub-Second Dynamics of Spontaneous Mimicry: An Electromyography Study Tracking Infant Caregiver Dyads during Free Play

Spontaneous mimicry (SM) is a ubiquitous feature of human communication (Heyes, 2021; Meltzoff & Williamson, 2017). Research shows that SM is both reflexive and flexible (Wang & Hamilton, 2012). It is sensitive to cues that signify implicit social rules and social hierarchy, suggesting that it is at least partly socially shaped. However, we have yet to map the ontogeny of SM, or its developmental factors (Slaughter, 2021). A marked difference in SM behaviour has been observed in atypical populations (e.g., ASD; Arnold & Winkielman, 2020) increasing the onus for further study. In infants, facial mimicry has been studied extensively and is the central focus of a long running debate surrounding the presence of SM in early infancy (Slaughter, 2021). However, most of these studies have used lab-based tasks or non-naturalistic block-design paradigms (Slaughter, 2021; Meltzoff & Williamson, 2017). The few studies that have observed naturalistic interactions used hand-coded video data, scoring onset and offsets of actions: mimicry was operationalised as an action onset in the observer that occurs within a specific timespan of a prior action onset in the interacting partner (Markodimitraki & Kalpidou, 2019). Here, SM behaviour is gauged in terms of frequency and total number of mimicked actions. They do not measure the magnitude of the action i.e. they cannot record graded changes in action. Employing electromyography (EMG) allows us to decipher moment-to-moment dynamics and sub-second changes. In the present study, we investigated facial SM behaviour in free-play interactions between 5-months-old infants and their caregivers. EMG electrodes are placed on the facial regions that overly the corrugator supercilii (frowning/eyebrow-movement) in both caregiver and infant. Lab based investigation of SM in infants have found evidence of infant SM of eyebrow movement at this age range (De Klerk et al., 2018). The caregiver and infant were tested while during tabletop free play sessions. The obtained EMG signal is rectified, band-pass filtered and z-scored. Artefacts are rejected by identifying and removing outliers that fall outside of one standard deviation above or below the mean. Cross-correlations are carried out to obtain a comprehensive overview of the temporal correspondence between the partners’ EMG waveforms. Granger causality analyses are also conducted on the EMG-waveforms of the interacting partners to identify if changes in the facial action of one predicts changes in that of the other. Based on our reading of the literature we had predicted that the cross correlations will be significant when the caregiver’s waveform is lagged (mother mimics the infant) but not when the infant’s waveform is lagged. Our target sample size is 20 dyads, and we are currently at the centriole. In our preliminary analyses (N - 9 dyads), in contrast to our expectations, the cross correlations were significant when the caregiver’s waveform preceded the infant’s (infant’s waveform is lagged). This was seen at lags between .2 and .6 seconds. Granger causality analyses will be performed to test if each of the waveforms can significantly predict the other. Control analysis will be performed with shuffled datasets to rule out spurious results

Assessing the Efficacy of Open-Source Solutions to Automated Facial Coding: A Methods-Comparison Study with EMG

Facial expressions are central components of face-to-face interactions and non-verbal communication. Most studies have measured changes in facial configuration by manually hand-coding videos of participants’ faces. This is relatively easy to setup and has facilitated theoretical developments in many fields e.g. spontaneous mimicry (REF). However, hand-coding does not track graded changes in action magnitude: they typically report onsets and offsets alone (REF). Without the action gradient, facial dynamics are reduced to binary events that do not differ in topography or temporal quality. The ideal alternative, Electromyography (EMG), requires wired sensors be placed on skin. This spawns the possibility of participant discomfort, introduces the requirement for resources and limits ecological validity. Automated facial coding may provide an optimal trade-off: non-intrusive instruments that assess magnitude. Cross-correlations will be used to assess the degree to which the opensource auto-coder package (Mémoire IRCGN [https://github.com/LafLaurine/imac2-memoire-ircgn]) can approximate EMG data (Corrugator supercilii) in naturalistic, face-to-face interactions between mother-infant dyads (N - 10 dyads; infant age range 4-6 months). The videos will also be hand-coded enabling for the findings to link to the published literature