Putting our heads together: interpersonal neural synchronization as a biological mechanism for shared intentionality

Interpersonal Neural Entrainment during Early Social Interaction

Currently, we understand much about how children's brains attend to and learn from information presented while they are alone, viewing a screen - but less about how interpersonal social influences are substantiated in the brain. Here, we consider research that examines how social behaviors affect not one, but both partners in a dyad. We review studies that measured interpersonal neural entrainment during early social interaction, considering two ways of measuring entrainment: concurrent entrainment (e.g., 'when A is high, B is high' - also known as synchrony) and sequential entrainment ('changes in A forward-predict changes in B'). We discuss possible causes of interpersonal neural entrainment, and consider whether it is merely an epiphenomenon, or whether it plays an independent, mechanistic role in early attention and learning.

Mother-child behavioral and physiological synchrony

The interactive, give and take "dance" that highlights the synchrony between parents and young infants during social interaction occurs at the behavioral as well as the physiological level. These dyadic processes seen across infancy and early childhood appear to contribute to children's development of self-regulation and general socio-emotional outcomes. The focus of this chapter is on dyadic synchrony, the temporal coordination of social behaviors and the associated physiology. Research on behavioral, brain, and cardiac synchrony is reviewed within a bio-behavioral synchrony model. Tutorials for analyzing these types of complex social interaction data are noted.

Bed-Sharing in Couples Is Associated With Increased and Stabilized REM Sleep and Sleep-Stage Synchronization

BACKGROUND/OBJECTIVES

Sharing the bed with a partner is common among adults and impacts sleep quality with potential implications for mental health. However, hitherto findings are contradictory and particularly polysomnographic data on co-sleeping couples are extremely rare. The present study aimed to investigate the effects of a bed partner's presence on individual and dyadic sleep neurophysiology.

METHODS

Young healthy heterosexual couples underwent sleep-lab-based polysomnography of two sleeping arrangements: individual sleep and co-sleep. Individual and dyadic sleep parameters (i.e., synchronization of sleep stages) were collected. The latter were assessed using cross-recurrence quantification analysis. Additionally, subjective sleep quality, relationship characteristics, and chronotype were monitored. Data were analyzed comparing co-sleep vs. individual sleep. Interaction effects of the sleeping arrangement with gender, chronotype, or relationship characteristics were moreover tested.

RESULTS

As compared to sleeping individually, co-sleeping was associated with about 10% more REM sleep, less fragmented REM sleep (p = 0.008), longer undisturbed REM fragments (p = 0.0006), and more limb movements (p = 0.007). None of the other sleep stages was significantly altered. Social support interacted with sleeping arrangement in a way that individuals with suboptimal social support showed the biggest impact of the sleeping arrangement on REM sleep. Sleep architectures were more synchronized between partners during co-sleep (p = 0.005) even if wake phases were excluded (p = 0.022). Moreover, sleep architectures are significantly coupled across a lag of ± 5min. Depth of relationship represented an additional significant main effect regarding synchronization, reflecting a positive association between the two. Neither REM sleep nor synchronization was influenced by gender, chronotype, or other relationship characteristics.

CONCLUSION

Depending on the sleeping arrangement, couple's sleep architecture and synchronization show alterations that are modified by relationship characteristics. We discuss that these alterations could be part of a self-enhancing feedback loop of REM sleep and sociality and a mechanism through which sociality prevents mental illness.

Neurobehavioral Interpersonal Synchrony in Early Development: The Role of Interactional Rhythms

Social interactions are essential for understanding others' actions and their mental and affective states. Specifically, interpersonal coordination - also referred to as synchrony - allows actors to adjust their behaviors to one another and thus demonstrate their connectedness to each other. Much behavioral research has demonstrated the primacy of mutually synchronized social exchanges in early development. Additionally, new methodological advances now allow us to examine interpersonal synchrony not only at the behavioral and physiological but also neural level. Nevertheless, it remains unclear how infants and their caregivers actually achieve interpersonal synchrony in their exchanges. Here we discuss recent evidence showing that adults provide rhythmical information during early social interactions with their infants, such as affective touch and singing. We propose that entrainment to these social rhythms underlies the formation of interpersonal synchrony and thus stimulates reciprocal interactions between infants and their caregivers.

What Guides Us to Neurally and Behaviorally Align With Anyone Specific? A Neurobiological Model Based on fNIRS Hyperscanning Studies

An emerging body of hyperscanning functional near-infrared spectroscopy (fNIRS) research shows interbrain neural synchrony (IBS) during different forms of social interaction. Here we review the recent literature and propose several factors that facilitate IBS, leading us to ask the following question: In a world full of people and opportunities to synchronize with them, what directs our neural and behavioral alignment with anyone specific? We suggest that IBS between what we deem the "mutual social attention systems" of interacting partners-that is, the coupling between participants' temporoparietal junctions and/or prefrontal cortices-facilitates and enhances the ability to tune in to the specific interaction, its participants and its goals. We propose that this process is linked to social alignment, reinforcing one another to facilitate successful and lucrative social interactions. We further suggest that neurochemical mechanisms of dopamine and oxytocin underlie the activation of this suggested loop. Finally, we suggest possible directions for future studies, emphasizing the need to develop a brain-to-brain neurofeedback system with IBS between the mutual social attention systems of the participants as the direct regulating target.

Effects of Interpersonal Sensorimotor Synchronization on Dyadic Creativity: Gender Matters

Although it is noted that interpersonal sensorimotor coordination can influence several high-level socio-cognitive processes, its impact on creative collaboration is nearly unexplored. Here, we investigated the effects of a form of sensorimotor coordination, that is, sensorimotor synchronization, on a subsequent creative collaboration task. 60 pairs (n total = 120 participants) formed by previously unacquainted individuals performed a tower-building task either jointly or alone, followed by a dyadic creativity task. Tower building time in the joint condition was recorded through a sensorized platform and creativity performance was evaluated by two independent raters based on the quantity and quality of generated ideas. We controlled for gender composition and for the disposition to cooperate and to adopt a creative, analytical style. Results showed that male-male couples were more creative after the joint-action condition, whereas female-female and mixed-gender couples were more creative after the solo condition. Regression analyses of tower building time on creativity performance revealed that building time was a significant predictor of creativity dimensions in male-male and in mixed-gender couples but did not predict creative performance in female-female couples. Overall, these findings suggest that the manipulation of sensorimotor coordination can influence performance in a subsequent creative collaboration task, with the nature, and magnitude of this effect depending on the gender composition of the dyads. These results have potential implications for the design of sensorimotor-based strategies to enhance dyadic creative performance in several contexts, especially for the organizational settings.