Brain Imaging fNIRS Neuroscience Parent-Child Interaction Psychology

Brains get “in sync” when mothers and children talk to each other

Engaging in a conversation is a highly complex social task with many implications for child development and wellbeing. The promotion of turn-taking during parent-child conversation is known to lead to higher social interaction quality. Conversely, low coordination and turn-taking during parent-child conversation are linked with atypical language development and other developmental difficulties in children. But what happens in the brains of mothers and their children when they talk to each other – do their brains get “in sync” with one another? And does the degree of brain-to-brain synchrony associate with social interaction quality?

Turn-taking is a vital component of verbal conversations. It involves a highly organised behavioural structure and timing that help the speaker and listener understand each other. Interactions featuring contingent verbal turn-taking and responsiveness are more effective for social learning in children. Verbal turn-taking during parent-child conversation also enhances behavioural coordination, particularly reciprocity (i.e. engaging with others to gain a mutual benefit). Accordingly, parent-child communication patterns at preschool age may affect the development of children’s social competences beyond language learning.

Communication between individuals, and more specifically turn-taking, has recently been linked to interpersonal neural synchronisation. Interpersonal neural synchronisation generally refers to the temporal coordination of behavioural, neural, and physiological activity between two or more interacting people, summarised under the umbrella term bio-behavioural synchrony. Within this domain, the neural aspect of interpersonal synchronisation is defined as the temporal coordination of concurrent rhythmic brain activities between individuals.

During verbal communication, internal (or endogenous) oscillators in the brain – groups of neurons that collectively show recurring (or periodic) activity – are involved in timing-related cognitive processes. More precisely, neural oscillators in one conversation partner both influence and adapt to the oscillators of the other partner(s). Such brain-to-brain synchrony is deemed necessary for interaction partners to understand each other and to feel socially connected during verbal conversation. Although some data exists on brain-to-brain synchrony during conversation between adults, this process remains poorly investigated in parents interacting with their children.

In a new study published in the journal Social Cognitive Affective Neuroscience (SCAN), functional near-infrared spectroscopy (fNIRS) hyperscanning was applied to look at brain-to-brain synchrony during free verbal conversation in 40 pairs of mothers with their 5-6 year old children. fNIRS measures individual brain activity within the outermost layers of the brain through infrared light absorption and therefore is completely non-invasive. It also has the major advantage of being much less sensitive to motion than other neuroimaging methods, which makes it a method of choice for real-time social interaction assessment, particularly in dyads involving children. Individual brain activity can subsequently be transformed into a time by frequency space and the signals of the interacting individuals assessed for their temporal alignment or synchrony (using wavelet transform coherence – WTC – analysis). In the present study, the free verbal conversation lasted for four minutes and was split into eight segments of thirty seconds each for analysis.

In addition to measuring brain activity using fNIRS hyperscanning, mother-child interactions were video recorded and analysed regarding different conversation patterns, amongst which turn-taking – defined as communicative reciprocity (i.e. alternating mutual communicative turns). Higher turn-taking was expected to be associated with increased brain-to-brain synchrony. This comes because turn-taking during parent-child conversation was previously shown to be more effective for social learning in children. Furthermore, it was also shown to enhance behavioural coordination / reciprocity, thereby indirectly linking turn-taking to social interaction quality.

The study data revealed two main findings. First, brain-to-brain synchrony between mothers and their children was observed to generally increase with conversation duration. The authors suggest that this pattern may be indicative of the constant re-synchronisation processes reflecting the high complexity of verbal communication, particularly as it unfolded coherently over time. Second, the link between increased brain-to-brain synchrony and conversation duration was particularly evident for mother-child dyads showing higher verbal turn-taking during the conversation overall. This second finding not only underscores the intrinsic relation between verbal turn-taking and brain-to-brain synchrony as it unfolds over time, but also suggests an indirect link between brain-to-brain synchrony during verbal conversation and social interaction quality.

The authors conclude that the observed link between conversational turn-taking and brain-to-brain synchrony opens up new possibilities to understand the potential functional role of bio-behavioural synchrony. This particularly applies to its neural component during verbal exchanges between mothers and their children. For example, their findings point towards the possibility of brain-to-brain synchrony serving as a potential neurobiological marker of successful coordination and social interaction quality in mother-child conversation.

Finally, the authors suggest that future studies could explore the role of neural synchrony in language acquisition. What also remains to be explored is the question whether mother-child and father-child conversation patterns differ and what such differences could mean for child development and social interaction quality.

This study is part of a series of collaborative investigations looking at parent-child interaction using a range of methods (CARE Studies). The corresponding paper was published open access and is freely available.

Original Paper:
Nguyen, T., Schleihauf, H., Kayhan, E., Matthes, D., Vrtička, P., Hoehl, S. (published online – June 15th 2020). Neural synchrony in mother-child conversation: Exploring the role of communicative featuresSocial Cognitive Affective Neuroscience

Dr Pascal Vrticka is a social neuroscientist with strong ties to developmental & social psychology. His research focuses on the psychological, behavioural, biological, and brain basis of human social interaction, attachment and caregiving. Besides measuring neurobiological responses to different kinds of social versus non-social information in single participants using (functional) magnetic resonance imaging ([f]MRI) and electroencephalography (EEG), Dr Vrticka most recently started to assess bio-behavioural synchrony in interacting pairs using functional near-infrared spectroscopy (fNIRS) hyperscanning. The main question thereby is how romantic partners and parents with their children get “in sync” when they solve problems together or talk to each other. Dr Vrticka furthermore relates the obtained individual and dyadic behavioural, biological, and brain measures to interindividual differences in relationship quality – particularly attachment and caregiving. In doing so, he refers to attachment theory that provides a suitable theoretical framework on how we initiate and maintain interpersonal relationships across the life span. With his research, Dr Vrticka is promoting a new area of investigation: the social neuroscience of human attachment.

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