Eye contact with babies synchronises brain activity

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Researchers at the University of Cambridge have discovered that eye contact between infants and adults cause their brain waves to become more synchronised with each other. These results were recently published in PNAS, with Dr Victoria Leong as the first author.

In their study, the researchers used electroencephalography to monitor brainwaves in infants and adults. In one experiment, infants were shown video recordings of an adult singing nursery rhymes. 3 types of video recordings were shown – with the adult looking directly at the infant, with the adult’s head turned away but their eyes oriented towards the infant, and with the adult’s head and eyes turned away at an angle. The researchers found that in the first two scenarios with eye contact, there was better synchronisation between the infant and the adult’s brain activity than in the third scenario.

A second experiment was conducted with infants and adults put together in real life. The adult either faced the infant directly or oriented their head and eyes away at an angle. Brainwaves in adults and infants were compared across the two different scenarios. As in the first experiment, eye contact caused their brain activity to be more in sync. In addition, the effect went both ways – the adult’s brain activity affected the infant’s, and vice versa.

These results highlight the important role that eye contact plays in communication, while uncovering an intriguing connection in brain activity between infants and adults when they interact. At the same time, the study invites many questions about how our brains think as we communicate with one another.

A previous study by Liu and colleagues in 2017, which was referenced by Leong in her paper, looked instead at adult pairs and also found increased coupling of brain activity during communication. In the study, the researchers monitored the brain activity of 15 adults as they listened to audio recordings of stories. Coupling was observed between listeners and the speaker they were listening to. However, this effect disappeared when the story was told in a language that the listener did not understand.

It appears that both speech and eye contact can get our brains to synchronise with each other. An intriguing question to explore is how each component contributes to this effect. Eye contact is a visual stimulus while speech is auditory. The first stages of their processing are carried out in different parts of the brain. Are the mechanisms by which they elicit brain activity synchrony different in both cases, or do they converge on a common pathway? These are complex questions that probe deep into our
understanding of neural function.

Another point of interest is how the brains of babies might respond to a language they do not understand. While brainwave  coupling was not observed in adults when they listen to an unknown language, perhaps babies respond differently during the course of language acquisition.

The idea that brainwave activity may be linked to language and cognitive development has been raised before. Previous research  by Benasich and colleagues published in 2008 has linked increased brain EEG activity in the high frequency gamma range to better language and cognitive abilities in children. The study by Benasich looked at bands of a different frequency from Leong’s study, and the studies do not directly relate to each other. Nevertheless, such studies tantalise with the possibility that brain waves detected by electroencephalography may be an avenue for us to better understand how we think and communicate.

We are still a long way from figuring out how communication works in our brains. However, by investigating human  communication in infants, at its most rudimentary stage, we can perhaps begin to learn what goes on in our brains when we talk to each other.

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