Babies learn to process emotion from the very first months of life

Interactions between caregivers, including early childhood education and care (ECEC) providers, and babies may help to shape the same brain regions adults use for vocal emotion processing, UK researchers have found.

The same brain network that adults use when they hear angry vocalisations and sounds is at work in infants as young as six months old, with the strongest evidence of this network shown in babies whose caregivers spend time controlling the behaviours of the baby, or using aggressive and abrasive tones, even when not directed at the child themselves.

The study, published in the open-access journal PLOS ONE, was conducted by Chen Zhao from the University of Manchester, with a key finding being that sensitivity to anger is, at least in part, a result of caregiver interactions.

The research builds on a multitude of existing findings showing that infants can distinguish the emotional content of their mothers’ voices long before they understand words, based on intonation, tone, rhythm, and other elements. In adults, that emotional content is processed in the frontal and temporal lobes. Brain imaging studies in infants have been performed to determine if the same is true in babies, but the noise of an MRI machine has made analysis of response to sounds challenging.

In the current study, the authors overcame the sound limitation by using a silent and non-invasive method that measures blood flow to cortical areas, while infants sat in their mothers’ laps and listened to recorded non-speech vocalisations that were angry, happy, or neutral in emotionality.

Separately, the team also observed the same mother-infant pairs during floor play, quantifying the mother’s interactions in terms of both sensitivity to infant behaviour as it changed, and directiveness, or the degree to which the mother sought to control the infant’s behaviour.

The researchers found that angry and happy sounds and words activated the fronto-cortical network, and the level of activation in response to anger was greater for those infants whose mothers were more directive in their interactions.

The results suggest that greater experience with directive caregiving, or the stress it produces, heightens the infant brain’s ability to detect and respond to angry vocalisations.

Speaking about his research, Mr Zhao said “Brain science shows that babies’ brains are sensitive to different emotional tones they hear in voices. Such tones can cause different activation patterns in the infant’s brain areas which are also known to be involved in processing voices in adults and older children.

These patterns also reveal that the early care experienced by babies can influence brain responses so that the more intrusive and demanding their mother, the stronger the brain response of these 6-month-olds is to hearing angry voices.”

The research may be read in full here.