A study assessed whether exposure to their own reflection influences the development of facial mimicry, a process associated with empathy and emotion recognition, in 4-month-old infants. The results showed that infants exposed to their own reflection showed greater increases in sensorimotor cortex activity when observing others' facial expressions, but this did not translate into increased facial copying behaviour.

Mimicry, the spontaneous tendency to copy others’ actions, plays an important role in facilitating social bonds, increasing empathy between strangers and promoting helping behaviours. Facial mimicry can begin early in life and is particularly relevant because it may help us recognise others’ emotions.

Some authors argue that the link between “seeing” and “doing” is innate and that infants can imitate others’ actions from birth. However, other studies suggest that this link may instead be shaped by sensorimotor experience throughout development.

Based on this latter hypothesis, a recent study examined whether exposure to one’s own reflection can influence the development of facial mimicry in infants. With the support of the Bial Foundation, the research was led by Dr Carina de Klerk from the University of Essex (United Kingdom) and involved infants aged around four months.

Over two weeks, one group of infants had daily contact with a small mirror embedded in a toy, while another group used the same toy without access to the mirror. Before and after this period, the infants watched videos of other babies displaying facial expressions while researchers simultaneously recorded brain activity using electroencephalography (EEG) and facial muscle activity using electromyography (EMG), allowing neural and behavioural responses to be assessed.

The results are reported in the article Two Weeks of Mirror Exposure Enhances Sensorimotor Cortex Activation but not Facial Mimicry in 4-Month-old Infants, published in the journal Developmental Science. When observing other infants’ facial actions, the infants in the mirror group demonstrated greater activation over sensorimotor regions involved in linking perception and action at post-test. This effect was particularly evident over the right hemisphere, in an area associated with face representation, suggesting that observing one’s own movements may strengthen neural circuits involved in perceiving others’ actions. However, no increase in facial mimicry, as measured by EMG, was observed. Although the neural processing of others’ facial actions was enhanced by sensorimotor experience, longer exposure may be required for this to translate into increased facial mimicry.

This study suggests that simple, everyday experiences, such as seeing one’s own reflection, can shape the social brain from a very early age. As Carina de Klerk notes, these findings "suggest that the neural mechanisms underlying social perception can be shaped by sensorimotor experience early in infancy, and may emerge before these changes are reflected in behaviour."

Learn more about the project “134/20 - Copy me, copy you: Investigating the development of facial mimicry” here.