The body helps us read emotions

Recognising other people’s facial expressions is essential for quickly understanding their emotional state, anticipating their reactions and tuning in to them. While some expressions are clear and unambiguous, others are subtle and ambiguous, and it is precisely these that represent a challenge for our brain.

A study coordinated by Paola Sessa of the Department of Developmental Psychology and Socialisation of the University of Padua in collaboration with Pier Francesco Ferrari of the University of Parma and published in «PNAS» under the title “Facial palsy reveals the sensorimotor contribution to facial-emotion recognition”, clarifies the role of the body in recognising other people’s emotions. The research shows that «our body participates silently every time a face becomes difficult to read».

For decades, cognitive neuroscience has grappled with two main hypotheses. 
According to the first, the brain recognises emotions mainly through visual analysis, comparing observed faces with patterns already stored in memory. According to the second, however, the motor systems used to produce facial expressions are also involved: it would be as though we internally simulate, in an “invisible” way, the movements of other people’s faces.

To test the contribution of the motor systems, the researchers involved people with congenital facial paralysis, as in Moebius syndrome, and people who had acquired paralysis during their lifetime. The comparison between the two groups made it possible to distinguish the role of facial movement from that of motor experience accumulated over time.

The participants watched short videos featuring two types of emotional expression: some very clear and easy to recognise, others more subtle and ambiguous. Their task was to identify the emotion expressed. In parallel, a specialised physiotherapist measured how much capacity for facial movement remained in the people with paralysis, without knowing the participants’ other information, that is, “blind”.

The results showed that, when expressions were ambiguous, the possibility of moving one’s own face helped people to recognise the observed emotion more accurately: in both groups, the greater the residual facial mobility, the greater the accuracy in recognition. This indicates that, when faced with unclear signals, the brain also relies on the face’s sensorimotor systems, that is, on the mechanisms linked to facial movements and sensations.

The most important difference, however, emerged with clear expressions. In people who had developed paralysis in adulthood, the ability to recognise them no longer depended on how much they were able to move their face. According to the researchers, this is because before paralysis these people had had many years of experience with facial expressions and had therefore built up a sort of visual “archive” of emotions, sufficient to recognise the more evident expressions even without the help of facial movement.

In people with Moebius syndrome, by contrast, paralysed from birth, the ability to recognise emotions continued to be linked to facial mobility even when expressions were clear. This suggests that the experience of moving one’s own face in the first years of life contributes to building the mental “archive” of expressions. Once formed through visual and motor experience, this repertoire can become, at least for the more evident emotions, more independent of facial movement.

This account reveals how facial movement is especially useful when the expression is ambiguous, while motor experience developed in the early years helps to build a stable repertoire for recognising even the clearest emotions.

The study therefore moves beyond the opposition between visual theory and sensorimotor theory, showing that the two systems collaborate to different degrees depending on the difficulty of the expression and the experience acquired over the course of development.

«Understanding what another person is feeling is not a spectator activity», emphasises Paola Sessa: the body comes into play above all «when a face becomes difficult to read». Even in healthy volunteers, in fact, temporarily limiting facial movements made it more difficult to recognise ambiguous expressions. The research thus opens up new questions about the possible role of facial rehabilitation in understanding emotions and about the importance of face-to-face interactions in the first months of life.

Pier Francesco Ferrari concludes that «that between faces is a conversation between bodies, even before it is between eyes», underlining how the result was born from the meeting of neuroscience, psychology, clinical practice and physiotherapy.

The research was supported by Fondazione Cariparo and is the result of the work of the Facial Expression, Embodiment & Emotion Lab of the University of Padua and of a multidisciplinary group of researchers and specialists.