2024-02-02 08:22:52
by Ruggiero Corcella
This is according to a study published in «Emotion» which involved a group of participants suffering from Möebius syndrome, a rare pathology which causes congenital paralysis of the facial muscles. What is the mechanism of sensorimotor simulation
Facial recognition is a fascinating and controversial field. Just think of the indiscriminate use as a means of mass control that is being made thanks to Artificial Intelligence, as Kate Crawford explains in depth in the book «Neither intelligent, nor artificial. The dark side of AI” (Ed. Il Mulino, and published by Ed. Solferino in the Artificial Intelligence Series). Yet, no AI is able (so far) to replicate what is innate in humans: we are experts at perceiving faces and able to extract emotional meaning from faces in a matter of a few hundred milliseconds, even unconsciously.
Now an Italian study published in the journal Emotion sheds light on the cognitive and neural mechanisms that translate the visual experience of others’ facial expressions into the perception of others’ emotions. The result? When we observe someone’s face, we better understand the intensity of the emotion felt if we can “wear” their facial expression on our face, even if this is reproduced in an imperceptible and completely unconscious way.
The mechanism of sensorimotor simulation
The study led by Professor Paola Sessa (funded by the CARIPARO Foundation for Scientific Research of Excellence), was conducted by Arianna Schiano Lomoriello, both from the Department of Developmental and Socialization Psychology and the Padova Neuroscience Center of the University of Padua, in collaboration with Professor Pier Francesco Ferrari, director of the Marc Jeannerod Institute of Cognitive Sciences in Lyon and professor at the University of Parma. «Several experimental evidence supports the idea that human beings understand the emotions of others in a precise way thanks to a mechanism known as “sensomotor simulation”, through which the observer recreates, at a peripheral level, and reactivates, at a neural, the sensorial and motor experience of another person on oneself, albeit unconsciously – explains Professor Sessa of the Department of Developmental and Social Psychology, University of Padua and of the Padua Neuroscience Center (PNC), of the same university – .
“In other words, through this process an observer’s brain internally simulates the sensations and movements associated with the experiences of the person being observed. This project aimed to delve deeper into the role of this mechanism in understanding emotions. In particular, we examined the impact of congenital facial paralysis, a condition that prevents both the use of specific facial muscles and the activation of neural circuits linked to the production of a particular facial expression, on the perception and understanding of emotions. The objective of the research was, therefore, to clarify the impact of congenital facial paralysis on the way of experiencing and interpreting the emotions of others, and more generally, to clarify the role of facial expressions in understanding others”, adds the professor Sessa.
The results of the study
The study involved a group of participants suffering from Möebius syndrome, (the world day of which was celebrated on 24 January) a rare clinical condition which causes a congenital paralysis of the facial muscles, preventing the expression of emotions, as a consequence of a malformation or agenesis (i.e. a lack) of the 6th and 7th cranial nerves, responsible for strabismus and facial amymia. The study involved eleven participants affected by Möebius syndrome (who are part of the Italian Möebius Syndrome Association) paired with a group of individuals without paralysis, in a highly sensitive task with the aim of evaluating the emotional intensity of facial expressions at different value.
The research highlights how participants suffering from Moebius syndrome, compared to the control group, perceive the intensity of primary emotions (sadness, fear, anger and disgust) as less intense. Furthermore, these emotions seem to be confused more with anger and surprise, indicating that the mental representation of emotions is partially different in people with the syndrome. Overall, these findings suggest that the congenital absence of the facial mimicry mechanism affects individual sensitivity to basic emotional expressions, also reducing the ability to distinguish between different emotions.
The previous study
This research is not the first that has involved this team of researchers on this topic; in fact, during 2022 they also conducted another study (published in Philosophical Transactions of the Royal Society B) which involved the same type of participants, using the high-density electroencephalography technique which allows recording electrical activity generated during the execution of an ad hoc task. The results of this study show different neural activation between the two groups. In particular, during the processing of faces with different facial expressions, an alternative neural circuit is activated in Möebius patients compared to the one classically recruited in participants without paralysis.
This alternative path is known to be less specialized in the analysis of movement – a central aspect in the analysis of facial expressions – but more involved in the analysis of the static characteristics of a face, therefore suggesting the existence of a compensation mechanism that allows individuals suffering from congenital paralysis to obtain performances (almost) similar to those of a control group and therefore to explain, at least in part, the adequate social skills of these individuals.
Rehabilitation treatments and future prospects
Furthermore, this aspect has opened the way to the idea of exploiting spontaneous mechanisms of brain plasticity for the development of rehabilitation treatments. «This knowledge can contribute to the development of targeted interventions to improve the ability of people with facial paralysis to decipher, understand and interact effectively with the emotions of others – underlines Dr. Schiano Lomoriello -. We therefore hope that these results can open new avenues for supporting patients with Moebius syndrome.” The research group is currently involved in a study in collaboration with the University of Parma and Marta Nichele, a physiotherapist tasked with conducting a functional assessment of the facial muscles and documenting the extent of facial paralysis.
The objective is to investigate the origin of compensatory mechanisms, comparing the performance and brain activation of individuals with non-congenital and transient paralysis with those of individuals with congenital paralysis. In this way, it will be possible to evaluate the impact of facial paralysis on the processing of facial expressions in individuals in whom compensation mechanisms have not been activated (at least in the same way). The aim of the project is to set up rehabilitation treatments that take into account this natural propensity of the brain to take over basic functions necessary by traveling along secondary roads.
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February 2, 2024 (modified February 2, 2024 | 09:19)
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