Reacciones musculares faciales ante imágenes con diferente contenido social. Un índice fisiológico de empatía afectiva

Abstract

Empathy has two components, the affective and the cognitive component. Affective empathy is the ability to emotionally tune into the emotions that other people experience. Its measurement has been done, traditionally, through self-report measures, however, there are some studies in Latin American population that have used physiological measures of affective empathy. Additionally, it has been hypothesized that people exposed to violent graphic content (e.g., armed conflict) may be desensitized to this type of stimulus. In this context, the objective of the present study was to evaluate the activity of the zygomatic and corrugator muscles to pictures with different social content, in order to establish the validity of these physiological measures as objective indicators of affective empathy. The electromyographic activity of these facial muscles was recorded in 60 subjects (30 with high affective empathy and 30 with low affective empathy), while observing pictures with positive, neutral and negative social content of the International Affective Picture System (IAPS). The results showed that the participants with high affective empathy responded with greater zygomatic muscle activity to positive social pictures ( F 2,96 = 5.93, p = .01, η p 2 = .11) and with greater corrugator muscle activity to negative social pictures ( F 2,96 = 4.85, p = .02, η p 2 = .09), in comparison with participants with low affective empathy. The correlation and regression analyzes show a positive and significant relationship between the scores in the empathic concern scale of the Interpersonal Reactivity Index (IRI) and the activity of the zygomatic muscle to positive social pictures (β = .39, R 2 = .15, t = 3.00, p = .004), and the corrugator muscle activity to negative social pictures (β = .27, R 2 = .07, t = 1.99, p = .05). The results suggest that the electromyographic activity of the facial muscles is an objective indicator of affective empathy. The increase in the activity of the zygomatic and corrugator muscles in people with high affective empathy, when they observe stimuli with different social content, can be supported by the mirror neuron system and the theory of simulation as an explanatory mechanism of empathy. The mirror neuron system is composed of a complex network of visual areas in the occipital, parietal and temporal regions and two predominantly motor regions, which interact to generate movements similar to those observed, in this case the facial expressions of the stimuli. This response in facial mimicry induces affective states similar to those observed, which leads to a response of affective empathy. Finally, the results of the present study do not support the hypothesis of a desensitization in the participants to negative social stimuli due to the fact of being Colombian, because independently of the level of affective empathy, all of them responded with greater activity of the corrugator muscle to negative social pictures in comparison with neutral and positive pictures. However, as shown in the results, this response was significantly higher in participants with high affective empathy. This result cannot be generalized to the entire Colombian population, given the small size of the sample and its origin. Overall, the results suggest that responses of the zygomatic and corrugator muscles to stimuli with different social content are reliable indicators of affective empathy, and can be used as physiological markers of this kind of empathy in neuroscience and psychophysiology research. No evidence of desensitization was found toward aversive social stimuli in this sample.