The effects of repetitive traumatic experiences on emotion recognition, facial mimicry and autonomic regulation

The present dissertation focuses on the influence of childhood experiences on social development. We aim to chart how the dynamic interplay of biological, social, and emotional influences shapes developmental trajectories. Specifically, we investigated the influence of childhood protracted conditions of maltreatment and neglect on the explicit recognition of facial expressions of emotions, along with, Facial Mimicry and vagal regulation in response to facial expressions of emotions - as physiological measures of humans' empathic resonance and self-regulation in social context, respectively. In four successive experiments, Sierra Leonean street-children and street-boys, exposed to high and protracted conditions of maltreatment and neglect, were compared to age-matched controls. In the first three experiments we revealed, both in children and adolescents, a significant influence of childhood maltreatment and neglect on explicit recognition of facial expressions of emotions, on Facial Mimicry and on vagal regulation. Trauma exposure induced a response bias for angry facial expressions recognition both in street-boys and street-children populations. Street-boys were also characterized for a significant suppression of overall Facial Mimicry responses, as well as, for a reduced and incoherent vagal regulation in response to facial expressions of emotions. Differently, street-children showed alterations of lower entities. Hence, instead of a general Facial Mimicry suppression, they presented an impaired Facial Mimicry modulation between positive and negative facial expressions of emotions. Moreover, street-children manifested an earlier development of the functional synchronization between vagal regulation and threatening stimuli in external environment with respect to age-matched controls. These different patterns of results showed by street-boys and street-children, suggested a possible and differentiated additive effect of trauma exposure. This last point was specifically addressed in the last experiment in which we evaluated the impact trajectories of prolonged experiences of maltreatment and neglect on the explicit recognition of facial expressions of emotion, Facial Mimicry and vagal regulation. We demonstrated that prolonged conditions of maltreatment and neglect not progressively influence the explicit recognition of facial expressions of emotions which appeared independent from the duration of trauma exposure. Moreover, we demonstrated that protracted trauma exposure induces specific alterations in Facial Mimicry and vagal regulation to others' facial expressions of emotions, which follow different impact trajectories. Longer trauma exposure accentuated an incoherent Facial Mimicry and a lower vagal regulation, particularly in response to angry facial expression of emotions. Differently, a compensatory vagal recruitment during the first years of trauma exposure was found, giving important suggestions about temporal windows in which rehabilitative interventions can likely contrast the occurrence of chronic outcomes. In conclusion, the present dissertation provides new and further evidence of the influence of childhood experiences on social development by confirming and better described the huge impact of prolonged experiences of maltreatment and neglect on the understanding of emotions, empathic resonance, and self-regulation in social contexts. It clearly appears that if, as Aristotle wrote, †œMan is by nature a social animal†� and, as recent neuroscientific evidence suggested the human mind is ontogenetically interpersonal and wired to be social, the early traumatic experiences negatively influence physiological mechanisms supporting our social nature.