Interpersonal consequences of diminished emotional expressiveness in schizophrenia:an investigation of facial expressions within face-to-face interactions
Background: This dissertation aimed at identifying possible behavioral mechanisms that contribute to the social isolation of people with schizophrenia apart from stigmatization and social withdrawal. People with schizophrenia have been consistently found to show diminished affiliative behavior, particularly concerning positive facial expressions. This thesis therefore investigated facial expressiveness and facial mimicry of people with and without schizophrenia to test whether diminished affiliative facial expressiveness associated with schizophrenia leads to rejection by interaction partners. Method: Facial expressions were captured via electromyography (EMG) at two muscle sites (Zygomaticus Major for smiling, Corrugator Supercilii for frowning) throughout dyadic face-to-face interactions. A novel method for the quantification of emotional facial mimicry in face-to-face interactions was developed and validated. EMG estimates of smiling, mimicry of smiles, and frowning exhibited by participants were used to predict the social evaluation of the interaction partner after a face-to-face interaction. The influence of facial affect recognition on emotional facial mimicry was additionally tested. Results: Emotional facial mimicry could be reliably quantified for the Zygomaticus (smiling) but not for the Corrugator (frowning). In people with schizophrenia, smiling behavior explained about 71% of the variance in the interaction partner’s social evaluation after the interactions. In patients, the relationship with smiling behavior was less pronounced and non-significant, while expressive negative symptoms were a good predictor. Facial affect recognition, predicted mimicry of smiles only in healthy controls. Conclusion: People with schizophrenia suffer from an empathic deficit that leads to social rejection by their interaction partners. Diminished smiling behavior in affiliative interactions is a viable proxy for this empathic deficit, which likely stretches to other nonverbal channels as well.