Face processing in schizophrenia: an investigation of configural processing and the relationship with facial emotion processing and neurocognition

Abstract

Cognitive impairment is a key characteristic of schizophrenia and is a clear predictor of functional outcome. This thesis explores the relationship between cognitive ability relating to social and non-social processing. Schizophrenia patients demonstrate an impaired ability to recognise, label and discriminate emotional expression within the face. The underlying mechanisms behind this social cognitive impairment are not yet fully understood. This thesis explores the notion that a basic perceptual impairment in processing facial information adversely impacts on the perception of more complex information derived from faces, such as emotional expression. Face perception relies on processing the featural characteristics of a face as well as the relationship between these features. Information pertaining to the spatial distances between features is referred to as configural information.

A group of schizophrenia patients and healthy control participants completed a battery of tasks that assessed basic neurocognition, facial emotion processing and configural face processing. A model of face processing was proposed and used to systematically pinpoint specific deficits that may contribute to impaired face processing in schizophrenia. The results indicated that schizophrenia patients show impairments on three broad constructs; basic neurocognition, facial emotion processing, and most pertinently, deficits in configural processing. It was revealed that although neurocognitive and face processing both explained a significant proportion of the variance in facial emotion processing, the effect of neurocognition was indirect and mediated by face processing.

To investigate the diagnostic specificity of these findings, a group of bipolar disorder patients was also tested on the task battery. The results indicated that bipolar disorder patients also show social and non-social cognitive impairments, however, not as severe as that demonstrated by the schizophrenia patients. Furthermore, the effect of neurocognitive performance on facial emotion processing appeared more direct for bipolar disorder patients compared to schizophrenia patients. Although deficits in face processing were observable in bipolar, they were not specific to configural processing. Thus, deficits in emotion processing were more associated to neurocognitive ability in bipolar disorder patients, and more associated to configural face processing in schizophrenia patients. The configural processing deficits in schizophrenia are discussed as a lower-order perception problem. In conclusion, the results of this thesis are discussed in terms of their implication for treatment.