Identification of facial expressions by epileptic and non-neurological subjects

• Main Author: Wishart, H. (Heather Ann)
• Other Authors: Memorial University of Newfoundland. Dept. of Psychology
• Format: Thesis
• Language: English
• Published: 1988
• Subjects: Face perception; Epileptics; Newfoundland studies; University of Newfoundland
• Online Access: http://collections.mun.ca/cdm/ref/collection/theses2/id/47073

Thesis (M.Sc.)--Memorial University of Newfoundland, 1988. Psychology Bibliography: leaves 114-122. The first goal of this thesis was to determine whether previous findings regarding facial expression processing among non-neurological subjects could be replicated with a modified experimental set-up. The second goal was to determine if there were any difficulties on the task unique to epileptics, subgroups of epileptics, or chronically ill patients. -- Epileptics, chronic illness control subjects (diabetics) and non-patient control subjects identified facial expressions, and their accuracy and latency were measured. Expressions were presented for 150 ms to one visual hemifield at a time. The presentation format was designed to detect the subjects style of processing, that is whether or not they processed the emotional expressions independently of the non-emotional facial characteristics. Subjects were tested following both neutral instructions and instructions intended to provoke anxiety. -- Previous related findings with non-neurological subjects were replicated in part with the present experimental set-up. A tendency toward a right hemisphere (left visual field) superiority emerged independently of potential interacting factors such as expression valence, subject gender and group. The expressions, in order of decreasing accuracy, were surprised, happy, sad and fearful. In order of increasing latency they were happy, surprised and sad. It was impossible to analyse latency data for fearful expressions. Non-neurological subjects appeared to use both independent and dependent styles of processing the expression with respect to the face dimension. -- There were not enough epileptics with well-defined foci to form subgroups based on lateralization and nature of the focus. Thus epileptics were subclassified according to seizure type (complex partial versus primary generalized) and according to whether they scored like a comparison group of psychiatric patients (PSY) or of non-psychiatric subjects (NonPSY) on the Personal Behavior Inventory. Groups differed in age and years of education so the effect of these variables was removed using analysis of covariance. No abnormalities in hemispheric asymmetry, accuracy, latency or style (e.g. independence versus dependence) of expression identification could be attributed to epileptics, epileptic subgroups or chronically ill people. However the groups appeared to react differently to the anxiety induction. Non-patients, diabetics and NonPSY epileptics maintained or improved their accuracy of identifying happy expressions, whereas PSY epileptics' accuracy decreased. No differences between seizure type subgroups emerged. Thus it may be more useful to group epileptics according to Personal Behavior Inventory scores than according to seizure type when trying to isolate those vulnerable to the effects of anxiety on the processing of facial affect information.