Categorization of Emotional Facial Expressions in Humans with a History of Non-suicidal Self-injury
Abstract
In social animals, such as humans, accurate emotion expression categorization is important for appropriate social functioning. Inaccuracy in emotion categorization can lead to inadequate social behavior, commonly seen in various psychiatric disorders. Non-suicidal self-injury (NSSI) is a psychiatric symptom involving deliberate self-inflicted injury of one’s body, without intent to die. NSSI has been regarded as a dysfunctional coping strategy for managing intensely difficult feelings. Difficulties in social interactions have been reported by individuals who engage in NSSI, which may be related to their emotion categorization performance. Participants (17-25 yrs) with a history of NSSI and healthy controls viewed videos of faces changing over 10 s from neutral to a prototypical expression of sadness, disgust, surprise, fear, anger or happiness. They were instructed to stop each video as soon as they felt they recognized the emotion presented, thus indicating the minimum intensity of expression needed for categorization. They were then asked to categorize the expression. Minimum facial expression intensity, accuracy of categorization, and reaction time were the behavioral dependent variables of interest. NSSI participants showed significant advantages compared to controls in their ability to categorize negative emotion expressions, specifically fear, anger, disgust, and sadness. They also were able to recognize the ambiguous emotion of surprise at a lower stimulus intensity. To date, treatments for NSSI have high drop-out rates. Results from this research could be used to inform further development of therapies for the alleviation or prevention of NSSI.