Attention and Memory Control in Nonclinical Dissociators

Dissociation is defined as disruption in ordinary integrated functions. In addition to the pathological dissociation in patients with dissociative disorders, some dissociative experiences are prevalent in general population. The tendency to dissociate in daily activities has been suggested as a trait-like proneness which is featured by distinctive information processing styles. It has been suggested that these cognitive styles may increase ones’ vulnerabilities to develop certain psychiatric disorders after stressful events. To fully understand how the information processing styles may underlie the cognitive functions of dissociation, researchers have adopted various paradigms in their investigation. However, two functions have not been examined and they may link to the symptoms that characterize clinical patients’ behaviors. The goal of this thesis is twofold. The first objective is to translate a standardized instrument which is designed to measure trait dissociation and examine its construct validity in Chinese culture. The second objective is to investigate the attention and memory control operations of individuals with high dissociation proneness. Three independent studies were conducted. The first study focused on the factor structure of the Dissociative Experiences Scale as this issue is currently under debate and has significant impacts on the integration of theoretical viewpoints on dissociation. Both the exploratory (EFA) and confirmatory factor analyses (CFA) were conducted in a large-scale college sample. A three-factor solution was first derived form the EFA and then verified with the CFA results via model comparison. The three-factor solution is the fittest model for the DES. The second study focused on nonclinical dissociators’ attentional control functions. A set switching paradigm was used to examine dissociators’ switching function under negative emotion. The results showed that high dissociators under negative emotion were faster in disengaging attention from a previous set and diverting their attention to a new set. High dissociators did not differ from low dissociators in their basic function of focused attention or set-switching in the baseline condition where emotion was not aroused. In the third study, a retrieval practice paradigm was adopted to examine dissociators’ selective retrieval function in memory control. Previous studies using this paradigm have shown retrieval-induced-forgetting (RIF) when participants need to selectively retrieve a particular category exemplar in the practice phase. Memory of the distractor exemplar was worse than the memory of unpracticed categorical exemplars. The results showed that the RIF effect was eliminated in high dissociators. The results suggest two possibilities. The first one is the capacity hypothesis that has been proposed to explain better working memory ability of dissociators. With enhanced capacity, dissociators are better in attentional control when in negative emotion and they do not need to inhibit task-irrelevant information in memory control. The second hypothesis is that the mental representations of dissociators may be fragmented so that they are experienced in switching between representations when necessary and do not need to inhibit task-irrelevant information in memory control. Future research should investigate which hypothesis holds true for dissociators and uncover how the control mechanisms interact with mental representations in different task contexts.