Amnesia and emotional arousal

Abstract: The purpose of the present thesis was twofold. First, to study the role of emotional arousal in memory processes, and secondly, to relate this concept to empirical findings of amnesia. In both clinical and experimental settings it has been observed that remembering is impaired for events occurring prior to, and after a traumatic critical event. This memory impairment is also demonstrated for the traumatic event per se. In relation to these phenomena an interaction is commonly observed such that remembering of events aquired in a state of high emotionality, or arousal, is inferior to events aquired in neutral low arousal conditions at short test intervals, but superior at delayed test intervals. The general notion to be tested was how and to what extent these phenomena are mediated by an increase in emotional arousal. In order to test this hypothesis a series of experiments was designed so that retrograde and anterograde amnesia, and amnesia for the traumatic event, could be studied so as to evaluate the locus of the emotional arousal and amnesia effects with respect to encoding (attention), storage (consolidation), and retrieval (reconstruction). Emotional arousal was induced by sources associated with the to-be-remembered (TBR) material (traumatic pictures), and by sources not associated with the TBR-material (injections of adrenalin). Memory performance was measured by recall and recognition techniques. Amnesia was obtained only when the source of arousal was associated with the TBR-items. It was concluded that amnesia in connection to hightened emotional arousal depends on attention demanding characteristics of the traumatic event, rather than physiological properties of hightened arousal per se. An interaction between factors at encoding and retrieval was proposed as an explanation for the amnesia effects obtained. An interpretation in terms of consolidation has, throughout this thesis, been shown to be invalid in explaining the memory phenomena referred to.