Electrophysiological correlates of anticipation and emotional memory

Abstract

This thesis investigated the role of anticipation as a mediating factor in the Emotion-Enhanced Memory (EEM) phenomenon. Using behavioural and ERP measures, three anticipatory conditions were explored: Informative, No-Cue and Non-Informative. The primary objective was to determine how far the pre-stimulus-Dm (Ps-Dm) effect is a reliable indicator of emotional memory encoding under different levels of anticipation, and if the preparatory process explanation accounts for any effects. This study also aimed to determine if there is an association between anticipatory activity at the pre- and post- stimulus phase, and the related behavioural outcome. One behavioural and three ERP studies were conducted to measure the difference due to memory (Dm) effect during an anticipatory phase. The Dm effect distinguishes between neural activity of subsequently remembered and forgotten items, providing an index of successful encoding. We employed an S1-S2 (Stimulus 1: Cues - Stimulus 2: Pictures) Cueing-Subsequent Memory Paradigm. Upper case letters (O, X, Z) served as cue stimuli (S1). Emotional and neutral images selected from International Affective Picture System (IAPS) were used as S2. Findings revealed a Dm effect for informative as well as for non-informative cue conditions when participants anticipated high-arousal emotionally negative pictures. This effect was found during the 400-600ms time window only when the cue remained on the screen. This effect was not significant for the studies in which the arousal level of anticipated negative pictures was mixed. Moreover, the behavioral findings mirrored the neural activity in this particular study. However, in rest of the studies, behavioral results could not corroborate neural activity. The results of the present set of experiments highlighted that emotional memory might be formed without specific information about the content or valence of imminent pictures.