title: ERP and behavioural evidence for direct suppression of unwanted memories.
abstract: There are some past experiences that we would prefer not to remember. Previous research has shown that repeatedly stopping retrieval of an unwanted memory increases the probability of later forgetting of that memory, and engages prefrontal control mechanisms to attenuate activity in the hippocampus. However, the mechanisms of preventing memory retrieval, and how these relate to the later forgetting, are yet to be fully understood. Here we present neural and behavioural evidence that two distinct strategies for retrieval stopping - direct memory suppression and self-distracting thought substitution - contribute to forgetting of unwanted memories in qualitatively different ways. Only direct memory suppression reduced centro-parietal positivity in the event-related potentials (ERP) between 300 and 600 ms post-stimulus, consistent with a reduction in the ERP correlate of recollection. Furthermore, only direct memory suppression produced later inhibitory forgetting that was predicted by an earlier negative ERP effect that may be associated with motor inhibition. In contrast, thought substitution produced later non-inhibitory forgetting and had no effect on the ERP correlate of recollection. Our findings demonstrate the first ERP and behavioural dissociation between inhibitory and non-inhibitory forgetting, and suggest that unwanted memories may be directly suppressed without selective retrieval of alternative memories.
authors: Memory and Consciousness Research Group, Department of Neurology and Centre for Advanced Imaging, Faculty of Medicine, Otto von Guericke University of Magdeburg, Germany. zara.bergstroem@med.ovgu.de
authors: Zara M
authors: ZM
authors: Bergström
authors: Jan W
authors: JW
authors: de Fockert
authors: Alan
authors: A
authors: Richardson-Klavehn
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D009483:Neuropsychological Tests; D012094:Repression, Psychology; D013997:Time Factors; D055815:Young Adult