Involuntary episodic memories are memories of events that come to mind spontaneously, that is, with no preceding retrieval attempts. They are common in daily life and observed in a range of clinical disorders in the form of negative, intrusive recollections or flashbacks. However, little is known about their underlying mechanisms. Here we report a series of experiments in which-for the first time-the activation of involuntary memories is controlled and predicted on the basis of manipulations done at encoding. During encoding, participants were presented with pictures of scenes paired with sounds. Both scene and sound could be either unique (derived from a category that was presented only once) or repeated (derived from a category that was presented several times). During retrieval, the participants conducted an attention-demanding sound location task employing sounds from the encoding phase. In addition to the sound location task, they were asked to record all memories that might spontaneously arise during this task. Unique sounds generated most involuntary memories, consistent with the notion of cue overload. Repeated sounds rarely generated involuntary memories, but often yielded memories of repeated scenes in a voluntary (strategic) recall condition. Retrieval times were lower for involuntary than for comparable samples of strategically retrieved memories, suggesting less executive control involved in involuntary recall. Our findings show that it is possible to control the activation of involuntary episodic memories of daily scenes on the basis of well-known mechanisms of associative memory. (PsycINFO Database Record (c) 2012 APA, all rights reserved).
"In addition to encoding large amounts of external information, humans engage in frequent ‘internally-generated’ activities such as recalling their past and imagining their future, both of which are associated with the episodic memory system –. Frequently, memories of the past and imaginations about the future are triggered by external cues in our environment, especially by sensory impressions . Marcel Proust  provides the most famous example of externally cued retrieval, describing how the taste of a madeleine cake dipped in a cup of tea led to an overwhelming deluge of memories from his childhood (p53). "
[Show abstract][Hide abstract] ABSTRACT: New episodic memories are retained better if learning is followed by a few minutes of wakeful rest than by the encoding of novel external information. Novel encoding is said to interfere with the consolidation of recently acquired episodic memories. Here we report four experiments in which we examined whether autobiographical thinking, i.e. an 'internal' memory activity, also interferes with episodic memory consolidation. Participants were presented with three wordlists consisting of common nouns; one list was followed by wakeful rest, one by novel picture encoding and one by autobiographical retrieval/future imagination, cued by concrete sounds. Both novel encoding and autobiographical retrieval/future imagination lowered wordlist retention significantly. Follow-up experiments demonstrated that the interference by our cued autobiographical retrieval/future imagination delay condition could not be accounted for by the sound cues alone or by executive retrieval processes. Moreover, our results demonstrated evidence of a temporal gradient of interference across experiments. Thus, we propose that rich autobiographical retrieval/future imagination hampers the consolidation of recently acquired episodic memories and that such interference is particularly likely in the presence of external concrete cues.
PLoS ONE 04/2014; 9(4):e93915. DOI:10.1371/journal.pone.0093915 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The topic of cognitive foresight in non-human animals has received considerable attention in the last decade. The main questions concern whether the animals can prepare for upcoming situations which are, to various degrees, contextually or sensorially detached from the situation in which the preparations are made. Studies on great apes have focused on tool-related tasks, e.g., the ability to select a tool which is functional only in the future. Dufour and Sterck (2008), however, investigated whether chimpanzees were also able to prepare for a future exchange with a human: an object exchanged for a food item. The study included extensive training on the exchangeable item, which is traditionally not compatible with methods for studying planning abilities, as associative learning cannot be precluded. Nevertheless, despite this training, the chimpanzees could not solve the deferred exchange task. Given that great apes can plan for tool use, these results are puzzling. In addition, claims that great ape foresight is highly limited has been based on this study (Suddendorf and Corballis, 2010). Here we partly replicated Dufour and Sterck's study to discern whether temporally deferred and spatially displaced exchange tasks are beyond the capabilities of great apes. In addition to chimpanzees we tested orangutans. One condition followed the one used by Dufour and Sterck, in which the exchange items, functional only in the future, are placed at a location that freely allows for selections by the subjects. In order to test the possibility that the choice set-up could explain the negative results in Dufour and Sterck's study, our second condition followed a method used in the planning study by Osvath and Osvath (2008), where the subjects make a forced one-item-choice from a tray. We found that it is within the capabilities of chimpanzees and orangutans to perform deferred exchange in both conditions.
Frontiers in Psychology 10/2013; 4:698. DOI:10.3389/fpsyg.2013.00698 · 2.80 Impact Factor
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