In their now "classic paper, Brown and Kulik (1977) reported that 79 of 80 US citizens remembered vividly the circumstances in which they had first heard about the assassination of President John F. Kennedy, 14 years earlier. The fact that this type of "recall involves mental illumination of a specific scene explains the flashbulb "metaphor. Since then, recollections of additional salient events, such as the Challenger disaster (McCloskey et al. 1988; Neisser and Harsch 1992), have been used to analyse further the flashbulb memory phenomenon. The basic observation that unexpected momentous events, public or personal, do tend to generate an apparently exceptional memory of the circumstances in which they were encountered, is clearly supported by both experimental research and common experience. Some important issues, however, remain unsettled. Among them: Are flashbulb memories faithful? And are the biological mechanisms that subserve such memories unique?
Accounts of flashbulb memory are characterized by lucid, vivid, and detailed recollections. But already at the outset of the investigation of flashbulb memory it became evident that these memories do not preserve all the details of the original scene (Brown and Kulik 1977). In addition, several studies have indicated that the reported details are not necessarily accurate to begin with, and furthermore, could change with time (McCloskey et al. 1988; Neisser and Harsch 1992). A methodological problem, invoked in response to claims that flashbulb memories are unreliable, is that personal consequentially and emotional significance are not easy to quantify and compare. Even though some signal public events are expected to generate flashbulb memories, in reality they do so in some "subjects but not in others (Conway 1995). The test protocol that is used to identify flashbulb memory could also itself influence the outcome, i.e., whether the recollection will be accurate or not (Koriat and Goldsmith 1996); "collective memory "cues and demand characteristic effects ("bias) may certainly colour the response. Such complications notwithstanding, it does appear that the fidelity of flashbulb memory, similarly to the fidelity of other "episodic recollections, must be treated with caution ("false memory).
Are flashbulb memories unique in their robustness and vividness? Some authors propose that this type of memory is not qualitatively different from other types of emotional memory (Christianson 1992; "fear conditioning). Others claim that flashbulb memories do comprise a distinct class of traces (Conway 1995). One type of suggestions is that the encoding of information during the "acquisition of the flashbulb memory is unique (Brown and Kulik 1977), in that it involves a particularly intense activation of specific brain circuits (e.g. "limbic system; Livingston 1967). This leads to the 'printing' of a highly detailed and robust "internal representation of the association of the salient event with the "context. Other types of explanations propose that there is nothing special about the encoding of flashbulb memory, but that this type of memory is special only because the intense emotional valence of the original event causes the information to be assigned extra importance over time, or be "retrieved extensively, resulting in a more robust, although not necessarily more faithful, memory (Neisser and Harsch 1992).
In recent years, brain research has unveiled clues to the biological mechanisms that encode the memory of intensely emotional and consequential events. These candidate mechanisms deal with two "levels of brain organization: the circuit level and the cellular level. The circuit mechanisms are assumed to involve subcortical modulation of the "cerebral cortex, which causes certain sensory events to be "perceived as highly salient because of the concomitant activation ("coincidence detection) of neuromodulatory systems such as the "acetylcholine and the "noradrenaline systems (Naor and Dudai 1996; McGaugh and Cahill 1997; Tang et al. 1997). This hypothesis is a neurobiological version of the 'unique acquisition' accounts mentioned above (Brown and Kulik 1977). The cellular explanations are based on the assumption that the consolidation of long-term memory is triggered by a certain configuration of transcription factors ("CREB, "immediate early genes, "spaced training). This configuration acts as a molecular switch that induces a wave of activation or de-repression of gene expression at the modulated "synapses, culminating in the remodelling of the network connections and in the stabilization of the memory (Bartsch et al. 1995). The idea is that those momentary events that give rise to a flashbulb memory, induce the right configuration of the transcription factors very rapidly—in a few seconds or a few minutes instead of several hours. If this is true, it implies that the kinetics of memory "consolidation is not fixed, but rather depends on the conditions of training (Frey and Morris 1997; Dudai and Morris 2000). It also suggests that a robust long-term memory trace can be induced by 'instant consolidation', without necessarily going through a labile short-term "phase. By the way, the notion that long-term memory can be established in the absence of short-term memory is in line with evidence from other "systems (e.g. Emptage and Carew 1993).
Whatever the mechanisms of flashbulb memory are, they should also explain why is it that intense emotional experiences lead to remarkable memories in some cases, but to obliteration of memory or repression of its retrieval in others (Loftus and Kaufman 1992).
Selected associations: Attention, Collective memory, Consolidation, Context, Surprise
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Have you ever been envious of people who seem to have no end of clever ideas, who are able to think quickly in any situation, or who seem to have flawless memories? Could it be that they're just born smarter or quicker than the rest of us? Or are there some secrets that they might know that we don't?