Непроизвольные воспоминания: триггеры и механизмы

Memory triggered by an environmental cue
Involuntary memory, also known as involuntary explicit memory, involuntary conscious memory, involuntary aware memory, madeleine moment, mind pops and most commonly, involuntary autobiographical memory, is a sub component of memory that occurs when cues encountered in everyday life evoke recollections of the past without conscious effort. Voluntary memory, its opposite, is characterized by a deliberate effort to recall the past.

There appear to be at least three different contexts within which involuntary memory arises, as described by J. H. Mace in his book Involuntary Memory. These include those that occur in everyday life, those that occur during the processes of voluntary and involuntary recall, and those that occur as part of a psychiatric syndrome.

The most common kind of these phenomena has been termed "precious fragments." This type includes involuntary memories as they arise in everyday mental functioning, which are characterized by their element of surprise: they appear to come into conscious awareness spontaneously. They are the products of common every day experiences such as eating a piece of cake, bringing to mind a past experience evoked by the taste. Research suggests that such experiences are especially strong and frequent in relation to one's sense of smell. The term "precious fragments" was coined by Marigold Linton, a pioneer in the study of autobiographical memory research. This is reflected, for example, in Proust's experience of remembering, upon dunking a madeleine cake in his tea in adulthood, a memory from childhood that occurred while eating madeleine dunked in tea. According to Mace, this suggests that autobiographical memories are organized primarily conceptually (“experiential type concepts: people, places, locations, activities, etc.”), while temporal associations are not retained over time the same way. However, one study also shows that recurrent involuntary memories post trauma can be explained with the general mechanisms of autobiographical memory, and tend to not come up in a fixed, unchangeable form. Thus, one report hypothesizes that dementia patients may still have available precious autobiographical memories that remain inaccessible until “suitable triggers release them,” prodding at the possibility for caregivers to be trained to reactivate these memories to elicit positive emotional effects and maintain patients’ life stories and sense of identity. He goes on to explain that these mental states were once experienced, rendering, by definition, their future spontaneous appearance into consciousness the act of remembering, though we may not always be aware of where or how we experienced this information the first time. Ebbinghaus also made the key note that these involuntary reproductions are not random or accidental; instead, "they are brought about through the instrumentality of other immediately present mental images," under the laws of association. This is distinct from involuntary memory, where individuals do not consciously retrieve memories that will be most helpful to their current situation; however, it remains unclear if this process is unconsciously undertaken by the brain. When dealing with involuntary word recognition tasks, activity in areas such as the left inferior frontal gyrus, left superior temporal gyrus, left hippocampus, and right superior occipital cortex have all been implicated.

While age plays a role in memory capabilities, it has been found that general strategies used to encode (to remember) memories is more important. Those that are better at memorizing information are more likely to have more involuntary memories. In younger children (ages 10 and under), it has also been found that inducing involuntary memory during testing produced significantly better results than using voluntary memory. This can be accomplished by posing a vague, mildly related question or sentence prior to the actual test question. In older children (aged 14 and above), the opposite holds, with strictly voluntary memory leading to better test results.

The reminiscence bump is the phenomenon where in memories formed during adolescence and early adulthood are more commonly remembered than those throughout other periods in life. This is due to the formation of self identity or the development of cognitive abilities across the lifespan. It has been found that this is true for both voluntary and involuntary memories. Age has been found to have a difference on the amount of memories recalled, but no age differences were found in the specificity of involuntary memories.

Emotion plays a strong role in relation to memory. It has been found that memories associated with stronger emotions (e. g.: being happy at your wedding) are more easily remembered and quickly recalled, as are those formed during moments of intense stress. The same holds true for involuntary memories, with happy involuntary memories occurring twice as often as unhappy or neutral involuntary memories.

Often people who have been the victims of some type of trauma describe vivid memories that intrude on their thoughts spontaneously and without warning. Such mental intrusions, if maintained over time compose the hallmark symptom of posttraumatic stress disorder (PTSD). The DSM IV defines a trauma as an event in which someone experiences, or witnesses' severe injury to themselves or others or a threat to their integrity. The person must also have responded with fear, helplessness or horror at the time of the trauma. The main psychological consequences of this include re experiencing the traumatic event (through both intrusive thoughts and images), avoidance of trauma related stimuli, and increased arousal levels. When it comes to involuntary memory, researchers are mainly interested in the concept of these trauma related intrusions, which generally involved some form of re experiencing the event, including a sensory component (e. g., imagery in any modality be it visual, auditory etc.). These intrusions, often termed "flashbacks", make the victim feel as though they are reliving the trauma, and cause high levels of emotional arousal, and the sense of an impending threat. Typically, they are parts of the traumatic event that were most salient at the time, known as "hotspots" and have the definitive feature that they cause high levels of emotional distress, and may be difficult to recall deliberately. Although this is a defining feature of PTSD, intrusive memories are also frequently encountered in anxiety based disorders, psychotic disorders and even within the general population. bipolar disorder, depression, and agoraphobia, are a few examples of disorders that have influences from flashbacks. Psychosis is defined as a range of perceptual presentations, with the associated symptoms frequently referred to as either positive or negative. Positive symptoms are delusional, and may include hallucinations, while negative symptoms are characterized by a "lack" of functioning, which may include a lack of affect (emotional feeling) and loss of motivation. However, only a small percentage had been diagnosed with PTSD when displaying PTSD like symptoms. Therefore, the more complex symptoms of psychosis may prevent the clinical detection required when diagnosing PTSD. In addition, those who have been diagnosed with PTSD and have an identified form of trauma show positive symptoms of psychosis such as delusions and/or hallucinations. Finally, it has been suggested that individuals suffering from psychosis may be more vulnerable to intrusions.