The clearing out of our personal history

How forgetting erases our memories and sharpens them at the same time

It is a common misconception that having a good memory equals remembering as much as possible. If you ever have frantically scoured your mind's storehouse for a misplaced key or a forgotten name, you can't help but consider oblivion a sign of mental degradation. But forgetting is also a productive force that filters personal  experiences and confers drama to our individual historic epic..

In all cultures there have been attempts to imagine forgetting figuratively. As "Lethe", as a stream of oblivion, it was painted among  the ancient Greeks. Strictly analytically, Hermann Ebbinghaus, the godfather of  memory research, demonstrated in the 19th century that within 30 minutes, half of all newly learned information units bite the dust. Luckily, the forgetting curve named after Ebbinghaus,  later flattens significantly.

As a study by US psychologist Michael Anderson proves, the data that "stick" always seem insufficient. His subjects documented the frequency of words, ideas or phone numbers book that had lapsed. Then they were asked to evaluate how much time these holes in their memory cost them. Conclusion: On average, we waste 40 days per year on recovering forgotten facts. People with a "sieve" in their head tip the scales at at least 60 days.

Psychologists have systematically examined  in recent years which factors determine the durability of the "memory trace". All impressions that are not repeated, which are not linked to other impressions and have no emotional significance naturally fade very quickly. Often, the supposedly "forgotten" stands out by its absence because it was never even laid down: If you can not remember your breakfast, your brain probably from the outset omitted to produce a "backup" of the experience.

In other cases, memories are unattainable because the appropriate "key" for their retrieval is missing. After a trip to the supermarket , the psychologist Michael Anderson was simply  unable to recollect in which parking area his car stood. Only after a long search, his mind "clicked": He hadn't arrived with his own vehicle but parked the car of his neighbor. The false association with his own automobile had blocked the reconstruction. Memory contents can be retrieved best when the appropriate context of the original storage is reinstated. That is underscored by the work of psychologist Alan Badeley from the University of Bristol, who had some of his subjects memorize learning material underwater, wearing wetsuits. These participants were later able to recollect much more of the input when tested again in this unusual environment.

Many "forgotten" facts are not really destroyed  but compressed to their essentials by an intelligent fusion process. People don't remember every lunch from their childhood; you just know how much you liked fish and chips- and that  you were always quarreling with siblings while eating. Barry Gordon, director of the Memory Clinic at Johns Hopkins University in Baltimore, compares our memory with the popular MP3 music files: All data that are not absolutely necessary for the listening pleasure are wiped away by with this form of compression.

According to psychologist Neil Macrae from Bristol, every successful act of recollection requires the hiding of irrelevant "resonances". If you want to remember where you parked today, you will have to decommission all the echoes of countless former parking operations in your head. The same goes for your latest password on your computer. Otherwise, any search ends in a chaos of nullities. This is partly a question of storage economics, emphasizes US neuroscientist James Olds: "We only work so well because we forget so efficiently." If we consistently kept  every detail, the limited space of our brains would cause  us problems. "The clear key is undoubtedly one of the main keys of the computer, and "Forget it!"belongs to the greatest achievements of our culture," Munich literary scholar Harald Weinrich draws parallels to other areas of life.

Barry Gordon even believes that only the "sacrifice" of remembrance of details allows creative thinking. "If too many details come up, one can no longer perceive a pattern." It is therefore the absence of a photographic reproduction that lends our mind the gift of "fuzzy logic, which makes creative mental leaps possible. Many memory artists with outstanding memory performance "stick" to concrete details and complain that they never get an original thought. One of them, Solomon Shereshevsky, could at any time recall the numbers 2345, 3456, 4567 and 5678 - without ever noticing the underlying schema.

Mental Health also presumes that we are not tortured by a meticulous recording of trivialities when we look back on our lives. That not every pain overwhelms us with the sum of all previously experienced aches. That we make our very own "movie", cobbled together from the remembered, the forgotten and the invented. At the very end, everyone is left with a curiously cut collage of their earthly existence, "a string of shining moments", as  Oscar Wilde so beautifully put it .

Total Recall - The curse of remembrance

If forgetting is mostly helpful, then it is to be expected that a superior memory might sometimes have detrimental effects on information processing, Simon Nørby from the Danish School of Education at Aarhus University explains in an enlightening new research review. Indeed, among others, Jill Price (also known  as “AJ”) a middle-aged woman who is dominated by her memory, is a case to the point. 

What makes her extraordinary is her ability to remember an immense amount of autobiographical  information without attempting to do so. Whenever AJ recollects a personal  memory,  it cues the retrieval of another  related memory in an unstoppable cascade. This quote demonstrates how AJ suffers from her unusual abilities; according to her, recall “is non-stop, uncontrollable and totally exhausting. . . . Most have called it a gift but I call it a burden. I run my entire life through my head every day and it drives me crazy”

AJ is one among several individuals with highly superior autobiographical memory (HSAM).  All such individuals, says Nørby, remember, personally significant information exceptionally well but typically perform on average on standard laboratory tests of memory. Moreover, individuals with HSAM exhibit an atypical high level of obsessive behavior that seems tied to  their mnemonic abilities. "For example, they often organize their memories chronologically  or  feel an urge to write them  down. " 

The case of AJ is intriguing, because it demonstrates how remembering too much may be  problematic  and also how a superior memory is not necessarily associated with excelling in other areas of life: "Similarly, in other investigations of individuals with HSAM, researchers  have made no mention of above-average performances in the educational system or the work domain."

The man without qualities

It seems almost unthinkable that a person could lose the memory of themselves. But Adrian Mills, a then 30-year-old Corporal of the British Army of the Rhine in Bielefeld, was robbed  of his "autobiographical memory", the memory of his own identity, by a ghastly incident. The first 29 years of his existence are gone; everything he felt and experienced lies hidden, swallowed by a rare "retrograde amnesia". Mills can no longer look back at his school year, his first love or the years of his professional activity. He has forgotten how grief, affection and anger feel like. The stories about their common past his wife tells to him are the stories of strangers. 

The recently deceased neurologist Oliver Sacks, who became famous through his insightful case descriptions, once called patient such as  Mills "lost souls". "Mnestic blockade" is the name of the bizarre state of consciousness, in which "autobiographical memory" gives up the ghost, while other aspects of memory are still working. Thus, "semantic memory" further provides factual knowledge ("Rome is the capital of Italy").

Why Forget? On the Adaptive Value of Memory Loss

http://pps.sagepub.com/content/10/5/551.abstract
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