The curious case of Hyperthymesia
Abstract
This paper discusses a mystery named Hyperthymesia (also known as HSAM) that, since its discovery in the early twenty-first century, has troubled psychologists and neuroscientists alike. It starts by presenting the first documented case of Hyperthymesia—that of AJ—and how it baffled the then researchers as they found it was way different from another case of superior memory. It presents the works of prominent researchers in this field and how they came up with potential ideas to help explain this curious business. Ultimately, it tries to take something from three different pieces of research to explain what causes Hyperthymesia.
Keywords:- Hyperthymesia, HSAM, Amygdala, Eidetikers, Superior memory, Autobiographical memory, Episodic memory, Semantic memory, Post-traumatic stress disorder (PTSD)
The Curious Case of Hyperthymesia
“There’s rosemary, that’s for remembrance; pray, love and remember” (Shakespeare, n.d., Hamlet, Act 4, Scene 5, lines 174-175)
I wonder if Shakespeare was aware of the concept of Hyperthymesia, although certainly not by that name which was coined a few centuries after his lifetime, when he penned that line about remembrance; since many with Hyperthymesia or HSAM, including AJ who was the very first person documented to have this condition, put this ability of theirs as more of a burden than a gift; a burden to live with past-traumas, to get blasted with uncontrollable fits of remembrance. But I shall leave it there as what Shakespeare likely considered while commenting on remembrance is somewhat outside our present purview, and instead elaborate HSAM based on the early research done and try to find a convincing answer to the many questions put forward by this phenomenon.
In the field of Psychology, there have been many complications and confusion trying to figure out the ways our brains deal with Memory. The many sections of memory, namely encoding, storage and retrieval, the many types of memory, namely sensory, short-term and long-term memory, implicit and explicit memory, episodic and semantic memory et cetera have been discussed and researched by many prominent researchers and further assisted by neurologists. However, it appears that even after years of thinking and evaluation, there remains a significant portion of it that we do not yet understand and/or are still scratching the surface of. One such less-understood and much-hypothesized aspect of memory is Hyperthymesia, also known as HSAM or Highly Superior Auto-biographical Memory. People with this extremely rare condition or disease or blessing or superpower have been diagnosed in very recent times and thus the research surrounding this is at its early stages and no prominent researchers seem to have arrived at a definite conclusion as to why those with Hyperthymesia seem to remember and recall the way they do—which is often very different than an average individual. That being said, these people exhibit a very strong autobiographical memory, calling to mind anything that has ever happened to them after a certain age. The way they recall crystal clear details of what they did a decade or so ago has perplexed us, regarding such things as how their mind encodes, stores and retrieves all that data with exceptional precision and consistency.
AJ- The first documented case of Hyperthymesia
In their seminal paper, Parker and his colleagues presented the very special case of AJ and introduced the term Hyperthymesia (Parker et al.). According to their report ‘A case of unusual autobiographical remembering’, the researchers revealed the exceptional and at times bewildering memory of Aj. AJ could remember, at ease, almost anything that happened to her from the age of 8 and everything from the age of 14 onwards, and according to the subject herself, the recollections were too vivid and detailed not to be compared to a video recording and her life, at times, like that of a split screen, in which on one side she would interact with the world at present and on the other side watching moments from her past play out in great detail. AJ seemed to remember historical events as clearly and accurately as personal events, but only if the event were of interest to her at the time and if it had impacted her personal life or not; which makes it apparent that for AJ, the episodic memories were much stronger and significant, to an extent that even the semantic memories—related to facts, dates and occurrences not directly relate to one's personal life—became exceptionally strong only when entwined with her personal life in some way or another. Furthermore, her case was very unlike people having a merely superior memory owing to the following reasons:
Unlike those with superior memory, AJ had never made use of memory encoding strategies and retrieval techniques to boost her memory abilities; instead, her memory seemed innate and stemmed somewhere from within her.
Whereas those with a superior memory can learn and apply such skills in a highly controllable manner for their benefit, her memory seemed uncontrollable as although she could easily recall her life events in vivid detail and even semantic details like dates(consistent with her calendar of events) very accurately, she failed to remember certain details regarding the attires of the interviewers just from the previous month or so, making it clear to us that she was not a so-called memorizer. As semantic memory is widely distinguished from episodic memory by psychologists, her remembering of dates may lead to suspicions about whether her ability to remember was wholly innate or not; AJ, however, did not seem to call to mind the many dates beyond her memory span with much accuracy and when the researchers asked her how she remembered those dates withing her memory span she answered that she just knew it. This again makes the case strong for the claim that her abilities were innate and that even her semantic memory was much influenced by her episodic memory.
Unlike superior memory individuals, AJ was not “capable of encoding and reciting prodigious amounts of new information using practised pneumonic strategies”( E.S. Parker et al. 2006). This reflects on her fairly average school and college grades and her own words when inquired about her school life: "I'm not a genius".
Lastly, the most pivotal distinction between AJ and people having a superior memory was that she primarily excelled at her autobiographical memory; something no other person just having a superior memory has shown signs of. Such people, unlike AJ, excelled at mostly factual information and not those related to their life events.
Having shown that AJ was not to be considered merely another person with superior memory, but one with a very unique autobiographical memory, it would be wise to review some hypotheses and theories that have tried to explain the case of AJ or the people with HSAM.
Literature Review
We can try to explain Hyperthymesia with the process of Eidetic memory, popularly termed Photographic memory. After all, people with HSAM remember their lives in vivid detail and seem to accurately describe scenes from a fairly monotonous day a few decades back; and that does seem somewhat similar to what those with eidetic memory do. Specifically, when shown a picture for some time, they can retain the visual sensation of that picture even after the picture is removed from their sight, similar to how people like AJ remember life events that had taken place many years ago. However, if we consider the research on this phenomenon of Eidetikers—that is what we call those with eidetic memory--, it becomes clear that Eidetic memory is just not what we must be looking for. The points in which Hyperthymesia are different from eidetic memory are as follows:-
Hyperthymesia is way more long-term than eidetic memory, which lasts " about half a minute to several minutes only" (Searleman, 2007, para. 2).
Hyperthymesia inculcates the strongest memories from adolescence onwards, whereas Eidetic memory mostly concerns children, with some researchers like Enrol Giray even arguing that what we call Eidetic memory is nothing but the immature version memory (Giray et al., 1977), which corrects itself as the child grows up; such researches are further corroborated by the statistically higher percentage of Eidetikers found among such children as having psychological disabilities that may originate from brain injuries.
Hyperthymesia has infamously haunted those suffering from it as they fail to forget any bad or depressing memory that they may have. It seems not to be in their control to erase certain unpleasant memories from their vault of autobiographical memory. On the other hand, Eidetikers can reportedly forget the eidetic image with a single blink of an eye.
Another very exciting notion, though currently considered redundant for a lack of proper scientific corroboration to back it up, was proposed by Dr Wilder Penfield. Penfield, in his research, supported the notion of there being a functionality of our brain that closely takes after a video recorder. He pinpointed the Parietotemporal cortex of our brain's right hemisphere as being the storage hub, quite similar to a memory card, of literally all our visual memories or past experiences. He went on to suggest that the Hippocampus region of the brain must act like the key to that very inclusive storage capacity of ours, also implying that if we did not have this Hippocampus which seems to deny us access to all our memories, it would be a pretty straightforward activity to access that brilliant storage we got. We could have said that the access to this storage capacity was exceptionally strong among those with HSAM, making them easily access the Parietotemporal region to recall all their life events in vivid detail. However, as mentioned earlier, this notion of secret storage is widely considered redundant these days, thanks to such researchers like Milner, Squire, Kandel, Tulving etc mostly contradicting Penfield on the one key aspect—, that memory was stored in a particular region of our brain—thus undermining his research.
Brandon A Ally and co have pointed out a further interesting aspect of our brains that may influence the way we deal with people who have Hyperthymesia (Ally et al., 2013). In research conducted on a blind person with Hyperthymesia, HK, these researchers did/tried to open up two new aspects of this condition. Firstly, since the subject in question was blind, it proved that seeing and visualising the experiences was not a must among people with HSAM; secondly, these researchers gave the lion’s share of the credit for HK’s highly superior autobiographical memory to a certain region in the brain called the Amygdala. This region, according to them, was responsible for adding an element of “emotional, social and self-relevance” (Ally et al., 2013, p. 166) to our autobiographical memories. Here we can easily see why they focussed on a region with the particular quality of injecting our episodic memories with aspects of emotion; by taking into account the significant impact emotions can have on memory. Far from being two different elements altogether, emotions impact our memories. The extreme case of this interrelation would be people who suffer from PTSD or shell-shock, as they may not remember the details of the battleground but tend to very hauntingly remember such sensory perceptions as the smell of gunpowder, the sound of machine guns firing, the sight of blood and gore etc. Besides we observe that many of the people of the USA recall exactly what they had been doing when 9/11 happened. These memories are often dwelt upon more than memories devoid of any special emotion, and the constant rehearsal plays a part in storing the memory, for easy retrieval late on. Emotions thus impact the encoding, storage and retrieval of our emotional memories, and the region that acts as charging our memories with emotion must be crucial in storing the memories. To get back to the researchers, they found out that HK's amygdala region was considerably larger in terms of volume than people with normal autobiographical memory. Furthermore, the amygdala region of HK had more connectivity with those regions of the brain responsible for the encoding retrieval of memory. Thus, to our satisfaction, the Amygdala does show the prospect of being credited with part of the reason for Hyperthymesia. That said, further research with more subjects is still pending to definitively accredit the Amygdala with this curious case of highly superior autobiographical memory.
Memory activation to explain Hyperthymesia
When we try to remember a certain event from our memory, our brains need to conduct a delicate process to get at the particular memory we were looking for. This process of getting at the already encoded and stored memory is termed retrieval and this retrieval process works in two different ways—either by conducting a rigorous search process to detect the specific memory we are looking for from apparently a gargantuan lot of memories, or by conducting faster but slightly more complicated and prone-to-interference while at the same time quicker process of search activation. In general, both these processes are initiated by a retrieval cue, which is like a small hint to what we are looking for and examination questions (not the MCQs as they can easily cloud our retrieval by forcing us to choose one of the two or more given options) which helps our brain somewhat know what kind of thing to look for. After receiving the cue, the brain performs one of the two processes mentioned to locate the memory. The former process involves our brains just going through memories at random unless we find the one particular memory we were looking for—it is like searching for a particular book in a gigantic library or locating a certain novel utterance in a thick book. The latter process does the searching too, but in a more structured and efficient way, thus potentially saving a lot of effort by co-ordinating the search process. The search activation process works given that all our memories are connected as if like a complex cobweb, meaning when the retrieval cue activates a memory, that memory, in turn, activates another connected memory, and so on to arrive at the desired memory in what can be called a top-down approach; making sure that a memory of something like psychological research does not activate a memory of watching a dinosaur run (unless these are somehow connected in someone’s memory). Though this processes is subject to such issues as one retrieval cue leading to two different memories due to some error in encoding the two memories, or the addition of a memory to that very cue aimed at replacing the former cue but ending up as two different memories from a single cue—such a situation arises often when a friend gets a new contact number and ends his previous number, we try to replace our memory of the old number with that of the new one, but our brain ends up attaching both the numbers to the same cue (the friend), leading to trouble—it helps us explain the state of those people with HSAM, by suggesting that these people have much stronger connection among their many autobiographical memories than an average person does, thus easily traversing the way through the web of memories from the centre (the retrieval cue) to the edges; further explaining their claims how to them one memory seems to elicit another and so on until they have recalled everything their whole life in detail.
Discussion
Why connections among their memories are exceptionally stronger takes me back to the possible role of the Amygdala as hypothesized by Brandon A Ally (Ally et al., 2013) and how emotion plays a significant part in encoding memory. These three aspects together start to make some sense about how those with Hyperthymesia remember so much. To combine the ideas,
1. Emotions greatly influence the way our memories are encoded.
2. The person with Hyperthymesia has an amygdala larger in terms of volume than that of normal people, and Amygdala emotionally charges our memories.
3. Exceptional connections among their memories are made, making it easy for them to call things in the distant past to mind, as those strong connections facilitate the seamless activation of one memory from the other.
That being said, a lot of further research remains to be done, especially regarding the prevalence of a larger Amygdala in people with Hyperthymesia, the role of the amygdala itself, and the solidity of the claim that our memories are connected to make chains of memories.
Conclusion
In the text, I have distinguished Hyperthymesia from other memory conditions like eidetic memory and superior memory; I further presented a short account of the literature having been conducted in this field; and proposed a theory to connect the few ideas to explain why people with HSAM remember the way they do. However, with only about 56 documented cases so far around the world, HSAM continues to be an extremely rare condition, making the research scarce and time-consuming. As a result, directly getting enough data from people having the condition is a hard criterion to meet, and the situation demands that all relevant psychological research and neuroscientific outcomes be taken into consideration to fully understand Hyperthymesia. Going into further research, the existing theories—that of the amygdala fusing our memories with emotion, resulting in very strong connections among the many memories, subsequently making them call to mind all those distant memories by an unhindered chain of activation aided by those strong connections that had been formed.
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