Hyperthymesia is a word derived from Greek work hyperthymesis meaning excessive remembering. Hyperthymesia is unusual mental state or unique neurological condition in which person memorizes vast number of life experiences that happened in past. They even remember a small event happened in their life that a normal person can not memorize it. They have deep kind of memory as compared to a person having normal memory. This is often referred to as highly superior autobiographical memory HSAM. People with hyperthymesia are just like normal persons with only difference that they can recall even a minor events happened in their life as compared to person with normal memory.
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For this reason, the present chapter begins by reviewing the evidence for the diagnosis of autistic disorder in S using criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision DSM-IV-TR of the American Psychiatric Association [ 6 ] and from proposed criteria for its fifth edition [ 7 ], the chapter also compares his symptoms with those from a famous case DT with Asperger syndrome [ 8 , 9 ].
It is concluded that S most likely had autistic disorder. Next, I reviewed the literature to determine whether the assumption that a superior memory may be the cause of autism symptoms would be acceptable or not. Finally, an alternative explanation regarding the possible relationship between superior memories and autism spectrum disorders is given by the mnesic imbalance theory, which posits that a faulty procedural memory is replaced, in some of its functions, by a relatively preserved declarative memory, resulting in all three diagnostic symptoms of autism [ 12 ].
Autistic disorder is the most clinically representative of the ASDs [ 13 ]. However, there are several difficulties in implementing this strategy. First, since the biographical texts are not usually oriented to describe symptoms of psychiatric disorders, possibly such symptoms were not mentioned even though they had been present.
Second, some behaviors from historical figures have been considered autism symptoms [ 15 - 17 ], but this attitude has been questioned because of doubts regarding whether the socio-cultural context was taken into account [ 18 ]. Third, it is necessary to find the motivation behind behaviors in order to determine whether they are autism symptoms or not [ 19 ]. Fortunately, although the psychologist who wrote the psychobiographical text to be discussed in the present chapter did not specifically search for autism symptoms, he pointed out several of these symptoms in S.
This historical figure lived in the twentieth century, hence, his socio-cultural context was relatively similar to ours; the motivation behind behavior from S were examined in detail by the author of that text [ 1 ]. In addition, there are three major cognitive theories that attempt to explain autism: mentalizing deficit, that is, deficit to infer mental states [ 20 ]; weak central coherence, which is defined as disability to see the overall picture but with ability to see details [ 21 ]; and finally, executive dysfunction, which is the disturbed activity of the mental processes which control actions [ 22 ], although there is a newer version of the first of them called empathizing-systemizing theory which surmises that autism may be explained by a hyper-developed drive to analyze or construct systems systemizing with a hypo-developed drive to infer mental states and to react to them with appropriate emotions empathizing [ 23 ].
Thus, the presence of the cognitive deficits predicted by such theories may be considered motivations associated with autism. Finally, in the present work, the DSM-IV-TR diagnostic criteria will be mentioned in the order in which they appear in that manual diagnostic [ 6 ]; every area of the core triad of impairments social interaction, communicative capacity and behavioral flexibility is discussed in order to establish whether S had autistic disorder.
A total of six or more items from criterion A core triad are required for the diagnosis of autistic disorder, with at least two from subcriterion A1 social interaction , and one each from subcriteria A2 communicative capacity and A3 behavioral flexibility , while each of the three subcriteria contains four items [ 6 ].
On the other hand, S had impairment in the use of nonverbal behaviors to regulate social interaction item A1a. In this example, the impairment seems secondary to weak central coherence [ 21 ].
Besides, S had failure to develop peer relationships item A1b , which was manifested in various ways. For instance, he had a very good wife and a very intelligent son, but S perceived them as through a haze; also he had difficulties understanding why his fellow men wanted to have any job, which seems to be in accordance with hypo-developed empathizing [ 23 ]. It might be explained as a sort of self-consciousness disturbance through mentalizing deficit [ 24 ] but it might also be explained more directly as secondary to hypo-developed empathizing [ 23 ].
In conclusion, the data suggest that S met three of the four items from subcriterion A1, since, unfortunately, the psychobiographical text does not provide enough data to make inferences about item A1c: lack of shared enjoyment [ 1 , 6 , 14 ]. This difficulty with abstract thinking verbal along with a higher tendency to use visual mental representations seems most easily explained by the mnesic imbalance theory [ 12 ] than by the three major cognitive theories, but also such a cognitive profile has been extensively described by the thinking in pictures hypothesis [ 25 , 26 ].
Both theorical proposals will later be explained in detail. On the other hand, S also met item A2c stereotyped, repetitive or idiosyncratic language , since he at least utilized some words that can be described as neologisms for the ADI-R [ 14 ].
For example, S used the word zhuk Russian: beetle when he meant chipped part , black bread , darkness and negligence , whereas to him the word gis Yiddish: to spill assumed the meanings of sleeve and the reflection of a face in the polished surface of the samovar [ 1 ]. This is similar to the phrases bread basket instead of home bakery, fifty five instead of grandmother, Annette and Cecile in order to say red and blue, as well as the words Blum instead of a teller of truth and hexagon instead of six , all which were spoken by children described by Leo Kanner, who has always been considered as the first to clinically describe autistic disorder [ 3 , 27 ].
However, a recent communication has suggested instead that Hans Asperger could have done so five years earlier [ 28 ]. However, his pronominal reversal seems to be related to self-consciousness disturbance shown by individuals with ASD [ 24 ]. In summary, there is evidence that S met items A2b and A2c, that is, two of the four items from subcriterion A2, however, there are no data to establish whether S had a delay in spoken language with failure to compensate through gestures item A2a , not to say that he had a lack of varied and spontaneous social imitative or make-believe play item A2d [ 6 ], though S always had problems with his ability to distinguish between his visual mental representations and the true word [ 1 ]; it is difficult, if not impossible, to develop make-believe play without such an ability.
S had an encompassing preoccupation with an interest that was abnormal in intensity and focus item A3a , specifically, on very detailed and specific visual mental representations. Also, he did not admit that the words Mariya , Masha , Marusya and Mary Russian variants of the same name could all apply to the same woman because each word would elicit visual mental representations, which were very distinct one from the other [ 1 , 6 , 14 ].
Apparently he showed an inflexible adherence to nonfunctional routines item A3b. For example, if S had to remember the phrase American Indian , then he needed to see a very long rope across the ocean from a Russian street to America; these mental journeys were made by him despite the fact that they made him feel exhausted, not by the amount of data stored, but because S felt like he really had done those long journeys. Another time he was asked to memorize a table whose numbers were arranged in a simple logical order: 1 2 3 4 — 2 3 4 5 — 3 4 5 6 — 4 5 6 7 — etc.
Then S produced visual mental representations in which the number six could be represented by a man with a swollen foot and the number seven by a man with a mustache. Later S remarked that if he had been asked to memorize the letters of the alphabet arranged in a similar order, then he would have proceeded with it in the same way because he would not have noticed such an arrangement [ 1 ]. Thus, the first example may be explained by executive dysfunction [ 22 ], whereas the second may be explained by weak central coherence [ 21 ].
The latter example may be explained by the mnesic imbalance theory [ 12 , 29 ], which will be explained later. Besides, S had a persistent preoccupation with parts of objects item A3d [ 6 ]. For instance, although his synesthesia was present since childhood, even in adulthood he kept showing much preoccupation because of the sensory experiences resulting from it. Thus, even when S was talking with famous people, he would be so interested in their voices that he could not follow what they said [ 1 ].
It can be concluded that S met items A3a, A3b and A3d from subcriterion A3, however, there is insufficient information to determine whether S had stereotyped and repetitive motor mannerisms item A3c. On the other hand, the APA also proposes to stop using these diagnostic categories and use the name ASD as a single diagnostic category [ 7 ].
This supports the view that the PDD-NOS should not be considered ASD because its diagnosis does not require compliance with the complete diagnostic triad of autism [ 35 ]. At first glance, one can assume that it is quite feasible that if the proposed criteria require two symptoms instead of one on impairment in behavioral flexibility restricted, repetitive patterns of behavior, interests, or activities any individuals who actually have diagnosis of some ASD will not meet these new criteria; in addition, at present the criteria regarding the impairments in social interaction and communicative capacity are not require to be completely fulfilled.
Consequently, the question arises whether S can meet these new criteria just as he met the necessary items from criterion A for the diagnosis of autistic disorder. On the other hand, subdomain A2 nonverbal communication includes item A2a delay in spoken language since this is evaluated by a failure to compensate through gestures [ 14 ]. Besides, subdomain A3 deficits in relationships contains the item on social imitative or make-believe play A2d because of the importance of these behaviors in early relationships [ 6 ].
Furthermore, stereotyped, repetitive or idiosyncratic language item A2c is integrated into subdomain B1 Behavioral stereotypies and the verbal rituals are integrated into the apparently inflexible adherence to nonfunctional routines according to the ADI-R [ 14 ].
Finally, criterion B of the DSM-IV-TR which requires abnormal functioning in social interaction, communication or play is replaced by criterion C in the proposed DSM-V criteria which only requires symptoms in early childhood [ 6 , 7 ].
For instance, DT memorized and recited 22, digits of pi and has an extraordinary ability to learn to speak new languages [ 9 ]; similary S had the ability to memorize long chains of digits and reproduce several stanzas of The Divine Comedy fifteen years after having read it and despite not knowing Italian. However, both S and DT showed impaired face memory. Besides, with respect to synaesthesia, DT experiences numbers as having shapes, colour, textures, as well as some words with colour, while S also had synesthetic reactions whenever he heard tones, voices and speech sounds.
Such reactions were puffs of steam, splashes, colourful visual flashes, flavours and even bodily sensations [ 1 , 9 ]. How many handshakes are there all together? How many mushrooms does each have? In order to solve this problem S imagined himself with them husband and wife [ 1 ]. On the other hand, DT has also used mental imagery in order to better understand emotions.
There are some differences between the symptoms from DT and S. In other words, the neologisms from S were created through semantic or perceptual association, whereas those from DT were through morphological or syntactic analysis.
DT has also shown impairment to initiate or sustain conversational interchange and both DT and S recognized that they were verbose and that this affected the conversations with others. When Leo Kanner wrote his clinical description of autistic disorder, he pointed out excellent rote memory in children with the disorder and hinted that such an overload may be involved in the development of the disorder [ 3 ]. More recently it has been proposed that a mnesic imbalance may be the cause of all symptoms of autism, so the mnesic imbalance theory posits that all three diagnostic symptoms of autism may be explained by faulty procedural memory with relatively preserved declarative memory [ 12 , 29 ].
Procedural memory can be defined as behavioral algorithms that operate at an unconscious level and declarative explicit memory is information that is subject to conscious verbal reflection; whereas declarative memory includes episodic, semantic and working memory, procedural memory is only one of the various non-declarative implicit memories, such as priming, emotional conditioning and conditioned reflexes [ 36 ]. It is important to remember the latter because there are authors who may be referring to different types of memory although with the same term, for instance, procedural memory has been described as all implicit memory [ 37 ], whereas, other authors have pointed out that it is only a subtype [ 12 , 36 , 38 , 39 ].
In addition, a study in high functioning adults with ASD observed that memory for emotionally arousing events was preserved over time [ 40 ], and this preservation is particularly important for teaching new abilities to children with low functioning ASD [ 41 ].
The mnesic imbalance theory is supported by clinical studies that have shown bad procedural functioning [ 42 - 44 ], or good declarative functioning in individuals with ASD [ 45 , 46 ]. For instance, in a study utilizing the Serial Response Time Task SRTT with element sequences to evaluate procedural learning in children and adolescents with autistic disorder, the results showed significant deficit in their procedural learning relative to Intellectual Quotient IQ -matched controls [ 43 ].
In contrast, some studies have challenged this finding, but it is important to note that all of these later studies had not use the same aforementioned task but rather tasks with 4-element sequences or shorter, as well as other changes in the application of the tasks [ 47 - 49 ], while significant improvement has been found in this sort of tasks in individuals with autistic disorder when the sequence length is short [ 50 ].
On the other hand, this deficit in procedural learning of sequences might be related to the poor short-term declarative memory shown on serial recall tasks in adults with ASD during a study, because its experiments demonstrated that their poor performance was due to faulty memory for the order of the items rather than because of memory deficit for the items themselves [ 51 ]. Besides, a study utilizing a picture-naming task showed that boys with High Functioning Autism HFA responded faster than control boys on lower-frequency words; then, its authors argued that the results support the notion of enhancement in declarative memory of people with ASD [ 46 ].
In addition, such a model is in accordance with a meta-analysis which found that picture vocabulary tests are the peak of ability relative to verbal IQ in high functioning individuals with ASD [ 54 ].
Furthermore, a study utilizing a composite measure as an index of procedural learning showed significant negative correlation between procedural learning and autism symptoms [ 42 ]. Moreover, in another study, a composite group that included children with autistic disorder, both with non-functional verbal language and no spoken language, a significant positive correlation was observed between autism symptoms and scores of an index of declarative memory, which suggests that the imbalance between declarative and procedural memory in ASD might be more important than the mere faulty procedural memory [ 44 ]; such an imbalance might contribute to a global cognitive imbalance.
This assumption is in accordance with results from a study in children with autism, which showed that those with a lower verbal than nonverbal IQ profile showed greater social impairment than those without this profile; this result was independent of scores in verbal or full-scale IQ [ 55 ]. Nevertheless, the mnesic imbalance theory does not suggest that declarative memory has to be above average in individuals with ASD; indeed, an impairment of episodic memory is in accordance with this theory [ 12 ].
In addition, the mnesic imbalance theory suggests that although procedural learning is significantly lower relative to declarative learning in individuals with ASD, this procedural memory can be developed [ 12 , 50 ]. Anyway, in this theory the imbalance between procedural and declarative memory is needed to account for the impairments in social interaction, communicative capacity and behavioral flexibility, as well as for the islets of ability and neurobiological findings observed in people with ASD [ 12 , 56 ].
However, it is important note that there are several deficits in declarative memory in individuals with ASD, but such deficits might be explained by overlap in the functioning of the memories. For instance, S and DT showed impaired face memory [ 1 , 8 ], which might be due to the difficulty to verbally describe all elements that make each face unique; consequently, facial memory has to be implicitly acquired through perceptual categorization, which is a type of procedural learning [ 57 ].
It is likely that some individuals with ASD see face learning as a task that should be performed by conscious memorization of each element of the face, which might explain the lack of developmental improvement in face learning that has been observed in autism [ 58 ]. Besides, utilizing functional magnetic resonance imaging, a study measured the activation over time of the amygdala in adults with ASD and the results showed a delay in the decrease of amygdala activity relative to control adults, which could be an action to improve face learning, since the participants with ASD had a reduction in the number of errors during a second set of the task of facial memory [ 59 ], while another study reported an association between increased amygdala activation and better facial memory in healthy people [ 60 ].
Furthermore, in individuals with autistic disorder, a study showed deficit of their facial memory awareness, that is, when participants were asked to say how they thought their performance in the task was, the answers did not correspond to reality [ 61 ].
The faulty perceptual categorization might be enough to explain the significant preference in individuals with ASD for utilizing an approach oriented to process parts rather than the gestalt during the Rey Osterrieth Complex Figure ROCF task [ 62 ]; this situation is equivalent to an increased number of elements, which might explain the difficulty for any individual with ASD to memorize the ROCF despite their tendency to use visual mental representations [ 26 ].
But the above mentioned deficit in facial memory awareness cannot be explained only by poor perceptual categorization. Another study showed that, whereas in typically developing adults the memory of actions is significantly better if the actions are self-performed enacted than if only observed, in adults with Asperger syndrome is not the case Figure 1.
Consequently, if the latter explanation is used not only for motor actions but also for mental actions, then one might have an account for the deficit in facial memory awareness. Impaired procedural memory is not only unable to aid declarative memory, but that declarative memory also has to replace faulty procedural memory in some of its functions, which implies an overload for consciousness.
This assumption is in accordance with a study that showed that children with ASD, in comparison to the control group, had significant difficulty in divided attention ability to simultaneously perform two independent tasks , which was significantly related to everyday working memory [ 64 ].
The above findings are in accordance with a review of memory in ASD that pointed out a deficit in episodic memory, but are not in accordance to its assumption of preserved memory for non-social stimuli [ 65 ].
On the other hand, one must keep in mind that although there are deficits in encoding and organization of episodic and autobiographical memory in people with ASD, their storage and retrieval are preserved [ 66 , 67 ]. Mean of correctly recalled items of the Free Recall Task of actions Enacted and Observed in Asperger and Comparison groups: The bars represent means and the whiskers represent standard error From Zalla et al.
On the other hand, some authors have thought that S could have had an ASD [ 4 , 5 ]; it has been surmised that his astounding memory interfered with his comprehension of what he heard or read [ 5 , 68 ].
However, such an assumption might be inaccurate because his cognitive difficulties could be due to the ASD he suffered, not to his memory. So, the mnesic imbalance memory posits a higher tendency to use explicit visual mental representations in people with ASD to solve problems [ 12 ]. Similarly, a study of individuals with declarative memory deficits due to neurological damage showed that creating mental imagery of events from a personal perspective may improve episodic memory [ 69 ], therefore, people with ASD might try to improve their poor episodic memory through mental imagery.
In addition, another study found that mental imagery was effective at enhancing the task of relearning after brain injury [ 70 ], so mental imagery might be used against motor deficits secondary to faulty procedural memory [ 12 ]. Finally, other study reported that understanding expressions idioms is associated with more sophisticated and figurative mental images [ 71 ]; consequently, the creation of mental images in people with ASD might be a small successful attempt in order to understand abstract thinking as well as mental states of others, for example, mentalizing deficit in children with autistic disorder was initially tested using the unexpected transfer test of false belief [ 20 ], but both typically developing 3 year olds and children with autism significantly improve on that test when they use thought bubbles, that is, visual representations of mental states [ 72 , 73 ].
In view of this scenario, it is possible that neither his astounding memory nor his encompassing preoccupation for very detailed and specific visual mental representations were the cause of the cognitive problems of S, but rather some other factor might be the cause of these three features in S and such a factor might be the mnesic imbalance since procedural memory seems to be required for the development of analogical inference, which is a sort of reasoning performed primarily through unconscious algorithms that might be at the heart of abstract thinking and verbal comprehension [ 74 - 76 ].
Hyperthymestic Syndrome: Extraordinary Memory for Daily Life Events
There are a number of forms of extraordinary memory. There is factual memory: Kim Peek has memorized over books. There is numeric memory: Daniel Tammet memorized Pi to 22, digits. There is eidetic-like, photographic memory: Stephen Wiltshire memorized Rome from the air after a minute helicopter ride over the city. But extraordinary memory is not limited to savants.
Data Protection Choices
Do you remember what you had for dinner two years ago today? What about two weeks ago? But a small number of people, including a California woman named Jill Price, can remember such events in great detail. They have a condition called hyperthymesia syndrome. This is often referred to as highly superior autobiographical memory HSAM. In extensive testing, she demonstrated the ability to recall details of events that happened on specific days, spanning decades of her life.
Hyperthymesia is a condition that leads people to be able to remember an abnormally large number of their life experiences in vivid detail. American neurobiologists Elizabeth Parker, Larry Cahill, and James McGaugh identified two defining characteristics of hyperthymesia: spending an excessive amount of time thinking about one's past, and displaying an extraordinary ability to recall specific events from one's past. Individuals with hyperthymesia can extensively recall the events of their lives, as well as public events that hold some personal significance to them. Those affected describe their memories as uncontrollable associations; when they encounter a date, they "see" a vivid depiction of that day in their heads without hesitation or conscious effort.
Hyperthymesia (hyperthymestic syndrome)
Researchers at UC Irvine have identified the first known case of a new memory syndrome — a woman with the ability to perfectly and instantly recall details of her past. Her case is the first of its kind to be recorded and chronicled in scientific literature and could open new avenues of research in the study of learning and memory. Given a date, AJ can recall with astonishing accuracy what she was doing on that date and what day of the week it fell on. AJ first wrote McGaugh with the details of her extraordinary ability in According to McGaugh, her case is different from others who have been studied in the past with superior memory.