Limitless Recollection: The Phenomenon of Highly Superior Autobiographical Memory

Anoushka Bhatt

Illustrations by Anna Bishop

The Woman Who Never Forgets

We are highly dependent on our memories: they shape our understanding of the past, guide our present decisions, and influence our future aspirations [1]. Yet, our memories are notoriously imperfect. It’s easy for us to forget things, like that essay you have been meaning to finish for weeks, or the name of the person you were just introduced to. Therefore, it may seem ideal to be able to remember everything. Think back to your first day of school. Do you remember what you ate for breakfast that day? Or the clothes that you wore? Or what day of the week it was? Jill Price, known from her case study as ‘the woman who never forgets,’ involuntarily remembers each of these minute details with incredible clarity [2]. When provided with a date, Jill could specify what day of the week the date fell on and what she did that day — not due to rote memorization, but because of her exceptional ability to recall her past with remarkable detail and accuracy [2]. Jill is different from most people who have a ‘good memory,’ as she does not rely on techniques like mnemonics or repeated practice to remember information [2]. For Jill, remembering is automatic. Jill has a highly superior autobiographical memory (HSAM), in which innumerable details from the last week, the last year, and even the past few decades of her life indelibly stick in her mind [1]. After HSAM was initially discovered via Jill’s experiences, around 60 additional individuals with this extraordinary ability have been identified, and further exploration into HSAM’s causes has revealed interesting characteristics of the phenomenon [3]. A consideration of the typical memory processing pathways may result in a more comprehensive understanding of the mechanisms of HSAM.

Congratulations, Class of 2024!

Think back to your most memorable birthday, your worst day of middle school, or your high school graduation. These events are all autobiographical memories, recollections of your personal experiences that contain knowledge of the self and personal identity [4, 5]. Autobiographical memories are a type of explicit memory, which require conscious effort to recall [6, 7, 8]. Autobiographical memories are composed of episodic and semantic memories [6, 7]. Episodic memory refers to specific moments of life and includes qualitative details such as when, where, and how an event occurred [9, 10]. Recall the example of your high school graduation. Episodic memories of that day might include how hot it felt to sit in a black gown as the sun blazed down, or the moment you looked at your best friend as the class threw their caps into the air. Semantic memories, on the other hand, are made up of general factual and conceptual knowledge, including facts, rules, concepts, and associations [11, 12, 13]. For instance, you might remember your class size or be able to identify the notes playing from the piano on stage during the graduation march. Episodic and semantic memory work together to organize and connect your experiences in order to create rich autobiographical memories [14, 15].

What Did He Call Me?

To solidify your life experiences into autobiographical memories, the brain uses a process called encoding [16, 17]. Returning to your high school graduation, when it’s finally time to get your diploma, you hear your principal mispronounce your name. The sound associated with the mispronunciation is then processed in your working memory. While information is held in your working memory, it is in a temporary, malleable state. In the same way you edit files, memories can be changed before they reach the ‘filing cabinet’ in your brain [18, 19]. You are stunned, thinking, ‘what did he call me?’ As your attention shifts, your recollection of the mispronunciation reaches your hippocampus — an area of your brain that plays a large role in storing memories — where it is ‘filed’ alongside other associated memories [20, 21]. The sole memory of receiving your diploma when you graduated may bring to mind several other memories in which you experienced similar feelings of excitement, jittery anticipation, or even the anxiety of holding something fragile or important in your hand. Memories are not just linked linearly [22]. Rather, they comprise complex networks in which multiple memories are connected to one another. Each memory is linked to others through different concepts, events, or any other associations that connect them [22]. When the memory is ‘filed,’ a physical change in the brain — known as a memory trace — is formed, allowing the memory to be later accessed [22, 23].

Latte for Who?

Months later, when a barista mispronounces your name in a coffee shop, the memory file of your principal’s similar offense is retrieved by your hippocampus and temporarily returned to your working memory [24, 25]. ​​Memory retrieval is the activation of a memory trace in response to internal or external cues, thereby triggering the recollection of the memory [22, 26]. Memories may be retrieved through the use of conscious effort, while alternatively, an external cue can trigger memory retrieval spontaneously [26]. In the case of the barista, your feeling of annoyance spontaneously triggers the retrieval of the memory of the absurd way your principal pronounced your name. Each time you recall a memory, you reconstruct the original event, reassembling it from memory traces stored throughout the brain [26]. In the same way, you reassemble the memory of your principal’s pronunciation [27]. On the day of your graduation, your principal’s wording may have been only slightly off. Nonetheless, in your current recollection, his wording becomes exaggerated, morphing into a complete butchering of your name. Your original memory may be molded and reconstructed many times through repeated recollections of your experience [28, 29]. However, not every encoded memory is retrievable. Often, our memories fade and disappear [30]. One proposed explanation for the fading of memories is the trace and decay theory, which posits that forgetting may be attributed to the automatic decay or fading of memory traces [28]. For a few years after your graduation, the memory of your name being mispronounced — however altered — is still a memory that you can easily recall. Over time, as a memory becomes less recent and revisited, physical changes to the brain due to the formation of memory traces begin to fade until the memory is no longer accessible [28]. By your 25th-year high school reunion, you may not even remember that the incident at your graduation happened at all. As years pass and new memories are formed, old information becomes harder to retrieve, ultimately wearing away [31]. The speed at which memory decay occurs depends on the salience, or personal relevance, of the memory [32]. When a memory is connected to a more intense emotional experience — as is the case with most autobiographical memories — the memory decays at a slower pace, making it less likely to deteriorate entirely [30].

It’s All Coming Back to Jill Now

Surprisingly, in some individuals, many memories seem to decay at an even slower rate, and in some cases, they may not even decay at all [28, 33]. Individuals with HSAM can recall minuscule autobiographical details from decades ago, long after these details would have faded in the brains of individuals who do not experience the phenomenon [28]. HSAM is characterized by the ability to accurately recall an exceptional number of experiences and their associated dates from events occurring throughout one’s lifetime [28, 34]. Because remembering is automatic with HSAM, individuals who experience the phenomenon do not need to rehearse information in order to remember all of their autobiographical memories; they are simply unable to forget their memories. [28, 34, 35]. As a person who most likely does not have HSAM, you might only remember the most significant parts of your high school graduation, like walking across the stage. But Jill Price can remember what she ate for breakfast that day, the color of her dad’s tie, and the exact time she received her diploma, even decades after the fact: all because of her HSAM. If Jill’s principal had mispronounced her name, she would encode it similarly to someone who does not experience this memory phenomenon [28, 35]. Yet, once it was time for Jill to retrieve that memory, she would likely be able to recall the exact way in which her name was pronounced — as well as numerous other adjacent details — with shocking accuracy, indicating that the process of memory consolidation in Jill’s brain differs from that of people who do not have HSAM [35]. For example, when asked to recall the third time she drove a car, Jill immediately responded, ‘January 10, 1981. Saturday. Teen Auto,’ recalling a memory from when she was fifteen years old as easily as one can remember what they had for dinner last night [36]. Moreover, Jill’s memories very closely resemble her original memories, even after they are retrieved and re-filed multiple times [28, 37].

Recollect and Reconnect

So what makes the memories of people with HSAM different? One theory asserts that there is a biological difference between the brains of those with and without HSAM [34, 35]. While there are no major anatomical differences in the brain structures of people with and without HSAM, differences in connectivity between brain regions may underlie the phenomenon [38, 39]. Differences in neural connectivity between the frontal lobes and the hippocampus — two brain areas involved in memory processing — are characteristically exhibited by people with HSAM [34, 40, 41]. The hippocampus is involved in encoding autobiographical memories and the frontal lobe is involved in categorizing and classifying these memories, thereby aiding in the consolidation of long-term memories [42, 43]. However, there are mixed findings in the specific changes in connectivity between the hippocampus and frontal lobes observed [34, 40]. Both increased and decreased connectivity between the frontal lobes and hippocampus of people with HSAM have been observed, which calls for investigation into how these differences in connectivity contribute to the memory phenomenon [34, 40]. Increased connectivity between the hippocampus and the frontal lobe may lead to stronger associations between memories that already exist or may suggest that pre-existing memories are receiving new information and therefore being altered [34, 44]. Decreased connectivity between the hippocampus and frontal lobes, on the other hand, may suggest that the brain has a reduced capacity to prioritize information, and is, therefore, less selective about what information it stores [40]. When connections between the hippocampus and frontal lobes are compromised, the brain consolidates far more information than it typically would, regardless of the information’s saliency [40]. However, we cannot make assumptions about what changes in connectivity suggest [38, 45]. Alternatively, the unique patterns of connections in a brain with HSAM could also be a result of the memory phenomenon, not the cause of it [38]. The repeated use of connections between the frontal lobe and the hippocampus may reinforce a relationship between the two brain regions, which may induce the aforementioned connectivity differences [38]. Another lesser-explored theory of HSAM suggests that a psychological condition characterized by obsessive thoughts about one’s previous experiences may explain why some individuals can remember autobiographical memories better than others [28]. Regularly thinking about personal events helps strengthen the ability to recall them, thereby allowing individuals with HSAM to more effectively preserve their memories [46]. However, this psychological theory has not been confirmed and would contradict the idea that intentional rehearsal of memory is not necessary to experience HSAM [28]. In any case, some difference in memory mechanisms prevents people with HSAM from forgetting, though further research is required to uncover the precise neurobiological underpinnings of HSAM [28, 34, 40, 46].

The Double-Edged Sword of Never Forgetting

Forgetting is often a frustrating experience — the answer on the test you know you have read somewhere, the misplaced keys, the word on the tip of your tongue. As such, HSAM may seem like a gift. Wouldn’t it be nice to never forget important details of your life? Unexpectedly, evolution seems to indicate that it’s actually the brain’s job to forget [47]. Forgetting is not indicative of a failure of memory. Rather, it is an intentional and important evolutionary process. The brain needs to prioritize remembering important information, so it sacrifices storing extraneous information [48, 49, 50]. Some memories can actually be harmful, and memory decay can protect us from experiencing psychological harm [51, 52]. For example, survivors of trauma are sometimes able to heal faster when they forget their traumatic experience, suggesting that forgetting may be important for our well-being [47]. Forgetting also has a physiological advantage, as the process of remembering and retrieving memories requires a lot of effort [53]. Accurately recalling every detail of each autobiographical memory demands significant amounts of energy that the brain could otherwise allocate for other means [53, 54]. When you remember everything, it may also be difficult to differentiate between what is important to you and what is not [50, 54, 55, 56]. Those with HSAM, who cannot forget, often consider their condition as both a gift and a curse [57]. Take Jill Price, who sees daily life in a kind of “split-screen,” with present-day events, songs, smells, and even TV programs causing her to recall detailed memories that she can’t quell [36]. The weight of such memories impacts many aspects of life for those with HSAM and can lead to permanent changes in their emotional arousal, imagination, and sleep quality [58]. However, those with HSAM also value the positives of the phenomenon, appreciating easy access to the happiest memories of their lives [57]. Ultimately, obtaining a stronger understanding of memory and its mechanisms could help those who have trouble remembering things [35, 57]. Further research on the causes of HSAM and the differences exhibited by individuals who possess this unique phenomenon can help build a better understanding of the mechanisms behind memory [1]. Finally, for people with HSAM, further study into the phenomenon may provide useful insights and create avenues for receiving support, regardless of whether they feel as though their heightened ability to remember is a curse or a gift.

References

1. Ally, B. A., Hussey, E. P., & Donahue, M. J. (2013). A case of hyperthymesia: Rethinking the role of the amygdala in autobiographical memory. Neurocase, 19(2), 166–181. doi:10.1080/13554794.2011.654225

2. Parker, E. S., Cahill, L., & McGaugh, J. L. (2006). A case of unusual autobiographical remembering. Neurocase, 12(1), 35–49. doi:10.1080/13554790500473680

3. Ford, L., Shaw, T. B., Mattingley, J. B., & Robinson, G. A. (2022). Enhanced semantic memory in a case of highly superior autobiographical memory. Cortex, 151, 1–14. doi:10.1016/j.cortex.2022.02.007

4. Vranić, A., Jelić, M., & Tonković, M. (2018). Functions of autobiographical memory in younger and older adults. Frontiers in Psychology, 9. doi:10.3389/fpsyg.2018.00219

5. Lambert, H. K., & McLaughlin, K. A. (2019). Impaired hippocampus-dependent associative learning as a mechanism underlying PTSD: A meta-analysis. Neuroscience & Biobehavioral Reviews, 107, 729–749. doi:10.1016/j.neubiorev.2019.09.024

6. Jawabri, K. H., & Cascella, M. (2020). Physiology, explicit memory. In StatPearls. StatPearls Publishing. PMID:32119438

7. Simons, J. S., & Johnsrude, I. S. (2014). Temporal lobes. Encyclopedia of the Neurological Sciences, 2, 401–408. doi:10.1016/b978-0-12-385157-4.01180-5

8. Schendan, H. (2017). Implicit Memory. Reference Module in Neuroscience and Biobehavioral Psychology. doi: 10.1016/b978-0-12-809324-5.06459-2

9. Moscovitch, M., Cabeza, R., Winocur, G., & Nadel, L. (2016). Episodic memory and beyond: The hippocampus and neocortex in transformation. Annual Review of Psychology, 67(1), 105–134. doi:10.1146/annurev-psych-113011-143733

10. Pitel, A. L., H. Beaunieux, Desgranges, B., Sullivan, E. V., & Eustache, F. (2017). Memory disorders in alcohol use disorder without clinically-detectable neurological complication. Encyclopedia of Behavioral Neuroscience, 2, 447–454. doi:10.1016/b978-0-12-809324-5.00358-8

11. Brown, T. I., Rissman, J., Chow, T. E., Uncapher, M. R., & Wagner, A. D. (2018). Differential medial temporal lobe and parietal cortical contributions to real-world autobiographical episodic and autobiographical semantic memory. Scientific Reports, 8(1). doi:10.1038/s41598-018-24549-y

12. Schendan, H. E. (2012). Semantic memory. Encyclopedia of Human Behavior, 2, 350–358. doi:10.1016/b978-0-12-375000-6.00315-3

13. Richmond, L. L., & Burnett, L. K. (2022). Characterizing older adults’ real world memory function using ecologically valid approaches. Psychology of Learning and Motivation, 77, 193–232. doi:10.1016/bs.plm.2022.07.004

14. Wilson, A., & Ross, M. (2003). The identity function of autobiographical memory: Time is on our side. Memory, 11(2), 137–149. doi:10.1080/741938210

15. Meléndez, J. C., & Satorres, E. (2021). Autobiographical memory as a diagnostic tool in aging. Elsevier EBooks, 305–314. doi:10.1016/b978-0-12-818000-6.00028-7

16. Kapsetaki, M. E., Militaru, I. E., Sanguino, I., Boccanera, M., Zaara, N., Zaman, A., Loreto, F., Malhotra, P. A., & Russell, C. (2021). Type of encoded material and age modulate the relationship between episodic recall of visual perspective and autobiographical memory. Journal of Cognitive Psychology, 34(1), 142–159. doi:10.1080/20445911.2021.1922417

17. Bauer, P. J. (2020). Amnesia, Infantile. Elsevier EBooks, 2, 45–55. doi:10.1016/b978-0-12-809324-5.21207-8

18. Kaiser, J. (2015). Dynamics of auditory working memory. Frontiers in Psychology, 6. doi:10.3389/fpsyg.2015.00613

19. Cowan, N. (2017). The many faces of working memory and short-term storage. Psychonomic Bulletin & Review, 24(4), 1158–1170. doi:10.3758/s13423-016-1191-6

20. Dhikav, V., & Anand, K. S. (2012). Hippocampus in health and disease: An overview. Annals of Indian Academy of Neurology, 15(4), 239–246. doi:10.4103/0972-2327.104323

21. Capone, C., Pastorelli, E., Golosio, B., & Paolucci, P. S. (2019). Sleep-like slow oscillations improve visual classification through synaptic homeostasis and memory association in a thalamo-cortical model. Scientific Reports, 9(1). doi:10.1038/s41598-019-45525-0

22. Feld, G. B., & Born, J. (2019). Neurochemical mechanisms for memory processing during sleep: basic findings in humans and neuropsychiatric implications. Neuropsychopharmacology, 45(1), 31–44. doi:10.1038/s41386-019-0490-9

23. Fields, R. D. (2011). Imaging learning: The search for a memory trace. The Neuroscientist, 17(2), 185–196. doi:10.1177/1073858410383696

24. Jiang, L., & Rao, R. (2024). Dynamic predictive coding: A model of hierarchical sequence learning and prediction in the neocortex. PLoS Computational Biology, 20(2), e1011801–e1011801. doi:10.1371/journal.pcbi.1011801

25. Sheldon, S., Fenerci, C., & Gurguryan, L. (2019). A neurocognitive perspective on the forms and functions of autobiographical memory retrieval. Frontiers in Systems Neuroscience, 13. doi:10.3389/fnsys.2019.00004

26. Frankland, P. W., Josselyn, S. A., & Köhler, S. (2019). The neurobiological foundation of memory retrieval. Nature Neuroscience, 22(10), 1576–1585. doi:10.1038/s41593-019-0493-1

27. McCarroll, C. J. (2020). Remembering the personal past: Beyond the boundaries of imagination. Frontiers in Psychology, 11. doi:10.3389/fpsyg.2020.585352

28. Ricker, T. J., Vergauwe, E., & Cowan, N. (2016). Decay theory of immediate memory: From Brown (1958) to today (2014). Quarterly Journal of Experimental Psychology, 69(10), 1969–1995. doi:10.1080/17470218.2014.914546

29. Josselyn, S. A., & Tonegawa, S. (2020). Memory engrams: Recalling the past and imagining the future. Science, 367(6473). doi:10.1126/science.aaw4325

30. Cooper, R. A., Kensinger, E. A., & Ritchey, M. (2019). Memories fade: The relationship between memory vividness and remembered visual salience. Psychological Science, 30(5), 657–668. doi:10.1177/0956797619836093

31. Walker, W. R., Skowronski, J. J., Gibbons, J. A., Vogl, R. J., & Ritchie, T. D. (2009). Why people rehearse their memories: Frequency of use and relations to the intensity of emotions associated with autobiographical memories. Memory, 17(7), 760–773. doi:10.1080/09658210903107846

32. Santangelo, V. (2015). Forced to remember: When memory is biased by salient information. Behavioural Brain Research, 283, 1–10. doi:10.1016/j.bbr.2015.01.013

33. Santangelo, V., Pedale, T., Colucci, P., Giulietti, G., Macrì, S., & Campolongo, P. (2021). Highly superior autobiographical memory in aging: A single case study. Cortex, 143, 267–280. doi: 10.1016/j.cortex.2021.05.011

34. Santangelo, V., Cavallina, C., Colucci, P., Santori, A., Macrì, S., McGaugh, J. L., & Campolongo, P. (2018). Enhanced brain activity associated with memory access in highly superior autobiographical memory. Proceedings of the National Academy of Sciences, 115(30), 7795–7800. doi:10.1073/pnas.1802730115

35. Talbot, J., Convertino, G., Matteo De Marco, Venneri, A., & Mazzoni, G. (2024). Highly Superior Autobiographical Memory (HSAM): A systematic review. Neuropsychology Review. doi:10.1007/s11065-024-09632-8

36. Rodriguez McRobbie, L. (2017, February 8). Total recall: the people who never forget. The Guardian; The Guardian. 

37. Patihis, L., Frenda, S., LePort, A., Petersen, N., Nichols, R., Stark, C., McGaugh, J., & Loftus, E. (2013). False memories in highly superior autobiographical memory individuals. Proceedings of the National Academy of Sciences, 110(52), 20947–20952. doi:10.1073/pnas.1314373110

38. LePort, A. K. R., Mattfeld, A. T., Dickinson-Anson, H., Fallon, J. H., Stark, C. E. L., Kruggel, F., Cahill, L., & McGaugh, J. L. (2012). Behavioral and neuroanatomical investigation of Highly Superior Autobiographical Memory (HSAM). Neurobiology of Learning and Memory, 98(1), 78–92. doi:10.1016/j.nlm.2012.05.002

39. Brandt, J., & Bakker, A. (2018). Neuropsychological investigation of “The amazing memory man”.. Neuropsychology, 32(3), 304–316. doi:10.1037/neu0000410

40. Daviddi, S., Pedale, T., Serra, L., Macrì, S., Campolongo, P., & Santangelo, V. (2022). Altered hippocampal resting-state functional connectivity in highly superior autobiographical memory. Neuroscience, 480, 1–8. doi:10.1016/j.neuroscience.2021.11.004

41. Anderson, M. C., & Hulbert, J. C. (2020). Active Forgetting: Adaptation of Memory by Prefrontal Control. Annual Review of Psychology, 72(1). doi:10.1146/annurev-psych-072720-094140

42. Barry, D. N., Clark, I. A., & Maguire, E. A. (2020). The relationship between hippocampal subfield volumes and autobiographical memory persistence. Hippocampus, 31(4), 362–374. doi:10.1002/hipo.23293

43. Jamjoom, A., Gallo, P., Kandasamy, J., Phillips, J., & Sokol, D. (2017). Autobiographical memory loss following a right prefrontal lobe tumour resection: A case report and review of the literature. Childs Nervous System, 33(7), 1221–1223. doi:10.1007/s00381-017-3380-7

44. Eichenbaum, H. (2017). Prefrontal–hippocampal interactions in episodic memory. Nature Reviews Neuroscience, 18(9), 547–558. doi:10.1038/nrn.2017.74

45. Mazzoni, G., Clark, A., De Bartolo, A., Guerrini, C., Nahouli, Z., Duzzi, D., De Marco, M., McGeown, W., & Venneri, A. (2019). Brain activation in highly superior autobiographical memory: The role of the precuneus in the autobiographical memory retrieval network. Cortex, 120, 588–602. doi:10.1016/j.cortex.2019.02.020

46. Fawcett, J. M., Benoit, R. G., Gagnepain, P., Salman, A., Bartholdy, S., Bradley, C., Chan, D. K.-Y. ., Roche, A., Brewin, C. R., & Anderson, M. C. (2015). The origins of repetitive thought in rumination: Separating cognitive style from deficits in inhibitory control over memory. Journal of Behavior Therapy and Experimental Psychiatry, 47, 1–8. doi:10.1016/j.jbtep.2014.10.009

47. Nørby, S. (2015). Why forget? On the adaptive value of memory loss. Perspectives on Psychological Science, 10(5), 551–578. doi:10.1177/1745691615596787

48. Gruber, M., Ritchey, M., Wang, S., Doss, M. K., & Charan Ranganath. (2016). Post-learning Hippocampal Dynamics Promote Preferential Retention of Rewarding Events. Neuron, 89(5), 1110–1120. doi:10.1016/j.neuron.2016.01.017

49. Braun, E.K., Wimmer, G.E. & Shohamy, D. (2018) Retroactive and graded prioritization of memory by reward. Nature Communications, 9. doi:10.1038/s41467-018-07280-0

50. Murphy, D. H., & Castel, A. D. (2021). Responsible remembering and forgetting as contributors to memory for important information. Memory & Cognition, 49. doi:10.3758/s13421-021-01139-4

51. Brewin, C. R. (2018). Memory and forgetting. Current Psychiatry Reports, 20(10). doi:10.1007/s11920-018-0950-7

52. Strange, D., & Takarangi, M. K. T. (2015). Memory distortion for traumatic events: The role of mental imagery. Frontiers in Psychiatry, 6(27). doi:10.3389/fpsyt.2015.00027

53. Li, H. L., & van Rossum, M. C. (2020). Energy efficient synaptic plasticity. ELife, 9. doi:10.7554/elife.50804

54. Kluge, A., & Gronau, N. (2018). Intentional forgetting in organizations: The importance of eliminating retrieval cues for implementing new routines. Frontiers in Psychology, 9. doi:10.3389/fpsyg.2018.00051

55. Basu, R. (2022). The importance of forgetting. Episteme, 1–20. doi:10.1017/epi.2022.36

56. Ray, D. G., Gomillion, S., Pintea, A. I., & Hamlin, I. (2019). On being forgotten: Memory and forgetting serve as signals of interpersonal importance. Journal of Personality and Social Psychology, 116(2), 259–276. doi:10.1037/pspi0000145

57. MacMillan, A. (2017). The Downside of Having an Almost Perfect Memory. Time. https://time.com/5045521/highly-superior-autobiographical-memory-hsam/

58. Patihis, L. (2015). Individual differences and correlates of highly superior autobiographical memory. Memory, 24(7), 961–978. doi:10.1080/09658211.2015.1061011