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Aphantasia Logo
Back to all research
Aphantasia Logo

Building awareness and understanding of aphantasia through research, education, and community support.

About

  • What is Aphantasia?
  • What is Hyperphantasia?
  • Take Assessment
  • Getting Started
  • Newsletter
  • About Us
  • Contact

Community

  • Premium Membership
  • Find support
  • Discussions
  • Events
  • Visualize

For Professionals

  • Overview
  • Free Introduction
  • Counselor Training
  • Educator Training
  • List Your Practice
  • Pricing & Bundles

Resources

  • Articles & Stories
  • Videos & Interviews
  • Aphantasia Course
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Research

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© 2026 Aphantasia Network. All rights reserved.

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Ask AI About This Paper
Ask AI About This Paper

A case of Highly Superior Autobiographical Memory (HSAM) accompanied by highly frequent involuntary autobiographical memory

DOI: 10.1080/13554794.2026.2701703
Tags:
Memory
Cleary, A. M., Okada, N., Bearden, D. J., Alfonso, D., Mills, C., Neisser, J., McNeely-White, K. L., Pedersen, N. P., & Drane, D. L. (2026). A case of highly superior autobiographical memory (hsam) accompanied by highly frequent involuntary autobiographical memory. Neurocase, 32(4), 152–166. doi:10.1080/13554794.2026.2701703

Abstract

Highly Superior Autobiographical Memory (HSAM) is the rare ability to recollect nearly all of one’s past personal experiences with great detail and accuracy. When given a date, a person with HSAM can recall verifiable details about what they experienced that day. People with HSAM do not tend to stand out on standard neuropsychological assessments, common laboratory tasks, or other measures that assess intentional forms of memory. Some clues suggest that the superior autobiographical remembering of people with HSAM occurs involuntarily. In a newly identified case of a person with HSAM, we found evidence using the Involuntary Autobiographical Memory Inventory (IAMI) that the person’s involuntary memory indeed stands out. This person’s past-oriented Involuntary Autobiographical Memory (IAM) frequency was two standard deviations above the mean reported in previous research. while, in line with past research, her performance on standard neuropsychological batteries and laboratory tasks was unremarkable. We propose that these intrusive recollections facilitate the consolidation of memory for past events.

Authors

  • Anne M. Cleary1
  • Noah Okada1
  • Donald J. Bearden1
  • Demy Alfonso1
  • Caitlin Mills1
  • Joseph Neisser1
  • Katherine L. McNeely-White1
  • Nigel P. Pedersen1
  • Daniel L. Drane1

A case of Highly Superior Autobiographical Memory (HSAM) accompanied by highly frequent involuntary autobiographical memory

DOI: 10.1080/13554794.2026.2701703
Tags:
Memory
Cleary, A. M., Okada, N., Bearden, D. J., Alfonso, D., Mills, C., Neisser, J., McNeely-White, K. L., Pedersen, N. P., & Drane, D. L. (2026). A case of highly superior autobiographical memory (hsam) accompanied by highly frequent involuntary autobiographical memory. Neurocase, 32(4), 152–166. doi:10.1080/13554794.2026.2701703

Abstract

Highly Superior Autobiographical Memory (HSAM) is the rare ability to recollect nearly all of one’s past personal experiences with great detail and accuracy. When given a date, a person with HSAM can recall verifiable details about what they experienced that day. People with HSAM do not tend to stand out on standard neuropsychological assessments, common laboratory tasks, or other measures that assess intentional forms of memory. Some clues suggest that the superior autobiographical remembering of people with HSAM occurs involuntarily. In a newly identified case of a person with HSAM, we found evidence using the Involuntary Autobiographical Memory Inventory (IAMI) that the person’s involuntary memory indeed stands out. This person’s past-oriented Involuntary Autobiographical Memory (IAM) frequency was two standard deviations above the mean reported in previous research. while, in line with past research, her performance on standard neuropsychological batteries and laboratory tasks was unremarkable. We propose that these intrusive recollections facilitate the consolidation of memory for past events.

Authors

  • Anne M. Cleary1
  • Noah Okada1
  • Donald J. Bearden1
  • Demy Alfonso1
  • Caitlin Mills1
  • Joseph Neisser1
  • Katherine L. McNeely-White1
  • Nigel P. Pedersen1
  • Daniel L. Drane1
Aphantasia Logo

What This Study Is About

Researchers investigated a rare case of Highly Superior Autobiographical Memory (HSAM)—the ability to remember nearly every day of one’s life in vivid detail. The study specifically looked at whether these exceptional memories happen automatically and "pop" into the mind without effort.

How They Studied It

The researchers conducted an in-depth case study of a 16-year-old girl, referred to as "EE," who demonstrated remarkable memory for past events. They interviewed her using random dates (such as November 5, 2021) and asked her to describe what happened, what she wore, and what the weather was like. The team then verified her answers using news reports, weather archives, and family records. EE also completed the Involuntary Autobiographical Memory Inventory (IAMI), a questionnaire that measures how often memories come to mind spontaneously rather than through intentional searching.

What They Found

EE was able to correctly identify the day of the week and specific personal details for every date she was tested on, all of which were verified as accurate. While her performance on standard laboratory memory tests (like remembering lists of words) was normal, her score for involuntary autobiographical memory—memories that pop into the head unbidden—was significantly higher than average. Her frequency of these "intrusive" memories was two standard deviations above the mean reported in previous research, suggesting her brain is constantly and automatically revisiting the past.

What This Might Mean

This study suggests that the "secret" to HSAM might not be a better ability to memorize things on purpose, but rather a high frequency of involuntary recollections. These spontaneous memories may act as a constant "mental rehearsal," strengthening the memories over time until they become permanent. However, because this is a study of a single individual, more research is needed to see if this pattern holds true for all people with HSAM.

One Interesting Detail

When asked about a random date in 2021, EE not only remembered that it was the day of a local World Series parade, but she also correctly recalled that there was a "really pretty sunset" that evening—a detail the researchers were able to verify by finding a dated photo of that specific sunset posted online by a local photographer.
This summary was generated by AI and may contain errors. Always refer to the original paper for accuracy.
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