Hyperthymesia is an ability that allows people to remember nearly every event of their life with great precision. People may also refer to it as highly superior autobiographical memory (HSAM).

Hyperthymesia is rare, with research identifying only a small number of people with the ability. Studies on hyperthymesia are ongoing, as scientists attempt to understand how the brain processes memories.

In this article, we define hyperthymesia and explain the causes, characteristics, and diagnosis.

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People with hyperthymesia often remember exact dates relating to past personal experiences.

According to a 2017 study, people with hyperthymesia can accurately and readily recall numerous details about events that have occurred in their life.

These details can include exact dates and intricate information about previous experiences. Current research suggests that the ability is limited to autobiographical memory. This limitation means that people can only recall information about themselves and their past personal experiences.

People can retain information as either short-term or long-term memories. People with HSAM likely process short-term memories in a similar way to most other people. However, a 2016 study suggests that these individuals have better long-term memory.

HSAM is different than having a good memory. For example, people with HSAM do not use mnemonic devices to remember long strings of information.

People with hyperthymesia can recall details relating to past experiences with extreme accuracy.

Some researchers have noted that these individuals share some characteristics with people who have obsessive-compulsive disorder (OCD). For example, they may demonstrate obsessive tendencies.

People with both conditions also tend to have certain structural differences in particular regions of the brain. However, despite these similarities, there is no definitive link between having HSAM and OCD.

People with HSAM are unable to forget their life experiences. Further research is necessary to assess the long-term effects of this.

As there are relatively few people with hyperthymesia, there is a lack of research examining the causes. There are some theories as to what contributes to hyperthymesia, but the exact cause remains unknown.

Some research suggests that the cause of hyperthymesia may be biological, genetic, or psychological. However, more studies are necessary to gain a better understanding of what causes hyperthymesia.


There is some evidence that hyperthymesia may have a biological cause. One study suggests that people with HSAM may have hyperactivity in certain parts of the brain, such as the amygdala.

Another study suggests that people with HSAM have increased activity within different regions of the brain, such as the superior and inferior parietal lobe.


Another theory is that hyperthymesia may be genetic. However, current research is ongoing as to whether the ability has a genetic basis.


Some researchers believe that hyperthymesia may have psychological causes. This theory implies that people with HSAM obsessively think about their previous experiences. Regularly thinking about these events helps strengthen the ability to recall them. As such, this may enable people with hyperthymesia to preserve their memories.

As hyperthymesia is a rare ability, there is currently no formal way of diagnosing it.

Some research suggests that people with hyperthymesia have hyperactivity in certain parts of their brain. Doctors could potentially, therefore, assess whether a person has HSAM by taking an MRI scan while they undergo a memory test.

Complex memory tests can also help confirm whether someone has hyperthymesia. These tests can include an autobiographical memory assessment, which tests a person’s ability to recall specific events and facts from their earlier life.

A person with hyperthymesia can remember nearly every event of their life in a lot of detail. On the other hand, eidetic memory is the ability to accurately recall an image after only seeing it once for a short period.

Those who have a superior eidetic memory can continue to visualize something they have recently seen with great precision. They may be able to hold the intact visualization in their mind for up to several minutes.

For most people, eidetic memories tend to fade after a few seconds. In some cases, the visualizations may change or become stored as a long-term memory.

People often confuse eidetic memory with photographic memory. People who claim to have a photographic memory state that they can remember a visualization for a long time in the same detail as when they first saw it. However, scientific research debates the existence of photographic memory.

Similarly to people with hyperthymesia, people with a good eidetic memory do not rely on memory devices, such as mnemonics.

There is little research exploring hyperthymesia and eidetic memory. The reason for this may be that they are hard phenomena to test. However, it is likely that people with hyperthymesia do not have a superior eidetic memory.

More research is necessary into both eidetic memory and hyperthymesia to understand their similarities and differences.

Hyperthymesia is the rare ability to recall nearly all past experiences in great detail.

The causes of HSAM are currently unknown, but some theories suggest that it may have biological, genetic, or psychological origins.

There is currently no way to diagnose hyperthymesia formally. Possible ways to assess this may be through MRI scans and complex memory tests.

Hyperthymesia differs from eidetic memory in that it focuses on a person’s ability to recall their autobiographical experiences rather than to hold visualizations in their mind.

Further research is necessary to examine the differences and similarities between hyperthymesia and eidetic memory.