Having perfect memory is a skill that many people wish for. For many, being able to remember vivid details of a family gathering or being able to identify what day of the week a friend’s birthday fell upon without checking a calendar would be a blessing. But what if you were actually able to remember every single thing from every single experience of your life? 

Some individuals do in fact have this ability, and they can describe events they have personally experienced in extreme detail, even if it has been many years since the events had taken place. These individuals have a condition known as hyperthymesia or hyperthymestic syndrome, a condition later renamed Highly Superior Autobiographical Memory (HSAM). The term hyperthymestic syndrome comes from the Greek word thymesis which means “remembering” (1). 

HSAM was first reported by Professor James McGaugh, a Research Professor in the Department of Neurobiology and Behavior at the University of California, Irvine, and his colleagues in 2006 (2). Professor McGaugh and his team diagnosed a research participant named “AJ,” later known as Jill Price, with HSAM when they found that “when provided with a date, Jill could specify on which day of the week it fell and what she did that day” (3). 

Individuals with HSAM are able to most accurately give details about events they have experienced themselves. For example, when experimenters shared details about Princess Diana’s funeral, individuals with HSAM were able to recall their own personal recollection of the event better than a depiction that the experimenters presented (4). However, individuals with HSAM usually only have “modest advantages” in a few areas rather than having enhanced abilities across the board in areas such as “verbal fluency, attention/inhibition, executive functioning, mnemonic discrimination, perception, visual working memory, or the processing of and memory for emotional details” (4).

In a study conducted by LePort et al, it was found that there were nine brain regions--the uncinate fascicle, forceps major, parahippocampal gyrus, posterior insula, anterior putamen and caudate and anterior limb of internal capsule, posterior pallidum, anterior and middle temporal gyrus, lingual gyrus, and intraparietal sulcus--that “differed most consistently and meaningfully across analyses in the HSAM participants as compared to controls in terms of grey matter/white matter concentration, regional shape, or white matter tract coherence” (5). However, the researchers concluded that they would “refrain from interpreting” the results as there is not sufficient evidence to say that large gray matter concentrations in adults go together with better memory (5).

HSAM is a very specialized memory condition, with less than 50 individuals having the condition recognized. While neuroscientists are unable to conclusively determine the underlying causes of HSAM, more extensive research is being conducted on the condition and many similar rare conditions to determine how the brain can function in such a unique manner.


  1. Parker, E. S., Cahill, L., McGaugh, J.L. (2006). A case of unusual autobiographical remembering. Neurocase. doi: 10.1080/13554790500473680
  2. James L. McGaugh. UCI Center for the Neurobiology of Learning and Memory. Retrieved from https://cnlm.uci.edu/about/fellows/james-l-mcgaugh/
  3. Highly Superior Autobiographical Memory. UCI Center for the Neurobiology of Learning and Memory. Retrieved from https://cnlm.uci.edu/hsam/
  4. LePort, A. K. R., Stark, S. M., McGaugh, J. L., Stark, C. E. L. (2016). A cognitive assessment of highly superior autobiographical memory. Memory. doi: 10.1080/09658211.2016.1160126
  5. 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. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3764458/