Christian Jarrett at the BPS Research Digest has a nice post about 'HK', the patient who can recall in detail every single day of his life. His condition is called hypermnesia, and it's exceedingly rare, but by studying HK, cogntive science has been able to add quite a lot to our knowledge of how memory works. From the post:
For most of us, it's tricky enough to remember what we were doing this time last week, let alone on some random day years ago. But for a blind 20-year-old man referred to by researchers as HK, every day of his life since the age of about eleven is recorded in his memory in detail. HK has a rare condition known as hypermnesia, like the opposite of amnesia, and his is only the second case ever documented in the scientific literature (the first, a woman known as AJ, was reported in 2006; pdf).
Brandon Ally and his team have completed comprehensive tests with HK and they've scanned his brain and compared its structure with 30 age-matched controls. They found that HK has normal intelligence, that he performs normally on standard desktop tests of short and long-term recall, and that he has normal verbal learning skills. It's specifically his autobiographical memory that's phenomena.
Read the entire post at BPS Research Digest.