A few people remember almost every single day

Researchers at the University of California, Irvine studied 11 people who could recall an unusual amount of their own past, naming public dates almost as easily as personal ones, and gave them the same standard memory tests used on everyone else.

The group, now described as having highly superior autobiographical memory, performed far better than matched control participants at recalling personal events and public news from specific dates, yet scored about the same as controls on most standard laboratory memory tests, and brain scans found nine structures that measured differently from the comparison group.

The split result, exceptional for one kind of memory and ordinary for another, suggested the condition is not a general gift for memory but something narrower, tied to how personal and dated events in particular get stored and retrieved. The sample remained small, and later work has continued trying to pin down what, if anything, people with this memory do differently day to day that builds it.

Every date, kept, while most days fade.