Hyperthymesia

Hyperthymesia or hyperthymestic syndrome is a condition where the affected individual has a superior autobiographical memory. As first described in the Neurocase article "A case of unusual autobiographical remembering," the two defining characteristics of hyperthymesia are "1) the person spends an abnormally large amount of time thinking about his or her personal past, and 2) the person has an extraordinary capacity to recall specific events from their personal past".

Capabilities
Individuals with hyperthymesia can recall the most trivial of events. A hyperthymestic person can be asked a date, and describe the events that occurred that day, what the weather was like, and many seemingly trivial details that most people would not be able to recall. They can often recall what day of the week the date fell on, but are not calendrical calculators as people with autism sometimes are; the recall is limited to days on a personal "mental calendar". The mental calendar association occurs automatically and obsessively. Unlike some other individuals with superior memory, hyperthymestic individuals do not rely on practiced mnemonic strategies.

Cases of Hyperthymesia
So far only one case of hyperthymesia has been confirmed. Researchers Elizabeth Parker, Larry Cahill, and James McGaugh have studied the condition in a woman called "AJ," whose memory they characterize as "nonstop, uncontrollable, and automatic". AJ became aware of her detailed memory in 1978, when she was 12, and from 1980 on she can apparently recall every day.

Actress Marilu Henner claims to be hyperthymesiac.