Jan. 30, 2007 — What day of the week was January 13, 2000? Donny, considered the world's fastest and most gifted calendar prodigy, could answer correctly (Thursday) in 700 milliseconds. Now researchers think they know how he does it, and why.
In addition to explaining autistic savants like Donny and Dustin Hoffman's character in the 1988 movie "Rain Man," the findings shed light on music and language prodigies who may also suffer from autism and sometimes retardation.
Scientists previously believed these talents might be innate or involve complicated brain processing, but extensive testing of Donny suggests that at least some autistic people have a disruption in the reward and motivation system for a part of the brain that controls goal-directed behavior and reward-motivated learning. The person becomes obsessed with a certain activity, be it music, language or, in Donny's case, dates.
"Donny has a sort of addiction for dates, which probably developed when he was 5 or 6 years old," said Marc Thioux, who led the study.
"He spends most of his time repeating dates, asking for dates, answering questions about dates....His first question upon meeting you is to ask for your birth date," added Thioux, who is a scientist at the Behavioral and Cognitive Neurosciences Neuroimaging Center in the Netherlands.
For the study, which was recently published in the Journal of Experimental Psychology, Thioux and colleagues put 21-year-old Donny through a barrage of calendar and calculation tests. Some required that he name the day of the week for past and future years. Others put the question in reverse, such as, "What is the next year during which October 2 will be a Friday?" Still others tested his ability to add and subtract four- or five-digit numbers.
Donny aced virtually every test, although he failed to name weekday dates after the year 10,000, which the researchers suspect is because he has trouble solving math problems involving five digits.
Based on how Donny answered questions, his accuracy level and errors, the scientists determined he uses a two-step process to name dates.
First, he performs a calculation, sometimes using rules of calendars, such as the fact that the same calendar is repeated every 28 years. Next, he retrieves the correct weekday within one of the 14 possible calendars (seven for leap years and seven for non-leap years), which are stored in his verbal memory similar to how students memorize multiplication tables.
"The performance of one of the fastest savants ever described could be explained in a model that puts together basic elements of normal cognition: mental arithmetic and rote verbal memory," said Thioux.
Thioux and his team now believe that autistic savants have brain regions that function normally and some that function abnormally. The parietal region at the upper back of the brain is probably normal in calendar prodigies, since it is involved in rote memorization and simple calculation tasks.
