Sound Bite: K. Anders Ericsson, a professor of pyschology, is the original source for the 10,000 Hour Practice Rule also known as the 10 Year Rule of Necessary Preparation, touted by Malcolm Gladwell in his book Outliers. Ericsson, along wtih several other scientists, used data from their own years of practice experiments to come to this conclusion.
Innate Talent: Myth or Reality? Lynn Helding. Journal of Singing, Vol. 67, #4. March/April 2011.