http://thesciencenetwork.org/programs/the-science-studio/ent...
In the interview, he describes an experiment he did on himself. When he put a strong magnet on a certain spot on his head, his foot would turn outward. He was able to do this in a stable manner.
Then he repeated the experiment, but decided beforehand that he will turn his foot inward instead. When they did the experiment, his foot still turned outward. His assistant asked "what happened?" and Rodolfo Llinas said "I changed my mind". They repeated the experiment many times, and each time he changed his mind.
From this he concluded that he cannot differentiate when he decides to do something or when his body decides to do it, they both feel to him like he decided to do it.