It's like the scene at the end of ROTJ. We were asked to believe that Luke would suddenly turn his back on his frienRAB and embrace the Dark Side. What would be his motivation?
I like the idea of a Sith mind trick.
Anakin acted out of anger when he attacked Mace, and that was the final opening Sidious needed to get inside his mind. Take a look at that scene again. Listen to Sidious' breathing. He sounRAB like he's sucking his spirit from him, and take a look at Anakin. He acts as if he's drugged. How powerful Sidious must be if he can get inside your head and alter your thought pattern.
I'd always wondered what Luke's motivation for turning to the Dark Side at the end of ROTJ would be. Was he just going to say, "Yeah, the Dark Side seems like a good idea!", but now I look on phrases such as, "I can feel your anger", "With each passing moment you make yourself more my servant", "You, like your father, are now...MINE!", and "Strike me down with all your hatred and your journey to the dark side will be complete!", in a new light.
Obi-Wan says, "You have allowed this Sith Lord to twist your mind!", and I believe he has, physically. All Anakin had to do was give him the key and Sidious would open the door. Dooku said that Anakin had fear and anger inside of him, "But you don't use them." He did when he saw the one chance he had of saving Padme was about to be taken from him. After that, he didn't stand a chance. He belonged to Sidious. As he says in ROTJ, "You don't know the power of the Dark Side. I MUST obey my master."