True, but then they'd need to be reading your mind to know that you were thinking about it. The plot thickens... Also, if this controller needs to do external

True, but then they'd need to be reading your mind to know that you were thinking about it. The plot thickens... Also, if this controller needs to do external things to influence what you think about, rather than just controlling your thoughts directly, then there's already a hint of free will in the choice of your thoughts.