Just one more on the magic. I just got this email from Mind Hacks readers Stefano suggesting that stage magicians that use psychological language actually pollute the public’s understanding of science. He also gives a much better, and, I’m guessing, more accurate explanation of the hand-raising trick in Keith Barry’s TED performance.
As a psychologist, I have to say I dislike the new sort of mentalism that we’re seeing nowadays. Derren Brown (an incredibly talented performer, as you said) tries to portray his show as something more than old-fashioned magic by introducing psychological terms and studies, somewhat erratically. I understand that his use of scientific terminology might be part of the misdirection, but it really makes me cringe to see he perform ridiculous feats and justify it by citing things like the Milgram study, concentration abilities or persuasion techniques. Almost every time he mentions a psychological concept, he either misrepresents it or uses it to explain absurd stuff that he did with stooges or simply old magic tricks.
I didn’t know Keith Barry, but I have to say his TED lecture made me put him on the same category as Derren Brown: old mentalist tricks disguised as “persuasion and psychological techniques”. He even managed to fool you, it seems: the trick that you attributed to hypnosis has nothing to do with it, being achieved simply by the performer applying pressure on the feet of the subject instead of his hand. Notice how he never says where the pressure will be, and his left leg is covered by the table. His other live tricks are equally simple, and have nothing do with psychology, except for the fact that everything you do to an audience – even cheating/fooling them – is part of it.
Stefano makes an interesting point that these acts rely, in part, on misinforming people about psychology. Derren Brown is a classic example where he often gives explanations after the trick so the viewer feels they are being let in on the secret, but which are obviously misleading and so are part of the more general misdirection that the feats are achieved through the ‘power of the mind’.
In terms of the hand raising trick that Stefano mentions, looking back at the video, this seems a much more likely explanation. In which case, this is a ‘theory of mind‘ illusion, where we are fooled into attributing a different mental state to the person picked from the audience than they actually have.
I hope you don’t mind me publishing part of your email Stefano, I did try and email and ask but unfortunately the address wasn’t valid. Do get in touch if you have a website or blog and I’ll happily link to it and many thanks for your interesting commentary.
Mind Hacks 
yes, he touches the guy with his foot directly or, i think more likely, use some mechanical thingy triggered by a move of his foot. you can see it clearly when he does the stunt with the lady pointing at the guy and moving her arm. keith makes a move with his left foot accordingly every time. for the audience there the foot is hidden behind the cover of the black cloth, but the angle of the camera allows us to see it in the video.