I must confess that I have posted this on the spooky board also and it isn't actually hypnosis but may rely on a certain amount of suggestion so thought that you chaps may be able to help.

I read in one of Derren Browns book, (Tricks of the mind I think) about having a spectator mentally select a card from those on the table and then giving them a pendulum and getting them to focus on the card. The pendulum should start to swing to identify the card. Well out of curiosity I tried dropping this into a performance last Friday and failed miserably. I had a red and blue card at 90 degree angles to each other and got the spectator to hold the pendulum between the two. I tried to suggest that as they concentrated on the card the pendulum would move towards that card but the pendulum failed to move at all. Now I suspect this may be down to me not fully understanding what I’m doing but if anyone has any advice on how I may get this to work I would dearly like to try it again this Friday.

Bingo, your suggestion is wrong. I will help you for the sake that this is a pretty great trick and that if I tell you to re-read the chapter that explains it, you wont. So you do not tell them that the pendulum will magically pick their card. You have to tell them that they are going to help you. That they are trying to tell you what their card is without saying it. Tell them to only think about telling you what their card is but not to verbally announce it. Instead of making it look magical, make it look like you have created a connection between your minds. The pendulum comes into place because it will be impossible for them to try to send you their card through thought and not have their hand follow suit. Its like the old textbook psychology trick of trying to say the word instead of the colour. Give that a spank.

Readytogo thanks. I will re-read the chapter although I suspect you have psychologically forced me into doing so by your clever negative phrasing.

I shall indeed 'give it a spank.'