I wanted to have a discussion about the practical applications of real psychology and brain storm up just a list of careers where a good grasp of psychology is going to help you get ahead. It's my idea that maybe some interesting plots for effects can be born out of real world psychology and if the effect is structured well enough it's something which could play really well to the actual professions you got the idea from.

So the obvious ones are
therapist (this can bring a lot to the table in terms of ideas like an effect built around the classic rorschach ink blot test)

detective or forensic profiler (murder mystery is a classic plot and something I've been personally toying with for a while, but this is a great one to bring cold reading and psychometry into)

human resources.( Perhaps some sort of effect built around a subjects response to a mock job application or a joke job interview etc.)

business negotiator (I'm not sure if that is an actual job title but you know what i'm referring to, the kind of guy who works massive deals hoping to get the best price etc etc. Any sales based job is going to be easy for someone who could really do what we claim to do. Lol I wonder if there is an effect in convincing people to buy loads of crap, bank night is certainly along those lines.)

parent.. I'm sure the actual parents here could argue this one better than me but the idea's there.

So if you have any more just post em here and we'll bat around some effect ideas.

Used card dealer- Try to convince the spectator to take the worst card for the highest price and feel like they got a good deal.

There's definately and effect in sales psychology. The immediate one which springs to mind is bank night. Imagine having photos of cars on your envelopes and getting people to pick one, inside is a list of things wrong with the car and a life expetancy of anything from a week to a month, you get the only decent car at the end. A really nice variation would be if you could somehow have this info on the backs of the photos and just turn them around to show the audience. That will take some thinking though.

Another idea a little closer to what you suggested would be to have several photos of used cars and a list of their features. You can have people in the audience decide on a price for the cars. You could take different approaches for each car, for example have members of the audience role play an auction for one, bring a couple up on stage and give them the whole used car dealer spiel for another. Use an add a number effect to get the price of another etc. Now reveal the prices which you bought them for and show that in all cases the audience have paid double what you paid.

I think this would work best if you kept your numbers rounded off so go in increments of 1000 or 500. It's more believable that you could control these types of figures than 1752.

By having all the prices as double rather than just as they paid more it shows a much stronger manipulation was going on. Also you could claim at the start of the effect that you always get double and it doesn't matter that they know what you're up to you'll still get your way.

Geez I'm an idiot! I actually open my show with John Archer's "Blank Night" and I my character is some what of a Used car dealer "sleazy salesman" and it never occurred to me to alter the presentation for that! I mean I did alter his original patter but for whatever reason the bulb never went off in my head. Hope you don't mind if I use that?

Take and do as you will my friend. But just a quick thought. It's good in an opener to put your money where your mouth is, so even if you're going to do the car theme I'd suggest keeping money involved, maybe say that you dropped your wallet in one of these cars or something. That way the extra element of risk hightens the climax.