From the MIT Press Reader, an excerpt from The Science of Weird Shit:
The Psychology of the Psychic
There is a hidden cause behind a fun little demonstration of an ostensibly paranormal experience that I often include in public talks on anomalistic psychology, especially when I have a reasonably large audience. I explain to my audience that an important part of proper skepticism is to always be open to the possibility that you may be wrong. In that spirit, I tell the audience that I would like to do a little experiment with them to see just how psychic they are. I tell them that I am going to try to telepathically send a simple message from my mind to theirs. “I’m thinking of a number between one and ten,” I say. “Not three, because that’s too obvious. I want you to make a mental note of the first number that comes into your mind now!”
I then explain that, with such a large audience, we would expect around 10 percent of them to guess the number correctly just by chance, so we should only get ecstatically excited if considerably more than 10 percent of the audience get it right. I then, apparently somewhat nervously, ask, “Did anybody think of the number seven? If you did, raise your hand.” With a large audience, I can, in fact, be very confident that around a third of them will put up their hand.
Feigning surprise, I will try another, slightly more complicated example. “This time I’m thinking of a two-digit number between one and fifty. They are both odd digits and they are not the same. So, it could be fifteen — one and five, both odd digits, not the same — but it could not be eleven — both odd digits but they are the same. What is the first number that fits that description that comes into your mind now?”
I then ask, as if expecting no one to have got it right this time, “Did anyone think of the number thirty-seven?” Once again, about a third of the audience will put up their hand. I will then add, “Did anyone think of thirty-five?” About a further quarter of the audience will raise their hand. “Sorry, that was my fault,” I explain. “I thought of thirty-five first and then I changed my mind.”
What is going on here? Any audience members who believe in ESP may well think that it has just been demonstrated. More skeptical members may be at a loss to explain what they have seen (and possibly directly experienced). Is it possible that I had simply conspired with all those members of the audience who got it right by telling them in advance to raise their hands in response to my questions? That would seem unlikely....
....MUCH MORE
Ruling out the number three in the first paragraph brings to mind a little mental manipulation. Tell your audience to "think of a a number between one and four."
First off, three is the number that most often comes to mind in these set-ups. But the manipulation is in the "between one and four". Even though on the face of it you are giving the audience four choices, the "between" registers almost subconsciously, reducing the choice to "2" or "3".
The gentleman who told me this, it was during a conversation on active listening, said he had observed groups choosing "3" at up to 80% of responses while superficially assuming the correct odds to be 25%.
For more on active listening here's the Harvard Business Review, January 2, 2024:
What Is Active Listening?
Unfortunately no parlor tricks to amaze, astound and amuse your audience. Sorry.