The great mind-reading trick
It started about forty years ago. I was accompanying my wife Ingrid on a class trip to Denmark (photo above). The students were fifteen years old and quite enterprising. But in the evening, in the youth hostel where we were staying, they tended to get a little restless. On the first day a group of girls came over to me and said: “Your wife says you can do magic tricks. Please show us one.”
Okay, I said. I took five playing cards and placed them face down on the table. “You touch any card,” I said. “I will not look. And I will tell you which one you touched.” They tried it, and after an initial failure I started to reliably identify the touched card. So I was somehow peeking?! They covered my head, and even sent me out of the room. But I still got it right. Was there signalling? They sent my wife and young son out — to no avail. They started not touching the card, just pointing to it, from a foot up, in total silence. I could still tell which one they had pointed to. Every day, for a whole week, they would ask me to do the trick, again and again, and they looked for an explanation for my impossible skill. With no success.
I escalated things even further: I covered my eyes tightly with the fleshy parts of my palm, facing a student sitting less than a foot away. He or she would cautiously point to a card. There was no way I could see anything. The student would then say “Okay!” and I would uncover my eyes, and, looking straight into the eyes of the subject, instantly point to the chosen card. Scary.
They were completely baffled. One morning one of the boys named Oliver said had laid awake for two hours the previous night and had figured it out: “I know it for certain now how you do it: you actually do have supernatural abilities —you can read minds. You are only pretending you are using tricks!” That was pure desperation.
In the end I told them how I was able to do the trick. And I am now going to reveal it to you, so you can perform it on family and friends. I have done it on maybe a dozen occasions with large groups of people participating. And, ambitious as I am, I always do it with less than one minute of preparation.
In Denmark, with the kids, this is how it went: I had been talking to a random student, Sven, when the girls came over to me and asked me to do a trick. I said: “Okay, in a minute,” and turned back to Sven, while the girls sat on the ground in front of me, waiting. “So, anyway, it will look like a human body,” I said, “two arms, two legs and a head. You must tell me which it was.” Sven was completely mystified. “I don’t understand…” he said. “You will in a moment,” I replied, and turned back to the girls. They had heard everything, and didn’t understand it either. Unlike Sven, though, they assumed it was the continuation of my previous conversation with him. He knew it was not.
“Does anyone have playing cards?” I now asked. These were brought, and I told the kids to deal five on the table. I arranged them in the pattern shown in the picture, and then explained the rules: I close my eyes, you touch one of the cards, and I tell you which one you touched. I closed my eyes, and when they said “okay” I opened them again and, after some thought, pointed to the card on the top. “No, that’s wrong!” they said. “We touched this one,” pointing to the one on the right bottom.”
“Ah,” I said, “the right leg! You should have moved it.” I said this generally, to all the kids, but only one started to understand. That was of course Sven. “Well, let’s try again,” I said. “I need to find the right wave-length of your brains. That takes a few tries.” And when I opened my eyes this time I could see, out of the corner of my eye, Sven vigorously moving his head. I pointed to the top card, and the students cheered encouragingly: “Correct! Do it again.”
Before I did I looked at one of the girls and said: “Not so much. Just a little bit. I can easily see to the side.” She hadn’t a clue what I meant, and simply let it go. But Sven knew I was talking to him. On the third try I saw a very slight movement of his right hand, without looking in his direction. Humans can see things — especially movement — around 90° to each side. I guessed the right card, and from then on had no more errors. I would adjust the signal strength in front of the group: “A little more,” or “a little less.”
The students went nuts. They tried everything: they put my wife and son out of sight, out of the room, made absolutely sure my eyes were properly covered, pressed a pillow on my face, covered my head with a blanket. They tried not pointing directly at a card, and not looking at the cards or table when I opened my eyes to guess — all without success. I always got it right.
Sven became very good at what we were doing. At one stage I looked at one of the kids and said: “You should be investigating me as well, trying to find out how I am doing it.” — “Isn’t that what I am doing?” the kid probably thought, but said nothing. Sven, who until then had been fairly silent, understood I was speaking to him, and immediately burst into action. In fact he took the lead in the investigations. He insisted on my leaving the room when they chose a card, and was visibly devastated when I returned to the table and got it right. “How the hell is he doing this??” he exclaimed. Seconds before this boy had signalled me which card it was.
We were a great team. The students asked me if they could rearrange the cards — they could! — or use other objects. It took Sven and me one try to decide which was the head, the arms and the legs. Put five things on a table and two humans will easily agree on the pattern. I never discussed anything in private with him. As one stage the students asked if I could do the trick completely blindfolded, all of the time. “We can put the cards on the corners of the table, and one in the middle — you simply point in the right direction.” “That’s a tough one,” I said, to all of them. “I’ve never done it before. But maybe if one turn is the left leg, two the left arm… Okay, let’s try.”
Once again it was only Sven who caught what I was saying in the last part — even though I of course hadn’t looked at him. At the time Rubic’s Cube was the rage, and many of the students, including Sven, were learning to solve it. When the students had tied my eyes, very carefully, and said “Okay, we have chosen,” I immediately heard four twists of the cube on my right, where Sven was seated. I pointed in the direction of the right top of the table, and that was of course correct. He was really a superb partner.
Our last day in Denmark was revelation Sunday, and with all the students gathered around me, I told them: “There is only one explanation: someone was signalling me! He or she was doing the trick, not me. I was just the stooge.” Really? But who? “We sent your wife and even your son out!” they said. “Why do you think it had to be one of them?” I replied. “It was one of you!” WHO?? I made them guess. Sven immediate took charge: “Was it Daniel? Was it Nicole? I’m sure it was Stefan!” Until in the end he confessed that it had been him all along. Once again I tip my hat to my great partner in deception.
There is one more amusing incident I need to add. After we had revealed the trick, another class started trickling in: 17-year-olds, who got into conversation with our group. In a short while I saw our kids doing the mind-reading trick on them. But the new kids were sharp. They send all but the one guessing the card, Michael, to the back of the hall, where they could not see anything. I sauntered over to watch (and signal), but when they saw that the trick still worked the students confronted me: “Who are you?” I told them I was the janitor of the youth hostel and was just interested in what they were doing. But they didn’t buy it, and banned me as well to the other end of the room. Suddenly Michael was all alone, and we could only see the backs of the crowd of students gathered around him.
Suddenly there was a commotion and we rushed over. “It’s terrible. How is he doing it?” the new students were saying. I asked Michael what had happened. “I guessed!” he said, “And I got it right.” Interestingly the older students, after the completely isolated Michael had got it right just once, immediately abandoned their theory and started looking for something else. Our kids performed the trick a number of times more, with one of them signalling impudently.
Finally, on the bus back home, we got into a long discussion of what had taken place in the youth hostel. Why had the students spent so much time on making absolutely sure I could not see them choosing a card, and so little time on checking for signalling? Why had they made sure my family was not involved in a deception, but never thought to check whether it was one of their own? We drew conclusions on how one must best test hypotheses to check phenomena that seem inexplicable. And how you must always be wary of clever tricksters (meaning people like me). Perhaps most importantly: how simple a deception can be for it to still work, on everyone. They promised to remember this for the rest of their lives.