A series of electromagnetic pulses were being directed into my frontal lobes, but I felt nothing. Snyder instructed me to draw something. ''What would you like to draw?'' he said merrily. ''A cat? You like drawing cats? Cats it is.''

I've seen a million cats in my life, so when I close my eyes, I have no trouble picturing them. But what does a cat really look like, and how do you put it down on paper? I gave it a try but came up with some sort of stick figure, perhaps an insect.

While I drew, Snyder continued his lecture. ''You could call this a creativity-amplifying machine. It's a way of altering our states of mind without taking drugs like mescaline. You can make people see the raw data of the world as it is. As it is actually represented in the unconscious mind of all of us.''

Two minutes after I started the first drawing, I was instructed to try again. After another two minutes, I tried a third cat, and then in due course a fourth. Then the experiment was over, and the electrodes were removed. I looked down at my work. The first felines were boxy and stiffly unconvincing. But after I had been subjected to about 10 minutes of transcranial magnetic stimulation, their tails had grown more vibrant, more nervous; their faces were personable and convincing. They were even beginning to wear clever expressions.

I could hardly recognize them as my own drawings, though I had watched myself render each one, in all its loving detail. Somehow over the course of a very few minutes, and with no additional instruction, I had gone from an incompetent draftsman to a very impressive artist of the feline form.

…As remarkable as the cat-drawing lesson was, it was just a hint of Snyder's work and its implications for the study of cognition. He has used TMS dozens of times on university students, measuring its effect on their ability to draw, to proofread and to perform difficult mathematical functions like identifying prime numbers by sight. Hooked up to the machine, 40 percent of test subjects exhibited extraordinary, and newfound, mental skills. That Snyder was able to induce these remarkable feats in a controlled, repeatable experiment is more than just a great party trick; it's a breakthrough that may lead to a revolution in the way we understand the limits of our own intelligence -- and the functioning of the human brain in general.