How do you remove a person's watch without his noticing? It's easier than you might think.  The simplest watches to steal are the ones fitted with buckles—the kind with a tongue and a prong that work like a belt.  You make a C with your hand and press your thumb against the watch's face while your middle finger curls around the person's wrist. The tip of the middle finger should align with the tip of the tongue.  Most watches have a little loop to hold the tongue down, so first you need to free the tongue by curling your middle finger inward, easing the tongue back out of the loop.  Once this is done, your finger goes underneath the tongue and bends it all the way back, until the prong comes out of the hole.  You then flick it back down and push the tongue slightly askew so that the prong doesn't slip back into one of the holes as you yank the watch off the wrist.  Finally, in a quick, fluid motion, you pull your hand away while palming the watch in your curled fingers.  As with any magic trick, though, the mechanics are only a small part of the illusion; psychology is the secret sauce. First and foremost, you need an excuse to grab your mark's wrist, because if you yank at his watch for no reason he'll almost certainly notice. I usually steal a spectator's watch under the guise of doing a coin trick.  Let's imagine you're that spectator and the watch is on your left wrist. I remove a coin and ask you to hold out both of your hands, palms up. After placing the coin in your right hand, I'll tell you to close your fists as I grab both wrists, raise your arms almost to your face and clamp my fingers around the watch. "I'm going to show you how a coin can teleport," I say.  At this point I press down on the watch so that your touch receptors adapt to the sensation. The resulting sensory after-impression—literally, neurons still firing—makes it harder for you to feel the absence of the watch after it comes off your wrist (although it turns out that, while helpful, this isn't absolutely necessary).  As I begin unbuckling the strap, I may move your arms back and forth in short straight lines while saying something like, "If I shake hard enough, the coin will jump between your hands." In magic as well as in pickpocketing, it helps to move in quick back-and-forth spurts when you want to shake off a person's focus. If, however, you want him to follow your hand, it's better to move along a smooth, curved trajectory.  Neuroscientists think that these two forms of motion engage different parts of the visual system. Short linear bursts trigger saccadic eye movements—rapid but discontinuous focusing of the eyes during which visual awareness is suppressed for intervals as brief as 20 milliseconds—while curved movements activate smooth-pursuit neurons, brain cells programmed to follow moving targets. This adaptation makes sense given that a straight line is a relatively predictable path, so your eyes can safely jump ahead, while a curved trajectory is less predictable and must be tracked more closely.  If I know your name, I'll say it aloud a few times. Your name is like a tractor beam for attention. It pulls you in. Have you ever been in a noisy room when suddenly you hear your name called out amid the din? The ability to hear meaningful sounds selectively through white noise is called the cocktail-party effect. In a similar vein, experiments have shown that people can pick out their own names from a list of names even when under the spell of misdirection. If, however, the name is off by just one letter—Molly instead of Milly, or Bob instead of Rob—the word tends to go unnoticed.  To add another layer of smoke, I'll usually ask some questions. Are you right- or left-handed? Can you feel the coin in your hand? Parsing a question, accessing the necessary information and formulating an answer are fairly demanding cognitive tasks, enough to bring about a so-called inattentional state.  Once the watch is finally loose, I slip it off your wrist. No matter how many times I do this, I always think my victims are going to notice. But, as experience and experiments have shown, they rarely do. A number of studies have demonstrated that people experience visual blindness when they're distracted—what psychologists call inattentional blindness. It would appear that people also experience marked periods of tactile insensitivity when their attention wanders—the somatosensory analog to inattentional blindness. If seeing isn't believing, feeling isn't, either.  A version of this article appeared June 16, 2012, on page C2 in the U.S. edition of The Wall Street Journal, with the headline: Stealing a Watch,Made Easy.
To come away clean with a timepiece, prey on the psychology of inattention. says Fooling Houdini author Alex Stone.