newscripts MAGIC-TRICK SCIENCE, HALF-BRAIN SLEEP
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or ages, magicians have bewildered these were always correct, science would audiences with SLEIGHT OF HAND, have a very small role in life.” causing observers to ask, “How’d they do that?” Little did folks know, some magiur seals have also been bafing sciencians aren’t entirely sure either. tists with SLEIGHT OF BRAIN they A team of cognitive neuroscientists reperform while asleep. Activity across a cently collaborated with Teller, the silent half seal’s entire brain dampens when the animal of famed magic duo Penn & Teller, to answer sleeps on land, just as it does for humans. a burning question he had about one of his But when a seal is in water, half of its brain tricks. Teller sleeps while the other half remains active. wanted to The “cute thing” about the phenomenon, know why his says Jerome M. Siegel, a neurobiologist at version of the the University of California, Los Angeles, classic “cups who studies seals, is that “when they’re and balls” in water, you can tell which sides of their illusion—a brains are asleep” just by looking at the Abracadabra: trick that dates back animals. Similar to humans, the right side “Cups and to Rome in 3 B.C.— of the brain controls movement on the left balls” may be fools people as well as side of the body and vice versa. So if a seal’s an old trick, but it’s no dog. it does. left flipper is moving to keep its head above During the trick, water but the other flipper is immobile, Teller sets one small ball on top of each of the left hemisphere of the critter’s brain is three overturned cups. He then picks up asleep, Siegel explains. a cup with one hand and tilts it so the ball When the animals take an aquatic nap, falls into his other hand. At the same time, they also keep one eye open. “We think the the hand holding the cup slips a new ball function of this sleep state is to allow the underneath it and places it back on the table. animals to stay vigilant in the water,” Siegel The magician follows suit with the other cups says. “Fur seals are often eaten by sharks.” and, finally, reveals the hidden balls with a Along with an international team of flourish. researchers, Siegel recently took advantage Teller had postulated of seals’ asymmetric that the trick works— brain behavior to study even with transparent the chemistry of sleep. cups—because observBy monitoring the brain ers watch the falling ball waves and circulating rather than his hands. neurotransmitters in the The research team, led noggins of four seals, by Stephen L. Macknik the team determined of the Barrow Neurologithat acetylcholine—the cal Institute, in Arizona, same chemical that tested that idea by causes muscles to showing experiment parcontract—decreases on Fur seal: Whole-brain sleep if by ticipants videos of Teller the sleeping side of the land, half-brain sleep if by sea. performing the illusion brain (J. Neurosci., DOI: and tracking their eye movements. 10.1523/jneurosci.2603-12.2013). Serotonin, Surprisingly, Teller’s guess about the suca neurotransmitter frequently linked to sleep, cess of “cups and balls” was incorrect: The remained at the same level across the seals’ researchers demonstrated that a person’s brains during their watery slumber, however. eyes don’t stray far from the magician’s “Many health food stores sell serotonin hands (PeerJ, DOI: 10.7717/peerj.19). Eyes as something to induce sleep,” Siegel says. did stray, however, when Teller lifted a ball According to the results, he adds, this pracaway from the top of a cup. tice is likely nonsensical. Just because Teller’s intuition was wrong, Macknik tells Newscripts, doesn’t detract from the magician or his tricks. “One of the LAUREN WOLF wrote this week’s column. purposes of science is to overcome comPlease send comments and suggestions to mon sense and intuition,” Macknik says. “If
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See Teller perform “cups and balls” at http://cenm.ag/magic. MARCH 11, 2013
