by Sam Kean
On June 3, 1918, a woman known only as Madame M. burst into a Paris police station, panting and near tears. She told the policeman on duty that she knew of at least 28,000 people, mostly children, being held hostage in Paris basements and catacombs. Some were being mummified alive, some were being flayed and experimented on by sadistic doctors, all were enduring unimaginable torture. When asked why no one had noticed this vast conspiracy, M. explained that every victim had been replaced by an aboveground “double”—a near-perfect replica who assumed the original person’s identity. To verify her story, she demanded that two policemen accompany her immediately. They did—straight to an asylum.
M. had worked for years as a couture seamstress and designer, but for the psychologists who examined her, the salient part of her biography concerned her five children. Four had died as infants, including twin boys, a double blow that basically unsprung her mind. She began telling people that her little ones had been poisoned or abducted, and from there the fantasies only got wilder. M. spun tales of such complexity, in fact, that even she sometimes got lost in the labyrinth. She was supposedly descended from King Henri IV; but to erase her identity and cheat her out of her inheritance—including eighty billion francs and Rio de Janeiro—spies had dyed her flaxen hair chestnut, put drops in her eyes to change their size, and “stolen her breasts.” How this meshed with the catacombs plot wasn’t clear, and in general the tale held little interest for her doctor, Joseph Capgras: he’d seen plenty of lunatics invent grand genealogies for themselves. But one detail did strike Capgras as unusual, and significant—M.’s belief in doubles. She kept repeating that word, doubles, and insisted that even her last remaining family members, a daughter and her husband, had been murdered and replaced.
How had M. determined they were doubles? With the same skilled eye that had made her a couture seamstress. When relating stories to Capgras, M. would highlight the exact shade of ivory buttons on a garment, the exact type of satin lining in a coat, the exact kind of white feather adorning a hat. Similarly, with people, she might recall the precise hazel of someone’s eyes and the precise length of men’s mustaches, and she mapped people’s scars and freckles with the same precision that ancient astronomers had charted the heavens. The problem is, people change: they get haircuts, nick their hands with knives, eat éclairs and gain a pound. And whenever the people in M.’s life changed, her brain would count them as a new person—a double—as if the “old” person had disappeared.
In fact, as the doubles themselves accumulated new wrinkles or went a little balder month by month, she confabulated doubles for them, and then doubles of the double-doubles. Eventually, she said, eighty doubles of her husband appeared. Her daughter was more promiscuous still, appearing in two thousand avatars between 1914 and 1918. There’s no record of what happened to M., but in all likelihood she ended her sad life in an asylum.
After Capgras published his case report, other neuroscientists began to notice this doubling delusion in their patients, and Capgras syndrome is a well-recognized if rare ailment today. Most Capgras victims in decades past identified the imposters in their lives as actors or living waxworks; as new technologies emerged in the past century, the intruders became aliens, androids, and clones. Like M., some Capgras victims spun fabulous soap operas involving switched births and foiled inheritances. But just as often, victims complained about mundane things. One Capgras victim agonized to his priest that he’d committed bigamy, since he was now married to two women—his wife and her double. And not all the doubles were human. Some people sensed imposter cats and poodles. One person felt his hair had abandoned him, leaving an imposter wig.
As for the victims’ relationships with the doubles, those varied. Some accepted the interlopers. One sweet old woman began making three cups of tea each afternoon—for her, for her husband’s double, and for her missing husband himself, just in case he returned that day. Other people found Capgras syndrome erotic. One Frenchwoman in the 1930s had complained for years about her awkward lover; luckily, his double proved a stud. Male victims liked that their wives’ bodies seemed electrifyingly new every few weeks. (One cheeky doctor has even declared the syndrome the secret to connubial bliss, since each sexual encounter feels fresh.) Still, most Capgras victims fear the doubles and grow paranoid. And attempts to reason with them often backfire. Some loved ones have tried reminiscing with victims, by sharing details of their lives that only the two of them could know. But this proof of their genuineness can spook the victims, since the “imposter” obviously tortured this out of the missing person. A few victims have even killed doubles. A Missouri man decapitated his stepfather in the 1980s and then dug through his severed neck looking for the “robot’s” batteries and microfilms.
To explain the origins of the syndrome, Capgras seized on one telltale fact: that victims can recognize their loved ones’ faces, even while they deny it’s “really” them. In other words, victims perceive people accurately but don’t react appropriately to what they perceive—which implies that the root of the problem is emotional, since emotions help shape those reactions. Unfortunately, Capgras fell in with Freudians and decided to reinterpret his syndrome as a psychosexual neurosis (mostly a repressed desire for incest, natch). But doctors soon discovered that toxins, methamphetamines, bacteria, Alzheimer’s disease, and blows to the brain could also induce Capgras syndrome, which weakened the Freudian theory. That accidents and disease could cause the syndrome suggested an organic basis, and neuroscientists eventually circled back to Capgras’s prescient guess about emotions.
The full explanation of Capgras syndrome requires a quick trip back to face-blindness. The face-blind often cannot recognize even loved ones without using context clues or resorting to tricks. Nevertheless, many face-blind people do recognize faces on some level, no matter what they claim. Scientists have run experiments in which they gave a face-blind person—call him Chuck—a stack of Polaroids, some showing strangers, some showing loved ones. The scientists also placed electrodes on Chuck’s skin to measure his emotional response to each picture. (Whenever someone experiences an emotion, his skin begins to sweat ever so slightly, even if he can’t feel the moisture. Sweat contains dissolved salt ions, which increase the electrical conductivity of skin.*) When Chuck starts flipping through the Polaroids, he’ll draw blanks on every face—don’t know, don’t know, still don’t know. But his emotions do know. Whenever he perceives a loved one, the electrical flow on his skin rises by a measurable amount. His mind has no conscious access to the face’s identity, but his subconscious bleats dad, dad, dad.
This cryptic emotional response implies that the human brain recognizes faces via two distinct circuits. Both rely on the brain’s automatic analysis of lines and contours and other visual features. But while one circuit alerts us that this face is so-and-so, the other circuit bypasses this conscious route, plugging instead into our emotional centers and calling up the appropriate admiration or disgust. Fully recognizing a face, then, requires both conscious recognition and also what’s called the “glow”—that ineffable connection we feel with someone else. Face-blind people get the glow, but because their visual recognition circuits are faulty, they have to rely on voice or some other clue to actually identify someone.
Now imagine the mirror image of face-blindness: imagine recognizing the face, but feeling no glow. That’s Capgras syndrome. Give victims a stack of Polaroids, and their brains respond to loved ones and strangers with identical flatness. Even when they recognize Mom, their skin, and more to the point their hearts, feel no limbic tingle. That’s not to say that Capgras victims are emotionally stunted. They can usually feel the full range of human emotions—for other stimuli. Faces, though, cannot conjure up the proper feelings, and it’s the chasm between what they once felt upon seeing a loved one and the deadness they now feel that inflicts the agony.
This dual-circuit theory of Capgras received a further boost from V. S. Ramachandran, the neuroscientist who developed the mirror-box th
erapy for phantom limbs (he has a thing for oddball neurology). Ramachandran was treating a thirty-year-old Brazilian man named Arthur who’d bashed his head on a windshield during a car accident. Arthur recovered his speech, memory, and reasoning skills, and never experienced any hallucinations or paranoia. But he confided to his doctors that someone had kidnapped and replaced his father. A rather intelligent man, Arthur knew on some level that this made no sense—why on earth would someone pretend to be his dad? Yet he couldn’t shake the idea.
On a hunch, one day Ramachandran had Arthur’s father walk down the hall and telephone his son, to isolate the effects of voice. To everyone’s delight, the Capgras delusion evaporated. Father and son instantly reconnected—at least for the duration of the phone call. Once they met face-to-face again, Arthur’s suspicions returned. Ramachandran traced this split to a simple anatomical fact. The brain routes both visual and auditory input into the limbic system for subconscious processing, but it uses different neural channels for each sense. Apparently, inside Arthur’s brain, the vision-limbic circuit had suffered damage, while the hearing-limbic circuit had been spared. As a result, his father’s voice retained its glow.
So why didn’t Arthur feel the glow when he spoke to his father face-to-face? The short answer is that we dedicate so much of our brain to processing visual cues—half the cerebral cortex gets pulled in at various points—that vision overwhelms our other senses. So Arthur ignored his father’s voice, however authentic, because in his eyes the man looked so uncannily sinister. Indeed, circumstances play an important role in Capgras delusions. Another way to think about Capgras is that it’s a feeling of jamais vu, the inverse of déjà vu: instead of déjà vu’s tantalizing familiarity in a strange context, Capgras victims sense a sinister strangeness in what should be a safe, familiar context.*
To me, Capgras is one of the most poignant neurological disorders out there. Other neurological diseases can sabotage people’s ability to recognize loved ones, of course. But if dear Uncle Larry suffers from Alzheimer’s and suddenly can’t place you, most people accept that Larry isn’t “there” on some level. Moreover, Larry doesn’t single out any one person. A Capgras victim, meanwhile, seems fully there: his memory and speech and sense of humor remain intact, as do his emotions overall. He still adores the idea of you. But if you reach out to hug him, he’ll reject you—reject you personally.
Beyond the emotional distress, Capgras can also plunge victims into existential quagmires. Consider those people who see doubles of themselves, especially lurking in the mirror. Oddly, these people understand how mirrors work; they realize that every other person on earth sees a genuine reflection there. They nevertheless insist that the mirror is lying in this special case: that’s a double of me. As with Capgras generally, some people respond magnanimously to this intrusion. One man, although irked to find that his mirror-double always wanted to shave or brush his teeth at the same time, couldn’t really hold a grudge against the imposter. Another noted that his double “wasn’t a bad-looking fellow.” More often, though, victims see a mirror-double as sinister: a stalker bent on replacing them. The families of some victims have to cover up mirrors and even reflective windowpanes with curtains, lest the victims catch an inadvertent glimpse and attack.
Above all, Capgras syndrome exposes a rift between reason and emotion inside the brain. We’ve already seen how reason and emotion can support each other. But they can also work at cross-purposes, and Capgras syndrome implies that, of the two, emotion is more primal and more powerful: why else would victims jettison all reason and invent doppelgangers and worldwide conspiracies just to explain a personal feeling of loss? Victims who don’t acknowledge themselves in mirrors even argue for suspending the laws of physics. In some cases you wouldn’t think your mind could survive such a rupture with reality. But it can: its defenses are ingenious, designed to silo your insanity to one topic and spare the mind in general.
While lounging around one afternoon in the spring of 1908, a middle-aged German woman felt an unseen hand grip her throat. She thrashed and gasped as it crushed her windpipe, and only after a great struggle did she manage to pry it loose with her right hand. At which point the offending hand—her own left hand—fell limply to her side. A few months prior, on New Year’s Eve, she’d suffered a stroke, and ever since then her left hand had been lashing out like a rotten child—spilling her drinks, picking her nose, throwing off her bedcovers, all without her conscious consent. Now the hand had choked and bruised her. “There must be an evil spirit in it,” she confessed to her doctor.
Two similar cases popped up in the United States during World War II. Both victims, one woman, one man, suffered from epilepsy and had had their corpus callosums surgically severed to head off seizures. (The corpus callosum, a bundle of neuron fibers, connects the left and right hemispheres.) The seizures did quiet down, but a distressing side effect emerged: one hand took on a life of its own. For weeks afterward the woman would open a drawer with the right hand and the left hand would snap it shut. Or she’d start buttoning up a blouse with her right and the left would follow along and unbutton it. The man found himself handing bread to his grocer with one hand, yanking it back with the other. Back at home, he’d drop a slice into the toaster and his other hand would fling it out—Dr. Strangelove meets The Three Stooges.
As more and more cases emerged, neurologists started calling this syndrome “capricious hand” and “anarchic hand,” but most now refer to it as alien hand—the unwilled, uncontrolled movements of one’s own hand. Alien hand can strike people after strokes, tumors, surgery, or Creutzfeldt-Jakob disease, and while cases usually disappear within a year, sometimes the hand anarchy persists for a decade.
Most cases of alien hand fall into one of two categories. The first involves “magnetic” clasping. A couch potato’s hand snatches the remote and won’t relinquish it. A pinochle player can’t let go of a card she’s dealing. A bingo player uses a nearby chair to pull himself to his feet and drags it all the way to the bathroom without realizing he’s still holding on. That last incident seems unfathomable—how could he not know?—but more often than not, the victim remains oblivious to what his alien hand is doing until something bad happens. It’s a spooky echo of the biblical command for one hand to keep secrets from the other.
The second type of alien hand pits righty against lefty in active opposition. One hand answers the phone, the other hangs up. One hand pulls your pants up, the other drops them to your ankles. And playing checkers? Fuggedaboutit—one hand repeatedly undoes the other’s moves. In a variation, the offending hand might refuse orders: it won’t dust part of the furniture or soap up half the torso in the shower. And in some victims, the two types of alien hand combine. One poor man, a seventy-three-year-old stroke victim with no history of sexual exhibitionism, would occasionally look down in public to find his fly open, his left hand going to town. And boy, once his hand clamped on, there was no letting go.
Many people refer to their alien hands as “imps” or “devils,” and they often take harsh measures to control the mischief, up to and including beatings. Other victims pin their hands between a piece of furniture and the wall to trap them, or muzzle them in oven mitts. Often these measures fail, though—the hand pulls a Houdini—and some people live in constant terror of what it will do next. Alien hands have snatched boiling pots off the stove and grabbed at napkins on fire. They’ve swung axes, and suddenly yanked the steering wheel while driving. About the only known case of a benevolent alien hand involved a woman whose left hand would snap her cigarette case shut before she could get a smoke out.
Through autopsy work, neuroscientists have determined what sort of brain damage causes alien hand. First, victims probably suffer damage to sensory areas. Those areas provide feedback whenever we move our arms voluntarily, and without that feedback, people simply don’t feel as if they’ve initiated a movement themselves. In other words, victims lose a “sense of agency”—a sense of being in control of t
heir actions.
Magnetic grasping usually involves the dominant right hand and usually requires additional damage to the frontal lobes. The job description for the frontal lobes includes suppressing impulses from the parietal lobes, which are curious and capricious and, as the lobes most intimately involved with touch, want to explore everything tactilely. So when certain parts of the frontal lobe go kaput, the brain can no longer tamp down these parietal impulses, and the hand begins to flail and grab. (Neurologically, this flaring up of suppressed impulses resembles the “release” of the snout reflex in kuru victims.) And because the grasping impulse springs from the subconscious, the conscious brain can’t always interrupt it and break the hand’s grip.
Hand-to-hand combat—with one hand undoing the other’s work (pants up/pants down)—usually arises after damage to the corpus callosum, damage that disrupts communication between the left and right hemispheres. The left brain moves the right side of the body, and vice versa. But proper movement involves more than just issuing motor commands; it also involves inhibitory signals. When your left brain tells your right hand to grab an apple, for instance, the left brain also issues a signal through the corpus callosum that tells your right brain (and thus, left hand) to cool it. The message is, “I’m on it. Take five.” If the corpus callosum suffers damage, though, the inhibition signal never arrives. As a result the right hemisphere notices that something’s going on and—lacking orders not to—lurches with the left hand to get in on the action. It’s really an excess of enthusiasm. And because most people perform most tasks with their right hands, it’s usually the left hand that jumps in late and causes this type of alien anarchy. Overall, if magnetic grasping usually involves the dominant half of the brain asserting its dominance even more, then left hand–right hand combat usually involves the weaker half rebelling and trying to win equal status for itself.
