The Science of Intuition: An Eye-Opening Guide to Your Sixth Sense
By Annie Murphy Paul
July 14, 2011
Some people think of intuition as a mystical power. Skeptics write it off as a matter of lucky guesswork. But scientists who study the phenomenon say it's a very real ability that can be identified in lab experiments and visualized on brain scans. Read on for gripping findings about your gut feelings, plus surprising ways to tune in to your body's signals and tap the inner powers of your mind.
Research shows that our instincts often hit us first on a visceral level, telling us what we need to know well before our consciousness catches up. Here's what happens when your intuition gets physical.
It's easy to tell something's afoot when your heart is pounding, you're drenched in sweat, and your stomach is tying itself in knots. But even if the shift in your pulse or perspiration is subtler, your intuition may still be trying to deliver a message.
Last year Barnaby Dunn, PhD, a scientist at the Medical Research Council in the UK, conducted a study in which he measured how accurately subjects could count their heartbeats during timed intervals. Then he asked them to play a game, turning over cards from four different decks and winning or losing money based on the cards they drew. What they didn't know was that the decks were rigged: Two had more high-value cards, and two were stacked with losers. As the subjects played, a sensor recorded changes in their heartbeats. After just a few rounds, the monitor showed a dip in players' heart rates whenever they went near certain decks. The body, not the mind, became aware of the difference in the decks first—and Dunn found that some individuals who'd been better able to measure their own heart rates performed better in the game overall.
Scientists at the University of Iowa had performed a similar study earlier, measuring the perspiration on people's palms. What they found: Players started generating stress responses to the bad decks—i.e., sweatier palms—within ten cards. Yet they didn't start suspecting that the decks were rigged until they'd turned over about 50 cards, and not until 80 cards were they able to fully explain how the decks were stacked. Their clammy hands were signaling suspicion long before their conscious minds made the connection.
Tune In: You may be able to better follow your heart (and your sweat glands) by practicing meditation. A 2005 study found that in meditators, brain regions associated with sensitivity to the body's signals and sensory processing had more gray matter. The greater the meditation experience, the more developed the brain regions.
Human eyesight might seem straightforward: The eye receives images, the brain processes them. But we actually have two vision tracks—one conscious, the other intuitive—and as a result, the eye sees far more than we generally realize. For instance, in a phenomenon known as blindsight, people who have gone blind because of brain damage can still navigate an obstacle course or identify emotion on a person's face, even though they can't consciously see it. Their intuitive vision track is receiving visual stimuli, even though their conscious vision track isn't; they know what's around them—they just don't know how they know.
Blindsight patients are an extreme example, but they illustrate a phenomenon everyone experiences: We absorb and retain visual information that doesn't penetrate our conscious mind. Joy Hirsch, PhD, director of the fMRI Research Center at Columbia University Medical Center, has shown that our brains react with anxiety to images of faces expressing fear—even when such images are flashed so quickly we have no idea we've seen them. "The amygdala, which plays an important role in emotional processing, activates in response to these pictures even when they're displayed for only 33 milliseconds—too fast to register in our conscious awareness," says Hirsch. This reaction stems from our earliest origins: When our ancestors confronted strangers, those who quickly discerned the newcomers' feelings and motives were more likely to survive.
Tune In: "We all process things that we're not consciously aware of—it's a feeling of knowing that uses an older brain structure," says neuroscientist Beatrice de Gelder, PhD, who researches blindsight. But because we're so dependent on our sense of sight, she says, we're not used to trusting our intuitive vision track. "If you find yourself in a situation that's making you feel nervous, you may have spotted a reason for concern without even knowing it," says Hirsch. "Pay attention to the sensation."
You may know what it's like to live on carrot sticks and rice cakes. You may not know that eating intuitively—paying attention to your inner satiety meter—is far more likely to lead to a healthy weight than dieting. After assessing the eating habits of 1,260 female college students, Tracy Tylka, PhD, an associate professor of psychology at Ohio State University, found that those who relied on internal hunger and fullness cues to determine when and how much to eat had a lower body mass index than women who actively tried to control their weight through calorie restriction.
In another study, published in 2005 in The Journal of the American Dietetic Association, women who practiced intuitive eating over the course of two years maintained their weight and achieved lower cholesterol levels, lower blood pressure, higher self-esteem, and greater levels of physical activity—while women who dieted over the same period regained any weight they managed to lose and experienced no improvements in their physical or mental health. Further research has shown that intuitive eaters are less likely to think about how their body appears to others, and more likely to spend time considering how their body feels and functions.
Tune In: Becoming an intuitive eater requires the willingness to sit and listen to your stomach's signals. Eat every three to four hours, before extreme hunger sets in, and stop when you feel nourished and energized, not stuffed. Imagining the portion you want to consume before a meal—and what that will physically feel like afterward—is another way to start trusting your gut.
On The Nose
There's a reason we say that a bogus idea doesn't "pass the smell test": Research suggests that our nose plays a major role in certain of our judgments, even if we're not aware of the scents we're detecting. In a recent Israeli study, men were asked to sniff a jar containing either fresh women's tears or saline. The participants who smelled tears rated photographs of women as less sexually attractive, and when the researchers tested the men's saliva, they discovered lower levels of testosterone, which correlates with decreased aggression. The scent of tears may have physiologically prompted the men to be more nurturing and appeasing, and less interested in sex.
But scents don't just shape our impressions of a person; they can sway our behavior as well. Research shows that particular odors encourage shoppers to linger over a product and may even make them willing to spend more money. In one study carried out at a clothing store, the scent of vanilla doubled the sales of women's clothes.
Tune In: While no one has found a way to increase the number of receptors in the human nose, new research suggests that smelling sweat (your own or someone else's) may increase your nose's sensitivity (thanks to chemicals in the steroids naturally produced by sweat glands). More reason to get moving: Exercise itself temporarily improves your olfactory sense, because adrenaline constricts blood vessels in the nose, increasing nasal airflow. Smell receptors that line the inside of your nose regenerate roughly every three weeks, but if you live in an urban area, air pollution can damage the receptors, meaning countryside vacations may temporarily boost sniffing prowess.
Your powers of deduction, reason, and cognition are all important factors in your perception of the world. But your judgment is working even when you're not conscious of the gears turning—and even when you're not conscious, period.
Driven by Distraction
If you had to guess whether it's easier to take in new information when your attention is focused or when you're distracted, you'd guess the former, right? If so, you'd be wrong. In a study published in Nature Neuroscience in 2009, researchers presented subjects with a series of abstract images. The participants gave their full attention to half the pictures but were deliberately distracted by another task while viewing the rest. When shown the images again and asked to identify which they'd seen before, they fared better with the pictures they'd viewed while distracted. "Our intuitive brains are processing information even when we're not paying attention," says Ken Paller, PhD, a coauthor of the study. "And with the brain's analytical system occupied by another task, the intuitive system—which excels at picking up the gist of a scene or situation—is better able to do its work."
Similarly, Ap Dijksterhuis, a psychologist at Radboud University in the Netherlands, has found that distraction can help us make better decisions. In 2006 Dijksterhuis asked study subjects to evaluate four models of cars based on 12 variables. He found that only about 25 percent of those who were given uninterrupted time to ponder their choice opted for the best model, compared with 60 percent of people who were asked to make a spontaneous decision after looking over the cars and then performing another task. "While they were focusing on something else, the unconscious mind was processing the information and integrating it into a valid selection," Dijksterhuis explains.
Tune In: Focus, schmocus! Next time you're faced with a knotty problem, mull your options for a while, stop and concentrate on other things—then go with the first solution that comes to you. Pressing pause on your analysis gives your unconscious mind the bandwidth it needs to filter through the information and come up with the right answer.
Sleep On It
Images of things you encounter during the day (that puppy you pass on the street, the Caribbean cruise ad you see on TV) are stored in your brain, often playing out in a giant mash-up while you sleep (thus the dream where you're walking a beagle in Barbados). It's during the REM stage of sleep that your brain connects that instant replay to other relevant ideas. "REM sleep is good for problem solving and decision making because your brain is putting pieces together and trying out new alternatives," says Rebecca Spencer, PhD, assistant professor of psychology at the University of Massachusetts Amherst. "You gain insights that wouldn't occur to you when you're awake." REM also activates the emotion area of the brain, so "things that are most important to you on a gut level are prioritized," Spencer says.
Several studies have shown that aha moments come following REM sleep. In a 2011 study Spencer coauthored, subjects were asked to perform a gambling experiment that had a hidden underlying rule. One group previewed the task, got a normal night's sleep, and returned the next morning. A second group previewed the task, went about their daytime routine, and returned 12 hours later. Twice as many people who'd slept between previewing and completing the task figured out the rule as the people who'd stayed awake.
Deirdre Barrett, PhD, a professor at Harvard Medical School and author of The Committee of Sleep, studies the ways in which dreams themselves can yield practical insights. In one of her studies, more than one-third of the subjects reported that a dream about a problem guided them to a solution. "Dreams help us get unstuck from our waking mind-set," Barrett says. "They allow us to see solutions that aren't apparent to our logical, conscious minds."
Tune In: Don't lose sleep over a difficult decision; tuck in and let your intuition percolate. To help foster dreams, Barrett recommends "dream incubation": Write down a problem and think about it just before bed, then let your intuitive solution emerge with the morning sun.
Annie Murphy Paul's latest book is Origins: How the Nine Months Before Birth Shape the Rest of Our Lives (Free Press).