How can a cellist play like an angel? Why am I engrossed in my book when others struggle with reading? And while we’re at it, can you tell me why my child won’t stop screaming?
Now neuroscience offers the answers—or so say the news headlines. The brains of musicians “really do” differ from those of the rest of us. People with dyslexia have different neural connections than people without the condition. And your screaming toddler’s tantrums originate from her amygdala, a brain region linked to emotions. It’s all in the brain!
Neuroscience is fascinating. But it is not just the love of science that kindles our interest in these stories. Few of us care for the technical details of how molecules and electrical charges inthe brain give rise to our mental life. Furthermore, invoking the brain does not always improve our understanding. You hardly need a brain scan to tell that your toddler is enraged. Nor is it surprising that an amateur cellist’s brain works differently than Yo-Yo Ma’s—or that the brains of typical and dyslexic readers differ in some way. Where else would those differences reside?
These sorts of science news stories speak to a bias: As numerous experiments have demonstrated, we have a blind spot for the brain. In classic work on the “seductive allure of neuroscience,” a team of researchers at Yale University presented participants with a psychological phenomenon (for instance, children learning new words), along with two explanations. One invoked a psychological mechanism, and the other was identical except it also dropped in a mention of a brain region. The brain details were entirely superfluous—they did nothing to improve the explanation, as judged by neuroscientists. Yet laypeople thought they did, so much so that once the brain was invoked, participants overlooked gross logical flaws in the accounts.
Why people fall in love with brain-based explanations, however, has remained a scientific mystery. Past studies make it clear that neither the use of vivid brain images, nor the complexity, nor the science jargon alone drives people’s preference for brain explanations of psychological phenomena. Although they play a role, the fascination with the brain remains even when scientists remove these factors. Reductionism, the tendency to explain scientific phenomena at one level by appealing to a more basic level (such as reducing biology to chemistry), presents another explanation. Researchers have found that people do, indeed, prefer reductive explanations. But the preference to reduce psychology to neuroscience is particularly strong—more so than in other scientific domains.
Several recent investigations by my lab shed new light on the mystery. In a series of studies, my colleagues and I invited hundreds of participants—all nonscientists—to “play clinician.” They had to diagnose a clinical condition using either a brain or behavioral test. The two tests were equally likely to provide a diagnosis. In every case, however, people thought that the brain test was more informative, and they drew inferences that went far beyond what the test actually suggested. These assumptions, in turn, revealed that people hold beliefs about the brain that may help to explain why they fall for neuroscientific explanations in the first place.
To imagine these experiments, suppose that you, as a clinician, had to diagnose a patient who might have autism. The diagnostic test focuses on a well-studied characteristic of the condition: that people with autism struggle to infer what other people might know and think in a given situation as separate from their own knowledge and thoughts. You present your patient with a video featuring one character, Bob, moving the car keys of another character, Jane, when she isn’t looking. The patient must predict whether Jane will search for her keys where she previously left them or where Bob put them (a fact known only to the patient). Because many people with autism assume others have the same knowledge they themselves have, when a patient with autism is shown this video, the patient will expect Jane to search for her keys where Bob left them. Your goal is to detect whether your patient is surprised when Jane instead searches the area where she put her keys.
At this point, you have a choice: You can observe the patient’s reaction using a behavioral method, such as eye-tracking technology. With this approach, you can detect surprise if the patient stares at Jane for a long time. Or you can use a brain-monitoring technique where a “spike” in activity indicates surprise. Which test is better?
In truth, the two tests are equivalent. But, as you might expect, most people favor the brain test. To find out why, my colleagues next asked participants to consider a different scenario. Once again, the patient was suspected of having autism, but this time, the symptom participants were looking for was a sensation: a hypersensitivity to sound, which causes people with autism to get distracted by noises. As before, this condition was diagnosed using either behavior (where eye movement reveals the patient’s distraction) or brain monitoring (where distracting noises would increase brain activity). But this time, the preference for brain tests was far weaker.
Why do people prefer the brain-based evidence when they consider someone’s thoughts more than when they focus on sensations? My colleagues and I suggest the difference reflects how people perceive thoughts on the one hand and sensations on the other. People tend to interpret sensations as “embodied”—that is, we link them to specific body parts. We hear with our ears and see with our eyes. But thoughts, by contrast, seem strangely ethereal, even though we rationally know they “live” in the brain. This tendency to view the mind as distinct from the body is called dualism. My group has investigated this intuition extensively in past work and found it slips into many of our tacit assumptions about cognition. For example, people suspect that thoughts are more likely than sensations to remain in the afterlife but less likely to show up in a brain scan. So science notwithstanding, at heart, we are closet dualists—we conceive of the mind as distinct from the body.
Dualism could help to explain the seductive allure of neuroscience. That’s because our dualist intuitions put us in an uncomfortable position whenever we encounter evidence that our ethereal thoughts interact with the body. In a recent experiment, when I asked people to reason about the causes of everyday actions, such as reaching one’s arm toward a coffee mug, people rated thoughts (thinking about coffee) as more surprising causes of their arm’s action than perceptions (seeing the coffee). So although we readily attribute people’s actions to their thoughts, deep down, this effect of mind on matter is unsettling. But brain-based explanations alleviate this tension. If it is the brain—part of one’s body—that made one’s hand (body) move, then there are no more ghostly interactions between mind and matter—mystery solved! Brain explanations are seductive, I argue, because they alleviate a mind-body tension created by our dualist intuition. And because this dualist tension is particularly acute for thoughts, the allure of the brain explanation is stronger for thinking than sensing, which we align with the body.
There is more to our infatuation with the brain than just dualism, however. Not only do many individuals consider brain-based explanations more attractive, but my lab has also found evidence that people tend to believe information linked to the brain can reveal a person’s inborn “essence.” So when participants learn that a woman’s depression was diagnosed with a brain test, they incorrectly conclude that depression runs in her family and that the symptoms will last a long time. If her condition was diagnosed with a behavioral assessment, participants are less convinced of a family connection or that symptoms will persist for a lengthy period. (In reality, the test type has no bearing on these matters.)
We believe these findings reflect a second principle of intuitive psychology: Essentialism is the belief that living things are what they are because of an immutable essence that resides in each person’s body. When people think a depression diagnosis involved a brain scan, their essentialist intuition that “what’s in the body is innate” makes them perceive the patient’s depression as inborn and unchangeable. Essentialism, then, offers another explanation for the brain’s seductive allure.
On a rational level, we all know that thinking happens in the brain and that our brain isn’t our immutable essence or destiny. But as the studies in my lab make clear, our intuitive psychology suggests otherwise. The consequences are far-reaching. Not only do these beliefs kindle our irrational love affair with the brain, but they can also seriously sway our thinking about psychological disorders and promote stigma toward patients.
Thankfully, our rationality can keep these biases at bay, promoting better science literacy and a kinder society. To do so, we must face our biases by taking a hard look within.
Are you a scientist who specializes in neuroscience, cognitive science or psychology? And have you read a recent peer-reviewed paper that you would like to write about for Mind Matters? Please send suggestions to Scientific American’s Mind Matters editor Daisy Yuhas at [email protected].