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Top Ten Myths About the Brain

When it comes to this complex, mysterious, fascinating organ, what do—and don’t—we know?

By Laura Helmuth

1. We use only 10 percent of our brains.
This one sounds so compelling—a precise number, repeated in pop culture for a century, implying that we have huge reserves of untapped mental powers. But the supposedly unused 90 percent of the brain is not some vestigial appendix. Brains are expensive—it takes a lot of energy to build brains during fetal and childhood development and maintain them in adults. Evolutionarily, it would make no sense to carry around surplus brain tissue. Experiments using PET or fMRI scans show that much of the brain is engaged even during simple tasks, and injury to even a small bit of brain can have profound consequences for language, sensory perception, movement or emotion.

2. “Flashbulb memories” are precise, detailed and persistent.
We all have memories that feel as vivid and accurate as a snapshot, usually of some shocking, dramatic event—the assassination of President Kennedy, the explosion of the space shuttle Challenger, the attacks of September 11, 2001. People remember exactly where they were, what they were doing, who they were with, what they saw or heard. But several clever experiments have tested people’s memory immediately after a tragedy and again several months or years later. 

3. It’s all downhill after 40 (or 50 or 60 or 70).
It’s true, some cognitive skills do decline as you get older. Children are better at learning new languages than adults—and never play a game of concentration against a 10-year-old unless you’re prepared to be humiliated. Young adults are faster than older adults to judge whether two objects are the same or different; they can more easily memorize a list of random words, and they are faster to count backward by sevens.

But plenty of mental skills improve with age. Vocabulary, for instance—older people know more words and understand subtle linguistic distinctions. Given a biographical sketch of a stranger, they’re better judges of character. They score higher on tests of social wisdom, such as how to settle a conflict. And people get better and better over time at regulating their own emotions and finding meaning in their lives.

4. We have five senses.
Sure, sight, smell, hearing, taste and touch are the big ones. But we have many other ways of sensing the world and our place in it. Proprioception is a sense of how our bodies are positioned. Nociception is a sense of pain. We also have a sense of balance—the inner ear is to this sense as the eye is to vision—as well as a sense of body temperature, acceleration and the passage of time.

5. Brains are like computers.
We speak of the brain’s processing speed, its storage capacity, its parallel circuits, inputs and outputs. The metaphor fails at pretty much every level: the brain doesn’t have a set memory capacity that is waiting to be filled up; it doesn’t perform computations in the way a computer does; and even basic visual perception isn’t a passive receiving of inputs because we actively interpret, anticipate and pay attention to different elements of the visual world.

6. The brain is hard-wired.
This is one of the most enduring legacies of the old “brains are electrical circuits” metaphor.

But one of the biggest discoveries in neuroscience in the past few decades is that the brain is remarkably plastic. In blind people, parts of the brain that normally process sight are instead devoted to hearing. Someone practicing a new skill, like learning to play the violin, “rewires” parts of the brain that are responsible for fine motor control. People with brain injuries can recruit other parts of the brain to compensate for the lost tissue.

7. A conk on the head can cause amnesia.
Next to babies switched at birth, this is a favorite trope of soap operas: Someone is in a tragic accident and wakes up in the hospital unable to recognize loved ones or remember his or her own name or history. (The only cure for this form of amnesia, of course, is another conk on the head.)

8. We know what will make us happy.
In some cases we haven’t a clue. We routinely overestimate how happy something will make us, whether it’s a birthday, free pizza, a new car, a victory for our favorite sports team or political candidate, winning the lottery or raising children. Money does make people happier, but only to a point—poor people are less happy than the middle class, but the middle class are just as happy as the rich. We overestimate the pleasures of solitude and leisure and underestimate how much happiness we get from social relationships.

9. We see the world as it is.
We are not passive recipients of external information that enters our brain through our sensory organs. Instead, we actively search for patterns (like a Dalmatian dog that suddenly appears in a field of black and white dots), turn ambiguous scenes into ones that fit our expectations (it’s a vase; it’s a face) and completely miss details we aren’t expecting. In one famous psychology experiment, about half of all viewers told to count the number of times a group of people pass a basketball do not notice that a guy in a gorilla suit is hulking around among the ball-throwers.

10. Men are from Mars, women are from Venus.
Some of the sloppiest, shoddiest, most biased, least reproducible, worst designed and most overinterpreted research in the history of science purports to provide biological explanations for differences between men and women. Eminent neuroscientists once claimed that head size, spinal ganglia or brain stem structures were responsible for women’s inability to think creatively, vote logically or practice medicine. Today the theories are a bit more sophisticated: men supposedly have more specialized brain hemispheres, women more elaborate emotion circuits. Though there are some differences (minor and uncorrelated with any particular ability) between male and female brains, the main problem with looking for correlations with behavior is that sex differences in cognition are massively exaggerated.

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