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Hamlet and the Power of Beliefs to Shape Reality

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


Writing at the close of the nineteenth century, William James, the father of modern psychology (and Henry’s brother), observed that, “Whilst part of what we perceive comes through our senses from the objects around us, another part (and it may be the larger part) always comes out of our own head.” We now know that it is, in fact, the larger part: perception is just as much about construal, belief, the interaction of environment and memory as it is about sensory inputs. It’s a top-down world out there.

What’s more, our beliefs and construals can actually alter our reality. What we believe can, quite literally, be what becomes true. As an example, take intelligence, something that many people believe to be a genetically predetermined entity. While intelligence may indeed have a large genetic component, that is far from all it is.

For many years, Carol Dweck has been researching two theories of intelligence: incremental and entity. If you are an incremental theorist, you believe that intelligence is fluid. If you work harder, learn more, apply yourself better, you will become smarter. If, on the other hand, you are an entity theorist, you believe that intelligence is fixed. Try as you might, you will remain as smart (or not) as you were before. It’s just your original luck. Dweck has repeatedly found that how someone performs, especially in reacting to failure, largely depends on which of the two beliefs he espouses. An incremental theorist sees failure as a learning opportunity; an entity theorist, as a frustrating personal shortcoming that cannot be remedied. As a result, while the former may take something away from the experience to apply to future situations, the latter is more likely to write it off entirely.


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In a recent study, a group of psychologists decided to see if this differential reaction is simply behavioral, or if it actually goes deeper, to the level of brain performance. The researchers measured response-locked event-related potentials (ERPs)—basically, electric neural signals that result from either an internal or external event—in the brains of college students as they took part in a simple flanker task. The student were shown a string of five letters and asked to quickly identify the middle letter. The letters could be congruent—for instance, MMMMM—or, they might be incongruent—for example, MMNMM.

While performance accuracy was generally high, around 91%, the specific task parameters were hard enough that everyone made some mistakes. But where individuals differed was in how both they—and, crucially, their brains—responded to the mistakes. First, those who had an incremental mindset (i.e., believed that intelligence was fluid) performed better following error trials that those who had an entity mindset (i.e., believed intelligence was fixed). Moreover, as that incremental mindset increased—in other words, the more they believed in an incremental theory of intelligence—positivity ERPs on error trials as opposed to correct trials increased as well. And, the larger the error positivity amplitude on error trials, the more accurate the post-error performance.

So what exactly does that mean? From the data, it seems that a growth mindset, whereby you believe that intelligence can improve, lends itself to a more adaptive response to mistakes – not just behaviorally, but also neurally: the more someone believes in improvement, the larger the amplitude of a brain signal that reflects a conscious allocation of attention to mistakes. And the larger that neural signal, the better subsequent performance. That mediation suggests that individuals with an incremental theory of intelligence may actually have better self-monitoring and control systems on a very basic neural level: their brains are better at monitoring their own, self-generated errors and at adjusting their behavior accordingly. It’s a story of improved on-line error awareness—of noticing mistakes as they happen, and correcting for them immediately.

The way our brains act, it seems, is sensitive to the way we, their owners, think, from something as concrete to learning, the subject of the current study, to something as theoretical as free will. From broad theories to specific mechanisms, we have an uncanny ability to influence how our minds work—and how we perform, act, and interact as a result.

At the end, I keep coming back to Hamlet, perhaps one of our most famous examples of frequent, near-obsessive introspection and self-contemplation, someone who was intimately aware of the connection between mindset and subsequent reality. In an exchange with Guildenstern and Rosencrantz, he famously remarks, “Why then ’tis none for you; for there is nothing either good or bad, but thinking makes it so.”

To Hamlet, Denmark is a prison; to his companions, it is no more so than the world at large. How they see it affects how it is—not inherently good or bad, but good or bad as perceived through their own frame of mind. It is, in essence, the exact same principle: our world is what we perceive it to be, and our place in it, how we imagine it. If we think of ourselves as able to learn, learn we will—and if we think we are doomed to fail, we doom ourselves to do precisely that, not just behaviorally, but at the most fundamental level of the neuron.

This post is modified from an earlier version that I wrote for my Artful Choice blog on Big Think.

Maria Konnikova is a science journalist and professional poker player. She is author of the best-selling books The Biggest Bluff (Penguin Press, 2020), The Confidence Game (Viking Press, 2016) and Mastermind: How to Think Like Sherlock Holmes (Viking Press, 2013).

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