A Trick of the Mind: How the Brain Invents Your Reality

What causes hallucinations? How do conspiracy theories take root? Why are some people convinced a lucky hat can help them catch more fish? Neuroscientist Yon tackles these questions and more in his riveting debut exploration of how the brain shapes perception. The account draws from philosopher Karl Popper’s theory that people live in the worlds of matter, mind, and ideas. To navigate them, Yon argues, the brain functions as a kind of internal scientist, continually evaluating input and constructing or editing perceptual models to help make better predictions. (In linguistic models, for example, “I put butter on my...” primes the brain to hear a word like “toast”; when an unexpected “semantic violation” like “socks” follows instead, it elicits a mental jolt.) Upon encountering a mismatch between data and expectation, the brain must decide whether to revise its model, a choice that’s highly dependent on its overall sense of the world’s unpredictability. Social calamities like the Covid-19 pandemic make the brain more open to editing its models, but can cause it to inadvertently latch onto “malignant ideas” or assign outsize significance to unimportant evidence, creating mental distortions. Yon persuasively argues that better understanding how the brain’s perceptual models work might reveal how to improve social communication, combat harmful dogma, and treat mental illnesses. It’s a scintillating and surprisingly accessible look at why humans think as they do. (Sept.)