Common Myths About the Human Brain That Science Has Moved Past

The 10% myth is perhaps the most durable neuroscience misconception in popular culture, appearing in self-help books, films, and advertisements. Its origin is murky — likely a misquote or misinterpretation of early psychology research — but its staying power is remarkable.

Functional MRI scans show activity across the entire brain over the course of a day. Even during sleep, large portions of the brain remain metabolically active. From an evolutionary standpoint, the brain consumes roughly 20% of the body's energy despite being about 2% of its mass. Maintaining idle neural tissue at that metabolic cost would be biologically nonsensical.

The left-brain/right-brain framework contains a kernel of truth — certain functions are lateralized, meaning they lean toward one hemisphere. Language production, for instance, is predominantly left-hemisphere in most right-handed people. But lateralization of specific functions is not the same as a person having a dominant side that shapes their entire personality or thinking style.

Research published in PLOS ONE by University of Utah scientists found that while task-specific networks activate particular regions, people do not show stronger left- or right-hemisphere networks overall. Creativity and logic both engage distributed networks spanning both hemispheres.

For most of the 20th century, neuroscience held that adults were born with all the neurons they would ever have, and that loss was permanent. Research over the past few decades has fundamentally revised that view.

Neuroplasticity — the brain's ability to reorganize synaptic connections in response to learning, experience, and injury — is now well established across the lifespan. The hippocampus, a region central to memory and learning, has been a particular focus of neurogenesis research. While the degree and significance of adult neurogenesis in humans remains an active area of scientific debate, the broader principle that the adult brain retains substantial adaptive capacity is not seriously contested.

What feels like multitasking is more accurately described as task-switching. Research in cognitive psychology consistently shows that alternating between tasks increases error rates and reduces efficiency compared with completing each task sequentially. The mental overhead of reorienting attention — sometimes called the "switch cost" — adds up significantly over time.

Simple automatic behaviors (walking while talking, for instance) can run in parallel because they draw on different neural systems. But two tasks that both demand working memory and focused attention compete for the same limited cognitive resources.

Decades of research by cognitive psychologists — including landmark work on eyewitness testimony — has demonstrated that human memory is far more malleable than intuition suggests. Recalling a memory is an active process that can subtly alter it, a phenomenon called reconsolidation.

False memories can be implanted under certain conditions, and details from post-event information frequently blend into original recollections. This has significant real-world implications, from legal testimony to how we understand our own life histories. It also doesn't mean memory is useless — rather, it is a sophisticated, adaptive system optimized for meaning rather than perfect accuracy.