Humans Only Use 10% of Their Brain

Humans do not use only 10% of their brains. Modern neuroscience shows that the entire brain has a purpose and remains active throughout the day, even during sleep.

Although some tasks activate certain regions more than others, there is no part of the brain that is literally unused or unnecessary.

What We Used to Think

The myth gained traction in the early 20th century, possibly due to:

• Misinterpretation of neurological research about “silent cortex” regions
• Popular psychology writings exaggerating human potential
• Hollywood and self-help books repeating the claim
• A sticky, optimistic idea: “Imagine what we could do with the other 90%!”

By the 1950s this idea was being taught in classrooms, repeated in advertising, and quoted by motivational speakers.

When It Was Disproved

By the 1990s, functional neuroimaging technologies—including fMRI and PET scans—showed that:

• No area of the brain is completely inactive
• Even simple tasks engage multiple regions
• Damage to even small areas has measurable consequences
• Energy consumption is high across the entire brain

These findings directly contradicted the 10% claim.

Why It’s Wrong

• Neurological evidence: Every region of the brain has a measurable function.
• Evolutionary evidence: It makes no sense for humans to evolve a large, energy-hungry organ and only use a small portion of it.
• Injury evidence: Damage to any part of the brain impairs something; there is no “spare 90%” available.
• Imaging evidence: Brain scans reveal activity throughout the cortex, cerebellum, and subcortical structures.

In short: we use 100% of our brain—just not all at the same time.