The ten-percent brain has no hidden reserve

The promise is irresistible: ninety percent of the brain sits dormant, awaiting a method that will unlock it. Scott Lilienfeld and colleagues trace why the slogan fails. Brain imaging finds activity distributed across regions even during simple tasks and rest; damage to small areas can cause specific losses; and metabolically expensive tissue is unlikely to persist unused.

This does not mean every neuron fires at once, which would be neither efficient nor healthy. Different networks contribute at different times, and people can certainly learn new skills. The correction is about unused anatomy, not human potential. Improvement comes from changing connections and strategies in a brain already at work, not switching on a vast silent continent.