You are left-brained or right-brained
The old claim turned out to be wrong and was rejected by evidence.
TaughtLogical, analytical people are left-brained. Creative, artistic people are right-brained. It is a personality type rooted in your brain.
NowA 2013 study analyzing over 1,000 brains found no evidence that people have a stronger left or right network overall. Some functions are lateralized; personalities are not.
What actually happened
The kernel of truth is real. Roger Sperry's Nobel-winning split-brain work in the 1960s showed the hemispheres specialize, and language processing genuinely does lean left in most people. That finding then escaped the laboratory and mutated into a personality theory sold in books, corporate workshops, and classroom posters.
Jared Nielsen and colleagues at the University of Utah tested the popular claim directly, using resting-state fMRI on 1,011 people aged 7 to 29 to look for individuals whose overall brain networks were left- or right-dominant. They found lateralized networks, as expected, but no evidence that any individual is globally left- or right-brained. Being good at math does not mean half your head is doing the work.
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Who was taught this
Still standard through 2016, so anyone who finished school between 1950 and 2013 learned the earlier version.