People who can't understand words are better at picking up lies about emotions. People are usually no better than chance at detecting lies from a liar's demeanour1,2, even when clues to deceit are evident from facial expression and tone of voice3. We suspected that people who are unable to understand words (aphasics) may be better at spotting liars, so we tested their performance as lie detectors. We found that aphasics were significantly better at detecting lies about emotion than people with no language impairment, suggesting that loss of language skills may be associated with a superior ability to detect the truth.