Humans can accurately report how confident they are in their decisions. A study compared two theories about how this confidence is determined. The researchers found that people do consider uncertainty when reporting confidence, which suggests that the brain can use sensory information to make these judgments. However, people's behavior doesn't always match the predictions of the Bayesian theory, which suggests that simpler models may better explain how confidence is reported. These findings suggest that understanding how confidence works in the brain may require considering practical limitations.