Why are we so bad at knowing we’re being lied to?

People's typically poor aptitude at telling when others are lying has partially to do with the sophisticated parts of the brain that the liar uses to construct the lies. However, when a liar lies, other parts of the brain are activated as a side effect--those parts of the brain are not as sophisticated, and the behaviors they cause are easier to detect if you know what to look for. Luckily, what to look for is contained in this infograph: