polygraph tests (i.e., lie detectors). In the classic form, the test detected arousal of the sympathetic nervous system, indicating that someone was lying and anxious about not getting caught. The trouble is that you’d get the same anxious arousal if you’re telling the truth but your life’s over if that fallible machine says otherwise. Moreover, sociopaths are undetectable, since they don’t get anxiously aroused when lying. Plus subjects can take countermeasures to manipulate their sympathetic nervous system. As a result, this use of polygraphs is no longer admissible in courts.
