Meprobamate reduces accuracy of physiological detection of deception.

Normal male subjects attempted to deceive an experimenter recording electrodermal, respiratory, an cardiovascular activity. Those who had ingested a placebo or nothing were detected with statistically significant frequency on the basis of their phasic electrodermal responses, which clearly distinguished them from truthful suspects. That was not the case with deceptive subjects who had ingested 400 milligrams of meprobamate, nor did the examiner detect which subjects had received the drug.