Aurora, Colorado. Judge William Sylvester ruled that authorities may administer a so-called “truth serum” to the July movie theater shooting's defendant in order to determine whether or not he is genuinely insane, should he enter a plea of not guilty by reason of insanity. "It shall also be permissible to conduct a narcoanalytic interview of you with such drugs as are medically appropriate, and to subject you to polygraph examination," Sylvester wrote in his ruling. The counsel for the defense moved unsuccessfully to oppose.
A truth serum is not a truth serum. It lowers inhibitions. A lie detector is not a lie detector. It indicates stress patterns.
"It's an extraordinarily unusual procedure to use," Columbia University professor of psychiatry Steven Hoge, told ABC (Ng, 2013). "The fact that they've linked it to the use of polygraph makes me concerned that they do believe that it is indeed a 'truth serum' and there's no evidence to support that."
The judge’s order did not specify which chemical might be used as the supposed truth serum. The substances most commonly referred to and contemporarily used as truth serums are sodium amytal (amobarbital) and sodium pentothal (thiopental), barbiturates with disinhibiting effects. Both have suffered blows to their credibility for, among other things, fostering false memories (e.g., Shock, 1998). Reducing higher cortical functions could make an individual more truthful – hence the expression, “A drunk man tells no lies,” but that expression is not altogether accurate. Not only can a drunk person lie, that individual can spew forth heaping fantasies and inaccuracies. “There's no scientific evidence that Sodium amytal or other supposed truth serums increase the accuracy of memories,” Lilienfeld (2009) noted on this website, adding that “there's good reason to believe that truth serums merely lower the threshold for reporting virtually all information, both true and false.”
This problem is no recent revelation. Macdonald warned back in 1955 that despite all the publicity over drugging suspects in order to obtain confessions, the methods were unreliable. “The term 'truth serum' suggests the existence of a drug with the remarkable property of eliciting the truth. The reputation enjoyed by truth serum is based on spectacular newspaper reports rather than on carefully documented case reports in professional medical or legal journals,” wrote Macdonald (p. 259). “It might be thought that no problems would arise from the use of drugs on persons who are, in fact, innocent. Unfortunately, persons under the influence of drugs are very suggestible and may confess to crimes which they have not committed.”
Polygraphy fares little better. The polygraph, which records physiological signs of stress like changes in heart rate, respiration, and perspiration, is something of an intimidation device. Despite some polygraph promoters’ claims of 90-100% accuracy, laboratory tests show polygraph accuracy rates more consistently about 60% (Vergano, 2002), little better than chance, with an error rate where false positives outnumber false negatives by as much as 2 to 1 – in other words, experts who make errors are twice as likely to say innocent people are lying than to say the guilty are telling the truth (Kleinmuntz & Szucko, 1984). Physiological and emotional stress, especially when you’re suspected of wrongdoing, does not prove you’re lying (National Research Council, 2002; Saxe, Dougherty, & Cross, 1985); in fact, many inveterate liars spin lies more easily than they tell the truth, and psychopaths may feel unstressed telling either. The polygraph is a useful prop. It may deter wrongdoing by those who believe it works (Ben-Shakhar, 2008) and it can provide a polygrapher with a theatrical tool to help elicit admissions during post-polygraph interviews (Maschke & Scalabrini, 2005). For reasons such as these, polygraphs are generally not admissible as evidence in courts,
No method of lie detection is foolproof. In fact, their use may lull the users into overconfidence that they have unearthed the truth when, in fact, they have not. Ford (2006, p. 174) categorically states, “There are still no techniques that consistently meet the legal standard of scientific evidence and very few that scientists even consider acceptable. Detecting deception is still very much a ‘best-guess’ game.” How in the world can anyone gamble with such methods in such a high-stakes court case? Who would bet the legal status of a mass murderer on any procedure potentially as unpredictable as a roulette wheel?
And what does any of this have to do with proving sanity?
Ben-Shakhar, G. (2008). The case against the use of polygraph examinations to monitor post-conviction sex offenders. Legal and Criminological Psychology, 13, 191-207.
Ford, E. B. (2006). Lie detection: Historical, neuropsychiatric and legal dimensions. International Journal of Law and Psychiatry, 29, 159-177. Retrieved March 14, 2013, from http://huie.hsu.edu:2067/science/article/pii/S0160252706000094
Kleinmuntz, B., & Szucko, J. J. (1984). A field study of the fallibility of polygraph lie detection. Nature, 308, 449-450.
Langley, T. (2012). Batman and psychology: A dark and stormy knight. New York: Wiley.
Lilienfeld, S. (2009, July 7). Michael Jackson, truth serum, and false memories. Retrieved March 14, 2013 from http://www.psychologytoday.com/blog/the-skeptical-psychologist/200907/mi...
Macdonald, J. M. (1955). Truth serum. Journal of Criminal Law & Criminology, 46, 259-263.
Maschke, G. W., & Scalabrini, G. J. (2005). The lie behind the lie detector. (4th digital ed.). Retrieved August 18, 2011, from AntiPolygraph.org: http://antipolygraph.org/lie-behind-the-lie-detector.pdf
National Research Council, Committee to Review the Scientific Evidence on the Polygraph. (2002). The polygraph and lie detection. Washington, DC: National Academies Press.
Ng, C. (2013, March 13). 'Truth serum' draws skepticism in case of accused Aurora shooter James Holmes. Retrieved March 13, 2013, from http://abcnews.go.com/US/truth-serum-draws-skepticism-case-accused-auror...
Saxe, L., Dougherty, D., & Cross, T. (1985). The validity of polygraph testing: Scientific analysis and public controversy. American Psychologist, 40, 355-366.
Stocks, J. T. (1998). Recovered memory therapy: A dubious practice technique. Social Work, 43, 423–436.
Vergano, Dan (2002, September 9). Telling the truth about lie detectors. Retrieved August 18, 2011, from USA Today: http://www.usatoday.com/news/nation/2002-09-09-lie_x.htm
Note: The paragraph on polygraphy comes from Batman and Psychology: A Dark and Stormy Knight (Langley, 2012, pp. 76-77).