I came across more interesting research about possible “placebo effects” in decision making.  According to the two studies cited below, receiving formal training in lie detection (e.g. so that law enforcement officers are more likely to detect a untruthful statement by a suspect) has a curious effect.  The training greatly increases confidence of the experts in their own judgments even though it may decrease their performance at detecting lies.  Such placebo effects were a central topic of The Failure of Risk Management.  I’m including this in the second edition of How to Measure Anything as another example of how some methods (like formal training) may seem  to work and increase confidence of the users but, in reality, don’t work at all.

  • DePaulo, B. M., Charlton, K., Cooper, H., Lindsay, J.J., Muhlenbruck, L. “The accuracy-confidence correlation in the detection of deception” Personality and Social Psychology Review, 1(4) pp 346-357, 1997
  • Kassin, S.M., Fong, C.T. “I’m innocent!: Effect of training on judgments of truth and deception in the interrogation room” Law and Human Behavior, 23 pp 499-516, 1999

Thanks to my colleague Michael Gordon-Smith in Australia for sending me these citations.

Doug Hubbard

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