Police lie detection: Accuracy, training and new directions

Our review of the research on lie detection accuracy in the forensic context supports the view that some law enforcement professionals are highly expert lie detectors, but only if their abilities are assessed with appropriate materials. We identify other problems in the existing literature, and discuss recent advances in studying how law enforcement officials make accurate judgments of the truth by using examples drawn from existing studies. We also find advances in the ability to train people to improve lie detection accuracy since the early 1990's; these advances reflect scientists and trainers using more sophisticated teaching materials, including more appropriate deception stimuli. In the 1990's average gains in lie detection accuracy after training were about 4 percent. Since 2000, post training gains in lie detection accuracy as high as 37% have been reported. We end by reviewing some new directions in terms of theoretical models and empirical findings related to a better understanding of the factors involved in accurate lie detection. Although scientists and law enforcement professionals sometimes have different goals, in recent years the applicability of scientific research to the investigative needs of police professionals has been greatly increased.