The ability to accurately assess the veracity of statements is an important component of the criminal justice system. We depend on police officers to determine if a suspect is lying or telling the truth; we depend on juries to determine if the defendant’s case or the prosecutions’ case is more believable; we depend on parole boards to determine if a prisoner is ready to be returned to society. In other words, we place a great amount of trust in people’s ability to differentiate between a truthful statement and a lie. The question is, do we place too much trust in this ability? Are humans able to function as accurate lie detectors, or are our attempts to determine the truth just a shot in the dark?
Psychological research suggests that some people are certainly better than others at detecting whether someone is lying or telling the truth; we call these people “wizards”. Research has also shown, however, that employees of the criminal justice system, from judges to police to FBI agents, are no better than the average person at detecting lies, and that the commonly used Reid interrogation method is detrimental for lie detecting abilities.
Rachel Adelson has published an informative article on indicators of lying and on training of law-enforcement officers to be better at detecting liars, and Richard Gray has published a similar article, pointing out many common misconceptions about our ability to detect lies. These articles show a glimmer of hope that lie detecting abilities can be improved and honed. However, psychologist Maureen O’Sullivan advises that efforts be reserved for refining the talents of “wizards” and other individuals who already show some innate talent at determining truthfulness, and cautions that even those who are naturally good at lie detecting still need to put in a considerable amount of work to improve their skills to a useful level.
Another important research finding is that police officers and other authority figures tend to have great confidence in their ability to detect lies even if their lie detecting abilities are no better than the average person’s. Further, jurors place a great amount of trust in the decisions of police officers, believing law enforcement to be more accurate in lie detecting than the average person. So while police can be wrong just as often as you or I would be, police officers themselves and jurors that listen to the police officers’ findings are much more convinced that the police’s conclusion is the right one.
And while the status of human’s lie detecting abilities is still up for debate, it’s now commonly accepted that the polygraph, a machine invented by Leonarde Keeler in the 1930s designed to detect lies, is not up to par. Polygraph tests are no longer admissible as evidence in federal court, and most states have followed suit. Although many people are still under the impression that the polygraph is always able to tell if someone is being deceitful, at best, the polygraph functions as a measure of psychological intimidation designed to push suspects towards confessing.
Weaknesses in lie detecting can largely contribute to wrongful convictions. Police mistakenly determine that an innocent suspect is lying about their innocence, and are confident in their determination. They may administer a lie detector test that further bulks up their confidence and may even produce a confession. Prosecutors, juries, judges, and sometimes even defense attorneys often end up being convinced by the police, rather than assessing the evidence and facts for themselves and “checking the police’s work”, and an innocent suspect ends up convicted and sentenced. Our justice system is based on the assumption that we can accurately determine the truth, but does not have enough safeguards in place to ensure that the truth is always actively sought. This is just another example of how wrongful convictions are not a problem that is easily solved, and require changes at all levels of the criminal justice system.