Whoever fights monsters...

Detecting Deception

There’s a developing science looking at whether we can tell when a person is lying―or not lying. The developing science shows empirically that persons who are lying about a specific thing have different characteristics than persons who are not lying about a specific thing. The problem is that the evidence is based on group studies. Basically, researchers give a group of people a task, ask some of them to lie about it and others to tell the truth, and they observe the behaviours of the people in both groups - the discipline hasn’t developed to the point where one can reliably determine whether a person is lying.

However, there are factors that strongly suggest a person is lying, such as: 

• if a person hesitates when s/he is describing something, or if s/he makes lots of errors when describing what s/he witnessed, these are clues that the person may be lying
• If a person is actually telling the truth, the person’s speech should be natural, and the description should include lots of details about what happened. It should be delivered in the same pitch of voice, without unnatural pauses, and the speech tense should be consistent.
• some research has shown that when people lie, they often avert their gaze from the person they’re talking to, although other research has shown that some people maintain very strong, unnatural eye contact when lying
• Smiling―the frequency of smiles or laughs―can sometimes be counted, but such gestures have to be relevant. If a person smiles at the wrong time or laughs at things that aren’t funny, those are also indicators of lying
• the frequency of a person’s eye blinks can indicates nervousness, and therefore may be an indicator of lying
• Fidgeting, excessive body movement, shrugs, head movements, and shifts in body position have all been correlated at times with lying, but they’re not exact―there may be other legitimate reasons for such behaviours

Although these are likely indicators of deception in group studies, they can’t be used reliably and specifically to tell whether an individual is lying or not.

Polygraph tests, often referred to as lie detector tests, measure the following physiological variables while a person answers questions or listens to information: 

• blood pressure
• breathing
• heart rate
• sweating (Galvanic skin response, Electrodermal response)

These physiological responses to lying are not thought to be under conscious control. The theory is that if these responses increase during questioning, the individual is experiencing anxiety due to lying. There are three major problems: 

• anxiety while answering the questions does not tell you WHY the person is feeling anxious (maybe they’re not guilty but are anxious about people thinking they are!)
• individuals can be trained to control these responses (intelligence/military officers)
• psychopaths will not experience anxiety while lying and are thought to be able to beat this test quite easily 

While the polygraph test may be an effective investigative tool, the findings or interpretations of polygraph results are not admissible in court. Some police officers have reported that they do not actually care about the results or interpretation of the polygraph test, but they say it’s always useful if an individual offers to undergo polygraph examination because the investigators see it as an opportunity to interview the person. 

There is no real answer as to how effective polygraph tests are for detecting deception. What can be said is that they are accurate at detecting anxiety.