The polygraph test, which measures changes in heart rate, blood pressure, breathing, and sweating, is frequently called a lie detector test. The idea is that these physiological responses can reveal whether someone is lying or telling the truth. The investigator asks control questions to establish a baseline as well as questions pertaining to the case. It is assumed that if the person is lying, anxiety levels will jump, triggering changes in these involuntary bodily functions. However, physiological responses are not one-size-fits-all. An honest person may be nervous when answering truthfully and a dishonest person, especially one who has practiced lying, may not be anxious. Levels can also change due to other factors including confusion, PTSD, nervousness, alcohol or drug withdrawal, psychosis, hypoglycemia, or fear.
Most experts in the scientific and legal fields don’t view polygraphs as being very reliable, so psychologists have started gathering cues from facial expressions, body language, and linguistics to detect deception. Psychologists plan to use this research to create software that can analyze facial expressions and writing style to spot liars.
While deciphering between truthful and dishonest statements is still an inexact science, the Institute for Analytic Interviewing based in Oakland, California is teaching interviewing skills to police interrogators, counter-terrorism agents, airport security guards, and officials from the FBI, CIA, and other federal agencies. Here are some deception cues they are trained to look for:
How Long It Takes to Answer the Question
Liars usually stall by asking for a question to be repeated or clarified. They also show signs of thinking for longer than normal when a reply should not need much thought. However, when they have more time to plan, liars actually start their answers more quickly than truth-tellers.
Answering Questions with Questions
Instead of outright lying, a deceitful person will try to dodge the question altogether first by answering with another question, which is often meant to cast the original question as being preposterous. Examples of these questions include:
– Why would I do that?
– Do I seem like the kind of person who would do something like that?
– When would I have the time to do that?
– How would I get the resources to do that?
– Wouldn’t somebody have to be pretty stupid to do that?
Fewer First-Person Pronouns
Liars try to distance themselves from taking responsibility for their actions by describing events in a passive voice. For example, saying, “The door was locked” rather than, “I locked the door.”
Truthful statements often include specific details, some of which may not be relevant to the question being asked. This happens because honest respondents are recalling from long-term memory and several facts are stored around each experience.
On the other hand, someone fabricating will usually keep their story short and simple, sometimes claiming memory loss by using statements such as “I don’t remember” as an excuse. Most people don’t have the imagination to make up superfluous details and keeping their statement brief minimizes the risk of getting caught in a lie.
Lack of or Negative Emotion
Liars tend to omit emotions or use less emotional descriptions when telling their version of the story. In written accounts, negative emotion words such as hate, worthless, and sad are more prevalent.
Although they provide as little detail as possible, deceptive witnesses frequently use oaths such as “I swear,” “on my honor,” “with God as my witness,” or ”cross my heart” to make their statements sound more credible.
According to Jack Schafer, former FBI agent and author of The Like Switch, there are a couple key techniques you can use to detect deception without people knowing what you’re up to.
Yes or No Question
A yes or no question should result in a yes or no answer. When someone is not able to or does not want to answer yes or no, they will resort to half-truths, allusions, assumptions, innuendos, suppositions, and other great lengths to maintain an illusion of the truth. If someone fails to answer yes or no to a direct question, ask the question again. If they cannot give you a straight yes or no answer, then there is a high likelihood that this person is hiding something.
Why Should I Believe You?
When honest people are asked why others should believe them, their answer is usually something to the effect of, “Because I am telling the truth” without the need to further justify the answer. Deceitful people have a much harder time saying that they are telling the truth because they aren’t. Instead, they say things such as “I have no reason to lie,” “I’m an honest person,” or “You don’t have to believe me if you don’t want to.”
These techniques are not flawless, but if someone exhibits these cues and sidesteps direct questions, red flags should pop up. It doesn’t automatically mean they are lying, but you should be aware that they may not be giving you full disclosure.