Which of the following is a problem associated with using polygraph results as an indicator of whether or not a person?

Lying and deception are common human behaviors, but until relatively recently, there has been little actual research into just how often people lie. A 2004 Reader's Digest poll found that as many as 96% of people admit to lying at least sometimes.

One national study published in 2009 surveyed 1,000 U.S. adults and found that 60% of respondents claimed that they did not lie at all. Instead, the researchers found that about half of all lies were told by just 5% of all the subjects. The study suggests that, although prevalence rates vary, there likely exists a small group of prolific liars.

The reality is that most people probably lie from time to time. Some of these lies are "little white lies" intended to protect someone else’s feelings (“No, that shirt does not make you look fat!”). In other cases, these lies can be much more serious (like lying on a resume) or even sinister (covering up a crime).​

A few of the potential red flags that might indicate that people are deceptive include:

• Being vague; offering few details
• Repeating questions before answering them
• Speaking in sentence fragments
• Failing to provide specific details when a story is challenged
• Grooming behaviors such as playing with hair or pressing fingers to lips
  

If you suspect that someone might not be telling the truth, look at these indicators to help distinguish fact from fiction:

When it comes to detecting lies, people often focus on body language “tells,” or subtle physical and behavioral signs that reveal deception. For example, shrugging, lack of expression, a bored posture, and grooming behaviors such as playing with hair or pressing fingers to lips can give away a person who is lying.

However, although such body language cues can sometimes hint at deception, research suggests that many typical "suspect" behaviors are not always associated with lying. Howard Ehrlichman, a psychologist who has been studying eye movements since the 1970s, has found that they don't signify lying at all. In fact, he suggests that shifting eyes mean that a person is thinking, or more precisely, that they are accessing their long-term memory.

Similarly, other studies have shown that, although individual signals and behaviors are useful indicators of deception, some of the those most often linked to lying (such as eye movements) are among the worst predictors.

The lesson here is that, although body language may be helpful, it is important to pay attention to all the possible signals.

One meta-analysis found that, although people often rely on valid cues for detecting lies, the problem might lie with the weakness of these cues as deception indicators in the first place.

Uncertain speech can belie discomfort and consciousness of guilt. If the person seems unsure or insecure, they are more likely to at least be perceived as lying.

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Look for someone who is telling a lie to leave out important details. After all, they can't be called out for lying about a minor element of a story (and therefore the entire fabrication) if they don't relate it in the first place.

Researchers have come up with a strategy to ferret out lies using the concept of cognitive load. In a study of people asked to report stories in reverse rather than chronological order, the additional challenge made other verbal and nonverbal cues more apparent.

Not only is telling a lie more cognitively demanding, but liars typically exert considerable mental energy on monitoring their behaviors and evaluating responses to maintain credibility.

Lying is more mentally taxing than telling the truth. If you add even more cognitive complexity, behavioral cues may become more apparent.

In another study, 80 mock suspects told the truth or lied about a staged event. Some were asked to report their stories in reverse order and some in chronological order. The researchers found that the reverse-order interviews revealed more behavioral clues to deception.

In yet another experiment, 55 police officers watched taped interviews from the first experiment and were asked to determine who was lying and who was not. The investigation revealed that law enforcement officers were better at detecting lies in the reverse-order interviews than they were in the chronological interviews.

Some experts suggest that relying too heavily on certain signals may impair the ability to detect lies.

Listen to your gut reactions. Researchers had 72 participants watch videos of interviews with mock crime suspects. Some had stolen a $100 bill off a bookshelf; others had not. All suspects were told to say they had not taken the money. Interviewers were unable to consistently detect lies, accurately identifying the liars only 43% of the time and the truth-tellers, 48% of the time.

Researchers used implicit behavioral reaction time tests to assess the participants' more automatic and unconscious responses to the suspects. The subjects were more likely to unconsciously associate words like "dishonest" and "deceitful" with the suspects who were actually lying. They were also more likely to implicitly associate words like "valid" and "honest" with the truth-tellers.

The results suggest that people may have an unconscious, intuitive idea about whether someone is lying.

Conscious responses might interfere with our automatic associations. Instead of relying on instinct, people focus on stereotypical behaviors associated with lying, such as fidgeting and lack of eye contact. However, an overemphasis on such unreliable indicators make distinguishing between truth and lies difficult.

People are surprisingly bad at detecting lies. One study, for example, found that people were only able to accurately detect lying 54% of the time in a lab setting—hardly impressive when factoring in a 50% detection rate by pure chance alone.

Researchers at UCLA conducted studies on lying and analyzed 60 studies on deception to develop recommendations and training for law enforcement. The results of their research were published in the American Journal of Forensic Psychiatry. Lead researcher R. Edward Geiselman suggests that, although detecting deception is never easy, quality training can improve a person's ability to detect lies:

"Without training, many people think they can detect deception, but their perceptions are unrelated to their actual ability. Quick, inadequate training sessions lead people to over-analyze and to do worse than if they go with their gut reactions."

Hosted by Editor-in-Chief and therapist Amy Morin, LCSW, this episode of The Verywell Mind Podcast, featuring psychologist Paul Ekman aka "the human lie detector" shares why people lie and how to tell if someone is lying. Click below to listen now.

The reality is that there is no universal, surefire sign that someone is lying. All of the signs, behaviors, and indicators that researchers have linked to lying are simply clues that might reveal whether a person is being forthright.

Next time you are trying to gauge the veracity of an individual's story, stop looking at the clichéd “lying signs” and learn how to spot more subtle behaviors that might be linked to deception. When necessary, take a more active approach by adding pressure and make telling the lie more mentally taxing by asking the speaker to relate the story in reverse order.

Finally, and perhaps most importantly, trust your instincts. You might have a great intuitive sense of honesty versus dishonesty. Learn to heed those gut feelings.