In the past, police practices in detecting deception have relied on observation of verbal reports. Behavioral cues such as tone of voice, eye movements, and facial expressions are useful in detecting deception. However, recent research suggests that behavioral cues are not the best way to determine whether a person is lying or not. Moreover, a study conducted by a professor of psychology in San Francisco, David Matsumoto, and CEO of Humintell, found that different cultures exhibit distinct voice characteristics that can be used to detect lies. Chinese participants have higher vocalizations, while Hispanics have lower-pitched voices.
As for the effectiveness of non-verbal cues in detecting deception, research has shown that they are not very accurate. For example, flipping a coin is no more effective than comparing two different people’s words and images. Similarly, it takes more than one study to find a single reliable non-verbal cue. Yet, many practitioners have shown that their methods do have some useful effects, including those that help them identify people’s intentions. Fortunately, in the case of police, accurate deception detection is a vital tool.
Despite the success of recent studies on non-verbal cues, many studies are not able to detect deception. Researchers at the University of California at Berkeley conducted experiments on people’s ability to detect deception. They found that participants were better able to classify words associated with lying when shown pictures of truthful people. The researchers also found that images and words related to truthfulness were associated with higher accuracy than words and images associated with liars.
Physiological responses were more likely to be detected when deception is judged. The most common movements associated with deception were more gaze aversion, leg/foot movements, fidgeting, and trunk/leg movement. In addition, the presence of a smile or a smirk may indicate the presence of a liar. In this way, nonverbal cues in a lie can be detected.
In interviews, a deceptive person is unable to conceal his or her actions. The interviewer can present more evidence if she has more evidence to verify the identity of the accused. Similarly, if the crime victim is a liar, presenting evidence may make the deception more difficult to maintain. The more evidence, the more difficult it will be for the liar to maintain the deception.
There is no definitive evidence that nonverbal cues are the most significant indicators of deception. Nevertheless, research has revealed that there are other factors in human interactions that affect the ability to detect deception. For example, a person’s eye movement might indicate a person’s intention to avert attention. In a situation where the eye and the tongue are not visible, the nonverbal cues may help the person to stay safe.
In contrast, a person’s behavior can be used to determine whether someone is lying. Observations of nonverbal behaviors are the best way to detect lies. A liar’s eyes and body language are distorted. By analyzing the behaviors of others, the person can tell that the speaker is telling a lie. It has been reported that a liar will appear more nervous when compared to a person who is not lying.
According to Vrij et al., the nonverbal signs that liars use are the most likely to be identified by humans. Moreover, the SPOT program is useful in detecting possible terrorists in interview situations. Further, a SYNEROLOGY training course teaches lawyers and law enforcement personnel how to spot a liar.
In other studies, attending to nonverbal cues were associated with the presence of a liar. As a result, the presence of a liar’s gaze and body language could indicate deception. Similarly, the liar’s gaze would be a warning sign. Observers who are able to perceive this kind of movement are more likely to detect a liar than a person who is not.