Most recently, deception has been defined as a fundamental element of human communication that can most accurately be conceptualized as an attempt at communicating anything that the communicator considers to be false to a receiver. Notably, this definition does not restrict deception to humans, as deceptive behavior is evident among nonhuman species through behaviors such as camouflaging and mimicry. Further, this definition requires that the deceiver has consciously misled a receiver whereas other definitions have included unconscious misleading as a characteristic of deceit; the role of intentionality in deception continues to be a discrepancy between definitions. Evolutionary theorists propose that deception evolved for prosocial purposes such as promoting social cohesion, and antisocial purposes such as exploiting others.
This distinction delineates the two main types of deception: low-stakes deception and high-stakes deception. Low-stakes lies (i.e., “white lies”) are the most common form of deceit, perpetuated at least once every day for most people, and typically are trivial in nature. Insincere flattery is a clear example of low-stakes lying. Alternatively, high-stakes lies are those told when telling the truth would have severe consequences for the liar. As such, high-stakes lies—relative to low-stakes lies—are of greatest relevance to the legal system. Indeed, legal professionals, such as law enforcement officers and judges, are charged with the task of identifying diverse forms of deception, including highly consequential displays, such as those performed by persons suspected of serious crimes. Fortunately, a number of reliable indicators of deception, particularly those that may present in high-stakes situations, have been identified. Further, various strategies to discern sincerity are available to investigators, including the polygraph test, behavioral analyses, and other specific interrogative approaches. Conversely, police officers use deception to gain valuable information from suspects. Experts have developed a variety of theories to describe the characteristics of deceptive behavior (e.g., motivational impairment effect, inhibition hypothesis) and have also noted several common pitfalls that interfere with accurate deception detection.
The motivational impairment effect theory proposes that liars who are highly motivated to successfully deceive others provide more observable clues to their deceit and subsequently are more likely to be caught in their lie. In light of this theory, high-stakes, emotional lies, such as those told in legal settings, arguably should be easier to detect than trivial white lies because of the detrimental consequences for the liar if his/her insincerity is detected. According to proponents of the motivational impairment effect, attempts to monitor various communication channels (e.g., verbal, facial, and behavioral) that could betray the liar draw on cognitive resources, increasing cognitive load. For example, the liar has to produce a credible story without providing contradictory or suspicious details, mask his/her genuine emotions with more socially appropriate facial expressions, and monitor his/her nonverbal behavior. The combination of high motivation and increased cognitive load during high-stakes deception makes the deceiver less able to adequately control his/her behavior, which in turn makes the liar more susceptible to detection. However, high-stakes emotional lies may not be more readily detected, due in part to reliance on common pitfalls in deception detection.
Despite the potential rich source of information provided by the high-stakes, emotional deceiver, criminal justice professionals (e.g., judges and police officers) and laypeople alike typically detect deceit at the level of chance. This low accuracy rate may be due, in part, to the tendency of individuals attempting to evaluate deceptiveness within the legal system to be led astray by relying on stereotypes, including cues that either have yet to be empirically validated or have been dispelled as being indicators of deception. For example, individuals often consider “looking up and to the left” as a cue to deception; however, research has revealed that there is no credibility to this widely accepted cue. Nervousness and fidgeting are other stereotypical behaviors often wrongly considered to accompany deceptiveness. The reliance on these unsupported cues by legal professionals likely contributes to their poor rate of accuracy when detecting deception.
Overconfidence in one's assessment of credibility also tends to lead to inaccuracy by those trying to assess sincerity. This pattern has been seen not only with laypeople but also with professional lie detectors within the legal system, such as police officers. Further, overconfidence often leads to tunnel vision—a dangerous bias that can cause legal professionals to overlook important facts including exonerating evidence. Natural biases also may play a role in the inability to accurately detect deception. For example, laypeople typically hold a truth bias (the tendency to perceive others as truthful more often than not), whereas law enforcement officers may hold a deception bias (the tendency to perceive others as deceptive more often than not). As such, there are a variety of factors that may lead a lie detector astray and that likely lead to poor detection rates.
Fortunately, some facial, behavioral, and verbal cues have been found to be associated with deception that can aid law enforcement officers as they evaluate suspects' sincerity. There are three main communication channels (i.e., verbal, facial, and behavioral) through which deceivers may betray themselves. Facial expressions, in particular, are a valuable source of emotional information because of the strong connections between facial muscles and areas in the brain that are responsible for the processing of emotion. Charles Darwin was one of the first to study this intimate facial muscle-brain connection and proposed the two-part inhibition hypothesis. He surmised that individuals cannot fully simulate facial muscles associated with a particular emotional facial expression without genuinely feeling that emotion (e.g., people cannot produce full-face expressions of sadness if they are not feeling sad). On the other hand, individuals cannot completely suppress activation of facial muscles associated with a particular emotion they are genuinely feeling (e.g., people cannot fully stop themselves from looking sad when they are sad). These phenomena result in deceptive displays that include either incomplete facial expressions (e.g., facial expressions that only appear on the upper or lower half of the face) or emotional “leakage” of one's true emotion (e.g., brief flashes of true emotion on either the upper or lower half of the face, also known as microexpressions). As such, the face is a valuable channel of emotional information during deception detection.
Additionally, particular body language cues have been identified as being associated with deception in high-stakes situations. For example, liars focused on appearing sincere likely avoid stereotypical behavior considered by many people to be indicative of deceptive behavior, such as gaze aversion and fidgeting. As such, in an attempt to look less deceptive liars may overcompensate by maintaining eye contact for an unnatural length of time and overly restrict their body movement. Further, during everyday interactions people typically accompany their speech with illustrators (i.e., hand movements); however, the cognitive load associated with deception typically results in a reduction of this type of behavior. Although there are specific types of behavior related to deception, it is best to compare the target's behavior during an interrogation following a crime, for example, to his/her baseline (i.e., regular) behavior to assess for changes in behavior.
High-stakes deception also has been associated with particular linguistic characteristics. As with behavioral changes, the increase in cognitive load may result in the liar using fewer words, a slower rate of speech, longer pauses between words, and more frequent hesitations. Further, liars may provide fewer contextual details and fewer reproduced conversations in order to better remember the lie so that they are able to repeat the lie consistently during subsequent reproductions. As such, individuals charged with assessing the veracity of a potentially deceptive target can look to linguistic cues during their evaluation.
One of the most influential theories of deception within law enforcement involves the effects of emotional arousal. The theory behind the emotional arousal hypothesis is that the deceiver, relative to the truth-teller, will experience particular emotions resulting in heightened arousal that manifests as psychophysiological changes. Heightened emotional arousal as a result of deception is the basis for the polygraph—a technique that currently is employed by law enforcement worldwide. The polygraph typically measures a suspect's physiological response to sets of questions that vary in nature (e.g., neutral versus crime-relevant). The physiological measures of interest include blood pressure, heart rate, electrodermal activity (perspiration on the skin), and respiration. Polygraph results are evaluated by subjectively comparing question type with the physiological response exhibited by the suspect. The polygraph operates on the assumption that individuals will demonstrate significant changes from baseline arousal when responding to questions deceptively, relative to responding honestly.
There are a number of different approaches to questioning during a polygraph test, such as the control question technique and guilty knowledge test. Investigators employing the control question technique use neutral (e.g., Is your name Wayne?), relevant (e.g., Were you involved in the girl's disappearance?), and probable lie questions (e.g., Have you ever taken something that did not belong to you?) to compare variations in arousal associated with each type of question. Investigators employing the guilty knowledge technique examine the suspect's physiological responses during questions and associated answers to identify concealed knowledge. For example, an investigator may ask, “What type of gun was used?” and will provide possible answers, such as “Handgun? Automatic? Rifle?” The assumption behind the guilty knowledge test is that only someone who knows which is the correct answer (e.g., the murder weapon) will have a physiological response when they respond negatively (i.e., deceptively) to the actual type of gun used in a crime. While the polygraph continues to be a commonly used method of detecting deception for law enforcement, serious empirically based criticisms regarding the validity of the polygraph as a form of deception detection have arisen over the years. For example, polygraph results are subjectively scored, which can lead to disagreement between polygraph administrators. Further, the heightened physiological response considered to be indicative of deception during a polygraph test can occur for various reasons other than deception, such as the anxiety associated with being suspected of a crime.
Although there are various communication channels that can betray the deceiver, it is often suggested that credibility assessments should be done in a holistic manner using multiple cues as there is no one single behavioral cue that reliably and accurately discriminates liars from truth-tellers. Although focusing solely on physiological arousal has limitations, combining the results of a polygraph test with facial, behavioral, and verbal cues may lead to more accurate evaluations of sincerity.
The prohibition of “third-degree” tactics that were once used by police officers during interrogations has led to an increase in the use of strategic deception as an investigative technique. In the mid-20th century, although law enforcement agencies denied using third-degree tactics, police officers perceived that sometimes these tactics were useful for encouraging guilty suspects to confess to crimes. Inflicting physical or mental pain (i.e., third-degree force) in order to gain information in various legal contexts was a common practice. Physical third-degree tactics include torture and physical assault, whereas psychological third-degree tactics include threats to a suspect's loved ones and deprivation of basic necessities (such as food and water). Not surprisingly, in interrogative contexts this coercion can lead to false confessions; an innocent individual may confess to a crime to escape an extended period of torture or denial of basic needs. Increased recognition of the detrimental consequences associated with these strategies, such as enduring long-term psychological distress and false imprisonment, has resulted in prohibitions against third-degree interrogation methods among domestic police practices. Nonetheless, coercive and interrogative third-degree tactics continued to be used in military settings, such as Afghanistan, Iraq, and Guantanamo Bay, where the deprivation of basic human rights and the torture of detainees has led to widespread condemnation. Indeed, as a result of the controversy surrounding the ethics and efficacy of third-degree tactics, the American Psychological Association (APA) has recently implemented a measure that prohibits member psychologists from participating in many forms of military interrogations.
In response to the considerable problems and questionable benefits of third-degree tactics, many police forces have turned to the use of deceptive behavior to gain information from suspects. Some police deception is generally considered acceptable, such as undercover operations, but other forms of deceptive behavior have been classified as police misconduct. For example, tampering with evidence collected from a crime scene or falsely testifying in court is not permissible by law. As such, police deception may be used at all stages of the legal system, from initial investigations, to interrogations, to giving testimony in court, and manifests in various forms (e.g., sting operations, decoys, withholding or distorting information during interrogation, and altering evidence).
Police deception in the form of undercover operations arguably is the least controversial form of police deception; however, this strategy can bring undercover officers strikingly close to ethical and legal violations. For example, sting operations such as the Mr. Big technique, developed in Canada and prohibited in various other countries, remain controversial. The Mr. Big technique is an elaborate sting that involves several undercover police officers posing as a criminal organization. This organization befriends a suspect whom the police believe perpetrated a serious crime but do not have sufficient evidence to bring the case to trial. The operation proceeds through a series of stages aimed at gaining the trust of the suspect (e.g., providing money) and instilling fear in the suspect (e.g., mock assaults) leading to an invitation that the suspect join the organizing contingent, proving his/her loyalty to the head of the organization (Mr. Big) by confessing to the crime in question. Confessions are recorded and used at trial. The controversial aspect of the Mr. Big technique is that it can lead to innocent suspects falsely confessing for various reasons, including peer pressure or fear of upsetting the head of a criminal organization. Despite being linked to false confessions, deceptive techniques, such as sting operations, remain among the arsenal of acceptable police conduct in many contexts.
In sum, deception is a common aspect of everyday communication with consequences that range from minor to severe depending on context. Although reliable cues to deception can be gleaned from verbal, facial, and behavioral communication channels, common pitfalls may lead lie detectors astray. Deception is particularly controversial when employed within the criminal justice system by both suspects and law enforcement officials and can have severe consequences for all of those involved.
See Also: Confessions, Coerced; Deceptive Interrogation; Polygraphs
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