Deceit is part and parcel of daily life. It not only frequents news headlines in conjunction with political chicanery, corporate scandals, campus cheating, telemarketing scams, identity theft, online predators, and terrorist plots but also permeates the fabric of everyday conversation. People who complete diaries of their communication report 20 to 33 percent of their interactions include some form of deceit and they average two lies per day (DePaulo et al. 1996; Hancock et al. 2004). Biologically, deception is regarded as adaptive, as a part of natural selection that improves chances of survival for animals that are most successful at it. Thus, deceit is not limited to humans. Other species have developed very sophisticated forms of deception ranging from camouflage and mimicry to misdirection, bluffing, and hiding of resources.
Definitions of deception vary but most emphasize that it is an intentional act in which senders knowingly transmit messages intended to foster false beliefs or conclusions by recipients (Knapp & Comadena 1979). Self-delusions are excluded, as are mistaken representations or role-playing in which the audience willingly suspends disbelief. This definition broadens the scope of the concept beyond outright lies to include such forms as omissions, intentional ambiguity, evasions, exaggerations, and the like. Human deception also includes not just deception for self-benefit but also deception intended to benefit others or the interpersonal relationship between sender and receiver. White lies intended to spare another’s feelings, for example, are considered deception just as are blatant falsehoods intended to bilk targets of their fortune or to cover up treasonous acts.
Theories Of Deception
Research on deception has centered largely on one of two issues: deceptive message production and deception detection. Here we focus on theories that relate to message production – converting thoughts into verbal and nonverbal messages – and the message features that have been shown to be reliable indicators of deception.
The Leakage Hypothesis (see Ekman 1985) focuses on the neurophysiology, emotions, and cognitions of deceivers and how changes in these internal states due to deceptive attempts become apparent in behavioral displays. Involuntary signs – referred to as “leakage” because they “leak” out of the body unbidden – act as telltale signs to the actor’s true intentions or state of affairs. Originally, leakage and deception cues were considered to be separate indicators, the former referring to signs of the true emotional state of the deceiver and the latter as signs that one was in fact attempting to deceive. However, all involuntary behaviors are now typically called leakage. This perspective, which partly harks back to Freudian psychology and psychiatric views of human behavior, drives much of the quest for lie-detection tools like the polygraph or vocal stress analyzers that are intended to detect physiological arousal and emotional states.
The Four-Factor Theory (see Zuckerman et al. 1981) is an extension of the leakage hypothesis and attempts to refine the origins of telltale nonverbal indicators of deceit. This theory proposes that (1) arousal, (2) affective reactions, (3) cognitive difficulty, and (4) attempted control all affect deception displays. Deceivers are thought to experience higher levels of arousal that will result in changes such as faster blinking, higher vocal pitch, and more speech dysfluencies. Deceivers also may experience emotional reactions such as guilt and anxiety that are evident in their behavioral displays, often in the form of micromomentary facial expressions – fleeting indications of negative emotions that are seldom recognized by the naked eye. Deception is assumed to require more cognitive effort than does truth-telling. This effort should be reflected in such indicators as more pauses in speech, dilated pupils, and fewer speech-related gestures. Lastly, this theory proposes that deceivers will try to control their leakage, resulting in overly rigid and stilted nonverbal behavior.
Interpersonal Deception Theory (IDT; see Buller & Burgoon 1996) advances a series of propositions (general statements) intended to predict and explain the causes, processes, and consequences of deception in interpersonal interaction. In contrast to the psychologically oriented theories, it distinguishes between strategic and nonstrategic components of messages. The former refer to purposeful features of speech and the latter refer to nondeliberate behaviors including leakage and other forms of impaired performance. This theory argues that because deceivers connive and plan and adjust to accomplish their deception and to avoid detection, deceptive message production must look at these intentional strategies as well as at unintended and involuntary behaviors. Three classes of strategic activity identified by IDT are information management, which concerns the verbal content and style of messages; behavior management, which concerns the nonverbal behaviors that accompany a verbal message and are meant to create a normal communication style; and image management, which concerns general efforts to make oneself appear believable. A strategic perspective is consistent with viewing deception as a persuasive or self-presentational activity. Other key principles of IDT are that deception is adaptive and dynamic. Deceivers do not display the same behaviors constantly; they change in response to feedback from their targets. This means that there are no profiles of deception that can be counted on to remain stable over time. Lastly, deception is interdependent, meaning that what deceivers do is partly dependent on what co-interactants do. If a person questioning deceivers becomes very animated and involved, they will too, which can make them appear truthful. How deceiver and deceived interact and adapt to one another’s behaviors over the course of an interaction is a major focus of IDT.
Information Manipulation Theory (IMT; see McCornack 1992), like IDT, recognizes the strategic nature of interpersonal deception. Drawing upon Grice’s theory of conversation, IMT discusses four maxims that deceivers can violate to achieve their desired outcome. People can say less than is usually expected (the maxim of quantity), they can give untruthful information (the maxim of quality), they can say things that are irrelevant (the maxim of relevance), or they can say them in an unclear, ambiguous fashion (the maxim of manner). Deceivers rely on people’s assumptions that others’ messages are complete, truthful, relevant, and easily understood and they may covertly violate any of the four maxims to produce messages that are deceptive. Information Management Theory (see Burgoon et al. 1996), though similar, is a part of IDT that was developed independently of IMT. It adds a fifth dimension to IMT and elaborates on the semantic and syntactic tactics deceivers can use to intentionally alter the veridicality, completeness, relevance, clarity, and personalism of verbal messages.
The Motivation Impairment Effect (see DePaulo & Kirkendol 1989) hypothesizes that when deceivers try harder (i.e., are motivated), they end up with impaired nonverbal performance but also improved verbal performance, which should affect how detectable their deception is to observers. Challenges have been posed to this hypothesis in part because deceivers may show improved nonverbal performance and impaired verbal performance when they are highly motivated. In other words, motivation sometimes helps and sometimes harms performance but it need not have opposite effects on verbal versus nonverbal behavior.
Indicators Of Deception
Investigations of message features associated with deception have taken two approaches. The first has sought the behaviors that people perceive to be deceptive. Invariably, the number one answer worldwide to the question of how to tell when someone is lying is to look at their eyes. Yet research has confirmed that the eyes are not a good indicator of deceit (DePaulo et al. 2003), partly because skillful deceivers know to look their questioner in the eye. Other widely held stereotypes such as nervous gesturing are also not good indicators. The second approach is to identify actual verbal and nonverbal behaviors that separate truth-telling from deceit. These can be grouped according to IDT’s classifications of nonstrategic and strategic indicators and the division of strategic behavior into information, behavior, and image management.
Nonstrategic behavior includes all the telltale, nonverbal leakage cues of arousal, emotional states, and cognitive effort or difficulty (Vrij 2000). Arousal is the psychological activation in the autonomic nervous system, central nervous system, and/or limbic system. Examples of deception-triggered arousal are fidgeting, self-adaptors (self-touching), pupil dilation, blinking, pitch rise, postural rigidity, and a tense voice. Emotional states are overt reactions that signal discrete and transitory psychology feeling states. Examples include fewer authentic smiles, more forced smiles, and less vocal pleasantness. Micromomentary facial expressions of fear, guilt, or contempt are also purported by some to signal deceit.
Cognitive difficulty is associated with shorter utterances, longer delays in responding, more hesitations, looking away, and temporary cessation of gesturing. Greater cognitive effort need not signal deception, but deception may lead to greater cognitive difficulty. Other cognitive indicators may relate to memory processes and whether senders are accessing real versus fabricated or imagined memories of people and events. Unintended indicators of making up answers rather than reporting real answers include saying less and giving fewer details.
IDT also identifies impaired speech performance as nonstrategic activity. It includes more speech dysfluencies such as stutters, hesitations, and incoherent sounds; fewer punctuating head movements to accompany speech; more stilted posture; reductions in overall conversational involvement; mismatches between verbal and nonverbal channels; and behaviors that are unusual or “fishy-looking.”
Linguistic and content features of deceptive messages are understudied relative to nonverbal features. Deception has been associated with use of fewer words, sentences, and content details; simpler and less complex language; greater uncertainty shown through modal verbs and modifiers; and less personalism (e.g., use of first-person pronouns) and more language that instead refers to others. However, these patterns can reverse under many circumstances, making content and linguistic features very dependent on the specific context.
Behavior And Image Management Indicators
Behavior management is directed toward approximating normal conversational patterns. Image management strategies are more global changes in demeanor intended to preserve a credible image and evade detection. Deceivers may attempt to increase postural, gestural, facial, and vocal involvement. This may include a shift from psychological “distance” to closeness signaled through forward lean, increased eye contact, and direct facing. Deceivers may attempt to become more expressive facially, gesturally, and vocally while simultaneously conveying that they are composed and unstressed through postural stillness while listening and postural relaxation. Efforts to achieve fluid conversational coordination may include fewer pauses, smoother switches in turns between speakers, and more synchronization of behavior between sender and receiver. Deceivers may also strive to appear and sound pleasant. Finally, deceivers may adjust their levels of dominance and formality. They may opt to be submissive, meek, and overly formal if caught off guard but become more dominant and formal if they have time to plan or rehearse their deception. Dominance may include use of a loud, deeper-pitched, more variable voice; more expansive gesturing; and more asymmetrical, relaxed posture.
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