Deception (Lying)

Deception Definition

Deception   is most commonly defined as intentional attempts to mislead others through words or behaviors.

Deception can involve misrepresenting one’s actual beliefs, knowledge, feelings, characteristics, or experiences. The term lying is commonly used to describe explicit verbal deception (e.g., telling your boss that you were late for work because of traffic, when in reality you overslept). However, deception is more than intentionally providing others with false verbal statements; it also includes verbal omissions or the withholding of information (e.g., not telling your spouse about an affair). Deception can also be, and perhaps is most commonly, behavioral (e.g., concealing sadness by smiling, getting cosmetic surgery to appear younger). Lying and purposefully misleading others are generally viewed as socially unacceptable, although some forms of deception are socially accepted and expected (e.g., impression management), and social psychologists have found that individuals commonly mislead themselves in certain ways (self-deception).

Research on the Prevalence and Purposes of Deception

Deception (Lying)Only in recent years has systematic research been conducted to understand how often and why individuals deceive others. This work has led to an important conclusion: Everyone lies. The most direct evidence of this has been conducted by Bella DePaulo and her colleagues. Using survey and diary research methods, they have found that the overwhelming majority of people (approximately 99.5%) report lying daily, willingly describing in detail an average of approximately 1 to 2 explicit verbal lies per day. The most commonly reported lies involve the misrepresentation of one’s feeling and opinions (e.g., telling your grandmother that you like the out-of-style sweater she gave you) and providing false information about one’s actions, plans, and whereabouts (e.g., reporting that you were at the library studying when actually at the pub). Less frequent but still common lies concern misleading others about one’s knowledge or achievements (e.g., lying about one’s academic record), providing fictitious reasons or explanations for actions taken (e.g., blaming computer trouble for late work actually resulting from procrastination), and lies about facts and possessions (e.g., claiming to not have the money to loan to a friend). Commonly reported reasons for lying include to avoid embarrassment, to make a favorable impression on others, to conceal real feelings or reactions, to avoid punishment or aversive situations, and to not hurt others feelings (often called altruistic lies).

Research on Deception Detection

A long-standing interest among social psychologists and others concerns whether deception can be detected. The two approaches to deception detection have been at the interpersonal level and at the technological level.

In general, research indicates that people cannot detect deception during normal social interactions as much as they think they can. Typically, people can detect when others are being deceptive toward them at only a little above the level of chance guessing (i.e., a little more than 50% of the time). Noteworthy research by Paul Ekman and his colleagues has found that judges, police officers, psychiatrists, polygraph experts, business people, lawyers, and students are all not much better than chance at detecting lies. But interestingly, subsequent research indicates that some individuals who have had extensive and direct experience with detecting deception for their profession (e.g., secret service agents, sheriffs, and clinical psychologists with experience with criminal defendants) can do so at levels significantly better than chance. Potentially explaining why some individuals are better at detection than others, it has been found that deception is associated with some subtle behaviors. For example microexpressions, very quick facial expressions that last only a few tenths of a second and are difficult to suppress, have been found to be associated with lying (e.g., a frown quickly followed by a smile). Also found to be related is eye contact, with deceptive individuals often blinking more, having more dilated pupils, and engaging in either very little or an unusually high level of eye contact. Other potential indicators are a raised voice pitch, long response delays, the use of different words than normal, and the presence of inconsistencies among nonverbal cues (e.g., the deceptive person may seem to have normal facial expressions but awkward eye contact or interpersonal distance). Importantly, although indicators of deception have been found, it is clear that no single indicator is a highly reliable cue for lying in all situations. Furthermore, it has been found to be difficult to train people to be more accurate at detecting lies.

The polygraph machine, commonly referred to as the “lie detector machine,” is a device that measures physiological responses such as heart rate, blood pressure, breathing rate, and skin conductance (to measure sweating). These physiological measures are all associated with the autonomic nervous system, the activation of which occurs naturally in situations of threat, stress, and anxiety. The basic assumption underlying the polygraph is that physiological indicators of autonomic nervous system activation will occur when a person is attempting to lie or deceive. The common polygraph technique involves comparing an individual’s responses to control questions (e.g., “What is your name?”) with the individual’s responses to critical questions (e.g., “Did you steal the money?”). If an individual shows more physiological response when responding to critical questions, then deception is “detected” by the logic that only a guilty or deceiving individual would become anxious when responding. While under ideal circumstances, research shows that polygraph machines can detect deception at above-chance levels, they do so well below perfection. As a result, the scientific consensus is that they are far from infallible, and most researchers seriously question the validity of using the polygraph for important legal, security, or employment decisions. What is especially troublesome is that there is no widely agreed-upon method for administering or scoring polygraph examinations. As a result, operators have been found to disagree on the results. Furthermore, it is known that errors are common—both false negatives (declaring deceitful responses as truthful) and false positives (judging truthful responses as lies). There is also evidence that countermeasures—attempts to “beat” the polygraph by controlling physiological responses— can be effective. Lastly, in recent years newer and more sophisticated technologies such as “brain fingerprinting,” in which brain activation patterns are analyzed, have been offered as potentially more accurate methods for lie detection. However, like the polygraph, at this time the scientific evidence supporting the use of such techniques is weak.


  1. DePaulo, B. M. (2004). The many faces of lies. In A. G. Miller (Ed.), The social psychology of good and evil (pp. 303-326). New York: Guilford Press.
  2. Ekman, P. (2001). Telling lies: Clues to deceit in the marketplace, politics, and marriage. New York: W. W. Norton.
  3. National Research Council of the National Academies, Committee to Review the Scientific Evidence on the Polygraph. (2003). The polygraph and lie detection. Washington, DC: National Academies Press.