Cognitive Psychology: Looking Honestly into Lying

By Peter J. Hills, Michael Pake

Lying is a deliberate attempt to mislead someone verbally or by conveying a false impression through body language. Cognitive psychologists are particularly interested in lying, because it’s a special kind of thought process: unusually, it’s not designed to communicate truthfully with other people. Normal thought and communication is based on trying to provide accurate information (for example, a textbook wouldn’t be much good if it was designed not to tell the truth!). This difference makes lying an unusual process.

People lie at least twice a day and in approximately one-fifth of all interactions lasting more than ten minutes (politicians and the media, no doubt, lie even more often). Men and women lie an equal amount, but women are slightly better at detecting lying (at least among their same-sex friends).

Some people are more likely to lie than others (such as the manipulative and Machiavellian) and some are better at lying than others (the physically attractive and self-confident). Certain groups of people tend not to lie, such as people with a sense of social responsibility and those suffering from depression.

Understanding the cognitive psychology of lying

Although lying is quite frequent, cognitive psychologists have found that it’s a challenging process that demands a great deal of cognitive resources.

Research consistently shows that lying takes longer than telling the truth ‒ honest! The reason is that lying involves two stages: the decision to lie and then the construction of the lie. When someone asks a question to which a person may respond with a lie, the truth is more ‘active’ in the mind of the liar than the lie (unless it’s a highly practised lie ‒ ‘We won’t raise taxes or cut benefits!’). Therefore, if the person decides to lie, he must suppress the truth, which requires cognitive effort. He must then search his memory to produce a lie, using logic to construct a believable one; he also requires a theory of mind (that is, he has to understand how someone else may see the world).

Neuroscientists have discovered that when people are lying, different parts of the brain are active compared to when they’re recalling truthful events. Typically, when people are lying their pre-frontal cortex displays activity, which is the same brain region involved in high-level reasoning.

Developing the ability to lie

Given that lying depends on the liar’s theory of mind and his pre-frontal cortex, it’s no wonder that the ability to lie develops with age.

The temptation resistance paradigm is a typical experiment employed to test children’s fibbing abilities. They’re left alone in a room with a tempting item (such as a chocolate cake or a toy) that the experimenter tells them not to touch. Most young children (under 4 years of age) can’t inhibit the behaviour and they touch the object. When asked whether they touched the object, young children can’t verbalise a convincing lie ‒ they’re too creative and may accidentally indicate the truth in their lie (for example, ‘a mysterious man entered the room and touched it’). This indicates that young children are less able to lie verbally than adults.

The ability to lie develops in parallel with executive functions and theory of mind, and it tends to occur earlier than the ability to construct and maintain a believable lie. From about 7 years of age, children are able to maintain a lie.

Lying in the animal kingdom

Until relatively recent, biologists believed that animals were unable to lie. Work by psychologists, however, shows that many animal species can lie. In one example, researchers partially hid a grapefruit in a chimpanzee enclosure. They then showed the chimpanzees the empty grapefruit box. The chimpanzees were excited and went in search of the grapefruits as a group. They displayed no obvious detection of the grapefruit. But later in the day one of the chimpanzees (when alone) went straight to where the grapefruit was buried, dug it up and ate it. Clearly it had seen the fruit earlier but didn’t want to reveal that it knew the location, because the others would try to steal it.

Apes trained to use sign language, and who’re tested in a similar way as the temptation resistance paradigm, lie in a similar manner to young children. In one classic example, a gorilla was told not to eat a particular fruit, and then the experimenter left the room. The gorilla promptly ate the fruit. When the experimenter returned, the gorilla denied eating the fruit. The limitations of the gorilla’s language mean that researchers will never know whether it could construct a believable lie as to what happened to the fruit, but it was clearly able to lie about eating it.