If an adult person is not mentally ill and not mentally disabled, then he/she will answer YES to the following questions:

1. Do children sometimes lie?

2. Do teenagers sometimes lie?

3. Do college students and young adults sometimes lie?

4. Do adults sometimes lie?

It take it to be UNCONTROVERSIAL that children, teenagers, young adults, and adults sometimes tell lies.

There might be some who disagree about the claim that VERY YOUNG children tell lies (i.e. children who are only two or three years old), but my previous post in this series provides significant evidence to support this answer: YES, even VERY YOUNG children will sometimes lie.

So, if we all agree that children, teenagers, young adults, and adults sometimes lie, then why am I writing posts on this question? Because the real question is not whether people of various age groups SOMETIMES lie; rather, the real questions are these:

How MANY people lie and deceive?

How OFTEN do people lie and deceive?

How EASILY do people lie and deceive?

What MOTIVATES people to lie and deceive?

How GOOD are people at lying and deceiving?

My main point is that MOST children lie, MOST teenagers lie, MOST young adults lie, and that MOST older adults lie. Another point I want to make is that children OFTEN lie, teenagers OFTEN lie, young adults OFTEN lie, and older adults OFTEN lie. Scientific research can confirm or disconfirm these claims, and scientific research can inform us of the DEGREE to which lying and deception are common human behaviors. The MORE people that lie, the more skeptical we ought to be. The more OFTEN people lie, the more skeptical we ought to be. The more EASILY people will tell lies, the more skeptical we ought to be, and so forth.

The scientific study that I focused in on in the my previous post examined the behavior of VERY YOUNG children. The results of that study show that children as young as two years old will tell lies. In fact, between 25% and 33% of the younger children who ‘transgressed’ by disobeying the rule to not peek (at a toy placed behind them) before being asked to guess what sort of toy it was (based on sounds coming from the toy) lied and said that they had not peeked.

The children who were about three years old in that study who ‘transgressed’ lied at a significantly higher rate. Sixteen of the oldest children in this study were from 43 to 48 months old (3.6 to 4 years old). Ten of those children peeked at the toy, and nine of the ten who peeked lied, that is, 90% of the children who peeked in this older group lied about it!

But what about older children, children from ages four to ten? Perhaps as children grow up, they become more aware of the wrongness of lying and deception, and more aware of social conventions against lying and deception, and more aware of the implications and consequences of lying and deception. So, it is possible that lying and deception decline as children get older and become more mature.

We need to turn to scientific research to find out whether the strong tendency to lie at around three years of age declines, or increases, or stays the same, over the following years of childhood (i.e. from age four to age ten).

Kang Lee, who was one of the psychological researchers who authored the article that I discussed in the previous post, has done a lot of research on lying and cheating and truth-telling by children. One article, in particular, discusses research in recent decades about children lying [emphasis added]:

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Child Development Perspectives © 2013 The Society for Research in Child Development

Volume 7, Number 2, 2013, Pages 91–96

Little Liars: Development of Verbal Deception in Children

Kang Lee

University of Toronto

ABSTRACT— Lying is common among adults and a more complex issue in children. In this article, I review two decades of empirical evidence about lying in children from the perspective of speech act theory. Children begin to tell lies in the preschool years for anti- and prosocial purposes, and their tendency to lie changes as a function of age and the type of lies being told. In addition, children’s ability to tell convincing lies improves with age. In the article, I highlight the central roles that children’s understanding of mental states and social conventions play in the development of lying. I also identify areas for research to be done to develop a more comprehensive picture of the typical and atypical developmental courses of verbal deception in children.

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In the introduction of this article, Lee notes that “No research on lying was conducted between the early 1900s and 1980 (Lewis, Stanger, & Sullivan, 1989).” But this changed in recent decades [emphasis added]:

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Since the late 1980s, research on lying in children has increased, mainly due to three advancements in developmental psychology. One was research on children’s theory of mind (ToM), or the notion that individuals have intentions, desires, and beliefs, and will act accordingly (Wellman, 1992). Lying in essence is ToM in action, because to lie and to lie successfully, individuals must understand their mental state and their listener’s mental state. The second advancement was the increased recognition that culture-specific social conventions play an important role in the development of moral reasoning and behavior (Turiel, 1983). Lying, like any other moral or immoral behavior, increasingly is thought to be influenced not only by universal moral principles but by social conventions (Lee, 2000). The third advancement was the rapid rise in research on eyewitness testimony by children (Goodman, 2006) as a result of an increase in the number of legal cases involving children (Lyon & Dorado, 2008).

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In the article, Lee synthesizes data from several psychological experiments and provides a chart that indicates the percent of ‘transgressors’ or children who do something contrary to directions given by an adult and who then lie and indicate that they did not disobey the directions given by an adult:

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We can see that there is a significant increase in the percent of children who lie about their violation of the rule or instruction given by an adult. At age two only about 30% of ‘transgressors’ lie. At age three it jumps up to about 55%, and by age four about 75% of transgressors will lie. Then there is a smaller increase between age four and five, so that at five about 80% of transgressors lie. Then the trajectory levels out, and stays in the range between 80% and 85% for ages six through ten.

These empirical studies of lying indicate that MOST children who are three years of age or older will lie when they have broken a rule or disobeyed direction given by an adult. Furthermore, this tendency to lie increases significantly between age two and age five, and then levels out at a high percentage (between 80% and 85% of transgressors will lie), from age five to age ten.

So, we do NOT see the tendency to lie DECREASING as children grow older. Rather, it appears that the tendency INCREASES as they learn how to become better at the ‘skill’ of lying and deceiving others. By age five children become fairly skilled at lying and will very frequently lie, at least when they have disobeyed a rule or directions from an adult (‘transgression’), and they will lie even when there is no threat of punishment or no significant reward at stake (which is the case in these experiments).