The relation between children’s lie-telling and their social and cognitive development was examined. Children (3 - 8 years) were told not to peek at a toy. Most children peeked and later lied about peeking. Children’s subsequent verbal statements were not always consistent with their initial denial and leaked critical information revealing their deceit. Children’s conceptual moral understanding of lies, executive functioning, and theory-of-mind understanding were also assessed. Children’s initial false denials were related to their first-order belief understanding and their inhibitory control. Children’s ability to maintain their lies was related to their second-order belief understanding. Children’s lying was related to their moral evaluations. These finding suggest that social and cognitive factors may play an important role in children’s lie-telling abilities.

T he present study examined lying behaviour in children between 3 and 7 years of age with two experiments. A temptation resistance paradigm was used in which children were left alone in a room with a music-playing toy placed behind their back. T he children were told not to peek at the toy. Most children could not resist the temptation and peeked at the toy. When the experimenter asked them whether they had peeked, about half of the 3-year-olds confessed to their transgression, whereas most older children lied. Naṏve adult evaluators (undergraduate students and parents) who watched video clips of the children's responses could not discriminate lie-tellers from nonliars on the basis of their nonverbal expressive behaviours. However, the children were poor at semantic leakage control and adults could correctly identify most of the lie-tellers based on their verbal statements made in the same context as the lie. T he combined results regarding children's verbal and nonverbal leakage control suggest that children under 8 years of age are not fully skilled lie-tellers.

The development of lying to conceal one's own transgression was examined in school-age children. Children (N=172) between 6 and 11 years of age were asked not to peek at the answer to a trivia question while left alone in a room. Half of the children could not resist temptation and peeked at the answer. When the experimenter asked them whether they had peeked, the majority of children lied. However, children's subsequent verbal statements, made in response to follow-up questioning, were not always consistent with their initial denial and, hence, leaked critical information to reveal their deceit. Children's ability to maintain consistency between their initial lie and subsequent verbal statements increased with age. This ability is also positively correlated with children's 2nd-order belief scores, suggesting that theory of mind understanding plays an important role in children's ability to lie consistently.

Prosocial lie-telling behavior in children between 3 and 11 years of age was examined using an undesirable gift paradigm. In the first condition, children received an undesirable gift and were questioned by the gift-giver about whether they liked the gift. In the second condition, children were also given an undesirable gift but received parental encouragement to tell a white lie prior to being questioned by the gift-giver. In the third condition, the child's parent received an undesirable gift and the child was encouraged to lie on behalf of their parent. In all conditions, the majority of children told a white lie and this tendency increased with age. Coding of children's facial expressions using Ekman and Friesen's (1978) Facial Action Coding System revealed significant but small differences between lie-tellers and control children in terms of both positive and negative facial expressions. Detailed parental instruction facilitated children's display of appropriate verbal and nonverbal expressive behaviors when they received an undesirable gift.

Children's lie-telling behavior to conceal the transgression of a parent was examined in 2 experiments. In Experiment 1 (N = 137), parents broke a puppet and told their children (3-11-year-olds) not to tell anyone. Children answered questions about the event. Children's moral understanding of truth- and lie-telling was assessed by a second interviewer and the children then promised to tell the truth (simulating court competence examination procedures). Children were again questioned about what happened to the puppet. Regardless of whether the interview was conducted with their parent absent or present, most children told the truth about their parents' transgression. When the likelihood of the child being blamed for the transgression was reduced, significantly more children lied. There was a significant, yet limited, relation between children's lie-telling behavior and their moral understanding of lie- or truth-telling. Further, after children were questioned about issues concerning truth- and lie-telling and asked to promise to tell the truth, significantly more children told the truth about their parents' transgression. Experiment 2 (N = 64) replicated these findings, with children who were questioned about lies and who then promised to tell the 'truth more likely to tell the truth in a second interview than children who did not participate in this procedure before questioning. Implications for the justice system are discussed.