Children's conceptual knowledge of lying and its relation to their actual behaviors: Implications for court competence examinations

Child witnesses must undergo a competence examination in which they must show appropriate conceptual understanding of lying and truth-telling, and promise to tell the truth. Three experiments (Ns = 123, 103, 177) were conducted to address the assumptions underlying the court competence examination that (1) children who understand lying and its moral implications are less likely to lie and (2) discussing the conceptual issues concerning lying and having children promising to tell the truth promotes truth-telling. Both measures of lying and understanding of truth- and lie-telling were obtained from children between 3 and 7 years of age. Most children demonstrated appropriate conceptual knowledge of lying and truth-telling and the obligation to tell the truth, but many of the same children lied to conceal their own transgression. Promising to tell the truth significantly reduced lying. Implications for legal systems are discussed.