Lies and truth: a study of the development of the concept.

This study examined the developmental questions of when children begin to use the terms lie and truth, how they understand them, and when their understanding approaches that of adults. 150 subjects in 5 groups (nursery schoolers, preschoolers, first graders, fifth graders, and adults) were presented a series of 8 short puppet plays that systematically varied the presence of absence of the 3 prototype elements: factuality of a statement, the speaker's belief in the factuality or falsity of the statement, and the speaker's intent to deceive the listeners. The interactions of age, factuality, and belief most fully accounted for the use of the terms lie and truth. Persons at different ages differentially weighed the prototypic elements. Responses of fifth graders were transitional between those of the younger children and adults. The results are interpreted as supporting the development of definitional prototypes for these moral concepts.