Children's understanding of modal expressions: Understanding the relative certainty of beliefs.

Abstract

Insight into people's "native" or "folk" epistemology can be gained by examining the way people talk about their beliefs. The modal meanings that are encoded in language reflect people's evaluation of the importance of various aspects of both the sources and the certainty or reliability of their beliefs. The present studies examine children's awareness of the relative nature of the certainty of people's beliefs and, in particular, children's understanding of the language that is used to express this relativity. A series of three studies examines children's understanding of the relative certainty of beliefs as conveyed by three types of modal expressions: evidentials (e.g., see or dream), knowledge state terms (e.g., know or think), and modal auxiliary verbs (e.g., have to or could). Three-, 4-, and 6-year-olds heard statements based on these types of modal expressions. The task was a game in which children were asked to make a forced choice between two statements that convey different beliefs by evaluating the relative certainty of the beliefs as evidence for where an object was hidden. The results of these studies reveal that even children as young as age 3 are capable of understanding the relative nature of the certainty of beliefs as expressed in language though this understanding continues to develop through age 6. Children of all ages demonstrated an understanding of the relative certainty of beliefs as conveyed by knowledge state terms. Four- and 6-year-olds demonstrated an understanding of the relative certainty expressed by modal auxiliary verbs. However, only 6-year-olds demonstrated an understanding of the relative reliability of different evidential bases of beliefs as conveyed by evidentials. In addition, there appear to be substantial individual differences in children's understanding of the certainty of beliefs as conveyed by modal expressions. These results have implications for explaining children's understanding of other people's beliefs and the language that conveys beliefs, and for describing individual differences in the development of that understanding.