Young children's sensitivity to logical necessity in their inferential search behavior.

Young children's ability to evaluate the logical necessity of 2 types of inferences was studied in 2 experiments involving 68 3-7-year-olds. Children searched the doors of model houses in order to determine whether a house matched a description specifying certain numbers and types of occupants. A search task used in Experiments 1 and 2 allowed children to search for additional information if initial information was insufficient to support a logically necessary inference about whether the house was correct or incorrect. A judgment condition used in Experiment 2 required a "can't tell" response to insufficient information. Even 3-year-olds showed some ability to evaluate the logical necessity of an inference that confirmed a house was correct. Developmental changes involved increased reliability of individuals' performance and increased range of application of children's inference evaluation procedures to include more difficult, disconfirmatory inferences and cases where greater certainty in reasoning seemed to be required. Results are discussed in terms of an account of the gradual development and consolidation of an ability to evaluate the necessity of inferences, perhaps first apparent in preschoolers' sensitivity to conditions of sufficient and insufficient information in information-acquisition problems.