Evaluation of conditional and biconditional hypotheses in information-use tasks during adolescence

This article describes three studies of the evaluation of conditional and biconditional hypotheses by adolescents and young adults in the age range 11-29 years. Patterns of responding were in accordance with the predictions of the two-stage model of such tasks proposed by Langford (1992). Conditionals and biconditionals gave rise to similar response patterns, suggesting that they are interpreted in similar ways. Conditionals and biconditionals involving changes in variables were more difficult than those involving individual events. The mention of a second possible antecedent to the consequent had little influence on the tendency to convert conditionals to biconditionals. This contradicts the notion that discourse presuppositions are the major source of such conversion. The most plausible alternative explanation is the Piagetian view that individuals seek to avoid the complications of dealing with three factors.