Only in the past few years has it been recognised that there are two distinct forms of the Wason selection task: indicative and deontic, depending on which kind of conditional and instruction is employed. We use conditionals of an indicative form to codify both common sense and

scientific knowledge, and of a deontic form to express laws, regulations, social agreements, and moral rules. The Wason selection task has been extensively used in the experimental study of these two forms, and for very good reasons, as we shall see in this chapter. We will explore the possibilities of a decision theoretic analysis of the task: one that sees it as a decision problem requiring judgements of subjective probability and utility.