ABSTRACT
One of the most widely used tasks for studying hypothesis testing in inductive reasoning is Wason’s (1960) 2-4-6 problem. In this task, the experimenter tells the participants that he has a rule in mind concerning triples of numbers. The triple 2-4-6 is presented as satisfying the rule, and the participants’ task is to discover this rule by proposing triples. For each proposed triple, the experimenter says whether or nor it follows the rule. The participants are asked to write down each triple, the hypothesis under test, and the experimenter’s response. Whenever the participants think they have discovered the rule, they state it, and the experimenter says whether it is correct or incorrect. If incorrect, the participants continue to propose triples until they either discover the rule or give up. Two phenomena have been observed in the task. In general:
(1) Participants propose triples that are positive examples of the hypothesis they claim they are testing (e.g., the “increasing linear series” hypothesis is tested with triples such as 10-12-14, 10-20-30, etc.).
