This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
In 1960 the psychologist Peter Wason set subjects a deceptively simple task. He told them he had a rule in mind that applied to sequences of three numbers, showed them one example, 2, 4, 6, and asked them to discover the rule by proposing their own triples and being told, each time, whether the triple fit. Wason's actual rule was almost nothing: any three numbers in ascending order. Subjects, though, tended to form a much narrower hypothesis from the single example, commonly guessing something like even numbers increasing by two, and then went on to test that narrower guess almost exclusively with triples they expected to confirm it, 8, 10, 12 and the like, rather than triples designed to break it, such as 1, 2, 3. Most announced their overly specific rule with confidence, having never once tried to disprove it. Wason returned to the same territory in 1966 with the selection task, a four card problem asking subjects which cards they needed to turn over to test a conditional rule, and found the identical pattern: people reliably chose the cards that could confirm the rule and skipped the one card that could actually falsify it. Neither experiment was about anything paranormal or occult. Wason was studying ordinary logical reasoning in a laboratory setting, and what he found was a basic asymmetry in how people test their own beliefs, seeking confirmation far more readily than seeking the evidence that could take a belief apart.