BIS/BAS individual differences and the verification of conditional hypotheses

Two experiments were carried out to examine if the tendency either to verify or to falsify conditional hypotheses has roots in BIS/BAS individual differences (Carver & White, 1994). Experiment 1 presented the participants with a game version of the Wason selection task (Wason, 1966). The hypothesis to be tested was a rule: “Whenever a card has a (certain) letter on one side it has “gain (an amount of) euros” on the other”. Participants were told that the task-goal was to test if this rule was false. Letters could be accompanied either by a gain or by a loss. Of the four cards displayed, one represented a gain and another a loss. The value of gains and losses was manipulated: one card with a large gain and the other with a small loss (one task version), and vice-versa (the other version). Experiment 2 tested the hypothesis that falsification in this task is related to individual differences in BIS sensitivity, while verification is related to individual differences in BAS sensitivity. The results support this hypothesis in the light of the reinforcement sensitivity theory (Gray & McNaughton, 2000).