Working memory and everyday conditional reasoning: retrieval and inhibition of stored counterexamples. Thinking and Reasoning

Two experiments examined the contribution of working memory (WM) to the retrieval and inhibition of background knowledge about counterexamples (alternatives and disablers, Cummins, 1995) during conditional reasoning. Experiment 1 presented a conditional reasoning task with everyday, causal conditionals to a group of people with high and low WM spans. High spans rejected the logically invalid AC and DA inferences to a greater extent than low spans, whereas low spans accepted the logically valid MP and MT inferences less frequently than high spans. In Experiment 2, an executive-attention-demanding secondary task was imposed during the reasoning task. Findings corroborate that WM resources are used for retrieval of stored counterexamples and that people with high WM spans will use WM resources to inhibit the counterexample activation when the type of counterexample conflicts with the logical validity of the reasoning problem. The ability to think conditional, if-then, thoughts is considered as one of the cornerstones of our mental equipment. As Edgington (1995, p. 235) puts it, ‘‘there would not be much point in recognizing that there is a predator in your path unless you also realize that if you don’t change direction pretty quickly you will be eaten’’. Similarly, when someone warns you ‘‘If you don’t stop bugging me, I’ll beat you’’, and you want to avoid being beaten up by an angry person, you need to draw a conditional inference. Given the central role that conditional reasoning plays in our causal knowledge system and social interactions, it is not surprising that it has become one of the most intensely studied topics in human reasonin