When plausibility judgments supersede fact retrieval: the example of the odd-even effect on product verification

In the present study, we examined the conditions that favor the plausibility judgment strategy over the retrieval strategy when we verify some statements. In particular, we examined the effect of odd-even status of numbers on subjects' verification of single-digit arithmetic problems. In Experiment 1, we explored how factors such as problem difficulty and stimulus onset asynchrony (SOA) influence this effect in adults. In Experiment 2, we present evidence that this odd-even effect is also present in elementary school children, although it varies with the age of the children, the difficulty of the problems, and the SOA. We argue that the odd-even information is helpful in arithmetic verification tasks with difficult problems early in the verification processes and that the time course of these effects differs across ages. The present results are consistent with the view that the plausibility strategy is preferred over the retrieval strategy at an early stage of processing and with information that is not quickly accessible. Finally, we discuss the implications of the present experiments for understanding of single-digit arithmetic and for understanding the more general issue of how people coordinate use of multiple strategies.