When working memory mechanisms compete: Predicting cognitive flexibility versus mental set

Cognitive flexibility is a hallmark of individuals with higher working memory capacity (WMC). Yet, individuals with higher WMC sometimes demonstrate greater rigidity in problem solving. The present research examines a novel account for these contradictory findings-that different WMC mechanisms support versus constrain cognitive flexibility. Across three studies, participants completed the water jug task-a problem-solving task requiring them to first establish and then break mental set. Predictor measures targeted three WMC mechanisms: attention control, primary memory, and secondary memory. In Study 1, primary and secondary memory predicted breaking mental set in opposite directions. Higher primary memory facilitated breaking mental set, whereas higher secondary memory hindered it. Study 2 demonstrated that attention control moderates these effects. Study 3 replicated these results using a less restrictive sampling procedure (i.e., participants were provided the strategy needed to establish mental set). The present research supports the proposed theory of functional opponency in WMC.