Are Working Memory and Inhibition Distinct or Interacting Components of Executive Function? A Combined Task Approach

Working memory and inhibitory control are widely regarded as core executive function components. Traditional executive function tasks often fail to isolate these components, as they are rarely “process-pure”. This study measured working memory and inhibitory control (both response inhibition and interference control) concurrently within single paradigms, while reducing rule-learning confounds. Two novel tasks were developed: a modified flanker task (targeting interference control) and a spatial conflict task (targeting response inhibition). Each task consisted of multiple blocks of flanker or spatial trials, respectively. Working memory load was manipulated by preloading digit sequences before each block of inhibition trials (ascending = low load, random = high load), recalled after each block. The digit sequences changed for every block to maintain ongoing working memory engagement. Ninety-eight participants completed the spatial conflict task and ninety-seven completed the flanker task. Bayesian repeated measures ANOVAs revealed robust main effects of working memory and congruency on reaction times in both tasks, but provided evidence against over-additive interactions. Findings support the functional separability of working memory (as measured by declarative preload) and both types of inhibitory control in adults and highlight the utility of combined paradigms for more efficient assessment of executive function components with reduced task-related variance.