Inhibition and Updating Share Common Resources: Bayesian Evidence from Signal Detection Theory and Drift Diffusion Model

Inhibition and updating are fundamental cognitive functions in humans, yet the nature of their relationship—whether shared or distinct—remains ambiguous. This study investigates the relationship between inhibition and updating within a unified task framework using a novel paradigm that integrates the N-back task with the congruent/incongruent Stroop task, creating conditions that require either updating alone or both inhibition and updating. Employing Signal Detection Theory (SDT) and the hierarchical drift diffusion model (HDDM), the results provided overall extremely strong Bayesian evidence that participants exhibited longer response times and lower accuracy in conditions requiring both inhibition and updating, compared to those requiring only updating. SDT analysis revealed a decline in discriminability, while HDDM analysis showed slower drift rates, longer non-decision times and a lower decision threshold in inhibition-demanding conditions. Even after controlling for the congruency sequence effect and current stimulus attributes, the results remained robust, showing a larger inhibition effect size compared to the traditional Stroop task. These findings suggest that inhibition consumes cognitive resources, impairing updating performance, and implying that both functions may rely on shared cognitive resources. Overall, the results elucidate the relationship between these fundamental executive functions, supporting the notion that inhibition and updating share cognitive resources.