Behavioral and Computational Mechanisms of Independent Cognitive Stability and Flexibility Adaptation

Of the core faculties underlying higher order human cognition, two of the most fundamental are the ability to focus on particular task while avoiding distraction (cognitive stability) and the ability to switch to new tasks in light of changing circumstances (cognitive flexibility). Research into the regulation of stability and flexibility has revealed that they often display an inverse relationship: prioritizing task focus (stability) is associated with an impaired ability to switch to new tasks (flexibility), and vice versa. Such findings have led to the common conception that stability and flexibility are endpoints of a one-dimensional stability-flexibility continuum, a perspective that requires them to reciprocate in all cases. However, many empirical findings seemingly contradict a one-dimensional account, such that stability and flexibility might better be described by two separate dimensions. The relationship between stability and flexibility therefore remains unclear. In the current dissertation, I present three studies that investigated the behavioral and computational mechanisms underlying concurrent stability and flexibility regulation. In the first study, I test the assumption of an obligatory stability-flexibility tradeoff, demonstrating across three behavioral experiments that stability and flexibility can be regulated independently. Next, I explore the putative mechanisms explaining tradeoffs, revealing that tradeoffs can be attributed to cost-of-control calculations seeking to reduce cognitive exertion in contexts where it is not incentivized. Third, I conduct a formal model comparison between a one- and a two-dimensional model of stability and flexibility, demonstrating that only the two-dimensional account can accurately reproduce empirical data patterns. The better-fitting two-dimensional model also reveals the dissociable influences stability and flexibility have on the putative decision process underlying task shielding and switching. Finally, I summarize the results and explore the implications of these studies for translational research.