Searching for e(xecutive control) in the strength model of self-reg-ulation: an examination into the letter-crossing task

Searching for e(xecutive control) in the strength model of self-reg-ulation: an examination into the letter-crossing task

Self-regulation is the effortful process of controlling the self in order to meet goals or standards. The strength model of self-regulation poses that the resource behind self-regulation is limited in processing capacity, resulting in failures over time (i.e. ego-depletion). This theory was generally accepted until recently, when the literature encountered a replication crisis with widespread re-ported difficulties in replicating the depletion effect. This led to a conceptual crisis questioning whether the effect is legitimate, and if so, what powers this limited reserve. This thesis aims to address three major problems that have arisen in the literature. Since the self-regulation reserve has not been defined beyond a global limited reserve, almost any task can then be employed to induce depletion, provided it is effortful and demanding enough. Because of this, broad defini-tions of self-regulation measures have been applied. These self-regulation tasks, such as the let-ter-crossing task, are rarely scored and analysed. Subsequently, there is no established scoring method or knowledge as to what these tasks are measuring. Following the strength model of self-regulation, which implies depletion effects increase with ongoing processing and time, depletion effects should be observable over time on the letter-crossing task and transfer onto an effortful follow-up task. Over three studies (eight experiments), performance under a modified letter-crossing task was scored, analysed, and compared to standardised executive measures (Stroop, OSPAN, ISR, PI-ISR tasks) to address these three problems. Scoring was formed to measure tar-get accuracy, slope of accuracy over time, task completion time, and self-regulation failures in errors on the letter-crossing task. This revealed that accuracy provided the best measure for de-tecting depletion effects. Direct markers of depletion (functional) provided evidence for deple-tion transfer effects, whereas indirect markers (cognitive) served as theoretical suggestions for the origin of the self-regulation reserve. A downward performance trend line, a functional marker representing depletion effects, was present across the letter-crossing task, however, this depletion effect did not transfer onto the follow-up tasks as initially predicted by the strength model of self-regulation. Individual differences in letter-crossing performance did predict execu-tive functioning on some (OSPAN and ISR), but not all of the follow-up tasks. These findings suggested that components under each of the executive measures (inhibition: Stroop; updating: OSPAN; binding: ISR; and binding with proactive interference: PI-ISR) were related with letter-crossing ability. While each of the executive functioning tasks were correlated to letter-crossing ability, one executive function did not comprehensively account for letter-crossing ability. In-stead, some elements of updating ability (OSPAN) and binding ability (ISR) may employ similar working memory processes to that of the letter-crossing task and, when letter-crossing failures occur, show accountability on these tasks. These findings suggested that a global executive ability can account for letter-crossing ability. The thesis then proposes that self-regulation, as measured by the letter-crossing task, could be explained through higher executive cognitions required for active goal-maintenance, executive control, and working memory.