Characteristics of sustained attention in continuous performance task (CPT) and its variants

Abstract

Many activities require us to sustain attention over time. Yet laboratory tasks using the continuous performance task (CPT) show that people are unable to sustain attention over a long time. What mechanisms underlie sustained attention and what factors account for the vigilance decline? Two theories provide different perspectives on these questions. One class, termed “underload” theories, postulates that the simplicity and tedium of continuous performance tasks drive people to withdraw attentional resources from the ongoing task, redirecting resources to task-unrelated thoughts. In contrast, “overload” theories propose that the need to maintain constant focus on a task drains attentional resources. As resources are depleted over time, fewer are available for completing a task, such as maintaining control over motor impulsivity. Bearing in mind these different theoretical perspectives, this dissertation investigates the underlying mechanisms of errors in a novel gradual-onset continuous performance task (gradCPT). Study 1 provided an independent replication of rapid vigilance decline in the gradCPT within three 8-min blocks. This study found that the rapid performance decrement was modulated by high task-required response rate, but not by the repetitive nature of the task stimuli or the low target prevalence. Using a within-subject design, Study 2 confirmed the deleterious effects of high task-required response rate on gradCPT performance. This study showed that, compared with abrupt onset, the gradual onset of images enhanced CPT performance, suggesting that the gradual transition of images attenuated motor impulsivity. Individual differences in the gradCPT correlated with performance on a stop-signal task, suggesting that response inhibition in the gradCPT reflects executive control. Study 3 tested the relationship between CPT performance and health and financial concerns about COVID-19 in the middle of the pandemic. This study showed that the severity of COVID-related concerns did not correlate with CPT performance. However, CPT performance was worse for participants who reported to engage in mind wandering more frequently during the CPT. Taken together, this dissertation provides converging evidence that response inhibition is a significant component of the gradCPT. These findings are consistent with overload theories, which posit that the CPT is attentionally demanding and the demand to control repetitive motor responses drains attentional resources. Some of the findings also provide partial support for the underload theories, which posit that errors in the CPT reflect the allocation of attentional resources towards task-unrelated thoughts. These findings are consistent with the resource control theory, which postulates that executive control is required to suppress task irrelevant thoughts and to control motor impulsivity in the CPT. More empirical evidence is needed to characterize the relationship between executive control and vigilance performance.