| Description |
An important aspect of cognitive control is understanding the mechanisms behind the engagement of control and how those mechanisms relate to other aspects of executive attention. Researchers have extrapolated the existence of two important modes (proactive control and reactive control) that appear to operate in dichotomous fashion. Furthermore, research has demonstrated that individuals higher in executive attention may have a proclivity to use proactive control, which requires greater cognitive processing and resources. Through this dissertation, I explored the flexibility of proactive and reactive control engagement, under the theory that some patterns of control engagement may reflect flexibility in response to changing task demands in order to preserve cognitive resources. In previous experiments, we varied the fixation periods in a saccade task from short to long delays and investigated how that would influence control engagement. Results demonstrated that individuals with greater Working Memory Capacity (WMC) changed the way they engaged proactive control in response to changes in the temporal dynamics of the task. The dissertation extended these findings by using the Continual Performance Task (AX-CPT). In the first experiment, participants completed the AXCPT under balanced speed and accuracy instructions, which replicated the findings of other researchers in demonstrating that high-WMC individuals tend to favor proactive control. However, in the second experiment, participants were given instructions that stressed fast responding. Results demonstrated that both high-WMC and low-WMC iv individuals changed how they engaged control in response to speed stress, which appeared to reflect a down-regulation in proactive control rather than a switch to reactive control for individuals with greater WMC. In the third experiment, pupillometry was measured during the AX-CPT under balanced speed and accuracy instructions and demonstrated that high-WMC and low-WMC individuals differ in when and how they engage cognitive control, both prior to an accurate response and following an error. The results are discussed in the context of response-mapping strategies and individual differences in the degree and nature of control engagement. |
