Executive Functions in Young Adults: The Role of Information Processing Speed and Short-Term Memory
Executive functions (EF) continue to be one of the more difficult processes to understand, yet researchers agree that they are critical to our ability to successfully negotiate the complex tasks of day-to-day living. Current models of EF exist in the fields of cognitive psychology, development psychology, and neuropsychology, though these models often contradict each other and raise more questions than answers. The current study expands on existing knowledge by investigating the role of the underlying cognitive processes of EF. Specifically, this study examined the influence of short-term memory (STM) and information processing speed (IPS) on inhibition, switching, and planning abilities. Both STM and IPS have been linked to higher-level EF but have not been investigated in a comprehensive study of EF with a non-clinical population. Using hierarchical regression, STM did not predict EF performance above and beyond working memory (WM). Additional analyses were conducted to determine if STM affected EF indirectly by way of WM. Tests of the indirect effect of STM on each EF through WM, supported this claim. These results question the role of a storage system distinct from that which is included in the WM system. Additional hierarchical regressions found that IPS did not significantly predict either inhibition or switching when controlling for WM. However, IPS was a significant predictor of planning ability. This result supports a developmental understanding of EF whereby functions are related to each other in line with their developmental trajectory. Implications of these findings are discussed along with limitations and opportunities for future research.
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