The Malleability of Cognitive Control and its Effects on Language Skills
Dougherty, Michael R
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Cognitive control, or executive function (EF), refers to the mental ability to regulate and adjust behavior across domains in the face of interference, conflict, or new rules. Evidence from psycholinguistics suggests a role for cognitive control in a range of language processing tasks including syntactic ambiguity resolution and verbal fluency. Separate work demonstrates that EF abilities are malleable with extensive practice, such that training improvements transfer across domains to novel tasks that rely on the same underlying EF mechanisms (an effect dubbed 'process-specificity'). In uniting these two growing literatures, this dissertation investigated the (causal) role of cognitive control for language processing through two longitudinal training interventions. In one study, I demonstrated that practicing a battery of cognitive tasks conferred selective benefits on untrained reading tasks requiring syntactic ambiguity resolution. Compared to controls, individuals who responded most to an EF training task exhibited (1) higher accuracy to comprehension questions indexing offline reinterpretation, and (2) faster real-time recovery efforts to resolve among conflicting interpretations. A second experiment extended these findings by addressing the degree to which training on a single EF task was necessary and sufficient to confer transfer to untrained, related language measures. Participants were assigned to practice a single training task that was minimally different from other training groups' tasks in terms of EF demands. By and large, participants who practiced a high-EF training task were exclusive in demonstrating a cross-assessment improvement profile consistent with a process-specific account: Pre/post benefits across a range of ostensibly different linguistic (verbal fluency, syntactic ambiguity resolution) and non-linguistic (Stroop, recognition memory) tasks were observed selectively for conditions with high-EF demands; no benefits were seen for cases when the need for cognitive control was minimized. Together, these findings provide support for the malleability of EF skills and suggest a critical (and perhaps causal) role for domain-general cognitive control in language processing. Further, the present studies indicate that within the right framework, and having appropriate linking hypotheses, cognitive training may be a viable way to improve language use.