Abstract

The research reported in this thesis examined the nature of attention shift costs during the processing of complex linguistic stimuli. Experiment 1 tested the hypothesis that linguistic attentional shift costs would occur during the processing of grammaticized linguistic stimuli (function words embedded in sentence-like stimuli). In addition, potential underlying shift cost mechanisms were also investigated. Attention control was operationalized as shift costs obtained by adult English speakers in a 3-stage alternating runs paradigm (Wylie & Allport, 2000). This design enabled results to be analyzed in terms of whether task set reconfiguration processes or task set inertia processes underlie linguistic shift costs. Experiment 1 (Manuscript 1) revealed significant attention shift costs when shifting between tasks involving judgments regarding the meanings of grammatical (function) words. Further, the pattern of results that emerged from the 3-stage design implicated task set reconfiguration processes, but not task set inertia processes, in these linguistic shift costs. Experiment 2 (Manuscript 1) was designed to replicate these linguistic shift costs and investigate whether the degree of grammatical similarity between tasks affects shift costs. Findings again revealed robust linguistic shift costs and demonstrated that shift costs were lower when tasks involved shared attentional resources (processing the same grammatical dimension) as compared to unshared resources (processing different grammatical dimensions). Experiment 3 (Manuscript 2) investigated attention shifting in tasks involving the processing of grammaticized linguistic stimuli (as in Experiment 1 and 2) as well as nongrammaticized linguistic stimuli (content words) in both a first and second language. Participants were adult English-French bilinguals with greater proficiency in their first (English) than in their second (French) language as determined on a speeded word classification task. Findings revealed that participants displayed greater shift costs when performing in their less proficient language. This finding was found to be specific to performance with grammaticized linguistic stimuli and was not obtained with nongrammaticized linguistic stimuli. The results from all three experiments were consistent with a cognitive linguistic perspective that holds that the grammaticized elements of language play an attention-directing role. The results extend previous work by demonstrating shift costs with complex, contextualized stimuli and shift costs in a second language.