Poster A4, Thursday, August 16, 10:15 am – 12:00 pm, Room 2000AB
Lexical access and cognitive control in healthy bilinguals and bilinguals with aphasia: Evidence from the category generation task
Leela A Rao1, Claudia Penaloza1, Swathi Kiran1;1Boston University
Cognitive control plays a crucial role in lexical access in bilinguals by allowing them to switch between languages in a seemingly effortless manner (Friedman & Miyake, 2004; Green et al., 1998). However, the relationship between lexical access and varying degrees of cognitive control demand in the context of speech production remains unclear, especially in individuals with aphasia. The two constructs are frequently assessed together in tasks of semantic category or phonemic letter fluency, but the relative contribution of each to performance on the task is not well understood. In the present study, we investigated the relationship between lexical access and cognitive control in 17 Spanish-English speaking healthy bilingual adults (HB) and 10 Spanish-English speaking bilingual adults with aphasia (BAA) using a battery of language assessments and a semantic category generation task. The category generation task was modified to include three conditions requiring varying degrees of cognitive control: No Switch (NS), or word generation in just one language; Self-Switch (SS), or word generation by switching between languages at will; and Forced Switch (FS), or word generation by switching between languages across items. All participants were given one minute per condition to generate a word list. There were four categories (animals, food, clothing, and transportation), and condition-category pairings were counterbalanced across participants. Total number of items produced, proportion of accurate items to total items, error types, and proportion of direct translations to total number of accurate responses were calculated. Results demonstrated that HB produced significantly more accurate items in both languages than BAA across all conditions, though the number of errors made did not differ significantly across groups. HB also had a greater proportion of accurate responses to total responses across all conditions when compared to the BAA, indicating that HB produced more items with greater accuracy than BAA. Additionally, within-group trends demonstrated that both HB and BAA performed more accurately in the NS and SS conditions compared to the FS condition. However only BAA had a greater proportion of accurate responses on the SS condition (x̄ = .764, SD = .343) compared to the NS condition (x̄ = .666, SD = .363). Our findings suggest that lexical access in HB may become impaired with increasing cognitive control demands on lexical selection, reflecting a language-switching cost. However, lexical access in HB may not be more facilitated in contexts of unconstrained language selection (e.g. the SS condition) when compared to single-language contexts (e.g. the NS condition). In contrast, lexical access in BAA may be facilitated in unconstrained language contexts (e.g. SS condition) while also becoming impaired with increasing cognitive control demands. These results provide greater insight into the relative contributions of lexical access and cognitive control in verbal fluency performance of HB and BAA.
Topic Area: Control, Selection, and Executive Processes