Control mechanisms in aphasia
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1
San Francisco State University, Department of Special Education and Communicative Disorders, United States
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2
Boston University, Speech and Hearing Sciences, United States
Introduction
This study examines domain-specific and domain-general control mechanisms in bilingual aphasia and compares magnitudes of control in bilingual and monolingual aphasia.
Methods
Thirteen bilingual persons with aphasia (BPWA) and 13 bilingual healthy adults (BHA) completed four tasks (two non-linguistic: NL-Flanker, NL-Triad; two linguistic: LT-Flanker, LT-Triad) that evaluate control (Friedman & Miyake, 2004) and low- and high-complexity levels. All tasks include congruent and incongruent conditions. Congruent conditions are expected to incur faster reaction times (RTs) compared to incongruent conditions (Gray & Kiran, 2015; Green et al. 2010): i.e., the congruency-effect. For evidence of domain-general control, we expect congruency-effects in linguistic and non-linguistic tasks. For evidence of domain-specific control, we expect congruency-effects on linguistic or non-linguistic tasks.
Results
Non-linguistic Tasks
For each group, two repeated measures ANOVAs (R-ANOVAs) examining the effect of congruency as the repeated measure and target as the independent variable were performed. Results are significant at p < .05. NL-Flanker results revealed a significant main effect (ME) of congruency: BHA (F = 25.55) and BPWA (F = 6.86) were significantly faster on the congruent condition compared to the incongruent condition. NL-Triad results revealed a significant ME of congruency: BHA (F = 104.75) and BPWA (F = 20.18) were significantly faster on the congruent condition compared to the incongruent condition.
Linguistic Tasks
For each group, two R-ANCOVAs examining the effect of congruency as the repeated measure and target as the independent variable were performed. L-Flanker results for BHA and BPWA did not reveal significant MEs or interactions. L-Triad results revealed a significant ME of congruency showing that BHA (F = 16.30) are significantly faster on the congruent condition compared to the incongruent condition. BPWA results (F = 5.58) revealed a significant congruency by target interaction effect. Post hoc LSD pairwise comparisons revealed that BPWA are faster on English-congruent conditions compared to English-incongruent conditions.
In a follow-up study, 13 monolingual healthy adults (MHA) and 13 monolingual adults with aphasia (MPWA) completed two non-linguistic tasks. Data analysis mirrored the bilingual analysis. NL-Flanker results revealed a significant main effect of congruency: MHA (F = 14.37) and MPWA (F = 22.95) were significantly faster on the congruent condition compared to the incongruent condition. NL-Triad results revealed a significant ME of congruency: MHA (F = 91.79) and MAA (F = 72.83) were significantly faster on the congruent condition compared to the incongruent condition.
We calculated RT conflict-ratios (incongruent-congruent/congruent) for non-linguistic tasks to examine the magnitude of conflict between groups (MHA/BHA; MPWA/BPWA). Similar to the bilingual statistical design, two-way repeated measures ANOVAs were performed to evaluate the effect of group by task.
Between-subjects results revealed larger conflict-ratios for MPWA compared to BPWA (F = 6.82), indicating that MPWA required a greater amount of control to perform the tasks. For healthy adults, there was no difference in conflict-ratios.
Conclusions
BHA and BPWA results indicate low-complex control mechanisms are domain-specific; whereas high-complex control mechanisms are domain-general. Conflict-ratio results indicate that for healthy adults, the ‘bilingual advantage’ is not observed, whereas BPWA have an advantage compared to MPWA.
References
References
Friedman, N. P., & Miyake, A. (2004). The relations among inhibition and interference control functions: a latent-variable analysis. Journal of experimental psychology: General, 133(1), 101.
Gray, T., & Kiran, S. (2015). The relationship between language control and cognitive control in
bilingual aphasia. Bilingualism: Language and Cognition, 1-20.
Green, D. W., Grogan, A., Crinion, J., Ali, N., Sutton, C., & Price, C. J. (2010). Language control and parallel recovery of language in individuals with aphasia. Aphasiology, 24(2), 188-209.
Keywords:
bilingualism,
cognitive,
Control,
Aphasia,
Language
Conference:
54th Annual Academy of Aphasia Meeting, Llandudno, United Kingdom, 16 Oct - 18 Oct, 2016.
Presentation Type:
Symposium
Topic:
Academy of Aphasia
Citation:
Gray
TJ and
Kiran
S
(2016). Control mechanisms in aphasia.
Front. Psychol.
Conference Abstract:
54th Annual Academy of Aphasia Meeting.
doi: 10.3389/conf.fpsyg.2016.68.00085
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Received:
29 Apr 2016;
Published Online:
15 Aug 2016.
*
Correspondence:
Dr. Teresa J Gray, San Francisco State University, Department of Special Education and Communicative Disorders, San Francisco, CA, 94116, United States, teresag@sfsu.edu