Date of Completion

Fall 12-15-2020

Thesis Advisor(s)

Inge-Marie Eigsti

Honors Major

Psychology

Disciplines

Clinical Psychology | Cognitive Psychology | Developmental Psychology

Abstract

The strength of hemispheric lateralization appears to be a good predictor of language abilities in children with developmental language impairments. Studies of healthy adults, in contrast, have generally failed to identify any association between degree of lateralization and language abilities, perhaps due to limited sensitivity to individual differences in standardized language assessments. This study used fMRI to measure the lateralization of functional task-engaged language networks in 25 healthy right-handed adults. Linear regressions examined lateralization indices (LI) of language activation in inferior temporal, superior temporal, and frontal brain networks, as a function of syntactic complexity (via story retelling), a grammaticality judgment task, receptive vocabulary (Peabody Picture Vocabulary Test), and nonverbal IQ (NVIQ). These variables together accounted for a significant proportion of LI variance in the inferior temporal network, F(7,95) = 6.67, p = .001, R2=.73; the superior temporal and frontal models were not significant, p’s>.34. In the inferior temporal model, grammaticality judgment accuracy, receptive vocabulary, and number of subordinate clauses were each significant independent predictors of LI, p’s < .05, after entering NVIQ and story length in a previous step. Simple one-way correlations are shown in Table 1. Results indicate that lateralization may support functional specialization in language in healthy adults.

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