Morphological Awareness and Word Reading in Developing Readers: A Brain-Behavior Investigation

Abstract

Learning to read changes the mind and brain as children learn to access oral language visually. Skilled word reading relies on closely connected mental representations of word sounds, meanings, and printed forms (Lexical Quality Hypothesis; Perfetti & Hart, 2002). Morphological awareness, or sensitivity to units of meaning in language, is considered a “binding agent” that strengthens these connections (Binding Agent Theory; Kirby & Bowers, 2017). This dissertation advances these theories by asking: What is the influence of morphology on children’s word reading and neural architecture for learning to read? I address this question through a complementary brain-behavior approach that combines fNIRS neuroimaging with language and literacy assessments. In Study 1, I examine the hypotheses that Spanish-English bilingual children process polymorphemic words differently across auditory and visual modalities and that bilingualism influences polymorphemic word recognition. I find that children exhibit stronger engagement of left temporoparietal brain regions associated with integrating word sounds and printed forms when reading derived words (e.g., teach+er) than when listening to them. In other words, developing readers engage auditory-phonological representations when reading complex words with derivational morphemes. Furthermore, better readers in Spanish engage these temporal phonological regions more. This finding suggests that experience with Spanish as a heritage language may support the development of children’s sound-to-print associations and polymorphemic word reading in English. In Study 2, I examine the hypothesis that children benefit from morphological information during word reading, particularly if they have dyslexia. Primes are morphologically, phonologically, semantically, or unrelated to the target word. I find that children with dyslexia and typical readers exhibit morphological priming effects in left frontal and temporal regions associated with processing word sounds and meanings, offering neurocognitive support for Binding Agent Theory (Kirby & Bowers, 2017). Children with dyslexia recognized words fastest when preceded by morphological primes, whereas typical readers benefitted equally from morphological and semantic primes. Nevertheless, children with dyslexia exhibited hypoactivation in left frontal and temporal regions associated with processing word sounds and connecting them to print across all priming conditions. Although children with dyslexia process words preceded by several types of primes differently from neurotypical readers, targeted intervention in morphology may be especially helpful to their literacy development. Taken together, these dissertation findings shed light on the neural underpinnings of morphology and inform theoretical perspectives on the role of morphology in reading development across multilingual learners and children with dyslexia.