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Tracing adults’ word segmentation abilities: A comparison between younger and older bilinguals
Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 3 and 4
Patricia Fuente-García1, Julián Villegas2, Irene de la Cruz-Pavía3,4; 1University of the Basque Country, 2University of Aizu, 3University of Deusto, 4Basque Foundation for Science, Ikerbasque
Breaking down continuous speech into meaningful units is not a trivial task, yet humans accomplish this feat effortlessly. A wealth of work has shown that adults and infants automatically integrate a number of cues available in the signal and has revealed important changes in their relative weight and interplay across development (e.g., Mattys et al., 2005). However, a single study to date has examined whether their use remains constant throughout adulthood (Palmer et al., 2018). Similarly, the handful of studies available investigating the segmentation abilities of bilingual populations have exclusively focused on infants and young adults. In this study, we investigate whether adults’ segmentation abilities remain constant in healthy aging. Additionally, we explore bilinguals’ word segmentation abilities of a second language. Viewing bilingualism as a multifaceted construct and a continuum (Dash et al., 2022), our study seeks to understand whether and how four key dimensions of bilingualism—age of acquisition, language proficiency, language use and frequency of language switch—determine older bilinguals’ use of semantic, syntactic and phonological information in word segmentation. We tested 72 healthy older (60-79) and 87 young (18-35) Spanish-Basque bilinguals that varied greatly in their knowledge, use and age of acquisition of Basque, and two control groups of Basque-Spanish bilinguals (n=26; n=37, respectively). We assessed these factors using self-report and objective measures and controlled for fluid intelligence in both groups and for cognitive health and cognitive reserve in older bilinguals. Participants completed a segmentation task in Basque, adapted from Sanders and Neville (2000), which comprised 240 sentences of three types: (1) natural sentences, i.e. fully grammatical and meaningful; (2) jabberwocky sentences, where content words were replaced with nonsense words, but functors were preserved (i.e., grammatical, but not meaningful); and (3) phonological sentences comprising only nonsense words, but preserving all phonological information (i.e., neither grammatical, nor meaningful). Each sentence contained a target phoneme and participants’ task was to indicate whether it occurred word-initially or word-medially. Multiple regression analysis revealed that accuracy in the segmentation task was significantly above chance (all p≤.001) in all three conditions—natural, jabberwocky, phonological—and in both target positions—word-initial and word-medial—. Importantly, adding age as a fixed effect or in interaction with other factors did not improve model fitness. Conversely, frequency of language switch, proficiency, and fluid intelligence (all p≤.01) predicted segmentation accuracy. Further, proficiency interacted significantly with sentence type (p<.0001), as proficiency-related gains were greatest in natural sentences, followed by jabberwocky, and lastly by phonological sentences. Proficiency also interacted significantly with target position (p≤.001), as accuracy increases related to proficiency were larger in word-initial targets. These results evidence thus the stability of our segmentation abilities throughout adulthood and align with Palmer et al’s (2018) findings on statistical learning resilience to aging in speech segmentation. They also identify the role of specific bilingual dimensions in achieving native-like segmentation of a second language and suggest a particular role of proficiency in modulating word segmentation in adult bilinguals.
Topic Areas: Multilingualism, Speech Perception