PhD Oral Exam - Andrea Sander-Montant, Psychology

When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.

Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.

Abstract

The ability to understand spoken words develops within the first two years of life and serves as a building block for language development. Most theoretical accounts see both maturation and language experience as essential factors in this process but differ in how they conceptualize their relationship. Some view maturation as the primary driver, others emphasize experience accumulation, while more recent frameworks suggest complex interactions between these factors. However, most accounts have been tested only through computational modelling, with limited empirical evidence examining how maturation and experience jointly predict word comprehension across different contexts. This dissertation addresses these gaps through four interconnected studies.

Chapter 2 tested competing theoretical models by investigating chronological age and language experience as predictors of performance in the looking-while-listening (LWL) paradigm. I analyzed archival data from 155 bilingual and monolingual infants, leveraging the natural variation in their language experience. An additive model—where chronological age and language experience contribute independently—emerged as the most parsimonious explanation, challenging previous accounts favouring interaction relationships.

Chapter 3 evaluated the psychometric properties of LWL outcome measures using data from 602 children. This meta-analytic investigation revealed that the paradigm captures two distinct cognitive processes—detecting word-picture mismatches versus confirming matches—suggesting word comprehension requires different response strategies depending on context.

Chapter 4 extended these findings with new data from 69 infants, examining how behavioral (looking time) and physiological (pupil dilation) responses vary across trial types. Results revealed that the age-experience relationship systematically changed based on task demands: distractor-initial trials (requiring mismatch detection) showed additive effects of maturation and experience, while target-initial trials (requiring match confirmation) were largely predicted by experience alone.

Chapter 5 investigated how family language practices shape children’s relative language exposure in bilingual households. Data from 281 bilingual children demonstrated that individual parent language use was substantially more predictive of language exposure than broader family language strategies, with mothers’ influence being twice that of fathers.

Together, these findings reconceptualize word comprehension not as a unitary skill, but as a repertoire of responses that follow distinct developmental trajectories. The framework provides a more nuanced understanding of early language development with implications for theory, assessment, and intervention.