PhD Oral Exam - Melanie López Pérez, 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

Abstract Investigating the measurement of infants’ word-level knowledge through parent reports and looking-while-listening Melanie López Pérez, PhD Concordia University, 2026 To measure young children’s word knowledge, researchers typically use parent reports and looking tasks, which have reliable and valid aggregate scores (e.g., vocabulary size, mean performance). However, the literature is inconsistent as to whether they can capture word-level knowledge (e.g., whether a child knows 'ball’). Further, typical parent reports use a binary format (child knows/does not know the word) while looking tasks use continuous measurement (proportion time looking at labeled object), which may contribute to theoretical disagreements about whether words are acquired discretely or continuously. This dissertation addressed both of these issues. Chapter 2 examined word-level links between binary parent reports and looking-based word comprehension in monolingual and bilingual children aged 14–31 months. An initial link emerged but disappeared once controlling for child-level factors such as age and vocabulary size. In Chapter 3, I developed a continuous parent report measure where parents rated their certainty about children's word knowledge (comprehension and production) on a 1-6 scale. This was compared to binary parent reports and a looking-based measure in monolingual and bilingual children aged 8–31 months. Parents frequently endorsed certainty at the midpoint of the continuous scale, particularly for word comprehension, and they set high certainty thresholds before endorsing words as known. Moreover, although binary reports distinguished broadly between looking behavior for produced and not-produced words, only the continuous adaptation captured gradations for emerging words. Together, findings reveal several limitations in measuring word-level knowledge with current approaches, with gradient parent ratings as a promising new direction. Further, the theoretical divergence between continuous and binary conceptualizations of word knowledge may partly reflect measurement choice, with each approach potentially capturing a distinct word acquisition phase. New approaches are needed to more fully capture word-level knowledge.