Go with the flow: Investigating the dynamics of lexical access in child language production and comprehension

Abstract

Producing and comprehending language is no small feat, involving many different steps and types of representations. Despite this complexity, the language system is employed seemingly effortlessly by adults, and acquiring this system comes naturally to children. In adults, rapid and efficient language processing is enabled by the incremental, cascading, and interactive transfer of information across levels of representation. In this dissertation, I explore whether these interactive informational cascades are already present in the language system by early childhood or whether they develop later (e.g., with increased language experience or as the brain matures), and I probe the limitations of webcam eye-tracking approaches to ask these questions. I present three papers investigating the dynamics of information flow during four to five-year-old children’s language processing, using lexical processing as a case study. Paper 1 used a picture naming task to test for informational cascades during word production, finding evidence that cascaded processing arises in the language system by at least five years of age. Paper 2 used visual world eye-tracking to test whether informational cascades in four and five-year-old children are interactive, showing that young children are able to use top-down contextual information during language comprehension to pre-activate upcoming word representations and constrain bottom-up processing. Paper 3 assessed the suitability of webcam eye-tracking techniques for studying moment-to-moment processing in young children by testing the sensitivity of two webcam eye-tracking methods to detect evidence of incrementality in children’s word recognition. Taken together, the results of these studies demonstrate that the incremental, interactive informational cascades that are integral to adult language processing are robust and active early in life, suggesting that they are fundamental consequences of the language system architecture.