Abstract
Early vocabulary development predicts later cognitive functioning and school success. We sought to examine how processing differences across several skills that contribute to early word learning relate to variability in children’s vocabulary development. Building on recent direct measures of early vocabulary and language learning processes, we collected data from 166 children between 15- to 27-months in a single eyetracking task measuring lexical speed of processing, comprehension, novelty bias, word mapping and new word retention. We found clear differences in responding across the different measures and robust patterns of developmental change. Children’s comprehension grew over development, and across word classes they showed clearly distinct looking patterns, reflecting fundamental differences in word type processing and more efficient noun recognition compared to adjectives and verbs. Speed of processing and online comprehension showed strong relationships with concurrent vocabulary, similar to previous reports. Children also showed a strong improvement in referent selection over development, but as found in previous literature, they did not show evidence of retaining new word-object mappings formed on earlier trials of the task. Data driven classification found two robust clusters of children. One group showed faster speed of lexical processing, better comprehension and were better at linking new nouns to novel objects. Numerically, this group had the highest parent-reported concurrent productive vocabulary scores. Data are discussed in relation to similar work in the literature, what concurrent measurement of multiple word learning processes reveals about the system of multiple processes supporting early vocabulary development, and children’s individual trajectories of word learning.