The growth of a child’s early vocabulary is one of the most salient indicators of progress in language development, but measuring a young child’s comprehension of words is non-trivial. Parental checklists are prone to underestimation of a child’s vocabulary (Houston-Price et al., 2007; Brady et al. 2014), so it may be that more direct measures, such as measuring a child’s eye movements during comprehension, may provide a better assessment of children’s vocabulary. Prior research has found relationships between gaze patterns and vocabulary development (Fernald et al. 2006), and the present exploratory study investigates these relationships with verbs, along with a number of methodological considerations. In addition, recent research supports the idea that verbs may differ in difficulty of acquisition based on word class, with manner verbs being easier to learn than result verbs (Horvath et al. 2015). The present study has two aims: 1) investigate the effect of dynamic stimuli on correlations with vocabulary scores and 2) experimentally investigate the notion that manner verbs are easier to learn than result verbs.
Forty children (Mean age = 22.97 months) were recruited for participation and shown a vocabulary test. While no significant correlations were found between vocabulary measures and accuracy and latency, several experimental measures proved to be related to vocabulary development, including fixation density and length of first fixation to the non-target. Additionally, results indicate that children knew the same number of manner and result verbs. Finally, these results could inform vocabulary tests using eye-tracking measures that specifically target verb knowledge
