Sensitivity to Semantic Relationships in U.S. Monolingual English-Speaking Typical Talkers and Late Talkers

Purpose: Late talkers are a group of children who exhibit delays in language development without a known cause (Fisher, 2017). While a hallmark of late talkers is a reduced expressive vocabulary, little is known about late talkers’ processing of semantic relations among words in their emerging vocabularies. This study uses an eye-tracking task to compare two-year-old late talkers’ and typical talkers’ sensitivity to semantic relationships among early acquired words. Method: U.S. monolingual English-speaking late talkers (n = 21) and typical talkers (n = 24) completed a looking-while-listening task in which they viewed two images on a screen (e.g., a shirt and a pizza) while they heard words that referred to one of the images (e.g., Look! Shirt!; target-present condition) or a semantically related item (e.g., Look! Hat!; target-absent condition). Children’s eye movements (i.e., looks to the target) were monitored to assess their sensitivity to these semantic relationships. Results: Both late talkers and typical talkers looked longer at the semantically related image than the unrelated image on target-absent trials, demonstrating sensitivity to the taxonomic relationships used in the experiment. There was no significant group difference between late talkers and typical talkers. Both groups also looked more to the target in the target-present condition than in the target-absent condition. Conclusions: These results reveal that, despite possessing smaller expressive vocabularies, late talkers have encoded semantic relationships in their receptive lexica and activate these during real-time language comprehension. This study furthers our understanding of late talkers’ emerging linguistic systems and language processing skills.