Spoken Word Recognition in Typically Developing and Late-Talking Toddlers

Late language emergence (LLE) refers to significantly delayed development of single word vocabulary and word combinations in toddlers, 2 – 3 years of age. Commonly referred to as late talkers (LTs), these toddlers are at risk for chronic language weakness. Most research has focused on expressive output with little attention directed toward language processing. This project evaluated spoken word recognition in a late talker (LT) group and two typically developing control groups matched on chronological age or expressive language level. Participants were familiarized with a set of real words (Experiment 1) and trained on a set of novel words (Experiment 2). The set of real words contained a cohort pair (same initial consonant-vowel (CV) combination), rhyme pair (same offset), and semantic pair (taxonomically similar). Novel words referred to four novel creatures. Following familiarization, participants completed a simplified visual world paradigm task (Tanenhaus, et al., 1995) while their eye movements were tracked. Participants heard a phrase (Look at the bunny!) and saw a target image (bunny) and a competitor image (bubbles) during this passive task. Results of Experiment 1 revealed that age-matched controls and LTs demonstrated lexical competition but the LT group spent more time fixating on the competitor images compared to the age-matched typical comparison group. For Experiment 2, all three groups were able to learn at least a subset of the novel words, but the LT group required more input to learn the spoken words compared to both control groups. Our findings suggest that early deficits resolving lexical competition and learning new word forms may be present in some late-talking toddlers