Late-talking longitudinal word learning (Cheung et al., 2022)

Purpose: The aim of this study was to identify variability in word-learning mechanisms used by late-talking children using a longitudinal study design, which may explain variability in late-talking children’s outcomes.

Method: A cohort of typically developing children (n = 40) and children who were classified as late-talking children at age 2;0 (years;months; ≤ 10th percentile on expressive vocabulary, n = 21) were followed up at ages 3;0 and 3;6. We tested the cohort across tasks designed to isolate different mechanisms involved in word learning: encoding and producing spoken forms of words (using a nonword repetition task), identifying referents for words (using a fast mapping task), and learning associations between words and referents (using a cross-situational word-learning task).

Results: Late-talking children had lower accuracy on nonword repetition than typically developing children, despite most of the sample reaching typical ranges for expressive vocabulary at age 3;6. There were no between-groups differences in fast mapping and retention accuracy; however, both were predicted by concurrent expressive vocabulary. Late-talking children performed less accurately than typically developing children on cross-situational word-learning retention trials, despite showing no between-groups differences during training trials. Combining performance across all three tasks predicted approximately 45% of the variance in vocabulary outcomes at the last time point. 

Conclusions: Late-talking children continue to have deficits in phonological representation that impact their word-learning ability and expressive language abilities but do not show difficulties in fast mapping novel words. Late-talking children may also struggle to retain associative information about word–referent mappings. Late-talking children thus use some, but not all, word-learning mechanisms differently than typically developing children.

Supplemental Material S1. Additional analyses (syllable loss analyses for the nonword repetition task, receptive vocabulary analyses for each task, and correlations of task performance with expressive and receptive vocabulary).

Supplemental Material S2. Individual variation, late-talking children who did not reach typical expressive vocabulary range, and receptive ability within the late-talking sample.

Supplemental Material S3. Administration time and stimuli for word-learning tasks.

Cheung, R. W., Hartley, C., & Monaghan, P. (2022). Multiple mechanisms of word learning in late-talking children: A longitudinal study. Journal of Speech, Language, and Hearing Research. Advance onine publication. https://doi.org/10.1044/2022_JSLHR-21-00610