How the Language Development Survey Identifies Late Talkers: International Examples

The Language Development Survey (LDS) is  a vocabulary checklist that  parents complete in about 10 minutes. Studies conducted in the U.S. indicate that the LDS is an effective screening tool for identifying late talkers (LTs) in general population samples of toddlers. Correlations with concurrently administered language tests were high, and decision statistics such as sensitivity and specificity indicated that the LDS differentiated well between young children with expressive language delays and those with typical language development. Late talkers identified with the LDS at 24 to 31 months of age had significantly lower language scores than children with typical language histories through age 17, although few LTs had diagnosable speech-language impairment after age 6. When the LDS was used to identify late talkers in Greece and Korea, the children identified look very similar to U.S. LTs in terms of their vocabulary development. That is, they were acquiring the same words as typically developing peers but at a much slower rate. In research conducted with a large and diverse Dutch general population sample, only 29% of children delayed on the MacArthur-Bates Communicative Development Inventory (CDI) at 18 months were still delayed on the LDS at 30 months. Additionally, only 30% of the children delayed on the LDS at 30 months had been delayed on the CDI at 18 months. Thus, many children changed language delay status between 18 and 30 months. Demographic factors and behavioral/emotional problems as measured by the Child Behavior Checklist for ages 1.5-5 had significant but quite small associations with LDS scores and with language delay status at 18 and 30 months.  Conclusions of the research are: 1) late talkers can be reliably and validly identified using the LDS at 24 to 35 months of age; 2) language delay status at 18 months is not a good predictor of language delay status at 30 months; and 3) late-talking toddlers do not generally go on to manifest persistent language delay, but they do have weaker language skills through adolescence compared with typically developing peers. These international findings support a dimensional account rather than a categorical account of early language delay.