The development of phonological systematicity: Late talkers and typically developing children

Preliminary findings are reported from an ongoing study investigating the relationship of phonological systematicity to language delay or disorder in children who make a late start on word production. Based on formal testing at 2.6 years, we divided these children into ‘true’ (expressive) late talkers (LTs) and ‘transitional’ LTs (TLTs), depending on whether or not their expressive language falls at least 4.5 months below the norm at that age. An existing sample of 11 typically developing children (TDs) served as a comparison sample. All children are seen again one year after the first developmental milestone, with both naturalistic recordings and formal tests to assess linguistic advance.

Our hypothesis is that the LTs will fall into two groups identifiable from the earlier recordings: (i) children who are slow to make a start on word production but who show the same kind of systematization in their early word production as is found in the typically developing children and (ii) children whose word production displays little evidence of systematization. The prediction is that in the one-year follow-up recordings Group (i) will have caught up with the TDs, with their naturalistic recordings showing normal linguistic levels for their developmental level (i.e., a year after the first developmental milestone), as assessed for phonology, morphosyntax and lexical diversity as well as in age-based formal tests, while Group (ii) will continue to show language delay and will thus prove to be at risk of having Specific Language Impairment (SLI).

We have so far recorded only a few of the one-year follow-up sessions for the LTs, so that final outcomes cannot yet be reported. However, we have identified several differences in production between the (T)LTs and the TDs. In addition, the small sample of LTs do appear to fall into the two groups we expected to find, differing from the TDs in ways that correspond roughly to what we had predicted.