Prevalence and developmental course of 'secret language'

The prevalence and developmental course of supposed 'secret language' was e xamined in a cohort of twins and closely spaced singletons pairs, with syst ematic assessments at 20 months and again at 36 months. Two forms of appare nt 'secret language' were examined: (1) shared understanding-speech directe d generally but unintelligible to the parent, although apparently clearly u nderstood within the child pair, and (2) private language directed exclusiv ely to the other twin/sibling-not intelligible to the parent, but apparentl y clearly understood and used only within the child pair. Both occurred in singleton pairs, but the rate was much higher in twins. In most cases it se emed to be a developmental phenomenon occurring in the second year of life with the emergence of immature speech, and decreasing considerably over the next 16 months. A small group of children, primarily male twins, was repor ted to use a private language at 36 months. This group had poorer cognitive and language functioning and was characterized by highly dependent relatio nships. Some aspects of the twins' home environment were less stimulating a nd less responsive, most probably reflecting the abilities and relationship s of the children. A follow-up of these children when they were similar to6 years of age showed that language outcome was poor for the subgroup (n=4) who did not develop normal language alongside the use of a private language .