Monolingual or bilingual intervention for primary language impairment? A randomized control trial

This study investigated the clinical effectiveness of monolingual versus bilingual language intervention, the latter involving speech-language pathologist-parent collaboration. The study focuses on methods that are currently being recommended and that are feasible within current clinical contexts.

Bilingual children with primary language impairment who speak a minority language as their home language and French as their second (n=29, mean age=5 years) were randomly assigned to monolingual treatment, bilingual treatment, and no-treatment (delayed-treatment) conditions. Sixteen sessions of individual language intervention were offered, targeting vocabulary and syntactic skills in French only or bilingually, through parent collaboration during the clinical sessions. Language evaluations were conducted before and after treatment by blinded examiners; these evaluations targeted French as well as the home languages. An additional evaluation was conducted 2 months after completion of treatment to assess maintenance of gains. Both monolingual and bilingual treatment followed a focused stimulation approach.

Results in French showed a significant treatment effect for vocabulary but no difference between treatment conditions. Gains were made in syntax, but these gains could not be attributed to treatment given that treatment groups did not improve more than the control group. Home language probes did not suggest that the therapy had resulted in gains in the home language.

The intervention used in this study is in line with current recommendations of major speech-language pathology organizations. However, the findings indicate that the bilingual treatment created through collaboration with parents was not effective in creating a sufficiently intense bilingual context to make it significantly different from the monolingual treatment. Further studies are needed to assess the gains associated with clinical modifications made for bilingual children and to search for effective ways to accommodate their unique needs.