Problem Solving as a Function of Language

English-speaking monolingual and types of bilingual Navaho eighth grade pupils were compared on problem-solving tasks. IQ and reading comprehension were controlled. Predictions were made that compound bilinguals would require more trials in attempting to solve the experimental problems and solve fewer of them than would co-ordinate bilinguals, and also that co-ordinate bilinguals would do less well than English-speaking monolinguals. Findings indicated that the compound bilinguals did less well than the other two groups, but that there was no difference between the co-ordinate bilinguals and the monolinguals. Differences are explained in terms of Osgood's two-stage mediation model and interference. Implications for the language training of bilinguals are mentioned.