Speed of simple arithmetic in bilinguals

Four types of bilinguals solved simple addition problems that were auditorily presented in their preferred language, the language in which they first learned arithmetic, or in their nonpreferred language. Subjects responded in the language in which the problems were presented. Solution time averaged .227 sec faster in the preferred language and was an increasing linear function of the number of addition operations required. The intercepts of the preferred and nonpreferred language functions significantly differed, but the slopes did not. The preferred language advantage was attributed to faster encoding and/or response times in the preferred language. When bilinguals used only one of their languages in a given experimental session, encoding/response times in the two languages were equivalent and the preferred language advantage was eliminated.