Evaluating tact instruction in two languages for bilingual children with autism spectrum disorder

Bilingual individuals can acquire two languages simultaneously or sequentially. Study 1 examined the effects of simultaneous instruction (introducing tacts in both languages at the same time) and sequential instruction (introducing tacts in English, followed by a second language after mastery) with four children with autism. Both instructional procedures were effective, but simultaneous instruction promoted better conditional discriminations between the two languages than sequential instruction. Study 2 compared monolingual with bilingual (sequential) instruction with three participants. Teaching tacts in a single language was substantially more efficient than teaching tacts in two languages for all participants. As in Study 1, participants required additional simultaneous teaching after mastering sequentially taught targets to establish conditional discriminations, whereas monolingual instruction required no additional teaching. These results indicate that monolingual instruction is more efficient than sequential bilingual instruction, although sequential bilingual teaching can still be effective. The findings have important implications for designing bilingual instruction.