Vocabulary acquisition by mentally retarded students under direct and mnemonic instruction

Twenty EMR junior-high-school students learned the definitions of unfamiliar English vocabulary words under either direct instruction or mnemonic instruction in a crossover design. When in the mnemonic-instruction condition, students remembered 50% more vocabulary definitions than when they were in the direct-instruction condition. Only three of the 20 students failed to exhibit superior performance when in the mnemonic instruction condition. Supplementary analysis of the response data revealed distinctly different error patterns in the two instructional conditions. In particular, far more intralist intrusions were associated with direct instruction. Implications of these results were discussed.