Incidental teaching of mentally retarded students within a token system.

Six mentally retarded students were taught to name sight words during the token-exchange periods of a token-reinforcement system. Words appeared on 25% of the tokens, and a student was given two opportunities to name a word written on a token before the token could be exchanged. Sequential teaching of new sets of sight words via a multiple-baseline design was used to evaluate the procedure. Five of the 6 students acquired sight-word vocabularies. The data support the contention that token-exchange periods may be used for educational purposes.