Establishing conditional discriminations: Concurrent versus isolation-intermix instruction

This paper describes an investigation comparing the effectiveness and efficiency (sessions to criterion, errors to criterion, minutes of instructional time) of concurrent and isolation-intermix instruction in teaching four preschool children to read words found in community and school environments. Two students were taught words using constant time delay and two progressive time delay across the two different conditions. Concurrent instruction consisted of two sessions per day where two words were randomly presented within each session until criterion was reached and a conditional discrimination was established. The isolation-intermix condition involved two sessions per day where each word was taught in separate daily sessions until criterion was reached and a simple discrimination was established (isolation instruction); followed by random presentation of both words within each daily session until the conditional discrimination was acquired (intermix). Concurrent instruction resulted in students learning conditional discriminations in fewer trials and minutes of instructional time. These data suggest that teachers should structure their instruction to teach conditional discriminations from the beginning rather than teaching simple discriminations.