Use of a lag differential reinforcement contingency to increase varied selections of classroom activities.

Two students in a regular classroom kept picking the same activity. The teacher set a new rule: you must pick a different activity than last time before you earn a reward. This is called lag-1 differential reinforcement.

The researchers used an ABAB design. They turned the rule on, off, then on again. They counted how many new activities each child chose and how long the child stayed on task.

When the rule was on, both kids quickly started picking new activities. Their on-task time stayed high. When the rule was off, choices went back to the same old favorites.

The simple rule worked fast and did not hurt learning time.

Jones et al. (2010) and Wiskow et al. (2016) used the same lag trick with autistic kids and play or naming tasks. They all saw more variety, showing the idea travels across kids and materials.

Gardner et al. (2009) and Olin et al. (2020) pushed it into vocal work. They got more varied sounds and social answers from non-verbal or autistic children. Again, lag-1 did the job.

Dracobly et al. (2017) looked at lag-4 instead of lag-1. They found kids can learn to switch between "be repetitive" and "be varied" when each rule has its own cue. This adds a tool for times you want flexibility on demand.

You can cut stereotypy and boost flexibility tomorrow. Just tell the learner, "Pick something new before you get your token." Start with lag-1. No extra toys, no long setup. It works for class jobs, play items, or social questions. If you ever need more novelty, move to lag-2 or add a quick prompt. The whole package takes minutes to install and keeps academic engagement high.