When Standard Prompting Isn't Enough
Most ABA programs address non-compliance through a combination of prompting hierarchies and reinforcement schedules. But some children have a history of successfully escaping demands — and for them, the moment a request is made, their entire behavior system shifts into avoidance mode before any prompting can occur.
High-probability (high-p) request sequences are specifically designed for these cases. They interrupt the avoidance pattern before it starts by establishing a chain of successful, reinforced compliance — making the difficult request almost impossible to refuse.
The Mechanics of a High-P Sequence
A high-p request is any instruction the child complies with approximately 80% of the time or more without prompting. These are identified through baseline observation before the sequence is implemented.
The sequence looks like this:
- Present 3–5 high-p requests in rapid succession
- Deliver enthusiastic reinforcement for each compliance
- Immediately — within 5 seconds — present the low-p (challenging) request
- Reinforce compliance with the most potent available reinforcer
The speed of the transition matters. Waiting too long allows the child's arousal level to drop and the avoidance pattern to re-establish.
Clinical Applications
At PBS Midwest, high-p sequences are most commonly used in three contexts:
Transition resistance: Before asking a child to stop a preferred activity, run a high-p sequence with simple requests. The momentum of saying yes carries through the transition demand.
Work task initiation: Children who freeze at the start of work sessions benefit from 2–3 high-p requests embedded just before the first work trial. By the time the task appears, they're already engaged.
Communication: For children who consistently refuse verbal imitation targets, embedding the target word after several high-p motor imitations can dramatically increase compliance.
Teaching Parents the Sequence
One of the most impactful things a caregiver can learn is how to run a high-p sequence in daily life. PBS Midwest's parent training includes in-session practice and written protocols so families can use this approach consistently at home.