What Is the High-Probability Instruction Sequence?
The high-probability (high-p) instruction sequence is an antecedent intervention in which a practitioner delivers several requests the individual is highly likely to follow (high-p instructions) in rapid succession, immediately before delivering a request the individual is unlikely to follow (low-p instruction). The compliance momentum generated by responding to the high-p requests increases the likelihood that the individual will comply with the low-p request.
This procedure is rooted in the concept of behavioral momentum, first described by Nevin, Mandell, and Atak (1983). Nevin's research demonstrated that behaviors with higher rates of reinforcement are more resistant to change, analogous to how a heavier object in motion has more momentum and is harder to stop. Mace, Hock, Lalli, and colleagues (1988) extended this concept to the applied domain by demonstrating that a rapid series of reinforced responses could increase compliance with subsequent demands.
The Behavioral Momentum Metaphor
In physics, momentum equals mass times velocity. In the behavioral analogy:
- Mass corresponds to the rate of reinforcement in a given context. A response class with a rich history of reinforcement has greater "mass" and is more resistant to disruption.
- Velocity corresponds to the rate of responding. Rapid responding generates behavioral velocity.
By delivering high-p instructions quickly and reinforcing each compliance, the practitioner builds both reinforcement density (mass) and response rate (velocity). The resulting momentum carries the individual's compliance through the low-p instruction that follows.
Step-by-Step Implementation
Step 1: Identify High-Probability and Low-Probability Instructions
Observe the individual during typical routines and record which instructions they follow at least 80% of the time (high-p) and which they follow less than 50% of the time (low-p). High-p instructions are often simple, familiar, or preferred tasks such as "give me five," "touch your nose," or "hand me the blue block."
Step 2: Prepare the Sequence
Select three to five high-p instructions to deliver before the low-p instruction. The specific number may vary, but research generally supports using at least three high-p requests. Plan the reinforcement you will deliver following each high-p compliance.
Step 3: Deliver the High-P Sequence Rapidly
Deliver each high-p instruction quickly, with brief praise or tangible reinforcement following each compliance. The inter-instruction interval should be short, typically 3 to 5 seconds between the reinforcement for one response and the delivery of the next instruction. Speed is critical because the momentum effect diminishes with longer pauses.
Step 4: Deliver the Low-P Instruction Immediately
Within 5 seconds of reinforcing the last high-p compliance, deliver the low-p instruction. This timing is essential. Research by Mace and Belfiore (1990) demonstrated that delays between the high-p sequence and the low-p instruction reduce the effectiveness of the procedure.
Step 5: Reinforce Low-P Compliance
When the individual complies with the low-p instruction, deliver immediate and robust reinforcement. Over time, as compliance with previously low-p instructions increases, these instructions may themselves become high-p instructions.
Clinical Applications
Transitions
A child resists transitioning from preferred activities to less preferred activities. Before giving the transition instruction ("time to come to the table"), the practitioner delivers several high-p instructions: "give me a high five" (compliance, praise), "stand up tall" (compliance, praise), "spin around" (compliance, praise), then "come to the table" (low-p instruction).
Academic Tasks
A student refuses to begin writing assignments. The teacher delivers easy academic requests ("read this word," "point to the verb," "tell me the first letter") with brief praise, then transitions to the writing task ("now write the first sentence").
Self-Care Routines
A client resists tooth brushing. The clinician delivers a series of compliant requests during the morning routine ("wash your hands," "get your towel," "look in the mirror"), then delivers the tooth-brushing instruction within the established momentum.
Common Mistakes
- Using instructions that are not truly high-p: If the individual does not reliably comply with the preceding instructions, no momentum is generated. Verify compliance rates through direct observation before selecting high-p instructions.
- Pausing too long between instructions: Delays between the high-p sequence and the low-p instruction allow momentum to dissipate. Maintain a brisk, continuous pace.
- Failing to reinforce high-p compliance: The reinforcement following each high-p response is what builds the reinforcement density. Skipping reinforcement weakens the effect.
- Using the procedure coercively: The high-p sequence should feel natural, energetic, and positive. If the individual perceives the sequence as a setup or trap, they may become resistant to the entire procedure.
BCBA Exam Relevance
Exam questions on the high-p instruction sequence may ask you to identify the procedure from a clinical vignette, explain why it is classified as an antecedent intervention, describe the relationship to behavioral momentum theory, and select appropriate high-p and low-p instructions from a scenario. You should also understand the critical timing parameters and why this procedure is considered a reinforcement-based approach to increasing compliance.