Definition of a Behavioral Cusp
A behavioral cusp is a behavior change that has sudden and dramatic consequences because it exposes the person to new environments, new reinforcers and contingencies, and new behaviors, while also impacting people in the person's life. The term was introduced by Rosales-Ruiz and Baer in 1997. The key idea is that some behaviors are important not only for what they are, but for what they make possible.
A classic example is crawling. Before crawling, an infant explores only what is within reach. Once crawling is acquired, the infant can reach new objects, rooms, and people, contact new reinforcers, and be exposed to new risks. The caregiver also responds differently by baby-proofing the home and providing new opportunities. A single behavior change creates a broad range of subsequent changes.
Characteristics of Cusps
Rosales-Ruiz and Baer described several features. A behavioral cusp:
- Exposes the person to new contingencies and opens up new environments.
- Allows the person to acquire additional new behaviors, which may be more complex.
- Is typically valued by the community, so there is a high probability that caregivers, teachers, and peers will support or reinforce it.
- Often leads to reduced reliance on professionals and support staff.
- May be difficult to identify in advance, because its importance is judged by its effects.
Examples of Behavioral Cusps
- Crawling and walking: Mobility opens access to the environment.
- Reading: Reading gives access to text-based instruction, entertainment, information, and employment.
- Generalized imitation: A learner who can imitate can learn many new skills by observing others, without direct training of each skill.
- Making requests (manding): Functional communication allows access to reinforcers and reduces problem behavior.
- Using a bus or public transit: Independent travel allows access to jobs, social activities, and services.
- Self-management skills: Tracking one's own behavior supports independence in many domains.
- Joint attention and social play: Allows entry into social groups where new learning and friendships occur.
Cusps vs Pivotal Behaviors
These concepts are related, and the BCBA exam may ask you to distinguish them.
- A pivotal behavior is a behavior that, once learned, produces widespread, untrained changes in other behaviors. Examples include responding to multiple cues, self-initiations, and motivation, as studied by Koegel and colleagues. The focus is on collateral changes in other responses in the learner's repertoire.
- A behavioral cusp emphasizes access to new contingencies, environments, and social consequences, and the community's reaction to the new behavior.
Some behaviors can be both. For instance, learning to imitate is a cusp because it exposes the learner to new learning opportunities, and a pivotal behavior because it increases the acquisition of many other skills. Remember that pivotal behaviors lead to response generalization in a broad sense, while cusps focus on new access.
Why Cusps Matter in Treatment Planning
Treatment teams have limited time and resources, and goals compete. Selecting target behaviors with high potential impact allows learners to make faster progress toward independence and quality of life. When developing an assessment-based plan, behavior analysts consider:
- Relevance to the learner's life: Will the behavior be reinforced in the natural environment?
- Prerequisite value: Does it unlock other skills?
- Social validity: Do the client, caregivers, and community value the outcome?
- Safety and risk: Does it give access to environments in which the learner will be safe?
- Generality: Will it support generalization across settings, people, and behaviors?
The BACB Ethics Code requires behavior analysts to base goals on assessment, client preferences, and the broader context, and to prioritize behavior that improves the client's quality of life. Cusps are a useful lens for those decisions.
How to Identify Potential Cusps
Ask guiding questions
- If this behavior is acquired, what new environments will the learner enter?
- What new reinforcers will be accessible?
- What will caregivers, teachers, and peers do differently?
- Will this reduce the learner's dependence on others?
- Will it make future learning easier?
Use assessments and interviews
Skills assessments such as the VB-MAPP, ABLLS-R, and AFLS identify gaps in the learner's repertoire. Interviews with caregivers and the learner (where possible) reveal priorities and the demands of the home, school, and community. Observing peers of similar age shows which skills are most valued.
Review outcomes
Once a goal is taught, track downstream effects. If the learner begins to access new environments or acquires skills that were not directly taught, record those changes. This helps confirm whether the behavior functioned as a cusp.
Applying Cusps in Practice
Example: teaching functional communication
A child who engages in aggression uses minimal language. The team prioritizes manding for items, help, and breaks, since communication will give access to reinforcers in all environments, reduce problem behavior, increase peer interaction, and allow participation in more inclusive settings. Over time, the child's mands expand to requests for information, which supports additional learning.
Example: teaching a teenager to use public transit
A teenager with an intellectual disability learns to use the local bus using a task analysis, video modeling, and community-based instruction. The skill gives access to a job, community events, and friends, and parents need to provide less transportation support.
Ethical Considerations
- Do not prioritize a cusp solely because it is convenient for adults. Consider the client's preferences and dignity.
- Do not assume that a behavior is a cusp without evidence. Evaluate effects across time.
- Ensure safety precautions are in place when a skill expands the learner's access to higher-risk settings.
- Involve the client and caregivers in goal selection to maximize social validity.
Exam Strategies
- When a question describes a behavior that opens new environments and reinforcers, with community support, think behavioral cusp.
- When a question describes one behavior producing untrained improvements in many others, think pivotal behavior.
- Remember the crawling and reading examples because they are commonly used.
- For goal selection questions, look for answers that consider social validity, prerequisite skills, and future access to reinforcement.
Key Takeaways
A behavioral cusp is a behavior change that exposes the person to new contingencies and environments and gets a response from the community. Cusps differ from pivotal behaviors, which produce collateral changes. Include cusps in treatment planning to select goals that increase independence, learning opportunities, and quality of life.