By Matt Harrington, BCBA · Behaviorist Book Club · Research-backed answers for behavior analysts
Aberrant behavior in this context refers to challenging behaviors that interfere with a learner's participation in instruction, daily routines, and social activities, and that may pose risk to the learner or others. This includes behaviors such as aggression, self-injurious behavior, property destruction, tantrums, elopement, and severe non-compliance. The term is used descriptively rather than diagnostically and does not imply a specific etiology. The progressive behavior analytic approach treats all aberrant behavior as functionally maintained and subject to systematic assessment and intervention.
A reactive approach responds to aberrant behavior after it occurs — through planned ignoring, extinction, differential reinforcement of other behavior, or crisis procedures. A proactive approach modifies the conditions that make aberrant behavior likely before it occurs — through environmental modifications, schedule adjustments, demand modifications, and motivating operation interventions. The progressive model prioritizes proactive strategies because preventing aberrant behavior from occurring is more effective, less disruptive, and more consistent with the least-restrictive-procedures principle than managing it after the fact. Both approaches are necessary components of a complete behavior support plan, but proactive strategies should be developed first.
Setting events are contextual or biological variables that occur before the immediate antecedent-behavior-consequence sequence and that alter the probability or intensity of behavior. They do not directly trigger behavior but rather change the motivating conditions that make challenging behavior more or less likely. Common examples include sleep deprivation, illness or pain, dietary disruption, transitions between preferred and non-preferred activities, and communication breakdowns. Setting events are important to identify in FBA because interventions that address them can produce large reductions in challenging behavior that would not be achieved by modifying only the immediate antecedent or consequence.
FBA is the foundation of the progressive model's approach to aberrant behavior — but the progressive model expands the scope of FBA beyond standard antecedent-behavior-consequence analysis. A complete FBA within the progressive framework includes indirect assessment of setting events and biological variables, descriptive assessment across varied conditions and times of day, and functional analysis when indicated by the severity of the behavior. The assessment output informs both reactive procedures and the proactive strategy component of the intervention plan. FBA is treated as an ongoing process rather than a one-time event because behavioral function can change over time.
Motivating operations (MOs) are critical variables in the progressive conceptualization of aberrant behavior. Establishing operations increase the reinforcing effectiveness of the functional reinforcer maintained by challenging behavior and make the behavior more likely to occur. Abolishing operations reduce reinforcer effectiveness and decrease the probability of the behavior. The progressive model specifically targets MOs through proactive interventions — for example, providing access to the functional reinforcer noncontingently to reduce its reinforcing value, or modifying demand conditions to reduce the establishing operation for escape-maintained behavior. This MO-focused proactive component is a distinguishing feature of the progressive approach.
Preventative treatment refers to an intervention model in which the primary goal is to reduce the probability that aberrant behavior will occur, rather than to respond to it effectively after it has occurred. Preventative treatment is achieved through a combination of antecedent modifications, skill building, environmental redesign, and motivating operation interventions that collectively reduce the conditions that occasion challenging behavior. A behavior support plan oriented toward prevention produces fewer instances of challenging behavior and fewer situations that require reactive procedures, resulting in a safer and more positive learning environment for the client and more sustainable implementation conditions for caregivers and staff.
Skill deficits — particularly in functional communication, emotional regulation, and adaptive coping — are often functionally related to aberrant behavior. If challenging behavior is maintained by a function (e.g., attention, escape, access) that could be served by an adaptive skill the learner does not yet have, then building that skill is a direct and proactive intervention. Functional communication training is the most well-documented example: teaching a learner to request a break using words, AAC, or a gesture directly competes with escape-maintained challenging behavior by providing a more effective means of achieving the same outcome. Skill building as a component of aberrant behavior programming should be specified in the behavior support plan.
BACB Code 2.14 requires that a functional assessment be conducted before implementing behavior reduction procedures. The behavior intervention plan should document the results of the FBA, the function of the behavior, the specific intervention procedures being used, the rationale for selecting those procedures, and a data collection plan. For plans that include any restrictive or aversive procedures, additional documentation requirements apply including supervisor approval and caregiver consent. All behavior reduction programs should include defined mastery criteria or decision rules for modifying the program if the behavior is not decreasing on the expected trajectory.
When aberrant behavior is severe or poses immediate risk of harm, the progressive model does not deprioritize safety management. Reactive crisis procedures are developed and trained for any behavior with a significant risk profile, and these procedures take precedence when behavior occurs. However, even in high-severity cases, the proactive component of the program is critical because reducing the frequency and intensity of dangerous behavior through antecedent modification and skill building reduces the number of instances where reactive procedures are needed. The progressive model is not incompatible with safety management — it adds a preventative layer that makes the overall environment safer.
Caregivers who are unfamiliar with proactive behavior support may initially expect a behavior plan that focuses on what to do when challenging behavior occurs. BCBAs can address this by explaining the rationale for proactive strategies in practical terms: preventing the behavior from occurring in the first place means fewer difficult situations, less stress, and more positive interactions. Using concrete examples from the learner's own behavior patterns — how specific setting events or antecedent conditions reliably precede challenging behavior — makes the proactive framework immediately credible and personally relevant. Collaborative goal-setting that includes caregiver priorities reinforces that the plan is designed around the family's actual needs.
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All behavior-analytic intervention is individualized. The information on this page is for educational purposes and does not constitute clinical advice. Treatment decisions should be informed by the best available published research, individualized assessment, and obtained with the informed consent of the client or their legal guardian. Behavior analysts are responsible for practicing within the boundaries of their competence and adhering to the BACB Ethics Code for Behavior Analysts.