By Matt Harrington, BCBA · Behaviorist Book Club · Research-backed answers for behavior analysts
A preference assessment identifies which stimuli an individual chooses or engages with most from among a set of options — it predicts relative reinforcer value. A CSA goes further by testing whether engagement with each stimulus actually reduces challenging behavior during the assessment period. The critical distinction is that CSAs measure reinforcer competition — whether the alternative stimulus is potent enough to displace the motivation for challenging behavior. High preference does not automatically translate to high competition; a stimulus may be preferred but fail to compete with the reinforcer maintaining the challenging behavior.
Reinforcer competition refers to the phenomenon where access to one reinforcer reduces the motivational value of another. When a highly potent alternative reinforcer is freely available, the motivating operation (MO) for the challenging behavior is attenuated — the behavior is less likely because the reinforcer it typically produces is less valuable in that context. CSAs identify which stimuli produce this competition effect for a specific individual, providing pretreatment data that directly informs treatment design, particularly the selection of stimuli for non-contingent reinforcement schedules.
A CSA typically involves presenting individual candidate stimuli (selected from a preference assessment) one at a time during fixed-duration observation sessions. The observer records both time engaged with the stimulus and rate of challenging behavior. A control condition (no competing stimulus) provides a baseline comparison. Sessions are conducted in the same context where challenging behavior typically occurs. Results are analyzed by comparing challenging behavior rates and engagement levels across conditions, with stimuli ranked by their degree of competition effect.
High-competition stimuli are most commonly incorporated into treatment as components of non-contingent reinforcement (NCR) schedules, where they are provided on a time-based schedule independent of the occurrence of challenging behavior. This arrangement reduces the MO for the challenging behavior by providing the competing reinforcer freely, thereby attenuating the motivation that drives the behavior. High-competition stimuli may also be used to establish structured leisure skill programs, select preferred activities for DRI procedures, or identify materials for activity transitions where challenging behavior is most likely to occur.
Hagopian's research and clinical work has applied CSAs most extensively to self-injurious behavior and stereotypy maintained by automatic reinforcement, where the identification of stimuli that can compete with the sensory consequences of the behavior has direct treatment relevance. Applications have also extended to challenging behaviors maintained by attention, escape, and tangible reinforcers. The CSA has been used to inform treatment for individuals across a wide range of disability profiles and ages, demonstrating its broad utility as a pretreatment assessment tool.
Augmenting tactics are procedural modifications designed to increase the competition efficacy of stimuli that show partial but incomplete competition in the standard CSA. Examples include embedding brief instructions to engage with the stimulus, pairing the stimulus with an additional reinforcer dimension, manipulating access duration or contingency, or using prompting to increase initial engagement that then becomes self-sustaining. These tactics matter because they expand the pool of clinically viable competing stimuli beyond those that show strong competition effects in their unmodified form, giving clinicians more options for naturalistic intervention.
Yes — while CSAs originated largely in the automatic reinforcement literature, they have been applied to socially maintained challenging behaviors as well. For behaviors maintained by attention, the CSA might identify stimuli that compete with the attention MO by providing an alternative source of engagement that reduces the value of social attention. For escape-maintained behavior, stimuli that provide sensory input sufficient to reduce the aversiveness of task demands may produce competition effects. The interpretation of CSA results does differ across functions, and the treating BCBA should consider the function identified in the functional analysis when selecting and interpreting CSA stimuli.
CSAs should be re-administered when challenging behavior resurges after a period of treatment success, when current competing stimuli appear to have lost their efficacy (habituation), when the individual's overall preference landscape has changed significantly, or at regular intervals as part of ongoing treatment review (e.g., every 3-6 months for long-term clients). Because motivating operations and reinforcer values are dynamic, CSA results have a shelf life — treating them as permanent is a clinical error. Periodic re-assessment ensures that treatment plans remain aligned with current reinforcer dynamics.
Hagopian's work highlights an important secondary application of CSA findings: high-competition stimuli represent naturalistic leisure activities that the individual finds sufficiently engaging to prefer over challenging behavior. These stimuli are strong candidates for structured leisure skill instruction — building an independent, generalized leisure repertoire using materials the individual has already demonstrated strong engagement with. This connection between CSA and leisure programming is clinically powerful because it uses assessment data to drive both immediate treatment (NCR) and long-term quality-of-life goals simultaneously.
Conducting CSAs is consistent with Code 2.14 (selecting interventions based on scientific evidence and individual needs) and Code 2.15 (using least restrictive effective interventions) since CSA-informed approaches often reduce reliance on more restrictive components. Code 3.04 requires informed consent for assessment procedures, including the CSA. Ongoing monitoring obligations mean that BCBA practitioners should document CSA results formally, integrate them into behavior support plans, and update them when conditions change. Using CSA findings to support the selection of naturalistic, reinforcement-based intervention components reflects best-practice ethical service delivery.
The ABA Clubhouse has 60+ on-demand CEUs including ethics, supervision, and clinical topics like this one. Plus a new live CEU every Wednesday.
Ready to go deeper? This course covers this topic with structured learning objectives and CEU credit.
Competing Stimulus Assessments: Recent Advances and Applications — Louis Hagopian · 1 BACB General CEUs · $0
Take This Course →1 BACB General CEUs · $0 · BehaviorLive
Research-backed educational guide with practice recommendations
Side-by-side comparison with clinical decision framework
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.