By Matt Harrington, BCBA · Behaviorist Book Club · Research-backed answers for behavior analysts
Consent is a legal construct—the formal authorization for services or procedures provided by an individual with legal decision-making capacity, typically a parent or guardian for a minor client. Assent refers to the individual's own agreement or willingness to participate, independent of legal authorization. A parent may legally consent to an intervention on their child's behalf, but the child may not assent to the specific procedures. Both are ethically meaningful. Legal consent authorizes the service; assent—or its absence—provides ongoing clinical information about client welfare and the acceptability of the intervention approach being used.
In clients with limited verbal communication, assent is assessed through observable behavioral indicators. Approach behaviors—initiating interaction, reaching toward materials, positive affect, engagement with instruction—are generally treated as assent indicators. Avoidance behaviors—turning away, pushing materials away, escaping the instructional context, vocalization of protest, or increased problem behavior at activity onset—are generally treated as non-assent indicators. These definitions must be individualized for each client and interpreted in the context of each client's behavioral history and the functional properties of their behavior.
Consistent non-assent is a clinical signal requiring systematic review. The first step is functional analysis: is the non-assent behavior escape-maintained, or does it reflect genuine preference against the procedure? Second, review whether a different procedure format or instructional approach could achieve the same outcome with better acceptability. Third, evaluate whether the goal itself is one the client would endorse with greater understanding of its benefits. Finally, consult with the family and document the analysis. If the procedure is necessary for health or safety, the rationale must be documented, and the delivery format should be adapted to minimize aversiveness to the extent possible.
Assent is not a veto over all treatment decisions. Some interventions are necessary for safety, health, or fundamental quality of life, and these may require implementation even when the client signals non-assent in the moment. The ethics code recognizes this reality. What assent does require is that non-assent signals be taken seriously as clinical data, that less aversive alternatives be sought and implemented where they exist, that unnecessary discomfort is avoided, and that the overall treatment program reflects the client's welfare and preferences to the greatest possible extent given their clinical needs.
The 2022 BACB Ethics Code strengthened existing provisions around client dignity and autonomy and introduced more explicit language about considering client preferences in treatment decisions. Code 2.11 (Obtaining Informed Consent) establishes the baseline consent requirement. The broader ethical framework emphasizing client dignity, least restrictive procedures, and treatment efficacy creates strong support for assent practices. BCBAs who implement assent monitoring and embed client preference in program design are acting in alignment with the ethics code's core commitments to client welfare and self-determination.
Treatment planning that incorporates assent begins with goal selection. BCBAs should engage families and clients—using whatever communication modalities are available—in identifying goals that reflect the client's own priorities and quality of life outcomes. Preference assessments can inform both goal selection and the format of instructional delivery. Treatment plans should document the basis for each goal in terms of client and family priorities, not only diagnostic category or clinician judgment. Procedure selection should include a review of alternatives and a rationale for why the chosen approach is the most acceptable effective option for this client.
Motivating operations are environmental variables that alter the reinforcing or punishing value of stimuli and the frequency of behaviors associated with those stimuli. In the context of assent, motivating operations explain much of the variation in client cooperation across sessions and activities. An establishing operation that makes access to a preferred activity highly valuable will produce strong approach behavior; an abolishing operation—satiation, fatigue, illness, or recent access to the preferred item—will reduce engagement. Assent assessment must account for current motivating operations rather than treating a single session's cooperation pattern as a stable characteristic of the client's preferences.
Many families are not accustomed to framing their child's behavioral signals as meaningful input into clinical decisions. BCBAs should explain that monitoring client cooperation is both an ethical obligation and a clinical strategy that improves outcomes—that interventions conducted with client engagement tend to produce better and faster results than those implemented over resistance. Families should be told what specific behaviors are being used as assent indicators, how those signals influence session decisions, and how the overall program is designed to reflect their child's preferences and communication. This conversation should occur at program initiation and be revisited whenever assent patterns change significantly.
Yes, and best practice argues for doing so. Assent data can be collected using simple Likert-scale session ratings, frequency counts of specific approach or avoidance behaviors, or structured interval sampling of engagement indicators. The specific format should be practical enough to implement within session without disrupting instruction and sensitive enough to detect meaningful variation in client cooperation across time, activities, and instructional formats. When assent data are graphed alongside skill acquisition and behavior data, patterns become visible—certain activities, times of day, or clinicians may be associated with reliably better or worse assent, which is clinically actionable information.
Research and clinical experience suggest several long-term benefits. Clients who experience their therapeutic environment as responsive to their signals develop more positive therapeutic relationships, which increases engagement and motivation over time. Programs that are designed around client preferences tend to produce skills that generalize more readily because they are practiced in motivationally congruent contexts. Assent-consistent practice also builds a habit of self-determination in clients—learning that their behavioral signals have predictable effects on their environment is itself a foundational skill for autonomy. For families, observing a treatment model that respects their child's communication builds trust in the therapeutic process.
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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.