Third Wave ABA: Evolving Science and Practice on a Foundation of Human Dignity

Overview & Clinical Significance

The field of applied behavior analysis is experiencing a period of rapid evolution that has generated both excitement and anxiety among practitioners. New terms and approaches appear with increasing frequency: assent-based practice, compassionate care, trauma-informed ABA, neurodiversity-affirming ABA, social justice in behavior analysis, and what some call today's ABA. For many practitioners, the pace and volume of these changes raise legitimate questions about whether they represent genuine advances in the science and ethics of behavior analysis or whether they are superficial rebranding efforts motivated by social approval or marketing concerns.

Jonathan Tarbox's presentation addresses these questions directly by situating current developments within the broader historical trajectory of ABA's evolution and connecting them to the foundational value of human dignity. This framing is clinically significant because it provides practitioners with a principled basis for evaluating new approaches rather than either accepting everything uncritically or rejecting everything reflexively.

The concept of a third wave in ABA draws on the parallel evolution in cognitive-behavioral therapy, where the third wave brought acceptance-based, values-oriented, and contextual approaches that expanded the field's scope while maintaining its scientific foundation. In ABA, the third wave encompasses approaches that expand the field's concern beyond behavior change per se to include the quality, dignity, and social validity of how that behavior change is achieved and what it aims to accomplish.

The clinical significance of this evolution is immediate and practical. Behavior analysts must make daily decisions about how to interact with clients, which goals to prioritize, how to implement interventions, and how to respond when clients resist or protest. The third wave movements provide frameworks for making these decisions in ways that center the dignity and autonomy of the individuals we serve. A behavior analyst who understands assent-based practice will pause when a client withdraws assent rather than pressing forward. A practitioner informed by neurodiversity-affirming principles will question whether a targeted behavior is genuinely functional or merely normative. A clinician practicing compassionate care will consider the emotional experience of the client alongside behavioral outcomes.

These are not trivial distinctions. They represent meaningful shifts in how behavior analysts conceptualize their role, their relationship with clients, and the outcomes that define success. And as Tarbox argues, they are connected by common values that unite them under the umbrella of human dignity rather than being isolated movements competing for attention.

Background & Context

Understanding the current evolution in ABA requires placing it within historical context. The field has always been in motion, though earlier shifts may be less visible to practitioners who entered the field during periods of relative stability.

The first wave of applied behavior analysis, emerging from the experimental analysis of behavior in the 1960s and 1970s, was characterized by a focus on demonstrating that behavioral principles could be applied to socially significant problems. The founding values of this period were rigor, replicability, and social significance. The emphasis was on proving that ABA worked, and the primary concerns were methodological: Could behavioral interventions produce meaningful changes in important behaviors? Could these changes be attributed to the intervention rather than confounds? This era produced landmark demonstrations of behavioral technology applied to education, developmental disabilities, and institutional settings.

The second wave, roughly spanning the 1980s through the 2000s, was characterized by the expansion and professionalization of ABA as a service delivery field, particularly in autism services. The establishment of board certification, insurance mandates for ABA services, and the growth of ABA service organizations transformed the field from an academic discipline to a healthcare profession serving hundreds of thousands of individuals. The values of this period emphasized evidence-based practice, standardized training, and accountability through professional credentialing.

The third wave, which has been building over the past decade and accelerating in recent years, represents a values expansion that does not reject the methodological rigor or professional standards of earlier periods but adds new dimensions of concern. These include the dignity and autonomy of the individuals served, the social validity of not just the outcomes but the processes of intervention, the field's relationship with the communities it serves, particularly the autistic community, the cultural responsiveness of behavior analytic practice, and the alignment of daily practice with the ethical principles articulated in the BACB Ethics Code.

This evolution has been driven by multiple forces. Criticism from the autistic community about ABA practices that prioritize normalization over wellbeing has prompted serious self-examination within the field. The updated BACB Ethics Code (2022) elevated concepts like client dignity, autonomy, and cultural responsiveness to prominent positions. Research on topics such as assent, social validity, and values-based practice has provided empirical grounding for new approaches. And a generation of behavior analysts trained in the era of the ethics code has entered the field with different expectations about what ethical practice looks like.

The concern that some of these movements are merely fads or marketing schemes is worth taking seriously. When new terminology proliferates without clear operational definitions or empirical support, there is a legitimate risk of conceptual confusion and diluted practice. Tarbox's presentation helps practitioners distinguish between genuine advances that serve client dignity and superficial rebranding that serves other purposes.

Clinical Implications

The third wave evolution has immediate clinical implications for how behavior analysts conduct their daily practice.

Assent-based practice changes how clinicians approach intervention implementation. Rather than proceeding with planned procedures regardless of the client's apparent willingness, assent-based practice requires ongoing attention to whether the client is assenting to the intervention. This does not mean that therapy stops whenever a client protests; rather, it means that the client's assent or withdrawal of assent is treated as important clinical information that may require modification of the approach, pace, or goals of intervention. For practitioners, this means developing sensitivity to behavioral indicators of assent and distress, establishing clear protocols for responding to assent withdrawal, and recognizing that forcing compliance may produce behavioral change at the cost of the therapeutic relationship and the client's trust.

Neurodiversity-affirming ABA challenges practitioners to examine their treatment goals critically. The core question is whether a targeted behavior is being addressed because it is genuinely problematic for the individual (interferes with their safety, functioning, or quality of life) or because it deviates from neurotypical norms. Stimming behaviors, atypical social interaction patterns, and non-standard communication styles may all be appropriate targets if they cause the individual distress or impairment, but not if they are targeted simply because they look different. This examination requires honest reflection about whose values are driving goal selection and whether the individual has been meaningfully involved in that process.

Compassionate care adds an affective dimension to behavioral practice. This does not mean abandoning data-driven decision-making or becoming less rigorous. It means attending to the emotional experience of clients and families alongside behavioral outcomes, communicating with empathy and respect, and recognizing that the way an intervention is delivered affects its impact as much as the technical procedures involved. For practitioners, this translates to warm, responsive interaction styles during sessions, genuine engagement with families' concerns and perspectives, and willingness to modify plans based on the human impact of the intervention.

Trauma-informed practice, as discussed in other contexts, requires behavior analysts to consider how trauma history may influence behavior and to design interventions that prioritize safety and trust. In the third wave context, trauma-informed practice is part of the broader commitment to understanding behavior in its full context rather than treating it as disconnected from the individual's lived experience.

Social justice in behavior analysis extends the field's concern beyond individual clients to the systems and structures that affect the communities we serve. This includes addressing disparities in access to services, examining how our practices may inadvertently perpetuate harmful norms, and advocating for policies that support the wellbeing and rights of the individuals and communities we serve. While not every behavior analyst will engage in direct advocacy, the third wave asks all practitioners to be aware of these systemic issues and to consider them in their clinical decision-making.

The unifying thread across all of these movements, as Tarbox emphasizes, is human dignity. Each represents a different facet of the commitment to treating the individuals we serve as whole persons deserving of respect, autonomy, and genuine consideration of their preferences, experiences, and values.

Ethical Considerations

The third wave evolution is deeply connected to the BACB Ethics Code (2022), which many practitioners see as both reflecting and advancing these changes in the field.

Code 2.01 (Providing Effective Treatment) requires that behavior analysts provide services based on the best available evidence. In the third wave context, this means that effectiveness is not defined solely by behavior change but by behavior change that respects the client's dignity, aligns with their values, and produces outcomes that improve their quality of life. An intervention that suppresses a behavior while damaging the therapeutic relationship or the client's sense of self may not meet the standard of effective treatment even if the behavioral data look favorable.

Code 1.07 (Cultural Responsiveness and Diversity) directly supports third wave principles by requiring behavior analysts to consider cultural variables in their practice. This includes understanding how cultural backgrounds influence what is considered appropriate behavior, how families define treatment success, and how the power dynamics inherent in the therapeutic relationship may affect culturally diverse clients.

Code 2.09 (Involving Clients and Stakeholders) connects directly to assent-based practice and neurodiversity-affirming approaches. When clients are genuinely involved in goal selection and intervention planning, the resulting programs are more likely to reflect their values and priorities. This is particularly important for older clients and those in the autistic community who have articulated clear concerns about having goals imposed on them that serve social conformity rather than personal wellbeing.

Code 3.01 (Responsibility to Clients) obligates behavior analysts to prioritize client welfare, which in the third wave context extends beyond immediate behavioral outcomes to encompass the client's autonomy, dignity, emotional wellbeing, and self-determination. This broader conception of welfare aligns with the movements toward compassionate care, assent-based practice, and neurodiversity-affirming approaches.

Code 1.01 (Being Truthful) and Code 1.02 (Conforming with Legal and Professional Requirements) are relevant to Tarbox's concern about distinguishing genuine advances from marketing schemes. Behavior analysts have an obligation to represent their services honestly and to avoid using trendy terminology to attract clients without genuinely implementing the approaches those terms describe. Claiming to provide neurodiversity-affirming ABA while continuing to target normalization goals, or marketing compassionate care while implementing coercive procedures, would violate these ethical requirements.

The ethical challenge for practitioners is navigating the tension between tradition and evolution. Some behavior analysts feel that third wave approaches dilute the scientific rigor of the field, while others feel that traditional approaches fail to adequately protect client dignity. The ethics code provides a framework for resolving this tension: rigorous, evidence-based practice that centers client welfare, dignity, and autonomy. Neither abandoning scientific rigor nor ignoring client dignity meets this standard.

Behavior analysts should also consider the ethical implications of resistance to evolution. When the communities we serve, particularly the autistic community, express consistent concerns about our practices, the ethical response is to listen, reflect, and adjust rather than to dismiss those concerns as uninformed or as threats to the profession. Code 2.09's requirement for client involvement extends to listening to the broader community of individuals affected by our services.

Assessment & Decision-Making

Implementing third wave principles requires changes in how behavior analysts approach assessment and clinical decision-making.

Goal selection assessment should include a values-alignment component. Before establishing treatment goals, behavior analysts should assess whether proposed goals align with the client's own values and preferences, whether the goals serve the client's quality of life or primarily serve social conformity, whether the client or their representative has been meaningfully involved in goal selection, and whether the goals reflect cultural considerations relevant to the client and their family. This assessment does not replace functional assessment but adds a layer of ethical analysis to the clinical decision-making process.

Assent assessment should be formalized rather than left to informal clinical judgment. This means identifying behavioral indicators of assent and assent withdrawal for each client, establishing protocols for how to respond when assent is withdrawn, documenting assent assessment as part of ongoing service delivery, and training all staff who interact with the client to recognize and respond to assent indicators. The specifics will vary by client based on their communication abilities, behavioral repertoire, and sensitivity to different types of demand.

Social validity assessment should be ongoing rather than limited to treatment conclusion. Traditional social validity measures often ask caregivers about their satisfaction with outcomes at the end of treatment. Third wave practice suggests that social validity should be assessed throughout treatment, including the social validity of treatment goals, treatment procedures, and treatment outcomes as they unfold. This ongoing assessment allows for mid-course corrections when the client, family, or community finds aspects of the treatment unacceptable.

Clinical decision-making within the third wave framework involves balancing multiple considerations: behavioral effectiveness, client dignity, assent, cultural responsiveness, and quality-of-life impact. When these considerations conflict, the behavior analyst must make judgment calls that cannot be reduced to simple rules. For example, when a client withdraws assent from an intervention that addresses a safety concern, the behavior analyst must weigh the immediate need for safety against the importance of honoring the client's autonomy. These are complex ethical decisions that require reflective practice, consultation with colleagues, and ongoing dialogue with clients and stakeholders.

Practitioners should also assess their own readiness to implement third wave approaches honestly. This includes evaluating their training and competence in specific approaches, examining their own biases and assumptions about what constitutes appropriate behavior, assessing whether their current practice genuinely reflects the values they espouse, and identifying areas where additional training, consultation, or self-reflection is needed. This self-assessment is not a one-time exercise but an ongoing process that supports the continued evolution of practice.

What This Means for Your Practice

The third wave evolution in ABA is not an abstract academic discussion. It has immediate implications for how you interact with clients, set goals, implement interventions, and evaluate your own practice.

Start by examining your current treatment goals through the lens of human dignity. For each client, ask whether the goals you have set would be chosen by the client themselves if they could fully articulate their preferences. Ask whether the goals serve the client's quality of life or primarily make the client easier to manage. These questions may be uncomfortable, but they are essential for aligning practice with the values the third wave articulates.

Develop a formal approach to assent. Identify how each of your clients communicates willingness and unwillingness, and create clear protocols for responding when a client signals distress or withdrawal. Train your staff in these protocols and document your approach.

Engage with the autistic community's feedback about ABA. Read accounts from autistic adults who have experienced ABA services and consider their perspectives seriously. This does not mean accepting every critique uncritically, but it does mean recognizing that the people most affected by our services have valuable insights about how those services can be improved.

Distinguish between terminology and substance. When you encounter new approaches or terms, evaluate them based on whether they are operationally defined, supported by evidence, and genuinely implemented in practice. Adopt approaches that substantively improve your clients' experience and outcomes, and be skeptical of those that seem to be more about branding than practice.

Recognize that this evolution strengthens rather than weakens behavior analysis. A field that centers human dignity, incorporates feedback from the communities it serves, and continuously examines its practices is stronger, more ethical, and more sustainable than one that resists change.