What is Applied Behaviour Analysis?


Applied Behaviour Analysis (ABA), also called behavioural engineering, is a scientific technique concerned with applying empirical approaches based upon the principles of respondent and operant conditioning to change behaviour of social significance.

It is the applied form of behaviour analysis; the other two forms are:

  • Radical behaviourism (or the philosophy of the science); and the
  • Experimental analysis of behaviour (or basic experimental research).

The name “applied behaviour analysis” has replaced behaviour modification because the latter approach suggested attempting to change behaviour without clarifying the relevant behaviour-environment interactions. In contrast, ABA changes behaviour by first assessing the functional relationship between a targeted behaviour and the environment. Further, the approach often seeks to develop socially acceptable alternatives for aberrant behaviours.

ABA has been utilised in a range of areas, including applied animal behaviour, schoolwide positive behaviour support, classroom instruction, structured and naturalistic early behavioural interventions for autism, paediatric feeding therapy, rehabilitation of brain injury, dementia, fitness training, substance abuse, phobias, tics, and organisational behaviour management.

ABA is considered to be controversial by some within the autism rights movement due to a perception that it emphasizes indistinguishability instead of acceptance and a history of, in some embodiments of ABA and its predecessors, the use of aversives such as electric shocks.


ABA is an applied science devoted to developing procedures which will produce observable changes in behaviour. It is to be distinguished from the experimental analysis of behaviour, which focuses on basic experimental research, but it uses principles developed by such research, in particular operant conditioning and classical conditioning. Behaviour analysis adopts the viewpoint of radical behaviourism, treating thoughts, emotions, and other covert activity as behaviour that is subject to the same rules as overt responses. This represents a shift away from methodological behaviourism, which restricts behaviour-change procedures to behaviours that are overt, and was the conceptual underpinning of behaviour modification.

Behaviour analysts also emphasize that the science of behaviour must be a natural science as opposed to a social science. As such, behaviour analysts focus on the observable relationship of behaviour with the environment, including antecedents and consequences, without resort to “hypothetical constructs”.

Brief History

The beginnings of ABA can be traced back to Teodoro Ayllon and Jack Michael’s study “The psychiatric nurse as a behavioural engineer” (1959) that they published in the Journal of the Experimental Analysis of Behaviour (JEAB). Ayllon and Michael were training the staff and nurses at a psychiatric hospital how to use a token economy based on the principles of operant conditioning for patients with schizophrenia and intellectual disability, which led to researchers at the University of Kansas to start the Journal of Applied Behaviour Analysis (JABA) in 1968.

A group of faculty and researchers at the University of Washington, including Donald Baer, Sidney W. Bijou, Bill Hopkins, Jay Birnbrauer, Todd Risley, and Montrose Wolf, applied the principles of behavior analysis to instruct developmentally disabled children, manage the behaviour of children and adolescents in juvenile detention centres, and organise employees who required proper structure and management in businesses, among other situations. In 1968, Baer, Bijou, Risley, Birnbrauer, Wolf, and James Sherman joined the Department of Human Development and Family Life at the University of Kansas, where they founded the Journal of Applied Behaviour Analysis.

Notable graduate students from the University of Washington include Robert Wahler, James Sherman, and Ivar Lovaas. Lovaas established the UCLA Young Autism Project while teaching at the University of California, Los Angeles. In 1965, Lovaas published a series of articles that outlined his system for coding observed behaviours, described a pioneering investigation of the antecedents and consequences that maintained a problem behaviour, and relied upon the methods of errorless learning that was initially devised by Charles Ferster to teach nonverbal children to speak. Lovaas also described how to use social (secondary) reinforcers, teach children to imitate, and what interventions (including electric shocks) may be used to reduce aggression and life-threatening self-injury.

In 1987, Lovaas published the study, “Behavioural treatment and normal educational and intellectual functioning in young autistic children”. The experimental group in this study received up to 40 hours per week in a 1:1 teaching setting at a table using errorless discrete trial training (DTT). The treatment is done at home with parents involved in every aspect of treatment, and the curriculum is highly individualized with a heavy emphasis on teaching eye contact, fine and gross motor imitation, and language. ABA principles were used to motivate learning and reduce non-desired behaviours. The outcome of this study indicated 47% of the experimental group (9/19) went on to lose their autism diagnosis and were described as indistinguishable from their typical adolescent peers. This included passing regular education without assistance, making and maintaining friends, and becoming self-sufficient as adults. These gains were maintained as reported in the 1993 study, “Long-term outcome for children with autism who received early intensive behavioural treatment”. Lovaas’ work went on to be recognised by the US Surgeon General in 1999, and his research were replicated in university and private settings. The “Lovaas Method” went on to become known as early intensive behavioural intervention (EIBI), or 30 to 40 hours per week of DTT.

Over the years, “behaviour analysis” gradually superseded “behaviour modification”; that is, from simply trying to alter problematic behaviour, behaviour analysts sought to understand the function of that behaviour, what antecedents promote and maintain it, and how it can be replaced by successful behaviour. This analysis is based on careful initial assessment of a behaviour’s function and a testing of methods that produce changes in behaviour.

While ABA seems to be intrinsically linked to autism intervention, it is also used in a broad range of other situations. Recent notable areas of research in JABA include autism, classroom instruction with typically developing students, paediatric feeding therapy, and substance-use disorders. Other applications of ABA include applied animal behaviour, consumer behaviour analysis, behavioural medicine, behavioural neuroscience, clinical behaviour analysis, forensic behaviour analysis, increasing job safety and performance, schoolwide positive behaviour support, and contact desensitisation for phobias.


Baer, Wolf, and Risley’s 1968 article is still used as the standard description of ABA. It lists the following seven characteristics of ABA.

  • Applied:
    • ABA focuses on the social significance of the behaviour studied.
    • For example, a non-applied researcher may study eating behaviour because this research helps to clarify metabolic processes, whereas the applied researcher may study eating behaviour in individuals who eat too little or too much, trying to change such behaviour so that it is more acceptable to the persons involved.
  • Behavioural:
    • ABA is pragmatic; it asks how it is possible to get an individual to do something effectively.
    • To answer this question, the behaviour itself must be objectively measured.
    • Verbal descriptions are treated as behaviour in themselves, and not as substitutes for the behaviour described.
  • Analytic:
    • Behaviour analysis is successful when the analyst understands and can manipulate the events that control a target behaviour.
    • This may be relatively easy to do in the lab, where a researcher is able to arrange the relevant events, but it is not always easy, or ethical, in an applied situation.
    • Baer et al. outline two methods that may be used in applied settings to demonstrate control while maintaining ethical standards.
    • These are the reversal design and the multiple baseline design.
    • In the reversal design, the experimenter first measures the behaviour of choice, introduces an intervention, and then measures the behaviour again.
    • Then, the intervention is removed, or reduced, and the behaviour is measured yet again.
    • The intervention is effective to the extent that the behaviour changes and then changes back in response to these manipulations.
    • The multiple baseline method may be used for behaviours that seem irreversible.
    • Here, several behaviours are measured and then the intervention is applied to each in turn.
    • The effectiveness of the intervention is revealed by changes in just the behaviour to which the intervention is being applied.
  • Technological:
    • The description of analytic research must be clear and detailed, so that any competent researcher can repeat it accurately.
    • Cooper et al. describe a good way to check this: Have a person trained in applied behaviour analysis read the description and then act out the procedure in detail.
    • If the person makes any mistakes or has to ask any questions then the description needs improvement.
  • Conceptually Systematic:
    • Behaviour analysis should not simply produce a list of effective interventions.
    • Rather, to the extent possible, these methods should be grounded in behavioural principles.
    • This is aided by the use of theoretically meaningful terms, such as “secondary reinforcement” or “errorless discrimination” where appropriate.
  • Effective:
    • Though analytic methods should be theoretically grounded, they must be effective.
    • If an intervention does not produce a large enough effect for practical use, then the analysis has failed
  • Generality:
    • Behaviour analysts should aim for interventions that are generally applicable; the methods should work in different environments, apply to more than one specific behaviour, and have long-lasting effects.

Other Proposed Characteristics

In 2005, Heward et al. suggested that the following five characteristics should be added:

  • Accountable:
    • To be accountable means that ABA must be able to demonstrate that its methods are effective.
    • This requires the repeatedly measuring the success of interventions, and, if necessary, making changes that improve their effectiveness.
  • Public:
    • The methods, results, and theoretical analyses of ABA must be published and open to scrutiny.
    • There are no hidden treatments or mystical, metaphysical explanations.
  • Doable:
    • To be generally useful, interventions should be available to a variety of individuals, who might be teachers, parents, therapists, or even those who wish to modify their own behaviour.
    • With proper planning and training, many interventions can be applied by almost anyone willing to invest the effort.
  • Empowering:
    • ABA provides tools that give the practitioner feedback on the results of interventions.
    • These allow clinicians to assess their skill level and build confidence in their effectiveness.
  • Optimistic:
    • According to several leading authors, behaviour analysts have cause to be optimistic that their efforts are socially worthwhile, for the following reasons:
      • The behaviours impacted by behaviour analysis are largely determined by learning and controlled by manipulable aspects of the environment.
      • Practitioners can improve performance by direct and continuous measurements.
      • As a practitioner uses behavioural techniques with positive outcomes, they become more confident of future success.
      • The literature provides many examples of success in teaching individuals considered previously unteachable.



Behaviour refers to the movement of some part of an organism that changes some aspect of the environment. Often, the term behaviour refers to a class of responses that share physical dimensions or functions, and in that case a response is a single instance of that behaviour. If a group of responses have the same function, this group may be called a response class. “Repertoire” refers to the various responses available to an individual; the term may refer to responses that are relevant to a particular situation, or it may refer to everything a person can do.

Operant Conditioning

Operant behaviour is the so-called “voluntary” behaviour that is sensitive to, or controlled by its consequences. Specifically, operant conditioning refers to the three-term contingency that uses stimulus control, in particular an antecedent contingency called the discriminative stimulus (SD) that influences the strengthening or weakening of behaviour through such consequences as reinforcement or punishment. The term is used quite generally, from reaching for a candy bar, to turning up the heat to escape an aversive chill, to studying for an exam to get good grades.

Respondent (Classical) Conditioning

Respondent (classical) conditioning is based on innate stimulus-response relationships called reflexes. In his famous experiments with dogs, Pavlov usually used the salivary reflex, namely salivation (unconditioned response) following the taste of food (unconditioned stimulus). Pairing a neutral stimulus, for example a bell (conditioned stimulus) with food caused the dog to elicit salivation (conditioned response). Thus, in classical conditioning, the conditioned stimulus becomes a signal for a biologically significant consequence. Note that in respondent conditioning, unlike operant conditioning, the response does not produce a reinforcer or punisher (e.g. the dog does not get food because it salivates).


The environment is the entire constellation of stimuli in which an organism exists. This includes events both inside and outside of an organism, but only real physical events are included. A stimulus is an “energy change that affects an organism through its receptor cells”.

A stimulus can be described:

  • Topographically by its physical features.
  • Temporally by when it occurs.
  • Functionally by its effect on behaviour.


Reinforcement is the key element in operant conditioning and in most behaviour change programmes. It is the process by which behaviour is strengthened. If a behaviour is followed closely in time by a stimulus and this results in an increase in the future frequency of that behaviour, then the stimulus is a positive reinforcer. If the removal of an event serves as a reinforcer, this is termed negative reinforcement. There are multiple schedules of reinforcement that affect the future probability of behaviour.

The use of punishments, especially those that inflict sensory or physical pain, is an area of controversy.


Punishment is a process by which a consequence immediately follows a behaviour which decreases the future frequency of that behaviour. As with reinforcement, a stimulus can be added (positive punishment) or removed (negative punishment). Broadly, there are three types of punishment: presentation of aversive stimuli (e.g. pain), response cost (removal of desirable stimuli as in monetary fines), and restriction of freedom (as in a ‘time out’). Punishment in practice can often result in unwanted side effects. Some other potential unwanted effects include resentment over being punished, attempts to escape the punishment, expression of pain and negative emotions associated with it, and recognition by the punished individual between the punishment and the person delivering it.


Extinction is the technical term to describe the procedure of withholding/discontinuing reinforcement of a previously reinforced behaviour, resulting in the decrease of that behaviour. The behaviour is then set to be extinguished. Extinction procedures are often preferred over punishment procedures, as many punishment procedures are deemed unethical and in many states prohibited. Nonetheless, extinction procedures must be implemented with utmost care by professionals, as they are generally associated with extinction bursts. An extinction burst is the temporary increase in the frequency, intensity, and/or duration of the behaviour targeted for extinction. Other characteristics of an extinction burst include an:

  • Extinction-produced aggression: the occurrence of an emotional response to an extinction procedure often manifested as aggression; and
  • Extinction-induced response variability: the occurrence of novel behaviours that did not typically occur prior to the extinction procedure.

These novel behaviours are a core component of shaping procedures.

Discriminated Operant and Three-Term Contingency

In addition to a relation being made between behaviour and its consequences, operant conditioning also establishes relations between antecedent conditions and behaviours. This differs from the S-R formulations (If-A-then-B), and replaces it with an AB-because-of-C formulation. In other words, the relation between a behaviour (B) and its context (A) is because of consequences (C), more specifically, this relationship between AB because of C indicates that the relationship is established by prior consequences that have occurred in similar contexts. This antecedent-behaviour-consequence contingency is termed the three-term contingency. A behaviour which occurs more frequently in the presence of an antecedent condition than in its absence is called a discriminated operant. The antecedent stimulus is called a discriminative stimulus (SD). The fact that the discriminated operant occurs only in the presence of the discriminative stimulus is an illustration of stimulus control. More recently behaviour analysts have been focusing on conditions that occur prior to the circumstances for the current behaviour of concern that increased the likelihood of the behaviour occurring or not occurring. These conditions have been referred to variously as “Setting Event”, “Establishing Operations”, and “Motivating Operations” by various researchers in their publications.

Verbal Behaviour

B.F. Skinner’s classification system of behaviour analysis has been applied to treatment of a host of communication disorders. Skinner’s system includes:

  • Tact: A verbal response evoked by a non-verbal antecedent and maintained by generalized conditioned reinforcement……
  • Mand: Behaviour under control of motivating operations maintained by a characteristic reinforcer.
  • Intraverbals: Verbal behaviour for which the relevant antecedent stimulus was other verbal behaviour, but which does not share the response topography of that prior verbal stimulus (e.g. responding to another speaker’s question).
  • Autoclitic: Secondary verbal behaviour which alters the effect of primary verbal behaviour on the listener. Examples involve quantification, grammar, and qualifying statements (e.g. the differential effects of “I think…” vs. “I know…”).

Measuring Behaviour

When measuring behaviour, there are both dimensions of behaviour and quantifiable measures of behaviour. In applied behaviour analysis, the quantifiable measures are a derivative of the dimensions. These dimensions are repeatability, temporal extent, and temporal locus.

  • Repeatability:
    • Response classes occur repeatedly throughout time – i.e. how many times the behaviour occurs.
    • Count is the number of occurrences in behaviour.
    • Rate/frequency is the number of instances of behaviour per unit of time.
    • Celeration is the measure of how the rate changes over time.
  • Temporal extent:
    • This dimension indicates that each instance of behaviour occupies some amount of time – i.e. how long the behaviour occurs.
    • Duration is the period of time over which the behavior occurs.
  • Temporal locus:
    • Each instance of behaviour occurs at a specific point in time – i.e. when the behaviour occurs.
    • Response latency is the measure of elapsed time between the onset of a stimulus and the initiation of the response.
    • Interresponse time is the amount of time that occurs between two consecutive instances of a response class.
  • Derivative measures:
    • Derivative measures are unrelated to specific dimensions.
    • Percentage is the ratio formed by combining the same dimensional quantities.
    • Trials-to-criterion are the number of response opportunities needed to achieve a predetermined level of performance.

Analysing Behaviour Change

Experimental Control

In applied behaviour analysis, all experiments should include the following:

  • At least one participant.
  • At least one behaviour (dependent variable).
  • At least one setting.
  • A system for measuring the behaviour and ongoing visual analysis of data.
  • At least one treatment or intervention condition.
  • Manipulations of the independent variable so that its effects on the dependent variable may be quantitatively or qualitatively analysed.
  • An intervention that will benefit the participant in some way.

Methodologies developed through ABA Research

Task Analysis

Task analysis is a process in which a task is analysed into its component parts so that those parts can be taught through the use of chaining: forward chaining, backward chaining and total task presentation. Task analysis has been used in organisational behaviour management, a behaviour analytic approach to changing the behaviours of members of an organisation (e.g. factories, offices, or hospitals). Behavioural scripts often emerge from a task analysis. Bergan conducted a task analysis of the behavioural consultation relationship and Thomas Kratochwill developed a training programme based on teaching Bergan’s skills. A similar approach was used for the development of microskills training for counsellors. Ivey would later call this “behaviourist” phase a very productive one[58] and the skills-based approach came to dominate counsellor training during 1970-1990. Task analysis was also used in determining the skills needed to access a career. In education, Englemann (1968) used task analysis as part of the methods to design the Direct Instruction curriculum.


The skill to be learned is broken down into small units for easy learning. For example, a person learning to brush teeth independently may start with learning to unscrew the toothpaste cap. Once they have learned this, the next step may be squeezing the tube, etc.

For problem behaviour, chains can also be analysed and the chain can be disrupted to prevent the problem behaviour. Some behaviour therapies, such as dialectical behaviour therapy, make extensive use of behaviour chain analysis, but is not philosophically behaviour analytic.


A prompt is a cue that is used to encourage a desired response from an individual. Prompts are often categorized into a prompt hierarchy from most intrusive to least intrusive, although there is some controversy about what is considered most intrusive, those that are physically intrusive or those that are hardest prompt to fade (e.g. verbal). In order to minimise errors and ensure a high level of success during learning, prompts are given in a most-to-least sequence and faded systematically. During this process, prompts are faded quickly as possible so that the learner does not come to depend on them and eventually behaves appropriately without prompting.

Types of prompts Prompters might use any or all of the following to suggest the desired response:

  • Vocal prompts: Words or other vocalisations.
  • Visual prompts: A visual cue or picture.
  • Gestural prompts: A physical gesture.
  • Positional prompt: For example, the target item is placed close to the individual.
  • Modelling: Modelling the desired response.
    • This type of prompt is best suited for individuals who learn through imitation and can attend to a model.
  • Physical prompts: Physically manipulating the individual to produce the desired response.
    • There are many degrees of physical prompts, from quite intrusive (e.g. the teacher places a hand on the learner’s hand) to minimally intrusive (e.g. a slight tap).

This is not an exhaustive list of prompts; the nature, number, and order of prompts are chosen to be the most effective for a particular individual.


The overall goal is for an individual to eventually not need prompts. As an individual gains mastery of a skill at a particular prompt level, the prompt is faded to a less intrusive prompt. This ensures that the individual does not become overly dependent on a particular prompt when learning a new behaviour or skill.

Thinning a Reinforcement Schedule

Thinning is often confused with fading. Fading refers to a prompt being removed, where thinning refers to an increase in the time or number of responses required between reinforcements. Periodic thinning that produces a 30% decrease in reinforcement has been suggested as an efficient way to thin. Schedule thinning is often an important and neglected issue in contingency management and token economy systems, especially when these are developed by unqualified practitioners (see professional practice of behaviour analysis).


Generalisation is the expansion of a student’s performance ability beyond the initial conditions set for acquisition of a skill. Generalisation can occur across people, places, and materials used for teaching. For example, once a skill is learned in one setting, with a particular instructor, and with specific materials, the skill is taught in more general settings with more variation from the initial acquisition phase. For example, if a student has successfully mastered learning colours at the table, the teacher may take the student around the house or school and generalise the skill in these more natural environments with other materials. Behaviour analysts have spent considerable amount of time studying factors that lead to generalisation.


Shaping involves gradually modifying the existing behaviour into the desired behaviour. If the student engages with a dog by hitting it, then they could have their behaviour shaped by reinforcing interactions in which they touch the dog more gently. Over many interactions, successful shaping would replace the hitting behaviour with patting or other gentler behaviour. Shaping is based on a behaviour analyst’s thorough knowledge of operant conditioning principles and extinction. Recent efforts to teach shaping have used simulated computer tasks.

One teaching technique found to be effective with some students, particularly children, is the use of video modelling (the use of taped sequences as exemplars of behaviour). It can be used by therapists to assist in the acquisition of both verbal and motor responses, in some cases for long chains of behaviour.

Interventions Based on an FBA

Critical to behaviour analytic interventions is the concept of a systematic behavioural case formulation with a functional behavioural assessment or analysis at the core. This approach should apply a behaviour analytic theory of change. This formulation should include a thorough functional assessment, a skills assessment, a sequential analysis (behaviour chain analysis), an ecological assessment, a look at existing evidenced-based behavioural models for the problem behaviour (such as Fordyce’s model of chronic pain) and then a treatment plan based on how environmental factors influence behaviour. Some argue that behaviour analytic case formulation can be improved with an assessment of rules and rule-governed behaviour. Some of the interventions that result from this type of conceptualization involve training specific communication skills to replace the problem behaviours as well as specific setting, antecedent, behaviour, and consequence strategies.

Use in the Treatment of Autism Spectrum Disorders

ABA-based techniques are often used to teach adaptive behaviours or to diminish behaviours associated with autism, so much that ABA itself is often mistakenly considered to be synonymous with therapy for autism. According to a paper from 2007, it was considered to be an effective “intervention for challenging behaviors” by the American Academy of Paediatrics, though this has been refuted by more recent papers. ABA for autism may be limited by diagnostic severity and IQ.


Recent reviews of the efficacy of ABA-based techniques in autism include:

  • A 2007 clinical report of the American Academy of Paediatrics concluded that the benefit of ABA-based interventions in autism spectrum disorders (ASDs) “has been well documented” and that “children who receive early intensive behavioral treatment have been shown to make substantial, sustained gains in IQ, language, academic performance, and adaptive behavior as well as some measures of social behavior”.
  • Researchers from the MIND Institute published an evidence-based review of comprehensive treatment approaches in 2008. On the basis of “the strength of the findings from the four best-designed, controlled studies”, they were of the opinion that one ABA-based approach (the Lovaas technique created by Ole Ivar Løvaas) is “well-established” for improving intellectual performance of young children with ASD.
  • A 2009 review of psycho-educational interventions for children with autism whose mean age was six years or less at intake found that five high-quality (“Level 1” or “Level 2”) studies assessed ABA-based treatments. On the basis of these and other studies, the author concluded that ABA is “well-established” and is “demonstrated effective in enhancing global functioning in pre-school children with autism when treatment is intensive and carried out by trained therapists”. However, the review committee also concluded that “there is a great need for more knowledge about which interventions are most effective”.
  • A 2009 paper included a descriptive analysis, an effect size analysis, and a meta-analysis of 13 reports published from 1987 to 2007 of early intensive behavioural intervention (EIBI, a form of ABA-based treatment with origins in the Lovaas technique) for autism. It determined that EIBI’s effect sizes were “generally positive” for IQ, adaptive behaviour, expressive language, and receptive language. The paper did note limitations of its findings including the lack of published comparisons between EIBI and other “empirically validated treatment programs”.
  • In a 2009 systematic review of 11 studies published from 1987 to 2007, the researchers wrote “there is strong evidence that EIBI is effective for some, but not all, children with autism spectrum disorders, and there is wide variability in response to treatment”. Furthermore, any improvements are likely to be greatest in the first year of intervention.
  • A 2009 meta-analysis of nine studies published from 1987 to 2007 concluded that EIBI has a “large” effect on full-scale intelligence and a “moderate” effect on adaptive behaviour in autistic children.
  • A 2009 systematic review and meta-analysis by Spreckley and Boyd of four small-n 2000-2007 studies (involving a total of 76 children) came to different conclusions than the aforementioned reviews. Spreckley and Boyd reported that applied behaviour intervention (ABI), another name for EIBI, did not significantly improve outcomes compared with standard care of preschool children with ASD in the areas of cognitive outcome, expressive language, receptive language, and adaptive behaviour. In a letter to the editor, however, authors of the four studies meta-analysed claimed that Spreckley and Boyd had misinterpreted one study comparing two forms of ABI with each other as a comparison of ABI with standard care, which erroneously decreased the observed efficacy of ABI. Furthermore, the four studies’ authors raised the possibility that Spreckley and Boyd had excluded some other studies unnecessarily, and that including such studies could have led to a more favourable evaluation of ABI. Spreckley, Boyd, and the four studies’ authors did agree that large multi-site randomised trials are needed to improve the understanding of ABA’s efficacy in autism.
  • In 2011, investigators from Vanderbilt University under contract with the Agency for Healthcare Research and Quality performed a comprehensive review of the scientific literature on ABA-based and other therapies for autism spectrum disorders; the ABA-based therapies included the UCLA/Lovaas method and the Early Start Denver Model (the latter developed by Sally Rogers and Geraldine Dawson). They concluded that “both approaches were associated with … improvements in cognitive performance, language skills, and adaptive behavior skills”. However, they also concluded that “the strength of evidence … is low”, “many children continue to display prominent areas of impairment”, “subgroups may account for a majority of the change”, there is “little evidence of practical effectiveness or feasibility beyond research studies”, and the published studies “used small samples, different treatment approaches and duration, and different outcome measurements”.
  • An October 2019 report by the United States Department of Defence found that “76 percent of TRICARE beneficiaries in the ACD had little to no change in symptom presentation over the course of 12 months of applied behavior analysis (ABA) services, with an additional 9 percent demonstrating worsening symptoms.”
  • Controversy regarding ABA persists in the autism community. A 2017 study found that 46% of people with autism spectrum undergoing ABA appeared to meet the criteria for post-traumatic stress disorder (PTSD), a rate 86% higher than the rate of those who had not undergone ABA (28%). According to the researcher, the rate of apparent PTSD increased after exposure to ABA regardless of the age of the patient. However, the quality of this study has been disputed by other researchers.
  • A 2019 review article concluded ABA proponents have utilised predominantly non-verbal and neurologically different, children who are not recognised under this paradigm to have their own thought processes, basic needs, preferences, style of learning, and psychological and emotional needs, for their experiment. This also indicates a missing voice of children and nonverbal people who cannot express their view on ABA.

Use of Aversives

Some embodiments of applied behaviour analysis as devised by Ole Ivar Lovaas used aversives such as electric shocks to modify undesirable behaviour in their initial use in the 1970s, as well as slapping and shouting in the landmark 1987 study. Over time the use of aversives lessened and in 2012 their use was described as being inconsistent with contemporary practice. However, aversives have continued to be used in some ABA programs. In comments made in 2014 to the FDA, a clinician who previously worked at the Judge Rotenberg Educational Centre claimed that “all textbooks used for thorough training of applied behavior analysts include an overview of the principles of punishment, including the use of electrical stimulation.” In 2020, the FDA banned the use of electrical stimulation devices used for self-injurious or aggressive behaviour and asserted that “Evidence indicates a number of significant psychological and physical risks are associated with the use of these devices, including worsening of underlying symptoms, depression, anxiety, posttraumatic stress disorder, pain, burns and tissue damage.”


The value of eliminating autistic behaviours is disputed by proponents of neurodiversity, who claim that it forces autistics to mask their true personalities on behalf of a narrow conception of normality. Autism advocates contend that it is cruel to try to make autistic people “normal” without consideration for how this may affect their well-being. Instead, these critics advocate for increased social acceptance of harmless autistic traits and therapies focused on improving quality of life. Julia Bascom of the Autistic Self Advocacy Network (ASAN) has said, “ASAN’s objection is fundamentally an ethical one. The stated end goal of ABA is an autistic child who is ‘indistinguishable from their peers’ – an autistic child who can pass as neurotypical. We don’t think that’s an acceptable goal. The end goal of all services, supports, interventions, and therapies an autistic child receives should be to support them in growing up into an autistic adult who is happy, healthy, and living a self-determined life.”

It has been suspected that there might be a publication bias against those research articles share a controversial account of ABA. Publication bias could lead to exaggerated estimates of intervention effects.

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