About Applied Behaviour Analysis (ABA)

Applied Behaviour Analysis (ABA) is based on the theory that behaviours can be increased or decreased depending on the consequence the behaviour receives. If a specific behaviour is reinforced, than there is an increased likelihood of that behaviour occurring again in the future. ABA focuses on increasing behaviours of social significance such as academics, communication, social, play and self-help skills. ABA treatment for children with autism spectrum disorders is the only method that has proven to be effective and to produce lasting results.

The History of Applied Behaviour Analysis: It's not just Discrete Trial Teaching

Respondent and Operant Conditioning
The science of behavior began in 1938, when B.F. Skinner published The Behavior of Organisms, where he described the results of experiments on the lever-pressing behavior of rats for food or water. Based on his findings, he outlined two kinds of behavior; respondent behavior and operant behavior.

Respondent behaviors are elicited, or brought out, by stimuli that precede the behavior. Respondent behaviors are involuntary (e.g., reflexes) and occur whenever the eliciting stimulus is presented. For example, the reflex of pupil constriction when presented with a bright light in your eye.

Operant behaviors are not elicited by preceding stimuli but rather are influenced by stimuli that follow the behavior. Skinner found that most human behavior is a result of operant conditioning. Skinner named this new science the experimental analysis of behavior.

Skinner's procedures evolved into a methodology that provided for the experimental demonstration of principles of behavior. Skinner, his colleagues and students conducted thousands of laboratory experiments from the 1930s through the 1950s in which they discovered and verified the basic principles of operant behavior, by systematically manipulating the arrangement and scheduling of stimuli that both preceded (respondent conditioning) and followed behavior (operant conditioning).

Operant conditioning with humans
In 1949, Fuller conducted one of the first studies on the application of principles of operant conditioning with humans. The subject was an 18-year-old boy with profound mental retardation who was described as being in a vegetative state. He was unable to roll over and would only lie on his back. Fuller filled a syringe with warm sugar-milk solution and injected it into the subject's mouth every time the boy would move his arm, which he was capable of moving but would move it infrequently. Within only four sessions, the subject was moving his arm at a rate of 3 times per minute (Fuller, 1949).

The methodology of the experimental analysis of behavior was used by many researchers throughout the 1950s and early 1960s to determine whether the principles of behavior demonstrated in the laboratory setting could be replicated with humans. For example, Bijou (1955, 1957, 1958) researched principles of behavior with both neurotypical and mentally retarded subjects; Baer (1960, 1961, 1962) examined the effects of punishment, escape, and avoidance contingencies on preschool children; and Ferster & DeMyer (1961, 1962) conducted a systematic study of the principles of behavior with children with autism.

The majority of the early studies with human subjects were conducted in a clinic or laboratory setting. These early researchers were able to establish that the principles of behavior are applicable to human behavior, and they set the stage for the development of applied behavior analysis.

The field of applied behavior analysis, formally began with the 1959 publication of Allyon and Michael's paper entitled "The Psychiatric Nurse as a Behavioral Engineer". This paper describes a direct care personnel in a state hospital using a variety of techniques based on the principles of behavior to improve the functioning of chronic psychotic or mentally handicapped patients (Allyon & Michael, 1959).

In 1968, two significant events occurred that marked that year as the beginning of contemporary applied behavior analysis; the first publication of the Journal of Applied Behavior Analyis (JABA) and Baer, Wolf and Risley's landmark paper "Some current dimensions of Applied Behavior Analysis" (Baer, Wolf & Risley, 1968). The Journal of Applied Behavior Analysis was the first behavioral journal in the United States to deal with applied problems and gave researchers in the field of experimental analysis of behavior a means to publish their findings. The paper by Baer, Wolf, and Risley both defined the criteria for judging the adequacy of research in applied behavior analysis as well as outlines the scope of work for those in the field. Applied behavior analysis can be defined as follows:

"Applied behavior analysis is the science in which procedures derived from the principles of behavior are systematically applied to improve socially significant behavior to a meaningful degree and to demonstrate experimentally that the procedures employed were responsible for the improvement in behavior". (Cooper, Heron, Heward, p.14 )

The definition of applied behavior analysis identifies six key aspects of the field; a) the methodology of science guides its practice, b) behavior change procedures are applied systematically and the written description is complete and detailed to enable others to replicate the procedure, c) only those procedures that are derived from the basic principles of behavior should be used, d) ABA focuses on socially significant behavior, e) ABA seeks to make meaningful improvement in behavior of importance to the individual, and f) to demonstrate experimental control over the occurrence and non-occurrence of the behavior in order to demonstrate a functional analysis of the factors responsible for improvement (Cooper, Heron & Heward, 1987).

Over the past 30 years, there have been several thousand studies published documenting the effectiveness of applied behavior analysis across a wide range of; populations (children and adult with mental illness, developmental disabilities and learning disorders, animals, geriatric patients, addicts), settings (schools, homes, institutions, group homes, hospitals, organizations and businesses), and behaviors (language, social, academic, leisure and functional life skills, aggression, self-injury, oppositional and stereotypical behaviors).

Most recently, applied behavior analysis became most popular with the implementation of its principles being applied to children with autism.

Applied Behavior Analysis and autism
Research documenting the effectiveness of ABA-based interventions with people with autism began in the 1960s, with more comprehensive evaluations beginning in the early 1970s.

In 1972, Hingtgen & Bryson reviewed over 400 research articles concerning autism published between 1964 and 1970 (Hingtgen & Bryson, 1972). They concluded that ABA based interventions demonstrated the most consistent results. In a follow-up study, DeMyer, Hingtgen & Jackson (1981) reviewed more than another 1,100 studies conducted in the 1970s. Their examination included both studies that were based on the principles of ABA as well as interventions based on a wide range other theoretical disciplines. Based on their comprehensive review, they concluded that there is overwhelming evidence suggesting that ABA based interventions provided the best results for improving behaviors in children with autism. Children should receive as many contact hours as possible and programs should include therapists as well as parents who have been trained in behavioral techniques.

The effectiveness of a broad range of ABA-based interventions with children with autism has continued to receive much support in the literature. Baglio, Benavidiz, Compton, Matson & Paclawskyj (1996) reviewed 251 studies published between 1960 and 1995 concerning behavior therapies for children with autism.

Applied behavior analysis as a treatment for children with autism became most recognized with the work of Dr. Ivar Lovaas from the University of California Los Angeles. Dr. Lovaas conducted research involving 38 children (19 in the treatment group and 19 in the control group) with autism who participated in an intensive behavioral intervention program based on the methodology of applied behavior analysis consisting of 40 hours per week (Lovaas, 1987). After two years, 47% (9 out of 19) of the children in the treatment group, achieved normal intellectual and educational functioning with normal-range IQ scores. In contrast, 2% of the children in the control group (not receiving intensive ABA therapy) achieved normal educational and intellectual functioning.

In a follow-up study, McEachin, Smith and Lovaas (1993) investigated the nine children who achieved the best outcomes in the original Lovaas study (Lovaas, 1987). They reported that those children who were in the treatment group sustained their gains as compared to the children in the control group. Based on these results, they concluded that behavioral intervention may produce long-lasting and significant gains in young children with autism.

Following the work of Lovaas and colleagues, many researchers have investigated the outcomes of ABA-based programs (Birnbrauer & Leach, 1993; Harris & Handleman, 1994; Sheinkopf & Siegel, 1998) .The May Institute reported outcomes of 14 children who received 15-20 hours of discrete trial training in a home-based program (Anderson, Avery, DiPietro, Edwards, & Christian, 1987). Significant gains were reported in language, self-care, social and academic gains.

Components of an ABA program

  • Data: Applied behavior analysis is based on data, therefore, all programs should include some method to record consistent and reliable data regarding the child's progress. This could include graphs, charts, etc. which demonstrate the child's progress (e.g., skill acquisition, decrease in self-stimulatory behaviors). Data-based systems have many advantages including monitoring the child's progress, determining whether teaching methods need to be modified in order to be more effective and to help assure that all staff are working consistently and implementing the treatment program as planned.
  • Repeated Opportunities for Learning: In order to acquire a new skill, many people with ASD require multiple opportunities to learn. Typically developing children constantly acquire new skills by recognizing cues in their environment and imitating their peers. People with ASD, as compared to typically developing children, often have an inability to distinguish the important characteristics in their environment and therefore, are unable to retain information and then use it again in future situations. It is often necessary to teach new skills with repeated trials so that the new skill becomes ingrained and the child has more opportunities to recognize when the skill is to be used.
  • Generalization of skills: Generalization refers to the ability to demonstrate a skill that was taught under specific conditions, to novel situations such as in various locations, with different people, with different materials and when asked a different way. Many people with ASD have difficulty generalizing newly acquired skills. For example, a child with ASD may learn to sit when called to the table to do work, but when asked to sit at the dinner table or sit at school during circle time, he is unable to do so. It is essential to implement methods to ensure that skills are generalized in novel environments, with different people, under different conditions, using different instructions.
  • Shaping behavior: The most effective way to teach a child with ASD, is by breaking a skill into its essential parts and teaching each part, step by step. By gradually increasing our expectations of the child and reinforcing each attempt, we slowly shape the behavior of the child. For example, if we want to teach a child how to put on his jacket, we might begin by reinforcing the child when he gets his jacket and then gradually only reinforce him when he puts his arm in the sleeve and then reinforce only when both arms are in, and so on, until he is able to put on his jacket and zip it up independently.
  • Reinforcement: Most typically developing children find learning new things reinforcing. However, children with ASD typically require more formal types of reinforcement; such as a reward system to increase their motivation to learn. Every child with ASD is unique and therefore what motivates one child to learn will be different than what motivates another. It is essential that each program develops creative reinforcers based on the child's interests. These reinforcers are then provided when the child demonstrates a new skill or behaves appropriately. It is important to pair tangible reinforcers, such as food or toys, with social praise, such as a high five or hooray, so that the child eventually learns to find social praise motivating as well.
  • Increasing motivation to learn: Recent research has shown that when teaching a new or difficult skill, it is most effective to prompt the child immediately following the request (errorless learning). Errorless learning allows the student to always respond correctly, thereby, increasing the child's access to reinforcement and reducing the child's frustration. Prompting, either verbal or physical, is faded as soon as possible until the child is responding independently. Teaching sessions should include a variety of easy tasks, which the child has already mastered, as well as difficult tasks or skills which are being taught. By using interspersed trials, varying between easy and difficult tasks, the child feels more successful and is more motivated to learn and to attend to the teacher.

Discrete Trial Teaching
Discrete trial teaching (DTT), also known as discrete trial training or discrete trial instruction, is a very popular teaching methodology used in many Applied Behavior Analysis programs. This teaching methodology is very structured and used to teach many skills such as cognitive skills, self-help skills and communication skills. Discrete trial teaching involves breaking a skill down into small steps and teaching each step one at a time. For example, if teaching a child how to dress independently, one might begin by teaching the child to put on his underwear and then once the skill of putting on underwear is mastered, teach putting on socks and so on. Skills are taught in very short increments called trials. A trial consists of four components; an instruction (discriminative stimulus, SD), a response, a prompt (guidance/assistance) and a consequence (reinforcement). An instruction is given to the child, such as put on underwear. If the child responds correctly (within 3-5 seconds) by putting on underwear, a reinforcing statement, edible or small tangible item is given. However, if the child demonstrates an incorrect response or does not respond, a prompt (guidance/assistance) is given to teach him/her the correct response. All prompts are quickly faded to avoid making the child dependent on them, as the goal is to make the child respond independently.

For several years, research has demonstrated that discrete trial teaching has produced significant positive results for many people with ASDs. Over the years, the method in which DTT is implemented has evolved, however, the teaching structure continues to be helpful for most people with autism spectrum disorder.

ABA is not just DTT
Many parents and professionals misunderstand the terms ABA and DTT and use the terms interchangeably. Many people believe that ABA consists of sitting at a chair, working in a one-on-one type environment, doing repetitive drills, using the method of discrete trial teaching. Alternately, a parent might say that they are have a DTT program when in fact they have an ABA program that includes discrete trial teaching as an instructional method. The field of applied behavior analysis (ABA) refers to a range of strategies all based on research of how behavior is learned and modified. Discrete trial teaching is just one of the many teaching methodologies under the umbrella of applied behavior analysis (Bruey, 2004).

The pros and cons of Applied Behavior Analysis
Parental involvement is heavily emphasized in most ABA programs. Parents are encouraged to implement strategies taught during therapy to help reinforce skills already taught and to enable generalization of skills with other people and in other environments.

Despite the wealth of empirical support, there is much controversy surrounding applied behavior analysis programs. Opponents believe that behavioral programs produce robotic children, not children who think independently. There has been no research to substantiate this claim. On the contrary, one of the more consistent findings of the research is improved social skills in those children who have received treatment (Lovaas, 1987; Maurice, 1993). However, this criticism often refers to the fact that most children with autism have an inexpressive quality of their voice, which may cause them to sound somewhat robotic when they speak. This is similar to learning a new language. When you begin to speak the language, you sound rote, forced, unnatural, and it is difficult to find the right words and keep a conversation. With practice your speech comes with greater ease and you begin to sound more natural. You may also learn rote phrases to help in specific situations, such as finding the bathroom or ordering food. To become fluent in any language, it takes time and practice. Therefore, it proves the fact that children need lots of practice and many opportunities for learning.

Some people also question whether Lovaas (1987) used a representative sample of children with autism. However, research using a variety of samples (Anderson et al, 1987; Sheinkopf & Siegel, 1998; Birnbrauer & Leach, 1993; Fenske, Zalenski, Krantz & McClannahan, 1985) shows that unlike other treatments in the field of autism, there have been no studies that refute the effectiveness of behavioral intervention programs.

Research has indicated that the optimal intensity of discrete trial teaching is 40 hours per week. This is often a daunting challenge for parents and sometimes results in further stress placed on families. However, ABA is not an "all or nothing" approach. If forty hours per week is not feasible, the program may be implemented for 20 hours a week or whatever amount of time is feasible for the family. Results may not occur as quickly and children may not achieve as significant gains however, improvement is usually seen.

Another major obstacle to implementing a successful ABA program is finding qualified professionals to develop and supervise the program. There are currently very few places that require specific credentials for practitioners in the field of ABA. Since there is a huge demand for ABA service providers, many individuals or programs claim to be "doing ABA". Therefore, parents must be cautious when enlisting a supervisor for their child's program. Parents should review the providers formal training, experience and competency. ABA programs for children with autism should be designed and supervised by qualified behavior analysts, preferably individuals who are Board Certified Behavior Analysts or have the equivalent training and experience (for more information visit the Behavior Analyst Certification Board).

Allyon, T., & Michael, J.(1959). The psychiatric nurse as a behavioral engineer. Journal of the Experimental Analysis of Behavior, 2, 323-334.
Anderson, S.R., Avery, D.L., Dipietro, E.K., Edwards, G.L., Christian, W.P. (1987). Intensive home-based early intervention with autistic children. Education and Treatment of Children, 10, 352-366.
Baer, D. (1960). Escape and avoidance response of preschool children to two schedules of reinforcement withdrawal. Journal of the Experimental Analysis of Behavior, 3, 155-159.
Baer, D. (1961). Effect of withdrawal of positive reinforcement on an extinguishing response in young children. Child Development, 32, 67-74.
Baer, D. (1962). Laboratory control of thumbsucking by withdrawal and representation of reinforcement. Journal of Experimental Analysis of Behavior, 5, 525-528.
Baer, D., Wolf, M., & Risley, R. (1968) Some current dimension of applied behavior analysis. Journal of Applied Behavior Analysis, 1, 91-97.
Baer, D., Wolf, M., & Risley, R. (1987). Some still-current dimension of applied behavior analysis. Journal of Applied Behavior Analysis, 20, 313-327.
Baglio, C., Benavidiz, D., Compton, L., Matson, J., & Paclawskyj, T. (1996). Behavioral treatment of autistic persons: A review of research from 1980 to present. Research in Developmental Disabilities, 17, 433-465.
Bijou, S.W. (1955). A systematic approach to an experimental analysis of young children. Child Development, 26, 161-168.
Bijou, S.W. (1957). Patterns of reinforcement and resistance to extinction in young children. Child Development, 28, 47-54.
Bijou, S.W. (1958). Operant extinction after fixed-interval schedules with young children. Journal of the Experimental Analysis of Behavior, 1, 25-29.
Birnbrauer, J.S. & Leach, D.J. (1993). The Murdoch early intervention program after 2 years. Behaviour Change, 10, 63-74.
Bruey, C.T. (2004). Topics in autism: Demystifying autism spectrum disorders. A guide to diagnosis for parents and professionals. Bethesda, MD: Woodbine House, 2004.
Cooper, J.O., Heron, T.E., Heward, W.L. Applied Behavior Analysis. Upper Saddle River, New Jersey: Prentice-Hall, 1987.
DeMyer, M.K., Hingtgen, J., & Jackson, R. (1981). Infantile autism reviewed: A decade of research. Schizophrenia Bulletin, 7, 388-451.
Evans, Rachel (2006). The essential guide to autism. Essential-guide-to-autism.com.
Fenske, E.C., Zalenski, S., Krantz, P.J., & McClannahan, L.E. (1985). Age at intervention and treatment outcome for autistic children in a comprehensive intervention program. Analysis and Intervention in Developmental Disabilities, 5, 49-58.
Ferster, C.B., & DeMyer, M.K. (1961). The development of performances in autistic children in an automatically controlled environment. Journal of Chronic Diseases, 13, 312-345.
Ferster, C.B., & DeMyer, M.K. (1962). A method for the experimental analysis of the behavior of autistic children. American Journal of Orthopsychiatry, 32, 89-98.
Fuller, P.R. (1949). Operant conditioning of a vegetative organism. American Journal of Psychology, 62, 587-590.
Harris, S.L. & Handleman, J.S. (1994). Preschool education programs for children with autism. Austin, TX: PRO-ED.
Hingtgen, J.N., & Bryson, C.Q. (1972). Recent developments in the study of early childhood psychoses: Infantile autism, childhood schizophrenia, and related disorders. Schizophrenia Bulletin, 5, 8-54.
Lovaas, O.I. (1987). Behavioral treatment and normal educational and intellectual functioning in young autistic children. Journal of Consulting and Clinical Psychology, 55, 3-9.
Matson, J.L., Benavidiz, D.A., Compton, L.S., Paclawsky, T., & Baglio, C. (1996). Behavior treatment of autistic persons: A review of research from 1980 to the present. Research in Developmental Disabilities, 17(6), 433-465.
Maurice, C. (1993). Let me hear your voice. New York: Knopf.
McEachin, J.J., Smith, T., & Lovaas, O.I. (1993). Long term outcome for children with autism who received early intensive behavioral treatment. American Journal on Mental Retardation, 4, 359-372.
Sheinkopf, S.J., & Siegel, B. (1998). Home-based behavioral treatment of young children with autism. Journal of Autism and Developmental Disorders, 28, 15-23.
Skinner, B.F. (1938). The behavior of organisms: An experimental analysis. New York: Appleton-Century.