Assessing the Functions of Behavior: The Importance of Understanding Communicative Intent

Autism is associated with significant impairments in language/communication, deficits in social interaction and restricted interests/stereotypical behavior (American Psychiatric Association, 1994). Learners with autism have difficulty in all aspects of communication, including receptive understanding, expressive language, and comprehension. Even in learners with a well-established capacity to communicate, there are often very significant deficits in spontaneous communications, in complex communication, and in reciprocal communication. The deficits in communication have wide ranging effects on their ability to socially interact and on their behavioral regulation.

Learners with ASDs exhibit a wide variety of maladaptive behaviors. Some behaviors are stereotypical, repetitive (e.g., rocking, hand flapping), or ritualistic (e.g., lining things up) in nature. Other behaviors include self-injury, aggression, tantrums, and property destruction. These maladaptive behaviors often interfere with effective learning. Decreasing behaviors that are dangerous, that pose interference with learning, and that are stigmatizing is an important goal of behavior analytic intervention. It is important to identify the functions of these behaviors in order to effectively intervene. There are four primary functions of behavior that have been identified – attention (to gain attention), escape (to escape or delay demands or social interaction or a sensory aspect of the environment), tangible (to gain access to something desired), and automatically reinforcing (for intrinsic biological/sensory reasons).

Some stereotypical behaviors are automatically reinforcing, or inherently (biologically) rewarding to the individual. Often, however, the occurrence of challenging behavior is related to environmental events. Maladaptive behavior is generally maintained by either positive or negative reinforcement. Examples of positively reinforced behavior include engaging in disruptive behavior to access social attention and/or tangible items. Examples of negatively reinforced behavior include engaging in inappropriate behavior to escape from demands.


Functional Assessment


It is extremely important to understand what variables are maintaining a challenging behavior, and behavior analysts seek to identify the functions of behaviors. Determining the function of the behavior ensures that we have a complete understanding of why the learner engages in particular behaviors. Assessment of the function also enables the clinician to design an effective treatment plan. It is important that the function of the behavior be matched to the intervention chosen. If there is not good correspondence between the function of the behavior and the treatment plan, it is unlikely that the behavior will be successfully treated.

Identifying the function of the behavior has implications for the selection of antecedent strategies, for the development of replacement skills, and for the provision of contingent consequences. Antecedent strategies help to prevent the behaviors from occurring. If a learner is engaging in escape-motivated behaviors, antecedent strategies might include shorter work sessions or the interspersal of difficult tasks with easy ones. Replacement skills for an escape-motivated learner might consist of teaching the learner to request a break. Consequence strategies might include persisting with demands when challenging behaviors occur to prevent the learner from escaping in response to inappropriate behavior.

Functional assessment is crucial for the development of a behavior intervention plan with effective components. In general, the cause, or the function, of maladaptive behavior, is best determined by conducting a functional behavior assessment (FBA). Functional assessments generally involve using interviews, behavioral observation, and/or, environmental manipulations to determine the function of disruptive behavior.

In general, the more direct the information is about behavior, the more confidently we can make conclusions about the variables influencing it. Behavior analysts have a strong preference for direct observation as a means to gather information for functional assessments. While some assessments include checklists or interviews, it is important that the hypotheses be based on the observation of behavior. At times, these observations might be done by a trained observer who is recording events. At other times, staff members may be asked to complete ABC data sheets, in which they log the events that occur before (A: antecedents) and after (C: consequences) the behavior (B) of interest.

In many situations, behavior analysts also systematically manipulate variables to assess the impact of such manipulations. These systematic Functional Analyses require specialized training, but can yield extremely useful information that may be much more specific than what is learned through other functional assessment methods.

When functional assessments/analyses are completed, the variables that maintain the behavior have been identified. In other words, functional assessments lead to the identification of variables that are responsible for the continuance of the behavior. Functional assessment helps in understanding WHY the behavior occurs. It may be that the behavior is occurring to escape task demands or to access teacher attention or to get desired items. The behavior persists because it has worked in achieving those outcomes.

When the function of disruptive behavior has been identified, the learner can be taught to access the reinforcer maintaining disruptive behavior (e.g., attention, escape) using an adaptive form of communication. It is important that the individual communicate that desire in a more functional, appropriate, and pro-social manner. One goal of functional assessment is to identify the function so that an alternative, replacement skill can be determined. Selecting the modality of the replacement response is essential to effective functional communication training (FCT). In order for the replacement skill to become integrated into the learner’s repertoire, the response must be possible for the learner to engage in, efficient, and reinforced by others in the environment.


Functional Communication Training


Functional communication training (FCT) has been shown to be an effective treatment method for many topographies of problem behavior (Fisher, Piazza, Cataldo, Harrell, Jefferson & Conner 1993; Hagopian, Hagopian, Fisher, Sullivan, Acquisto & LeBlanc, 1998). FCT involves identifying the function of challenging behavior then providing the individual with an adaptive functionally-equivalent response to access that reinforcement. A functionally equivalent response allows access to the same type of reinforcement for the learner, but through a different response. A learner who has escaped demands through disruptive behavior can be taught to instead escape a demand by using a break card. A functionally equivalent response can serve to replace a challenging behavior by providing the learner with a different way to meet his/her needs. The nature of the communication response may be a vocal response, a card touch/exchange, sign language and/or a response made on an augmentative communication device.


Carr and Durand (1985) conducted functional analyses on the challenging behaviors of four learners. The results of the analyses indicated that the individual learners engaged in disruptive behavior for different reasons. Two learners engaged in disruptive behavior to escape from demands, one was accessing social attention, and one participant’s behavior was maintained by multiple functions.

After conducting the functional analyses, the authors taught different communication responses to the learners. In each case, they taught responses that matched that individual’s function of behavior. In addition, in each case, they taught irrelevant responses (i.e., responses that were not linked to the function of the individual’s challenging behavior.) For instance, teaching a learner to request a break if the behavior is escape-maintained would be considered a relevant response (matched to function). Teaching a learner with escape-maintained behavior to request attention would be considered teaching an irrelevant response. When participants were taught the relevant response matched to the function of behavior, disruptive behavior decreased and communication increased. Perhaps more impressively, the authors found that when irrelevant responses were taught, disruptive behavior continued and communication did not increase. This study supported the need to match treatment to function and suggested that challenging behaviors can be replaced with functional communicative responses resulting from FCT.

Efficiency of response is an important consideration (Horner & Day, 1991, Richman, Wacker & Winborn, 2001). Clinicians need to consider the amount of response effort, the consistency of reinforcement, and the immediacy of reinforcement. If an alternative communication response is difficult or results in delayed/less reinforcement than the target behavior, it is not likely that the new response will replace the maladaptive behavior. It is important that the behavior is assessed adequately for its function and that the right response is selected to train as an alternative/replacement skill.




One of the most important kinds of assessment done with learners on the autism spectrum is functional assessment of the challenging behaviors they exhibit. A thorough assessment of the functions of challenging behaviors ensures that behaviors are understood in terms of the functions they serve, the reasons for their continuance, and the communicative role that they play. Direct observational methods of such assessments are more valid and are preferable to interview or checklist assessments.

Treatments of challenging behaviors must be linked to these identified functions in order to ensure significant and lasting reduction of interfering behaviors. In addition, functional assessments help in identifying an appropriate skill to target as a replacement skill, so that the individual can get the need communicated in a more positive and successful way. Functional communication training leads to better behavioral outcomes, and is a natural extension of the functional assessment process.

Challenging behaviors do not occur randomly or inexplicably. The use of functional assessment and functional analysis procedures can unravel the mysteries of challenging behaviors. Functional communication training can help the individual to fulfill their needs and communicate their desires in efficient, effective, and positive ways.


Cecelia M. McCarton, MD is the founder and CEO of The McCarton Foundation. Mary Jane Weiss, PhD, BCBA is the Director of Research and Training at the Douglass Developmental Disabilities Center and a Research Associate Professor at Rutgers University. She consults to The McCarton School. Ivy Feldman, PhD is Educational Director and Jackie Hickie, MA, BCBA is Associate Educational Director at the McCarton Foundation




American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington DC.

Carr, E. G., & Durand, V. M. (1985). Reducing behavior problems through functional communication training. Journal of Applied Behavior Analysis, 18, 111-126.

Fisher, W., Piazza, C., Cataldo, M., Harrell, R., Jefferson, G., & Conner, R. (1993). Functional communication training with and without extinction and punishment. Journal of Applied Behavior Analysis, 26, 23-36.


Hagopian, L. P., Fisher, W. W., Sullivan, M. T., Acquisto, J., & LeBlanc, L. A. (1998). Effectiveness of functional communication training with and without extinction and punishment: A summary of 21 inpatient cases. Journal of Applied Behavior Analysis, 31, 211-235.


Horner, R. H., & Day, H. M. (1991). The effects of response efficiency on functionally equivalent competing behaviors. Journal of Applied Behavior Analysis, 24, 719–732.


Richman, D. M., Wacker, D. P., & Winborn, L. (2001). Response efficiency during functional communication training: Effects of effort on response allocation. Journal of Applied Behavior Analysis, 34, 73–76.

Have a Comment?