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Functional Analysis

Functional analysis examines the causes and consequences of behavior—it is a “powerful method of empirically identifying the variables that maintain a problem behavior” (Rummel, Garrison-Diehn, Catlin, & Fisher, 2012). One assumption of functional analysis is that behavior is contextual—it is influenced by the environment around the individual. Behavior has consequences and in operant conditioning terms these can be seen to reinforce or punish a behavior, making it more or less likely to occur in the future. Haynes & O’Brien (1990) define functional analysis as: “The identification of important, controllable, causal functional relationships applicable to a specified set of target behaviors for an individual client.” Read more
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What Is Functional Analysis?

Distinctive Features of Functional Analysis

Functional analysis is distinguished from other types of assessment by these features:

  • Functional analysis concerns itself with the function of behavior. It attempts to answer the question ‘Why is this behavior occurring?’ Determining the function of a given behavior by analyzing its antecedents and consequences allows the therapists to make hypotheses about how the behavior can be changed. For example, consider a patient who routinely talks about off-topic subjects through their therapy sessions. On its own this information is not very informative. They may do this as an attempt to avoid having to approach difficult material, or because their therapist is ineffective at keeping to an agenda.
  • Functional analysis assumes that behavior cannot be understood in isolation. An individual’s behavior only makes sense when it is understood in the context of his or her environment. For example, two clients attending a group treatment for post-traumatic stress disorder are observed to sit silently through the sessions. At face value the behavior appears to be the same. However, when context is included in the analysis it becomes apparent that one client has occasions where she would like to speak but is experiencing frequent flashbacks, whereas the other client sits next to a vocally dominant member of the group and has little opportunity to be heard.
  • Functional analysis concerns itself with the behavior of individuals. This is termed an ‘idiographic’ approach. It is contrasted with a ‘nomothetic’ approach which would investigate causes of behaviors across individuals.
  • Functional analysis leads directly to treatment interventions. “A well-done functional analysis leads logically to interventions that manipulate the environmental variables identified in the assessment” (Haynes & O’Brien, 1990).

The Three-Term Contingency

The three-term contingency is also known as the ABC contingency. It describes the relationship between a behavior, its consequence, and the environmental context.

  • Antecedents are defined as “environmental stimuli or events that are consistently present in the context in which the behavior occurs” (Cooper, Heron, & Heward, 1987).
  • Behavior can be defined as anything done by an individual, and can include private events such as thinking or feeling (Pierce & Cheney, 2004).
  • Consequences are defined as “changes in the environment that occur after the behaviour and that alter the probability of future occurrences of the behaviour” (Rummel et al., 2012).

Rummel et al. (2012) display the ACBT contingency in a deliberate fashion:

Antecedent : Behavior → Consequence

They note that the colon separating Antecedent and Behavior denotes that the Antecedent does not cause the Behavior, but sets the occasion for it. The arrow between Behavior and Consequence denotes that the Behavior produces the Consequence.

Relationships Between Behaviors and Consequences

If a consequence leads to an increase in a behavior’s frequency then the behavior is said to be reinforced by the consequence. Similarly, punishment describes the decrease in the frequency of a behavior as a function of the behavior’s consequences. When a behavior no longer produces a consequence it goes through the process of extinction. Contingencies of reinforcement and punishment are given below:

Following the behavior the stimulus is:
Presented Removed
Effect on the probability of behavior Increases Positive reinforcement Negative reinforcement
Decreases Positive punishment Negative punishment


  • Cooper, J. O., Heron, T. E., & Heward, W. L. (2007). Applied behavior analysis.
  • Haynes, S. N., & O’Brien, W. H. (1990). Functional analysis in behavior therapy. Clinical Psychology Review, 10(6), 649–668.
  • Pierce, W., & Cheney, D. (2004). Behavior Analysis and Learning New Jersey: Laurence Erlbaum Associates.
  • Rummel, C., Garrison-Diehn, C., Catlin, C., & Fisher, J. E. (2012). Clinical functional analysis: Understanding the contingencies of reinforcement. In W. T. O’Donohue & J. E. Fisher (Eds.),Cognitive behavior therapy: Core principles for practice(pp. 13–36). Hoboken, NJ: Wiley.