ABC Data: The Key to Understanding Behavior

ABC data offer a framework for understanding behavior and is the foundation of Applied Behavior Analysis (ABA). The term “ABC” refers to the context of a behavioral event, describing events that occur before and after a behavior you want to learn more about.

Professionals in the field of ABA often refer to ABC data as the 3-term contingency. The 3 terms include the antecedent (A), the behavior (B) and the consequence (C). Each component contributes to a greater understanding of why behavior continues. You then use this information to create a Behavior Intervention Plan (BIP) or to develop a plan for skill acquisition.

Although you most often associate evaluating ABC data with conducting a Functional Behavior Assessment (FBA) and developing a behavior reduction plan, these data also provide information to guide skill acquisition as well. Assessing the context within which a behavior occurs helps you understand that behavior. Whether it’s a behavior you want to see more or less of is irrelevant. Behavior follows natural laws, like gravity. All behavior, desired or undesired, follows these rules.


ABCs of Behavior Antecedent Behavior Consequence Setting Events Understanding the Context of Behavior Overt and Covert Behaviors ABC Data for Behavior Reduction Determining the Function of the Behavior ABC Data for Skill Development ABC Data Collection How much data do you need to collect? ABC Data Collection Tools ABC Data Collection Example Practice Identifying the ABCs

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ABCs of Behavior

All behavior occurs within a context. Some event or action occurs before the behavior and something else occurs after that behavior. This context helps you identify the factors that occasion the behavior as well as the maintaining variables. This leads to an understanding of motivation, allowing for the development of a plan for altering behavior. Conditions that occur closest to the behavior tend to have the greatest impact; however, some events or conditions that occur hours or even days before behavior may also influence that behavior.

ABC data collection is an integral component when conducting an FBA to hypothesized the function of the target behavior. This descriptive analysis allows you to develop a plan to alter the maintaining variables to change behavior. Although Functional Analysis (FA) is often considered the “gold standard” for identifying function, a descriptive analysis provides several distinct advantages according to Martens, DiGennaro, Reed, Szczech, and Rosenthal (2008):

  • Collected in the natural environment and does not appear contrived to the individual resulting in potentially more accurate data
  • Uncover information that is distinctive to the individual or setting
  • Reveal consequences delivered on a schedule that is difficult to duplicate in a contrived condition
  • Highly flexible in application
  • A direct measure of behavioral events as they occur


The antecedent occurs moments before the behavior of interest, usually within 30 seconds. You might call the antecedent the trigger or view it as what provokes the behavior. Antecedents that commonly trigger maladaptive behavior include:

  • Demand
  • Restricted attention
  • Denied access to a preferred item or activity
  • Environmental stimuli such as lights, noise or temperature
  • Transitions
  • Unstructured time

To understand the antecedent, ask yourself questions such as:

  • Where did the behavior happen?
  • When did the behavior happen? (i.e. time of day)
  • Who was with your child when the behavior happened?
  • What else is happening when the behavior happens? (i.e. noise in the room, other people in the area)

For example, you want to understand why your learner runs away from you when it’s time to sit at the table to do work. Look at what happens right before he runs away. What did you say or do? Who else was present in the room? What else was going on in the room at the time? What was he doing?

When considering the ABCs for skill acquisition, the antecedent is the discriminative stimulus (SD). The SD evokes a specific response that has been reinforced in the past (or is a response that you plan to teach). The SD signals the availability of reinforcement given the specific response and is the essence of teaching any skill.

For example, you want your learner to clap his hands when you say “clap.” You consistently provide reinforcement when he claps in the presence of the SD (“clap”) and withhold reinforcement when the behavior occurs in the absence of the SD. This builds stimulus control and is how skills develop.

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Behavior is anything that a person does. For the sake of ABC data, this is behavior you want to learn more about. This behavior may be desirable or undesirable.

In ABA, it’s critical that you define behavior in observable and measurable terms. After reading your definition, anyone should reliably identify whether the behavior occurs or not. Your definition, called an operational definition, must be crystal clear to ensure accurate data collection, especially if more than 1 person will collect data.

When defining the target behavior, include examples and non-examples to build clarity. Here’s an example:

Throwing: Any instance in which Henry moves objects not intended to be thrown through space farther than one foot using any part of his body.

Examples Include:

  • Pushing items off a shelf or table.
  • Throwing a marker farther than one foot.
  • Kicking a bucket resulting in the items in the bucket being dumped on the floor.
  • Holding an inset puzzle upside down while standing resulting in the pieces being dumped on the floor.

Non-Examples Include:

  • Turning an inset puzzle upside down over a table prior to completing the puzzle resulting in one or more pieces falling on the floor.
  • Kicking or throwing a ball in the gross motor space.

Each example or non-example should contribute to the precision of the definition. Avoid extraneous descriptions, but include enough to cover common situations that occur that may evoke questions from your interventionist. Read our post Operational Definitions: Clearly Define the Behavior for more information and examples of common target behaviors in ABA.

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The consequence occurs immediately after the behavior you want to learn more about, usually within 30 seconds. Although some delayed consequences influence behavior for some learners, when collecting ABC data, focus on what occurs immediately after the behavior.

Common consequences that maintain behavior include:

  • Attention in the form of praise, discussion or a reprimand
  • Escape from an aversive task or sensory stimulation
  • Access to a preferred item or activity

These maintaining consequences lead to a hypothesis of the function of that behavior (i.e. access or escape). When a consequence follows a behavior and that behavior occurs more often (or with greater intensity or for longer durations), that consequence has a reinforcing effect. When a consequence follows a behavior and that behavior occurs less often (or with less intensity or for shorter durations), that consequence has a punishing effect. Reinforcement or punishment is not an inherently good or bad consequence, but instead describes the effect of the stimuli on behavior (i.e. does the behavior increase or decrease).

This is where many techniques commonly recommended to reduce maladaptive behaviors fail. Techniques like 1-2-3 Magic offer 1 solution regardless of why the learner engages in the behavior. When you fail to consider the function of the behavior, you run the risk of reinforcing the very behavior you try to reduce.

For example, common parenting gurus like SuperNanny recommend putting a child in time out when he misbehaves. If that child engages in maladaptive behavior to escape a particular situation, then time out becomes an effective reinforcer and the behavior will occur more frequently in the future.

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Setting Events

Setting events are often referred to as the 4th term. These are factors that occur well before the behavior you’re interested in learning more about, sometimes hours or days before. While these events don’t directly impact behavior, take not of conditions that often influence the behavior of your learner. Common setting events include:

  • Hunger
  • Change in medication
  • Lack of sleep
  • Presence or absence of a specific person
  • Conditions in the room (i.e. temperature, noise, visual stimulation, etc.)
  • Change in routine

For example, Magito McLaughlin, D., & Carr, E. G. (2005) found that poor rapport led to an increase in escape-maintained behaviors, while these behaviors were reduced in the presence of staff who established good rapport with the subject. This shouldn’t be surprising when you consider your own feelings and behaviors around those you dislike versus those with whom you feel close, however it’s easy to overlook this as a possible setting event if the feelings are unknown or the individual isn’t directly involved in the interaction or behavior.

Although many setting events are observable, some such as mood are not quantifiable (Ramey, D., Healy, O., Lang, R., Gormley, L., & Pullen, N., 2019). This can make drawing parallels between a behavior and a setting event difficult, yet understanding setting events can help you determine why a behavior happens under different circumstances.

Download our Setting Events Checklist for a comprehensive list of setting events:

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Understanding the Context of Behavior

The SABCs can be used to understand the context of the behavior – the events that trigger and reinforce it. By looking at the most common antecedents and consequences you can begin to understand the behavior in a new way. Consider the following questions when analyzing the data you’ve collected:

Most Common AntecedentsMost Common Consequences
Did you ask your learner to do something he or she didn’t want to do?Did you reprimand your learner?
Was your learner playing alone?Did you withhold attention from your learner after the behavior?
Did you tell your learner “no?”Did you block access to what your learner wanted?
Did the behavior occur during transitions?Did you remove the demand after the behavior?
Did the behavior occur during unstructured time?Did you institute some form of “punishment” such as time out?
Did the behavior occur when your child didn’t have adult attention?Did you give your learner access to a preferred item?
Was there something else that happened just before the behavior?Was there something else that happened just after the behavior?

In this video, Amelia Dalphonse, MA, BCBA discusses the using context of behavior to understand why behavior continues.

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Overt and Covert Behaviors

Most often, you will focus your attention on behaviors you can observe. These are overt behaviors. In ABA, professionals rely on the ability to measure behavior and only behavior that can be observed can be measured.

It’s also important to note that behaviors occur that you can’t see. These are covert behaviors. These behaviors occur within the learner’s body and include things like thought. Cognitive Behavior Therapy (CBT) uses many of the principles of ABA to address covert behavior.

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ABC Data for Behavior Reduction

ABA programs frequently seek to reduce the occurrence of maladaptive behavior. ABC data collection procedures contribute to a general understanding of the context within which a specified behavior commonly occurs. Understanding this context allows for you to hypothesize the function of the behavior leading to effective interventions. This is the most common use for ABC data.

Take a look at this example of ABC data collected to understand the context of Ethan’s jumping:

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Determining the Function of the Behavior

ABC data helps you determine the function of a behavior. If a behavior persists then the learner is getting something from it. There are many tools to help you determine what a learner is getting from a behavior. Our post Functions of Behavior in ABA: Complete Guide goes into detail on this important topic.

Sometimes, as in the example from the video above, the ABCs provide sufficient information to make this determination. However, in some cases you may need to gather additional information via interviews and questionnaires to truly understand the motivation of the learner.

To help determine the function of a behavior, we have created interactive “quiz:”

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ABC Data for Skill Development

The ABC data collected offers insight into the learner’s motivation. Identifying conditions that evoke a specific response and cause that response to occur more or less often in the future provides an opportunity for you to develop an effective skill acquisition plan. When a learner struggles with skill acquisition, revisit the ABCs. Is there an antecedent (visual stimuli, physical or verbal prompt, etc) that evokes the desired response? Are there consequences that make that response more likely to occur? ABC data allows for objectively evaluating the conditions that produce the skill you want to teach. This helps you understand if the learner has become prompt dependent or is reliant on a high quality reinforcer.

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ABC Data Collection

Accurate collection of ABC data is critical for determining the function of the behavior and identifying the appropriate interventions to use with your client. However, this requires having someone trained in collecting data present when the behavior happens.

For this reason, it’s not uncommon for practitioners to simulate a situation to provoke the behavior. If a child becomes aggressive when a favorite item is taken away, then the instructor may set up various scenarios where they will take away the learner’s favorite item.

This practice should be avoided for a number of reasons:

  1. It causes undue stress on the learner. Many maladaptive behaviors are a response to stress in the learner’s environment. Evoking the behavior unnecessarily can put them in a stressful situation unnecessarily.
  2. When situations are staged to evoke the behavior, the data collected may not accurately reflect the circumstances surrounding the behavior outside that setting.

A better alternative is to teach the people who spend the most time with your clients to collect this data. Alternatively they can record video of what happens, however this may miss the antecedent, so should be used in combination with collecting data and/or interviews.

Data Collected by Staff and Caregivers

All descriptive data is subject to observer error or bias, but being aware of this tendency reduces the impact of these concerns. When training staff and caregivers to collect ABC data, ensure there are no punishing consequences in place when they self-report responding to a behavior in a way that doesn’t align with how you have asked them to respond.

Data from new staff and parents tend to be more reliable when you provide choices in the form of checkboxes as pictured below. You receive a more robust picture of behavioral incidents when the form is blank and left open for narrative statements. For best results, create a balance with these different types of data collection tools. Download our template that provides you with 4 different ABC or SABC data sheets.

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How much data do you need to collect?

How much data you need to find a pattern depends on the behavior and your circumstances.  There is no magic number.  Depending on how frequently the behavior occurs this could be days or even weeks.  Be patient and eventually you will find a pattern.

Let’s look at an example.  If your client Sammy bangs his head on the floor, you may need to look at ABC data to change this behavior. 

From the data here, can we tell why Sammy was banging his head on the floor? Having collected data just one time, it might not be clear.

From day 2, there seems to be a pattern developing.  In both instances Sammy was alone and he was picked up so he didn’t hurt himself.  But is it enough?  Does this prove that the antecedent is always that Sammy is alone?  Let’s look at the data for day 3.

On day 3 the antecedent seems different.  In this case he wasn’t alone.  What else could it be?  What if on this 3rd day you were also in the kitchen making dinner?  Does this change what you think might be causing the behavior?  It’s important to keep collecting data for several instances of the behavior.  The more data you collect the more accurately you’ll be able to determine the antecedents and consequences influencing the behavior.

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ABC Data Collection Tools

Standard ABC data collection templates like the downloadable ones above are a good option for a number of reasons. They’re:

  • Easy to use
  • Require little technical skills to record data
  • Can be printed to use when technology isn’t available

However, there are some issues with this format:

  • Data must be transferred into another tool to analyze it and summarize it for an FBA
  • Templates are not mobile-friendly

AID Document Creation Tools from Master ABA

We realize that many organizations have their own data collection and/or reporting tools. However, many of the options aren’t mobile-friendly and can be difficult to use. Our AID Document Creation Tools (an addon to the ABLE Support for BCBAs membership) allows you to collect data in mobile-friendly tables that is easily analyzed directly in the tool.

All the information is formatted for you to export into a PDF format that can be converted to Word for editing or copying into your company’s template.

AID provides you the tools you need to create meaningful Functional Behavior Assessments, Behavior Intervention Plans and Treatment Plans.

Learn more about this option in the course Success as a Master ABA Member.

Other Apps

There are many other web-based tools and apps that can work. Below are 3 templates we created that you can copy and use:

Get creative with your favorite tools!

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ABC Data Collection Example

Watch the video below for an example of one father collecting ABC data for his son, Ethan.

In this example, Tom collected the data pictured below.

Antecedent: Although Tom is doing something different in each instance, Ethan engages in the target behavior when Tom’s attention is restricted. More data may be required to determine if other factors are at play.

Consequence: In each instance of the behavior, Tom directed his attention to Ethan and told him to stop.

From this limited data it appears that Ethan engages in the target behavior when Tom is busy and not paying attention to him. Then, the behavior is reinforced when Tom pays Ethan attention by telling him to stop.

This example is an over-simplification to demonstrate how the forms can be used to collect and analyze the data.

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Practice Identifying the ABCs


Magito McLaughlin, D., & Carr, E. G. (2005). Quality of rapport as a setting event for problem behavior: Assessment and intervention. Journal of Positive Behavior Interventions, 7(2), 68–91. doi:10.1177/10983007050070020401.

Martens, B. K., DiGennaro, F. D., Reed, D. D., Szczech, F. M., & Rosenthal, B. D. (2008). Contingency space analysis: An alternative method for identifying contingent relations from observational data. Journal of Applied Behavior Analysis, 41(1), 69-81.

Ramey, D., Healy, O., Lang, R., Gormley, L., & Pullen, N. (2019). Mood as a Dependent Variable in Behavioral Interventions for Individuals with ASD: A Systematic Review. Review Journal of Autism and Developmental Disorders, 6, 255-273.