The three-term contingency is ABA’s core framework showing how behavior works: an antecedent triggers a behavior, which leads to a consequence that makes the behavior more or less likely to happen again.
What Is the Three-Term Contingency?
Applied Behavior Analysis relies on one simple truth: behavior doesn’t happen in a vacuum. Every behavior connects to what comes before it and what follows after.
The three-term contingency breaks this down into three parts that work together. Think of it like a chain reaction where each link affects the next one.
This model helps us understand why people do what they do. It also shows us how to help them learn better behaviors.
The Three Parts Explained
Antecedent: What Happens Before
The antecedent is anything that happens right before a behavior occurs. It sets the stage and makes the behavior more likely to happen.
Antecedents can be simple or complex. A ringing phone is an antecedent for answering it. Feeling hungry is an antecedent for looking for food.
In therapy settings, we often arrange antecedents on purpose. We might show a child a picture to get them to say a word. Or we might give clear instructions before asking someone to complete a task.
Environmental factors count as antecedents too. Bright lights, loud noises, or crowded spaces can all trigger certain behaviors.
Behavior: What Actually Happens
The behavior is the action we can see and measure. It’s what the person actually does in response to the antecedent.
Behaviors must be observable and specific. “Being good” isn’t a behavior because it’s too vague. “Sitting quietly for five minutes” is a behavior because we can see it and time it.
We focus on behaviors that matter for the person’s life. These might include communication skills, social interactions, or daily living tasks.
Some behaviors we want to increase, like asking for help appropriately. Others we want to decrease, like hitting when frustrated.
Consequence: What Happens After
The consequence is what happens immediately after the behavior. This determines whether the behavior will happen again in similar situations.
Consequences that increase behavior are called reinforcement. Getting praise after completing homework makes homework more likely next time.
Consequences that decrease behavior are called punishment. Losing TV time after breaking rules makes rule-breaking less likely.
The timing of consequences matters a lot. Immediate consequences have much more impact than delayed ones.
How the Three Parts Work Together
These three parts create a continuous cycle. Today’s consequence becomes tomorrow’s antecedent for the same behavior.
When a child asks nicely for a snack and gets one, they learn that polite requests work. The next time they’re hungry, they’re more likely to ask nicely again.
This cycle explains how both good and challenging behaviors develop. Understanding it helps us make positive changes.
We can change any part of the contingency to influence behavior. Sometimes we modify antecedents, sometimes consequences, and sometimes both.
Real-World Examples
Example 1: Morning Routine
Antecedent: Mom says “Time to get dressed”
Behavior: Child puts on clothes independently
Consequence: Child gets extra playtime before school
This positive cycle encourages independence and makes mornings smoother for everyone.
Example 2: Classroom Setting
Antecedent: Teacher asks a question
Behavior: Student raises hand and answers
Consequence: Teacher gives praise and a sticker
The student learns that participation leads to positive attention and rewards.
Example 3: Communication Training
Antecedent: Therapist shows picture of water
Behavior: Child says “water”
Consequence: Child receives a drink of water
This teaches functional communication by connecting words to their meanings and outcomes.
Using the Three-Term Contingency in Practice
Identifying Current Patterns
Before making changes, we need to understand what’s already happening. We observe and record the ABCs for specific behaviors.
This helps us see patterns we might miss otherwise. Maybe tantrums always happen before lunch when the child is hungry.
Data collection shows us which antecedents trigger problems and which consequences maintain them.
Modifying Antecedents
Sometimes the best approach is preventing problems before they start. We can change the environment or provide better cues.
Visual schedules help people know what’s coming next. Clear instructions reduce confusion. Removing distractions helps with focus.
Teaching coping skills gives people better ways to handle difficult antecedents when they can’t be avoided.
Adjusting Consequences
We make sure positive behaviors get rewarded and problematic ones don’t. This might mean changing what happens after both types of behaviors.
Praise, preferred activities, or tangible rewards can reinforce good choices. Natural consequences work better than arbitrary punishments for reducing problems.
Consistency across settings and people makes consequence changes more effective.
Common Mistakes to Avoid
Focusing Only on Consequences
Many people think behavior is just about rewards and punishments. But antecedents play a huge role too.
Setting people up for success by arranging good antecedents often works better than trying to fix things after problems occur.
Ignoring the Function
Not all behaviors that look the same serve the same purpose. A child might hit to get attention or to escape demands.
The function determines which consequences will be most effective. Attention-seeking behaviors need different approaches than escape behaviors.
Inconsistent Application
The three-term contingency only works when applied consistently. Mixed messages confuse people and slow down learning.
Everyone working with the person needs to understand and follow the same plan.
Making It Work for Your Situation
Start by picking one specific behavior to focus on. Trying to change everything at once rarely works well.
Observe and record the current ABCs for that behavior. Look for patterns over several days or weeks.
Make one change at a time so you can see what’s working. Small, consistent changes often produce better results than dramatic overhauls.
Remember that behavior change takes time. Stay patient and celebrate small improvements along the way.
The three-term contingency gives us a roadmap for understanding and changing behavior. When we use it thoughtfully, we can help people learn skills that improve their lives in meaningful ways.