A behavior becomes more probable because of a consequence that follows it. Reinforcement is that strengthening process. Positive reinforcement presents a rewarding stimulus; negative reinforcement removes an aversive one.

Reinforcement is defined by its effect, not by the subjective pleasantness of the consequence. Schedules of reinforcement determine the pattern and resistance to extinction of the behavior. Immediate reinforcement is generally more effective than delayed. Secondary reinforcers acquire power through association with primary ones.

Reinforcement shapes both adaptive skills and problematic habits. Applied behavior analysis uses systematic reinforcement to build communication, social, and academic repertoires. Understanding what reinforces a behavior in a given context is the first step toward changing it. Reinforcement is one of the most reliable levers available for behavior change.

• Consequence that increases behavior probability
• Can involve presentation or removal of stimuli
• Schedule affects pattern and persistence
• Central tool in applied behavior change