Behavior modification focuses on changing specific behaviors rather than traits or characteristics. It targets behavioral excesses that need reducing and behavioral deficits that need increasing. Procedures are based on behavioral principles derived from experimental research. Behavior is measured before and after the modification to assess the effectiveness of the intervention. Common applications include developmental disabilities, mental illness, education, rehabilitation, and child management. Functional assessment identifies the triggers and consequences of problematic behaviors. Reinforcement strengthens behaviors by adding or removing stimuli.