Complex sentence: Operant conditioning (or instrumental conditioning) is a type of learning in which an individual's behavior is modified by its antecedents and consequences; the behavior may change in form, frequency, or strength.
Split into simpler sentences: Operant conditioning (or instrumental conditioning) is a type of learning in which an individual's behavior is modified by its antecedents and consequences. Mechanisms of instrumental conditioning suggest that the behavior may change in form, frequency, or strength.