Focusing on strategies that involve the manipulation of antecedent stimuli, to influence behaviour. Description of a three-term contingency of reinforcement. A situation in which a behaviour will lead to a consequence. Partial rules: do not identify all three aspects of a contingency of reinforcement; but can still control our behaviour e. g. , consequences can often be implied. Contingency-shaped behaviour: behaviour that has been strengthened (or weakened) because of its immediate consequences in a particular setting. Strengthened gradually through trial and error, based on reinforcement and non-reinforcement e. g. , learning that other kids are impressed and offer praise when you do well in gym class. Behaviour that is controlled by the statement of a rule. When behaviour will lead to immediate and severe punishment. When trial and error could be costly. Although the reinforcer identified in a rule might be delayed for an individual, there might be other immediate consequences in the interim if the individual follows (or does not follow) the rule.