Behavioral spillover is the measurable effect that one behavioral intervention has on other behaviors that are not being targeted. Some definitions of behavioral spillover do not require that the first action was the result of an external intervention. Common requirements for defining behavioral spillover include requiring that the spillover must be both observable and causal. The two actions must be sequential and distinct, representing separate behaviors and actions, not two components or steps of a larger single process. The two behaviors must also share an underlying motivation.