Often operant behaviour is described as wilful, voluntary, free or intentional. The term operant is derived from the verb to operate which refers to behaviour that operates on the environment to produce consequences that subsequently strengthen the behaviour (BB). Reinforcement refers to the presentation or removal of a stimulus which results in an increase in the future frequency of a behaviour (Gilbert). Reinforcement can be either positive or negative. Behaviour-analytic research has identified conditions that cause reinforcement to be increasingly effective or allows behaviour to become more resistant to extinction. Positive reinforcement is the delivery of a stimulus which strengthens a behaviour (Birch &Milam). The decision for a victim
