Thorndike"s law of effect states that in a given situation, a response followed by satisfying consequences will become more likely to occur and a response followed by an unsatisfying outcome will become less likely to occur. The law of effect became the foundation for the school of behaviourism. Discovered this by putting a cat in a box and food outside and measuring and noticed that ability to get the food slowly improved with repeated trials. Operant behaviour means that an organism operates on its environment in some way; it emits responses that produce certain consequences. Operant conditioning is a type of learning in which behaviour is influenced by its consequences. Through operant conditioning, organisms learn to increase behaviours that benefit them and reduce behaviours that harm them. Skinner box used to study operant conditioning experimentally. Behaviour is recorded on a cumulative recorder and find that beneficial acts increase. **defined in terms of observable effects on behaviour.