In particular, he was interested in explaining 'spontaneous' behaviours: those that occurred in their complete form the first time they were performed and that seemed resistant to the effects of learning. He explains how behaviour can be considered a combination of these spontaneous behaviour patterns and as set series of reactions to particular stimuli. Behaviour is a reaction in that to a certain extent it is reliant on external stimuli, however it is also spontaneous since it is also dependent upon internal causal factors.