Pavlov was a behaviorist. This means that his theories focused on observable behavior, because behavior can be measured and thought can not. The human mind should be interpreted as a black box that can not be opened. Only was goes in the box and what comes out can be known. Scientific evidence is the keyword in his theory.Pavlov studied reflexes, automatic behavior that is caused by a stimulus from the environment. Some reflexes, such as blinking your eyes when a puff of air comes in it, or the sucking of a baby when something is put in his/her mouth. This automatic behavior can be manipulated. This is called conditioning. In this conditioning process, a unconditional stimulus is given to a person. This stimulus causes a reflex on its own. When the unconditional stimulus is now given to the person together with a stimulus that does not cause a reflex on its own. Thus, a unconditional stimulus is given together with a conditional stimulus. Because the presence of the unconditional stimulus, the reflex is caused. This process of stimulus-response is repeated for a number of times. After a while, the unconditional stimulus is not offered any more. Only the conditional stimulus is offered. Because of the repeated association of the unconditional and the conditional stimulus, the conditional stimulus will now cause the reflex on its own. Classical conditioning is succeeded. Pavlov's theories where very influential, in particular in the field of child psychology.