the behaviorist approach focuses on the environment and behavior. it's basic principle is the concept of parsimony, which seeks the simplest explanation of any event. some famous behaviorists are edwin lynn thorndike, john b. watson and john  broadus watson.
   behaviorism focuses on observable events which can be studied. stimuli and response are involved in this approach. they can be compared to cause and effect. 
   there are different types of stimuli and response; unconditioned response, unconditioned stimulus, neutral stimulus, conditioned(learned) stimulus and conditioned response.