What disciplines had the most influence on how Wundt Pavlov freud and piaget approached the study of psychology?

Each of these men approached psychology very differently. Ivan Pavlov, who was Russian, first studied physiology and veterinary medicine. Jean Piaget, who was Swiss, studied philosophy, sociology, and developmental psychology. Wilhelm Wundt, who was German, is regarded as one of the founders of modern psychology: he too first studied physiology as well as anatomy and medicine. And Sigmund Freud, who was Austrian, first studied philosophy, physiology, zoology, and neurology.