Ivan Petrovich Pavlov studied medicine in Russia and Germany, accepting posts in St. Petersburg as a professor in pharmacology and physiology. In 1889 Pavlov began experiments with dogs that proved their reflexes could be conditioned by external stimuli. Specifically, after they were conditioned by the ringing of a bell at feeding time, they would reflexively salivate upon hearing the bell, whether or not food was present. In 1904 Pavlov won the Nobel Prize for his work on digestive physiology, but he is most widely known today as an early influence on behavioral psychology.