ABSTRACT
Ivan Petrovich Pavlov's career as a scientist is certainly among the most interesting on record. In 1904, at the age of fifty-five, he won a Nobel Prize. To begin at the beginning: it has long been known that secretion of saliva starts at the sight and even the thought of appetising food; and, as Pavlov has demonstrated, the same is true for the secretions of the stomach, pancreas, Pavlov called this class of inhibitions 'internal', thus contrasting them with the 'external inhibitions' which have long been recognised and are caused by intensive, unaccustomed stimuli. As the term 'conditioned reflex' shows, Pavlov tried to explain the whole group of phenomena on the lines of the reflex scheme. According to him, the unconditioned reflexes, inborn in the individual, take place in the lower centres of the nervous system, while the unimpaired activity of the cerebral cortex is necessary to conditioned reflexes.
