Drawing on the social psychology of his day, propaganda theorist Edward Bernays confidently asserted that "in certain cases we can effect some change in public opinion with a fair degree of accuracy by operating a certain mechanism, just as a motorist can regulate the speed of his car by manipulating the flow of gasoline." Bernays advised that to change the attitudes of the masses, a propagandist should target its "impulses, habits and emotions" and make "emotional currents" work to achieve the goal.