对说服能力的系统性研究始于二战，因为美军意识到与被希特勒蛊惑的民族作战需要鼓舞军队士气，并说服民众支持战争。
The systematic study of persuasion began during World War II, when the US Army recognized that fighting a nation mesmerized by Hitler would require bolstering troop motivation and rallying popular support for the war.