间离效果，又称陌生化效果、疏离，是德国戏剧理论家、剧作家布莱希特所提出的戏剧表演理论，是指将观众疏远于戏剧或电影，这被布莱希特称为叙事剧（史诗剧）。布莱希特认为戏剧应为政治服务；观众对舞台上的戏剧投射情感会妨碍观众的冷静判断。在剧本的创作上，他多以异国的、模糊的时空背景，并运用说书人讲述故事，以达到观众与剧情间的疏离效果。

间离效果要求“演员不能表现出在周围的三堵墙之外有‘第四堵墙’存在[…] 观众不再有“自己作为真实事件的看不见的观察者”的这样一种错觉”（Willett 91）。直接对观众说话就是破坏舞台错觉并制造间离效果的一种方式。在表演中，当表演者“观察自己”时，他的目的是“为了让观众觉得奇怪甚至惊讶，他通过像陌生人一样审视他和他的工作来达到这一目的。”（Willett 92）关于“史诗剧”和布莱希特式戏剧，教师和学者仍有争议：布莱希特的“间离效果”究竟指的是观众还是演员还是两者皆有呢？

The distancing effect, more commonly known (earlier) by John Willett's 1964 translation the alienation effect or (more recently) as the estrangement effect (German:Verfremdungseffekt), is a performing arts concept coined by playwright Bertolt Brecht. Brecht first used the term in an essay on "Alienation Effects in Chinese Acting" published in 1936, in which he described it as "playing in such a way that the audience was hindered from simply identifying itself with the characters in the play. Acceptance or rejection of their actions and utterances was meant to take place on a conscious plane, instead of, as hitherto, in the audience's subconscious".