撒切尔效应，也叫撒切尔错觉是这样一种现象：在倒着的脸上的一些局部特征的变化很难被人发现，而这样的变化如果发生在正立的脸上则非常明显。名字来源于英国首相玛格丽特·撒切尔，她的脸据称最具有这样的特征。这是由彼得·汤普森首先提出的。

The Thatcher effect or Thatcher illusion is a phenomenon where it becomes more difficult to detect local feature changes in an upside-down face, despite identical changes being obvious in an upright face. It is named after the former British Prime Minister Margaret Thatcher, on whose photograph the effect was first and most famously demonstrated. The effect was originally created by Psychology Professor Peter Thompson in 1980.