Thatcher effect

"Thatcherization" redirects here. Not to be confused with Thatcherism.
The Thatcher effect, shown here on a photograph of Margaret Thatcher. The two upside-down images both appear superficially correct as faces. When these images are rotated, however, it becomes clear that the face on the right had its eyes and mouth inverted.

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 then British prime minister Margaret Thatcher, on whose photograph the effect was first demonstrated. The effect was originally created in 1980 by Peter Thompson, professor of psychology at the University of York.[1]

  1. ^ Thompson, P. (1980). "Margaret Thatcher: a new illusion" (PDF). Perception. 9 (4): 483–484. doi:10.1068/p090483. PMID 6999452. S2CID 32492890.