Oddly Wired
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perception

Your brain ignores facial details when a face is upside down.

The Thatcher effect causes inverted faces to appear normal despite grotesque distortions in the eyes and mouth.

When a face is right-side up, your brain processes the holistic structure and the individual features simultaneously. When inverted, the brain relies on individual feature analysis, missing the spatial relationship between the mouth and eyes. You only detect the distortion once the image is rotated to a standard orientation.

Your perception of faces is reliant on specific orientation rules.

Where this comes from

Study
Thompson, 1980, Perception
What the check found
The claim is an accurate description of the Thatcher illusion, first described by Peter Thompson in the 1980 paper 'Margaret Thatcher: a new illusion' published in the journal Perception.
Confidence
Well replicated
perceptionthatcher effectvision

Related

One of these every day, and every one names the study it came from. When a finding is contested, it says so.