Thatcher effect - Wikipedia
Hollow-Face illusion - Wikipedia
Facing This Way and That - Facial Illusions
The Optical Illusion That Makes Upside Down Faces Look …
Illusion of face
Thatcher Effect - Optical Illusion & Explaination
Inverted face illusion. When the pictures are viewed right side up ...
Inversion produces opposite size illusions for faces and bodies
Opposite size illusions for inverted faces and letters
Orientation-sensitivity to facial features explains the Thatcher illusion