My Wife and My Mother-in-Law (Old/Young Woman Illusion)

Who do you see first?

The drawing shows a woman in a feathered hat and a fur stole, seen from behind and slightly to one side. Read it one way and she's young, turned away from you so that only her ear, the curve of her cheek and chin, and one eyelash show. Read it the other way and she's old, in profile facing left, with a large nose, a thin mouth and her chin sunk into the fur.

Almost every line works twice. The young woman's ear is the old woman's eye, her cheek and chin make the old woman's nose, and her necklace is the old woman's mouth. Because the parts are shared, finding the second woman tends to take a while; once you have, perception keeps switching between them. If you're stuck, the buttons in the demo mark where each woman's features are.

Faces are recognised whole

The brain doesn't assemble a face from a checklist of parts. It matches the overall arrangement to a face almost at once, and once a match locks in, every ambiguous line nearby is read to fit it. A curve that could be a jaw or a nose gets assigned according to whichever face has won, and the rest of the drawing follows.

That's the idea behind predictive processing: perception is the brain's best current guess about what it's looking at, tested against the incoming signal. When two guesses fit the drawing almost equally well, perception settles on one, runs with it, and eventually swaps to the other, as with the Necker cube and Rubin's vase.

What you saw just before

Which woman you see first can be set up in advance. In a classic 1935 experiment, Robert Leeper showed people an unambiguous version of one woman before showing them the ambiguous drawing, and most of them then saw the woman they'd been primed with. A verbal description of one woman also worked, though less strongly (Leeper, 1935).

Your own age may play a smaller part. Michael Nicholls and colleagues found that older viewers guessed the woman in the picture was older than younger viewers did, and suggested that people tend to see someone from their own age group (Nicholls et al., 2018). A follow-up study found the same difference in age guesses, but no difference in which woman people actually reported seeing. Its authors concluded that viewers use their own age as a yardstick when estimating someone else's: age affects the judgement, not the perception (Brouwer et al., 2021).

From postcard to textbook

The earliest known version is an anonymous German postcard from 1888. The cartoonist W. E. Hill redrew it for the American humour magazine Puck in November 1915 under the title "My Wife and My Mother-in-Law", with the caption "They are both in this picture - find them." The psychologist Edwin Boring introduced it to the research literature in 1930 as "a new ambiguous figure", and it has been a textbook staple ever since. The drawing on this page is an AI-generated illustration in the same style, because Hill's version is still under copyright in the UK. It's close kin to the duck-rabbit, where the same lines also take on two complete identities.