How to trick people into thinking they're the size of Barbie Dolls

Imagine that you woke up to discover you had somehow shrunk to a doll's size. Would you think you were tiny...or that everyone else was a giant? Some Swedish psychologists decided the world deserved an answer to that age-old question.

This may all seem rather out there, but it actually speaks to some rather basic questions of how we perceive the world. While scientists have long agreed that there are a number of visual cues that go into the brain's interpretation of an object's size and distance. Admittedly, those cues can be rather spectacularly messed with if you know how, such as in the classic Ames Room illusion that you can see up top.

But let's leave aside external factors - what role do bodies play in people's perception of the world? For instance, if a tall person will perceive distances as being shorter than other people. And that's why researchers Sweden's Karolinska Institute decided to trick people into thinking they were alternately 13 feet tall and the size of a doll.

How to trick people into thinking they're the size of Barbie Dolls

They created the illusion by having people lie down on a table next to an artificial pair of legs of various different sizes. The participants wore goggles that showed them the images from a camera that was fixed on the artificial legs, creating the illusion that the actual legs the participant felt were the same as the artificial legs he or she was looking at. The researchers then could wander into the participant's field of vision, which would create conflict with the size cues of the artificial legs.

Once the researchers had tricked the participants into thinking they were less than a foot tall, they did the only thing that could conceivably be considered more humiliating: they made them play with blocks. The participants had to estimate the size of the blocks and then walk over to the blocks with their eyes shut, which required the participants to accurate judge distance after having all their size cues thrown off.

Lead researcher Henrik Ehrsson - who also tried the illusion on himself - explains why this proved so difficult for the test subjects:

"Tiny bodies perceive the world as huge, and vice versa. Even though we know just how large people are, the illusion makes us perceive other people as giants; it's a very weird experience."

He also thought of some possible applications for his size illusion, which just offers more proof that Swedish scientists are the most awesome kind of scientists:

"It's possible, in theory, to produce an illusion of being a microscopic robot that can carry out operations in the human body, or a giant robot repairing a nuclear power plant after an accident."

I'm honestly not sure how we get from "misjudging the size and distance of some blocks" to "pretending to be a tiny robot performing life-saving surgery in a person's body", but I love that those are the sorts of mental processes involved here.

Via PLoS ONE. Top image via.