More here.In Alice’s Adventures in Wonderland, the titular heroine quaffs a potion that shrinks her down to the size of a doll, and eats a cake that makes her grow to gigantic proportions. Such magic doesn’t exist outside of Lewis Carroll’s imagination, but there are certainly ways of making people think that they have changed in size.
There’s nowhere in the world that’s better at creating such illusions than the lab of Henrik Ehrsson in Sweden’s Karolinska Institute. In a typical experiment, a volunteer is being stroked while wearing a virtual reality headset. She’s lyng down and looking at her feet, but she doesn’t see them. Instead, the headset shows her the legs of a mannequin lying next to her.
As she watches, Bjorn van der Hoort, one of Ehrsson’s former interns, uses two rods to stroke her leg, and the leg of the mannequin, at the same time. This simple trick creates an overwhelming feeling that the mannequin’s legs are her own. If the legs belong to a Barbie, she feels like she’s the size of a doll. If the legs are huge, she feels like a 13-foot giant.
Van der Hoort performed this illusion on almost 200 people. Questionnaires revealed that they did indeed think of the mannequins as their own body parts. Familiar objects didn’t break the spell. When van der Hoort threatened the mannequins’ legs with a knife, the volunteers’ skin broke into a worried sweat, as if their real bodies were in danger. If he touched the doll’s legs with a pencil or his finger, the recruits thought they were being prodded by giant objects. Rather than feeling like dolls in a normal world, they felt like normal people in a giant world.
And:
van der Hoort, B. et al. (2011). Being Barbie: The Size of One’s Own Body Determines the Perceived Size of the World PLoS ONE, 6 (5) DOI: 10.1371/journal.pone.0020195
A classical question in philosophy and psychology is if the sense of one's body influences how one visually perceives the world. Several theoreticians have suggested that our own body serves as a fundamental reference in visual perception of sizes and distances, although compelling experimental evidence for this hypothesis is lacking. In contrast, modern textbooks typically explain the perception of object size and distance by the combination of information from different visual cues. Here, we describe full body illusions in which subjects experience the ownership of a doll's body (80 cm or 30 cm) and a giant's body (400 cm) and use these as tools to demonstrate that the size of one's sensed own body directly influences the perception of object size and distance. These effects were quantified in ten separate experiments with complementary verbal, questionnaire, manual, walking, and physiological measures. When participants experienced the tiny body as their own, they perceived objects to be larger and farther away, and when they experienced the large-body illusion, they perceived objects to be smaller and nearer. Importantly, despite identical retinal input, this “body size effect” was greater when the participants experienced a sense of ownership of the artificial bodies compared to a control condition in which ownership was disrupted. These findings are fundamentally important as they suggest a causal relationship between the representations of body space and external space. Thus, our own body size affects how we perceive the world.
) their brains "flipped" the image so that it looked normal to them and they no longer had to mentally compensate - very much like the point where you stop translating a foreign language into your native tongue and start thinking in it.
