The Weird Science of How We Perceive Our Bodies
What it means to have ‘alien hand syndrome’
The human body plays a crucial role in personal identity. And yet, evidence from brain injury patients, and the science of perceptual illusions, suggest that physical identity may be more fluid than we think.
A 2013 article appearing in the Journal of Neuropsychiatry and Clinical Neurosciences reported the curious case of an 82-year-old woman who believed she no longer controlled her left arm. Instead, it now belonged to her brother.
Six weeks earlier, she had suffered a stroke that affected the left side of her face, arm, and speech. Contacting her doctors, she complained that “her ‘brother’s arm’ did not do what she wanted and that this was causing her significant distress,” say neurologists Hannah Shereef and Andrea Cavanna.
“Most people are convinced that their body parts are, in fact, their own, but in some clinical conditions, this sense of ownership can be lost,” explains neuroscientist Nadia Barnsley of Neuroscience Research Australia in Sydney.
“I found myself looking at the dummy hand thinking it was actually my own.”
Though rare, according to Barnsley, the condition — known by neuroscientists as “alien hand syndrom”’ — is not unique. And, along with other perceptual disorders, it provides essential insights into how people mentally represent their bodies.
There’s little doubt that “body image is a complex concept that symbolizes the way in which people perceive themselves and the way they feel and behave in relation to their own body,” writes lead researcher Santiago Mendo-Lázaro in Frontiers in Psychology.
If people with alien hand syndrome can “lose” parts of their body, could it also be possible to “take possession” of new limbs that don’t belong to the body?
According to science, yes.
In a 1998 landmark study, researchers at the University of Pittsburgh performed an unlikely experiment, known as the “rubber hand illusion.” They asked participants to place one of their hands out of sight, behind a barrier. A lifelike fake hand was laid in front of them where their real one would…