In my last post I talked about embodiment illusions and how they influence our bodies, allow us to become different humans, change our biases and even our personalities.
I shortly already mentioned that the rubber hand illusion works just as well when you do it with a bright purple rubber hand, even though that is not a naturally occurring human skin-color. So I want to talk a bit more about ‘homuncular flexibility’ – the mechanism that allows us to experiences bodies that go beyond or are far different from the ‘standard’ possibilities a humanoid body offers us.
As happens often, art goes faster than science. The artist Stelarc was experimenting and performing with extra robot-hands long before Guterstam and others studied the embodiment illusion of owning a third virtual arm in 2011. They found that it was entirely possible for human beings to learn to use a third arm as if it was a part of their body.
Of course, the line between body and tool becomes blurred here – but we know from earlier research that this line is blurred anyway. Our peripersonal space (the space directly surrounding our body that is mapped and treated in a specific manner by our brain, for instance to detect threats) extends when we are using a tool to elongate our arm, and musicians change their own brains to incorporate their musical instrument within it.
However, as another study shows us, by Steptoe and others in 2013, this literal ‘incorporation’ of body extensions can go so far that the reaction of brain and body no longer distinguish between real body and extension. They gave people a virtual tail, with which they had to play a game in virtual reality. Providing further proof that scientists are mean, they then had the tail burst into (virtual) flame, and measured the reaction of the participants. Just as in the rubber hand illusion, hormones surged wildly, as if the own body was attacked.
Lanier also studied homuncular flexibility in 2006, transforming people into crabs and other animals with drastically different body-plans, but a lot of the work done in this field remains exploratory. Going beyond additional limbs and focusing on extra senses, the artist Moon Ribas worked for instance with a movement sensor to give herself literal eyes on the back of her head. She also had a vibrating electronic piece implanted in her arm, that is connected a website tracking seismic sensors over the whole world. In this way, she literally feels the world shake – even if it’s a tiny quake on the other side of the planet.
The question is – how far can we go? How many senses can we add, and how drastically can we change the body? In general, this line of scientific and artistic research shows how surprisingly difficult it can be to draw a clear line between what counts as our body, and what does not. Our brain at least seems to have a much more open-minded notion about it, with many gray areas in between!