Imagine looking down at your feet and seeing nothing but empty space. A paintbrush runs across your stomach. You can definitely feel the brush, but it looks like it's just sweeping across empty space.
So now you're invisible. Would you just walk around naked? Spend your life pranking as many people as possible? Would it be lonely?
With recent breakthroughs in cloaking technology, it may one day be possible to cloak the human body.
Besides the moral questions and general creep factor of a world where people can be invisible, researchers wanted to know how invisibility could change how we act and think.
So, they tricked people into thinking they were invisible, and studied them.
In one of the coolest studies we've ever read, published April 23 in the journal Scientific Reports, researchers used virtual reality to create a really elaborate illusion for the study participants.
Each participant strapped on a pair of virtual reality goggles, and looked down at their feet. The trick is that each person's virtual reality headset was displayed the view from a second headset mounted at equal height starting down at nothing. One of the researchers would then touch the participant with a paintbrush while simultaneously touching the same place in the empty space view.
It looked a little ridiculous:
The participants could feel the brush on their skin (or, at least, the pressure of it wiping their shirt), but when they looked down, the virtual reality goggles told them that nothing was there. Lead study author Arvid Guterstam tried the experiment himself, and he told National Geographic that being invisible is "great fun," but it's also "an eerie sensation. It's hard to describe."
Others in the study remained 'visible' people — they were simply shown a mannequin instead of empty space during the paintbrush trick.
Then the researchers moved on to measuring how people responded to being invisible. So naturally they swiped a knife at each person:
The 'invisible' people registered a slightly higher stress response to the knife that included sweating and an elevated heart rate. This suggests that the illusion definitely worked, and people accepted the invisible body as their own.
Something different happened in the next experiment though. This time when people looked up from their visible or invisible feet, they suddenly found themselves staring into a very serious-looking crowd of people staring back at them.
To the average person that's probably a startling and stressful moment. After all, statistics show that fear of public speaking is America's biggest phobia. But when you're convinced you're invisible, it's a much less stressful experience. The 'invisible' people had lower heart rates when they stared back at the unfriendly crowd. They also reported feeling about a third less stressed than the 'visible' people.
The study has a pretty obvious conclusion: People experience less social anxiety in front of a crowd if they think they're invisible.
The really cool part is that these people actually bought into the illusion, and for a few minutes they believed they were invisible. The study suggests that it's surprisingly easy to create a convincing out-of-body experience.
Our brain is what creates our body sense. Our brain processes all our senses and puts our body where those senses say it should be. All that an out of body experience requires is a mismatch between what you're seeing and what you're feeling.
The researchers think the study could be used to develop virtual reality treatments for people with social anxiety. It could also provide more insight into why amputees feel phantom pain or a way to make prosthetic limbs feel like they belong.
Future studies could investigate the social and moral implications of invisibility.
