Depending on who you ask, there are between 640 and 850 muscles in the human body. Either way, that’s a lot. There are also 206 bones in an adult human being. With that many muscles pulling on that many bones, even the simplest tasks are pretty complex. For example, take even the simple task of scratching your ass. Leaning over to one side, extending your arm, contracting your fingers and applying pressure to your derriere requires the control of more muscles than you would ever want to have direct control of.
Luckily, your brain handles all of this heavy lifting automatically in the background. You needn’t concern yourself with most of the details. Many other tasks are also handled on autopilot, such as judging where a ball will be in the near future so as to catch it. That’s complex calculus done on the fly.
Of course, in order for all of this to work, your brain has to take some things out of your control. And sometimes, your perceptions can outweigh what your body is physically feeling. This was shown to be true in a very clever study recently published from Northwestern University.
In the experiment, Yangqing ‘Lucie’ Xu, doctoral candidate in psychology, had participants hold a vertical stick with a weight hanging off of one side. Knowing that the stick would be pulling to one side, your brain automatically applies a slight twist of the wrist to accommodate the force, so perceiving where that weight needs to be countered is important information.
Xu asked the participants to tell her which direction the weight was hanging. Simple enough, right? At face value, sure. But for some of the participants, she used a set of mirrors to reverse the image, making people think the weight was hanging in the opposite direction.
What she found was that this visual stimulation was often more than enough to fool the participants into thinking that the weight was hanging in the opposite direction that it actually was. What’s more, the effect persisted even when they were told exactly what was going on. Despite knowing that they were looking at reverse images, they still reported feeling the weight on the wrong side.
The impulse is so strong, it even worked on the experimenters themselves, and they designed the experiment.