Hey,
Vsauce. Michael here. Where are your fingers? Seriously. It's a pretty easy question. You should be able to answer it. But how do you know? How does anyone know anything?
You might say, well, I know where my fingers are. I'm looking right at them. Or, I can touch them, I can feel them, they're right here and that's good. Your senses are a great way to learn things. In fact, we have way more than the usual five senses we talk about. For instance, your
kinesthetic sense, proprioception. This is what the police
evaluate during a field sobriety test. It allows you to tell where your fingers and arms and head and legs in your body is all in relation to each other without having to look or touch other things. We have way more than five senses, we have at least twice as many and then some. But they're not perfect.
There are
optical illusions, audio illusions, temperature sensation illusions, even
tactile illusions. Can you turn your tongue upside down? If so, perfect. Try this. Run your finger along the outer edge of the tip of your upside down tongue. Your tongue will be able to feel your finger, but in the wrong place. Our brains never needed to develop an understanding of upside down
tongue touch. So, when you touch the right side of your tongue when it's flipped over to your
left side you perceive a sensation on the opposite side, where your tongue usually is but isn't when it's upside down. It's pretty freaky and cool and a little
humbling, because it shows the limits of
