What Is Consciousness?

Hi Vsauce, Michael here, and a hemispherectomy is a surgical procedure in which half of a person's brain is removed. It is usually only done on very, very young patients because their brains are still plastic enough for the remaining half to take over the functions of the half that was removed. And it is usually done because a young child or baby has seizures and the only solution is to remove the part where the seizures occur. But here is my question. If you can live with half a brain,

what

would happen if I took two empty skulls and took half of your brain and dropped it into one body and the other half and put it into another body?

What person would you be? I mean, it's you. You are aware. You are aware of

what

happens to you from the perspective of yourself. Think about it this way. If you just look at something and feel what it feels like to be yourself, it feels a little like you're a thing inside a body looking through eyeballs. And no one else on Earth will ever see the world from that position. This awareness of your own experiences, the awareness that you are having them, the awareness that you are having your own thoughts constitutes what we call

consciousness

. But if I took your brain, split it in two, and put it into two different people, would they both be new, conscious people?

Well, one of the best places to start defining

consciousness

and understanding it is to start with things that we agree are not conscious. For example, Cleverbot. Cleverbot.com is an amazing website where a computer program will answer your questions very intelligently, but only because it is programmed to do so. We wouldn't consider it conscious because it has no sense of self. You don't feel anything. It has no inner life of its own. It's just a program that automatically responds to my input. Now I know I'm not like Cleverbot. I know that I feel things and that I have a sense of myself.

I have intentions. But how do I know you do? In fact, how do I know that everyone I know is like me? How do I know they're not just smart little versions of Cleverbot that know exactly what to say automatically? What I'm asking is incredibly philosophical, but it's a very famous and important question. I'm basically asking if it's possible that there is such a thing as a philosophical zombie. That's right, something that reacts, responds and acts like a normal human being but doesn't actually feel anything. He doesn't know that he has his own thoughts. It simply automatically responds like a robot in the appropriate manner.

Now, the surprising and burdensome thing about this question is that science does not have an answer, and it is not even clear that science will ever have an answer, much less an approach to finding that answer. All we have is the psychology of disorders of consciousness. Let's start with anosognosia. A common example of anosognosia in psychology classes is a patient who, for example, has lost the ability to move his left hand. When asked to raise their right hand, they will say, "Yes, no problem, here you go." But then when you ask them to raise their left hand, they say, "Oh, yeah, sure, no problem," but they don't move it.

And when asked why they don't move their left hand, instead of saying they can't, they make up some excuse. For example, "Oh, I didn't feel like it." Anton-Babinski syndrome is even more dramatic. Patients with this syndrome are cortically blind. They can't see anything. But they deny being blind. If you ask them a question, for example: "How many fingers am I holding up?" They will make an assumption, but if they are wrong, they will explain their inaccuracy with an excuse. For example, "oh, well, I don't have my glasses." People with anosognosia tend to be stroke victims, and there is some disconnect between what they are actually experiencing and their awareness of it.

They don't know that they can't see because the part of their brain that monitors visual information doesn't tell the brain anything. It's not even about telling the brain that there is no visual information, which means that the parts of your brain responsible for answering questions or creating speech have to completely create a confabulated response. Even though we have been able to study patients with anosognosia, we still have no idea how to solve our original problem. In fact, all we've gotten are more impossible questions about identity, questions that are so confusing that the best you can do with them is answer them yourself based on what you believe.

Here's another one. He is called the swamp man. Imagine I'm walking in a swamp and suddenly I'm struck by lightning and my entire body burns to a crisp, dissolving into pieces. But at the same moment, a second lightning bolt strikes nearby and causes a group of atoms and molecules to arrange themselves in exactly the same configuration that my body used to have, forming a second Michael. That's me? Would that be me? Here's an even better one. Imagine a surgeon comes in and starts removing cells from me and yours, replacing them exactly one at a time, replacing my cells in his body and his cells in my body.

At what point would he have officially turned me into you? No one on Earth has the definitive answers to these questions, but you know what we have? A sloping back. That's how it is. I've created a playlist with some of my favorite clips from all over YouTube about psychology experiments and illusions and all kinds of fun things to do with consciousness. All you have to do is click the link at the top of this video's description and then sit back and let the auto-playlist do the work for you. See you there and, as always, thanks for watching.

Hi Kevin, any new messages from YouTube? Actually, yes. I just received this message on Vsauce 2 from a user who doesn't create videos but organizes them into his own playlists. Yeah, yeah, that's great because there are so many videos on YouTube that we need people to help us organize them, especially by type. Imagine a channel of playlists ranging from great songs to listen to when it rains to the best explosions ever. Exactly. If you create a playlist that you think is really interesting and full of things we should know, send it to [email protected] and we'll feature the ones we really like because you've made YouTube a better, more organized place.

And after all, Vsauce is like a carpool lane. We'll all get to the interesting things faster because we travel together. Where did you get that?