Consciousness and the Brain: The Greatest Mystery of Being Human


By Mark Leary, Ph.D., Duke University

Scientists consider consciousness to be the granddaddy of all mysteries of human behavior. At the most simple level, the question of consciousness involves what causes us to be consciously aware of our experiences. How are we able to see colors, hear sounds, smell odors, experience sensations, and have emotions?

Human head with a luminous brain network.
Consciousness and the brain appear to be linked to each other in some manner, but not in a very precise manner. (Image: Lidiia/Shutterstock)

Consciousness and the Brain

If you ask most people where consciousness comes from, of course, they’ll say the brain, and there doesn’t seem to be much doubt that the brain is involved in consciousness. Obviously, activity in the brain is associated with seeing, hearing, smelling, sensing, and thinking, and if we damage the brain in certain ways, people are no longer conscious.

But here’s the problem—nobody has even the slightest idea of how the brain produces consciousness, if, in fact, it even does. Your brain is composed of about 100 billion neurons that send electrical and chemical signals among themselves, which receive input from receptors of various kinds located around the body, such as the receptors in your eyes, ears, or skin.

Transmission Is not Consciousness

So, it’s easy to see that neurons transmit information, somewhat like information is transmitted along a telephone line or within a computer network, and scientists know a great deal about how neurons communicate with each other.

But transmitting information is not consciousness. Telephone systems and computer networks receive, process, and pass along information, and they do things on the basis of the information they receive, but they don’t have a personality. But we not only receive and process information—for example about colors and sounds and physical touch—but also experience those things consciously. We see, we hear, we experience sensations, emotions, pain, and pleasure in ways that telephone and computer systems presumably don’t because they’re not conscious.

This is a transcript from the video series Understanding the Mysteries of Human Behavior. Watch it now, Wondrium.

The Explanatory Gap

So, the question is: Where do our personal subjective experiences come from?

To say it more vividly, your brain is made up of neurons, blood vessels, connective tissue, and other biological matter. Your brain is really just a piece of meat—a 3-pound piece of meat.

So, how does a piece of meat have sensations, images, thoughts, and emotions? How does a piece of meat make a mind or have conscious experiences?

Consciousness theorists call this question the ‘explanatory gap’ between explaining how the brain works and explaining what produces consciousness. We know a great deal about how the brain processes information, but we have no idea how it produces consciousness, despite centuries of philosophy and scientific research being devoted to this question.

An artistic image of the brain with graphic images on the left, and mixed colors spreading out on the right.
The explanation gap is the gap between understanding how an organic brain can generate consciousness. (Image: Kirasolly/Shutterstock)

There are, of course, many things that scientists don’t understand. But consciousness differs from many mysteries in that, not only do we not have any viable explanations about where consciousness comes from, but we don’t even have an idea about what kind of explanation would make any sense.

Learn more about the brain and self.

The ‘Binding’ Theory of Consciousness

That’s not to say that many theorists have not offered explanations of how the brain is related to consciousness. Many of the more recent explanations have tied in ideas from quantum physics. But most experts find all of these explanations seriously lacking, and we really don’t know.

One theory links consciousness to the processes through which the brain integrates information coming from various senses and “binds” them together into one experience.

For example, when you’re having a conversation with someone, the image of the person’s face and the sound of their voice are being processed in very different parts of your brain, and your interpretation of what they are saying is happening somewhere else.

Yet, you have a single unified experience in which the movement of the person’s mouth is timed perfectly with the sounds coming out of it, and you are instantly interpreting the words as you hear them.

Your brain is somehow taking very distinct inputs coming in through different senses and binding them together into one conscious experience. And one theory says that consciousness arises out of that binding process.

From Seeing to Consciousness

Well, maybe so, but we still haven’t explained where the conscious experience itself has come from. That is, even if we explain how the brain integrates various channels of incoming information, we still haven’t explained why you consciously see and hear the person.

But you do. You consciously see his blue shirt and his facial expression, and you consciously hear and interpret what he is saying.

We now have computer software that can register and report the color of his shirt, interpret his words, and even recognize his face, but again, the software probably does not have a conscious experience. If we didn’t already know that people have conscious experiences, there’s nothing whatsoever that we know about the brain that would lead us to think that they do. We can’t find anything in the brain that causes consciousness.

Learn more about defining reality in life sciences.

Maybe the Brain Doesn’t Make Consciousness

The difficulty in making inroads into the question of consciousness has led many scientists and philosophers to suggest that we must be thinking about the question entirely wrong—that our basic assumptions about how the brain works must be off base somehow.

Silhouette of a human head on a black background with neural linkages coming out into the surroundings.
Some experts theorize that consciousness may be external to us, and the brain just senses it in some way unknown to us. (Image: Zelenov Iuri/Shutterstock)

Some experts in consciousness have suggested that we have been wrong in assuming that the brain creates consciousness. They suggest that consciousness exists outside of us in the external world—like gravity or electromagnetism—and our brains are tapping into and using consciousness rather than creating it.

Other scientists have suggested that the problem is more apparent than real: that we’ve fallen into a trap of thinking about consciousness in a way that’s not accurate, so that we’re trying to solve a problem that doesn’t really exist.

Others are convinced that consciousness is just an unusually complex process that we simply don’t understand yet, but we will someday when we conduct enough research and have more information. But, for now, the fact is that we just don’t know what consciousness really is or where it comes from.

If you want to become an instant scientific celebrity—become as famous as Darwin or Einstein or Watson and Crick—the guys who discovered DNA—go out and discover the source of consciousness. It’s among the most baffling mysteries in all of science.

Common Questions about the Brain and Consciousness

Q. What is the ‘explanatory gap’ with regard to consciousness?

According to consciousness theorists, the ‘explanatory gap’ is the gap between explaining how the brain works and explaining what produces consciousness.

Q. What is the ‘binding’ theory of consciousness?

According to the binding theory of consciousness, our brain is somehow taking very distinct inputs coming in through different senses and binding them together into one conscious experience. And consciousness arises out of that binding process.

Q. Do all theories attribute consciousness to the brain?

Some experts in consciousness suggest that consciousness exists outside of us in the external world—like gravity or electromagnetism—and our brains are tapping into and using consciousness rather than creating it.

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