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Do We See Reality As It Is? by Donald Hoffman (Transcript)

Donald Hoffman at TED Talks

Full text of cognitive scientist Donald Hoffman’s talk: Do We See Reality As It Is? at TED Talk conference.

Listen to the MP3 Audio here: Do we see reality as it is by Donald Hoffman

TRANSCRIPT:

Donald Hoffman – Cognitive scientist

I love a great mystery, and I’m fascinated by the greatest unsolved mystery in science, perhaps because it’s personal. It’s about who we are, and I can’t help but be curious.

The mystery is this: What is the relationship between your brain and your conscious experiences, such as your experience of the taste of chocolate or the feeling of velvet?

Now, this mystery is not new. In 1868, Thomas Huxley wrote:

“How it is that anything so remarkable as a state of consciousness comes about as the result of irritating nervous tissue is just as unaccountable as the appearance of the genie when Aladdin rubbed his lamp.”

Now, Huxley knew that brain activity and conscious experiences are correlated, but he didn’t know why. To the science of his day, it was a mystery.

In the years since Huxley, science has learned a lot about brain activity, but the relationship between brain activity and conscious experiences is still a mystery. Why?

Why have we made so little progress?

Well, some experts think that we can’t solve this problem, because we lack the necessary concepts and intelligence. We don’t expect monkeys to solve problems in quantum mechanics, and as it happens, we can’t expect our species to solve this problem either.

Well, I disagree. I’m more optimistic. I think we’ve simply made a false assumption. Once we fix it, we just might solve this problem.

Today, I’d like tell you what that assumption is, why it’s false, and how to fix it.

Let’s begin with a question: Do we see reality as it is?

I open my eyes and I have an experience that I describe as a red tomato a meter away. As a result, I come to believe that in reality, there’s a red tomato a meter away.

I then close my eyes, and my experience changes to a gray field, but is it still the case that in reality, there’s a red tomato a meter away? I think so, but could I be wrong? Could I be misinterpreting the nature of my perceptions?

We have misinterpreted our perceptions before. We used to think the Earth is flat, because it looks that way. Pythagoras discovered that we were wrong.

Then we thought that the Earth is the unmoving center of the Universe, again because it looks that way. Copernicus and Galileo discovered, again, that we were wrong.

Galileo then wondered if we might be misinterpreting our experiences in other ways. He wrote:

“I think that tastes, odors, colors, and so on reside in consciousness. Hence if the living creature were removed, all these qualities would be annihilated.”

Now, that’s a stunning claim. Could Galileo be right? Could we really be misinterpreting our experiences that badly?

What does modern science have to say about this?

Well, neuroscientists tell us that about a third of the brain’s cortex is engaged in vision. When you simply open your eyes and look about this room, billions of neurons and trillions of synapses are engaged.

Now, this is a bit surprising, because to the extent that we think about vision at all, we think of it as like a camera. It just takes a picture of objective reality as it is.

Now, there is a part of vision that’s like a camera: the eye has a lens that focuses an image on the back of the eye where there are 130 million photoreceptors, so the eye is like a 130-megapixel camera.

But that doesn’t explain the billions of neurons and trillions of synapses that are engaged in vision.

What are these neurons up to?

Well, neuroscientists tell us that they are creating, in real time, all the shapes, objects, colors, and motions that we see. It feels like we’re just taking a snapshot of this room the way it is, but in fact, we’re constructing everything that we see.

We don’t construct the whole world at once. We construct what we need in the moment.

Now, there are many demonstrations that are quite compelling that we construct what we see. I’ll just show you two.

In this example, you see some red discs with bits cut out of them, but if I just rotate the disks a little bit, suddenly, you see a 3D cube pop out of the screen.

Now, the screen of course is flat, so the three-dimensional cube that you’re experiencing must be your construction.

In this next example, you see glowing blue bars with pretty sharp edges moving across a field of dots. In fact, no dots move. All I’m doing from frame to frame is changing the colors of dots from blue to black or black to blue.

But when I do this quickly, your visual system creates the glowing blue bars with the sharp edges and the motion. There are many more examples, but these are just two that you construct what you see.

But neuroscientists go further. They say that we reconstruct reality. So, when I have an experience that I describe as a red tomato, that experience is actually an accurate reconstruction of the properties of a real red tomato that would exist even if I weren’t looking.

Now, why would neuroscientists say that we don’t just construct, we reconstruct?

Well, the standard argument given is usually an evolutionary one. Those of our ancestors who saw more accurately had a competitive advantage compared to those who saw less accurately, and therefore they were more likely to pass on their genes.

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