Mind & Brain / Learning

Some of the most profound questions in science are also the least tangible. What does it mean to be sentient? What is the self? When the discussion turns to these imponderables, many minds defer rather than get mired in such muddy issues. Neuroscientist Gerald Edelman dives right in. A physician and cell biologist who won a Nobel Prize for his work on the structure of antibodies, Edelman is now obsessed with the enigma of human consciousness—except he doesn’t see it as a mystery. In Edelman’s grand theory of the mind, consciousness is a biological phenomenon. The developing brain undergoes its own process, similar to natural selection: Neurons proliferate and form connections in infancy; experience weeds out the useless from the useful, molding the adult brain in sync with its environment. Edelman first put this model on paper in the Zurich airport in 1977 as he was killing time waiting for a flight; since then, he’s written eight books on the subject, including most recently Second Nature: Brain Science and Human Knowledge. Edelman is also chair of neurobiology at Scripps Research Institute in San Diego, California, and founder and director of the Neurosciences Institute, a research center dedicated to unconventional “high risk, high payoff” science. In their conversations, he and DISCOVER editor Susan Kruglinski range far into this untamed territory, exploring synthetic consciousness, how to build a mechanical brain, the best way to teach robots—and why we all have rhythm.

You’ve coined the phrase “neural Darwinism.” What is it?

Many cognitive psychologists see the brain as a computer. But every single brain is absolutely individual, both in its development and in the way it encounters the world. Your brain develops depending on your individual history. So, for example, identical twins will not have identical brains because each brain is exposed to different circumstances. It’s very likely that your brain is unique in the history of the universe. Neural Darwinism looks at this enormous variation in the brain at every level, from the biochemistry to anatomy to behavior. [When coming up with the term] I personally borrowed from Darwin, who brought forth a great principle called population thinking, in which you could get species by selection in a population. That means if you had a vast population of animals and each differed, under competition certain variants that were on average fitter than the others would be selected, and their genes would go into the population. A similar principle could be applied to the development and the coordination of [human] brains. You have variant microcircuits in the brain.

Can consciousness be artificially created?

I believe that someday scientists will make a conscious artifact. And of course, there are certain requirements it would have to fulfill before scientists would be satisfied. For example, they might give a conscious artifact an ability to report through some kind of language, and then test it in various ways. They would not tell it what they are testing, and they would continually change the test. If the report corresponds to every changed test, then the scientists involved could be pretty secure in the notion that it is conscious. And of course, when they do, it will not be like us. In my opinion, it wouldn’t be alive. That might horrify people. How can you possibly have consciousness in something that isn’t alive? There are people who are dualists, who think that to be conscious is to have some kind of special immaterial agency that is outside of science. The soul, floating free—all of that. There might be people who say, “If you make it conscious, you just increase the amount of suffering in this world.” They think that consciousness is what differentiates you or allows you to have a specific set of beliefs and values, et cetera. You have to remind yourself that the body and brain of this artifact will not be a human being. It will have a unique body and brain, and it will be quite different from us. If they ever achieve it, it won’t be living.

Would a conscious artifact have the value of a living thing?

Well, I would hope it would be treated that way. Even if it isn’t a living thing, it’s conscious. If I actually had a conscious artifact, even though it was not living, I’d feel badly about unplugging it. But that’s a personal response.

By proposing the existence of artificial consciousness, aren’t you comparing the human brain to a computer?

No. For example, if you come into this room 10 times, you are not getting an identical set of signals each time, even though the room is relatively stable. Your brain has to be creative about how it integrates the signals coming into it. Computers don’t do that. Our brain is capable of symbolic reference, not just syntax. There’s a neurologist at the University of Milan in Italy named Edoardo Bisiach who’s an expert on a neuropsychological disorder known as anosognosia [a brain injury in which a patient is not aware of the impairment]. A patient with anosognosia often has a stroke in the right side, in the parietal cortex. That patient will have “hemineglect”: He or she cannot pay attention to the left side of the world. Shaves on one side. Draws half a house, not the whole house, et cetera. Bisiach had one patient who had this. He was intelligent. He was verbal. And Bisiach said to him, “Here are two cubes. I’ll put one in your left hand and one in my left hand. You do what I do.” And he went through a motion. And the patient said, “OK, doc. I did it.” Bisiach said, “No, you didn’t.” He said, “Sure, I did.” So Bisiach brought the patient’s hand into his right visual field and said, “Whose hand is this?” And the patient said, “Yours.” Bisiach said, “I can’t have three hands.” And the patient very calmly said, “Doc, it stands to reason if you’ve got three arms, you have to have three hands.” That case is evidence that the brain is not a machine for logic but in fact a construction that does pattern recognition. And it does it by filling in, in ambiguous situations.

Could we make something that has the equivalent consciousness of a mouse?

I would not try to emulate a living species because—here’s the paradox—the thing will actually be nonliving. Isn’t that something? There still might be an ethical problem but, you know...