They conclude that it is an inherent property of physical systems in which information moves around in a certain way — and that could include some kinds of artificial intelligence and even naturally occurring nonliving matter.
At the most basic level, consciousness is awareness, Dr. Barron and Dr. Klein say. A robot vacuum moves around and responds to information from the external world — when it is stopped by a wall, for instance. But the vacuum doesn’t have any experience, Dr. Klein says — it doesn’t feel like anything to be a Roomba.
He and Dr. Barron propose that it may well feel like something to be a honeybee, or another insect, although what that feeling is, no one knows.
They make their case this way:
■ Other scientists have argued that a part of the human brain called the midbrain can, on its own, give a person lacking more advanced parts of the brain simple awareness.
■ The insect brain does something similar to the midbrain in absorbing information from the environment, from memory and from the body to organize its activity.
■ If the insect brain does the same job as the vertebrate midbrain, then the insect has the capacity for awareness.
If this line of reasoning is correct, Dr. Barron and Dr. Klein say, a robot built with artificial intelligence that could integrate sensory data, memory and body awareness would have the capacity for the minimal level of consciousness they describe.
By the same token, plants do not have any structures that would allow for awareness, says Dr. Barron, nor does a simple animal like C. elegans, the roundworm used in so many experiments. It has 302 neurons. A honeybee, by contrast, has almost a million.
Dr. Koch said in an email that he thought Dr. Barron and Dr. Klein were making a reasonable argument. The brains of bees and flies, he wrote, “possess intricate circuitry an order of magnitude denser than the circuits of the celebrated neocortex,” which is central to human thinking.
Peter Godfrey-Smith, a philosopher at the City University of New York who writes about consciousness, said in an email that he found the argument by Dr. Barron and Dr. Klein plausible. But, he said, there could be many different kinds of awareness and insects might be aware of motion, for example, but “were not good candidates for feeling pain,” unlike octopuses and crabs.
“Insects might have subjective experience,” he wrote, “but not of a kind that has a lot of ethical consequences.”
Dr. Barron emphasized that the article was intended simply to propose a hypothesis rather than offer a proven conclusion. “We put it forward because we think we should have this debate,” he said.