Qualia, and the so-called "Hard Problem" of consciousness.

If you walk into the office of a scientist, chances are you'll see a white board hanging on the wall covered in scrawls. A molecular biologist's white board might be covered by hideous tangles of protein chains. A geophysicist might doodle India crashing into southern Asia.

The scribbles of Dr. Michael Gazzaniga, the director of the Center for Cognitive Neuroscience at Dartmouth, are more metaphysical. Arrows travel from a pair of eyes into a cartoon brain, finally ending at the word "Apple." Another picture bluntly sums up the modern debate over free will, with a stick figure's head labeled "Brain," and two bubbles point toward it - one labeled "Judge" and the other "Neu" - short for neuroscience. Floating uncertainly off to one side is a third bubble that asks, "Mind?"

Big questions are Dr. Gazzaniga's stock in trade. In the 1980's he helped found cognitive neuroscience, a discipline designed to find out how the mind emerges from the brain. Today, at age 65, he continues to oversee a busy lab where brain scans offer clues to how we unconsciously create theories to explain the outer world and our inner lives.

"There should be a one to one correspondence between brain events and conscious events and brain scientists will someday find the proper correlations."

The "hard problem" of consciousness, according to which scientific models cannot explain the "qualia" or "first order experiences", is misguided if it is used to imply that we need more than structures and functions to explain conscious experience.

First person experiences or qualia are the essentially subjective, personal feelings or experiences that each of us have (e.g. the feeling of "redness" or "cold"), and that cannot be described by words, formulas, programs or any other objective representation. According to some consciousness theorists, such as David Chalmers, an agent without such qualia would merely be a "zombie", a creature that may behave, sense and communicate just like a human being, but that would lack the most crucial aspect of consciousness. The "hard problem" of consciousness research then consists in elucidating the nature of first-person experiences.

We believe that this approach is essential misguided. If the hypothetical zombie behaves in all respects indistinguishably from a person with consciousness, then the principle of the identity of the indistinguishables would force us to conclude that the "zombie" has consciousness. How else would we know that the people around us aren't zombies? We assume they have conscious experience similar to ourselves because they behave in all other respects similar to us. But if you would take this reasoning seriously, then you might start to get nightmarish fantasies in which you are the only real, conscious person in the world, and all the others are merely sophisticated automatons that pretend to be like you.

Can neuroscientists say anything interesting about consciousness? Judging by the stream of books and conferences on the topic, you can safely assume they believe they can. What makes Benjamin Libet different from all the others writing on the subject, though, is that he has actually spent the past 40 years experimenting on the topic. His findings have played a central role in others' speculations. Now he has put his life's work into a single short book.

The core of Libet's findings can be simply summarised. If I sit on the edge of my bed and decide to wiggle my toes, the brain processes necessary for the wiggling to occur begin about half a second before I am aware that I have made the decision. Libet finds this troubling; if the brain processes precede my sense of having made a decision, what part does my conscious decision making play? Who indeed is the "me" that does the "deciding"?

No wonder physicists can't explain past, present and future. The passage of time is just an illusion that we can't live without, says Marcus Chown

DEEP in the Amazon rainforest, a tree frog sits on a log watching a fly. A genetic fluke has furnished the frog with a brain that perceives its surroundings as they were a second ago. When the fly comes within range, the frog lunges. But, with its out-of-date observation, it misses. Weakened by a rarely sated hunger, the frog falls off the log and dies.

It's a sad story. But if you think it is completely fanciful, think again. There is nothing in the laws of physics that says all creatures have to process data about their environment in the same way as we do. A "behind the times" perception like that of our deceased frog is only ruled out by the handicap it imposes. "Natural selection has equipped people and frogs to experience the world in the most effective way for their survival," says James Hartle of the University of California, Santa Barbara. "A frog that calculates the trajectory of a fly from the most recent data, eats; one that doesn't, starves."

"Experiences only look special from the inside of the system."
- Eugen Leitl