How do you define consciousness? It's a thorny question, and one that has puzzled scientists and philosophers. Last week at the World Science Festival in New York City, some of the world's top thinkers on this subject convened for a panel discussion on the "conundrum of consciousness."
"The basic idea of it is just the things you think of as belonging to your mind such as seeing things, hearing things, tasting things, thinking about things, deciding to do something, intending to do something, mental phenomena," said Colin McGinn, professor and Cooper Fellow at University of Miami. "Each of those things are described as conscious."
McGinn, a philosopher, said we might not understand the connection between mind and body because we suffer from a cognitive gap.
The "brain itself and consciousness exist in a non-miraculous harmony with each other, they're perfectly integrated," he said. "But we, with our recently evolved brains, can't conceive of these things in such a way as to articulate this natural coexistence. So we're rather like Neanderthals trying to understand astronomy or Shakespeare... We ought to take seriously the possibility that problems which have resisted human solution for lo these thousands of years might be problems we're just not able to come to terms with."
Christof Koch, professor of biology and engineering at the California Institute of Technology and the Allen Institute for Brain Science, said he thought that theory was defeatist.
"I think historically philosophers have a disastrous record of explaining things," he said. "I think you should listen to philosophers; some of the best ones are very good at asking questions. But historically if you go back to Aristotle and Plato and you look at every major philosopher, they fail to give satisfactory answers that are at least compatible with our modern scientific world view."
A classic experiment used to measure consciousness is the mirror test:
Other animals, including dolphins, also respond to this test:
CONSCIOUSNESS AND COMAS
Nicholas Schiff, director of the Laboratory of Cognitive Neuromodulation at Weill Cornell Medical College, studies people who are recovering from comas.
"The connection of people to each other that consciousness brings is really such a target for our optimization as physicians," he said. "It makes a big difference. If you have a family whose grandfather is slipping in and out of consciousness and you can give them a month or a few weeks to really connect with their grandchildren and their family because you understand something better about what's possible for them -- to keep their brain in a state where they are a part of the human community."
He cited a memorable case of a firefighter coming out of a coma after nearly a decade and speaking again to his loved ones: