DO YOU THINK that your newest acquisition, a Roomba robotic vacuum cleaner that traces out its unpredictable paths on your living room floor, is conscious? What about that bee that hovers above your marmalade-covered breakfast toast? Or the newborn who finally fell asleep after being suckled? Nobody except a dyed-in-the-wool nerd would think of the first as being sentient; adherents of Jainism, India’s oldest religion, believe that bees—and indeed all living creatures, small and large—are aware; whereas most everyone would accord the magical gift of consciousness to the baby.
The truth is that we really do not know which of these organisms is or is not conscious. We have strong feelings about the matter, molded by tradition, religion and law. But we have no objective, rational method, no step-by-step procedure, to determine whether a given organism has subjective states, has feelings.
The reason is that we lack a coherent framework for consciousness. Although consciousness is the only way we know about the world within and around us—shades of the famous Cartesian deduction cogito, ergo sum—there is no agreement about what it is, how it relates to highly organized matter or what its role in life is. This situation is scandalous! We have a detailed and very successful framework for matter and for energy but not for the mind-body problem. This dismal state of affairs might be about to change, however.
The universal lingua franca of our age is information. We are used to the idea that stock and bond prices, books, photographs, movies, music and our genetic makeup can all be turned into data streams of zeros and ones. These bits are the elemental atoms of information that are transmitted over an Ethernet cable or via wireless, that are stored, replayed, copied and assembled into gigantic repositories of knowledge. Information does not depend on the substrate. The same information can be represented as lines on paper, as electrical charges inside a PC’s memory banks or as the strength of the synaptic connections among nerve cells.
Since the early days of computers, scholars have argued that the subjective, phenomenal states that make up the life of the mind are intimately linked to the information expressed at that time by the brain. Yet they have lacked the tools to turn this hunch into a concrete and predictive theory. Enter psychiatrist and neuroscientist Giulio Tononi of the University of Wisconsin–Madison. Tononi has developed and refined what he calls the integrated information theory (IIT) of consciousness.
An Integrated Theory
IIT is based on two axiomatic pillars.
First, conscious states are highly differentiated; they are informationally very rich. You can be conscious of an uncountable number of things: you can watch your son’s piano recital, for instance; you can see the flowers in the garden outside or the Gauguin painting on the wall. Think of all the frames from all the movies you have ever seen or that have ever been filmed or that will be filmed! Each frame, each view, is a specific conscious percept.
Second, this information is highly integrated. No matter how hard you try, you cannot force yourself to see the world in black-and-white, nor can you see only the left half of your field of view and not the right. When you’re looking at your friend’s face, you can’t fail to also notice if she is crying. Whatever information you are conscious of is wholly and completely presented to your mind; it cannot be subdivided. Underlying this unity of consciousness is a multitude of causal interactions among the relevant parts of your brain. If areas of the brain start to disconnect or become fragmented and balkanized, as occurs in deep sleep or in anesthesia, consciousness fades and might cease altogether. Consider split-brain patients, whose corpus callosum—the 200 million wires linking the two cortical hemispheres—has been cut to alleviate severe epileptic seizures. The surgery literally splits the person’s consciousness in two, with one conscious mind associated with the left hemisphere and seeing the right half of the visual field and the other mind arising from the right hemisphere and seeing the left half of the visual field.