5Consciousness

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Unconsciousness is something you don’t really appreciate until you need it. Belle Riskin needed it one day on an operating table, when she awoke just as doctors were pushing a breathing tube down her throat. She felt she was choking, but she couldn’t see, breathe, scream, or move. Unable even to blink an eye, she couldn’t signal to the surgeons that she was conscious. “I was terrified. Why is this happening to me? Why can’t I feel my arms? I could feel my heart pounding in my head. It was like being buried alive, but with somebody shoving something down your throat,” she explained later. “I knew I was conscious, that something was going on during the surgery. I had just enough awareness to know I was being intubated” (Groves, 2004).

How could this happen? Anesthesia for surgery is supposed to leave the patient unconscious, “feeling no pain,” and yet in this case—and in about one in every 1,000–2,000 surgeries (Sandin et al., 2000)—the patient regains consciousness at some point and even remembers the experience. The problem arises because muscle-relaxing drugs are used to keep the patient from moving involuntarily and making unhelpful contributions to the operation. Then, when the drugs that are given to induce unconsciousness fail to do the job, the patient with extremely relaxed muscles is unable to show or tell doctors that there is a problem.

Fortunately, new methods of monitoring wakefulness by measuring the electrical activity of the brain are being developed. One system uses sensors attached to the patient’s head and gives readings on a scale from 0 (no electrical activity in the brain) to 100 (fully alert), providing a kind of “consciousness meter.” Anesthesiologists using this index deliver anesthetics to keep the patient in the recommended range of 40–60 for general anesthesia during surgery; they have found that this system reduces post-surgical reports of consciousness and memory of the surgical experience (Myles et al., 2004). One of these devices in the operating room might have helped Belle Riskin settle into the unconsciousness she so dearly needed.

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MOST OF THE TIME, OF COURSE, CONSCIOUSNESS IS SOMETHING WE CHERISH. How else could we experience a favorite work of art; the familiar lyrics of an old song; the taste of a sweet, juicy peach; or the touch of a loved one’s hand? Consciousness is a person’s subjective experience of the world and the mind. Although you might think of consciousness as simply “being awake,” the defining feature of consciousness is experience, which you have when you’re awake or when having a vivid dream. Conscious experience is essential to what it means to be human. The anesthesiologist’s dilemma in trying to monitor Belle Riskin’s consciousness is a stark reminder, though, that it is impossible for one person to experience another’s consciousness. Your consciousness is utterly private, a world of personal experience that only you can know.

How can this private world be studied? We’ll begin by trying to understand what it is like and how it compares with the mind’s unconscious processes. Then we’ll examine altered states of consciousness: sleep and dreams, intoxication with alcohol and other drugs, and hypnosis. Like the traveler who learns the meaning of home by roaming far away, we can learn the meaning of consciousness by exploring its exotic variations.