Dr. Oliver Sacks neared the age of eighty, he published this book, which includes memoir, patient reporting, and current scientific data about the brain.
Hallucinations, says this remarkable physician, are common phenomena that arise in healthy individuals as well as in patients with a variety of conditions. But people rarely report such experiences, lest they be thought crazy.
Treated with L-dopa, Parkinson's patients may have multi-sensory hallucinations. The bereaved see dead spouses. Many people feel companions beside them, sensed rather than visible, and one pet lover was frequently "visited" by his deceased cat. Some see print transformed to musical notation. For some, pictures come alive with movement. One woman "sewed" with hallucinatory thread.
People with Alzheimer's and other dementias may experience delusions of misidentification or duplication. Some patients think their partners are "duplicates" that have replaced the originals, or believe their residences have been replaced by identical fakes.
Hallucinogenic drugs, including mescaline, LSD and cannabis, have certain typical effects. Colours are enhanced, and people may notice "striking alterations of apparent size." Other "enhancements or distortions of the senses," include "temporary synesthesia," in which one experiences, for example, the smell of a sound, or the sound of a colour.
While Oliver Sacks was a resident doctor following his calling to neurology, he passed through a stage of self-experimentation with various hallucination-producing drugs. Experiencing bizarre hallucinations, he coped by writing about them "in clear, almost clinical detail," in order to become "an observer, even an explorer," rather than "a helpless victim of the craziness inside." Indeed, he was inspired to become an expert and begin a book on migraine while in an amphetamine haze.
A lifelong migraine sufferer, he studied his own headaches and those of his patients, noting that migraines generate particular hallucinations, typically olfactory warnings and geometric visual patterns. Similar patterns, Sacks points out, are present in "Islamic art, in classical and medieval motifs, in Zapotec architecture, in the bark paintings of Aboriginal artists in Australia...in virtually every culture, going back tens of thousands of years."
Epilepsy brings different hallucinations. Those who suffer from the so-called sacred disease may hallucinate warnings at the onset of a seizure: perhaps a blue star approaching the left eye, or a whirling object that closes in until the patient loses consciousness. Novelists Amy Tan and Fyodor Dostoevsky both experienced epileptic hallucinations. Some epileptics have memorable "ecstatic seizures" that can "shake the foundations" of their belief.
Following a certain type of brain surgery, patients can experience complex hallucinations "of deformed and dismembered faces...with exaggerated, monstrous eyes or teeth" that are "typical of abnormal activity in an area of the temporal lobes." Psychotics experience similar hallucinations, but in post-surgical patients, Sacks emphasizes, these are "neurological faces, not psychotic ones."
It is common for patients who are blind due to cortical damage to deny this reality. People with Anton's syndrome hallucinate a world they insist they can see, and "walk boldly in unfamiliar places." Asked to describe a room, they do so with fluency and confidence, even though their claims are "entirely incorrect."
Hallucinations also visit during high fevers. This is especially common in children, and can involve "distortions in proprioception" that may, for instance, cause a prone patient to feel she is standing tall. Fever-produced hallucinations can also "provide, or seem to provide, moments of rich emotional truth...revelations, or breakthroughs of deep intellectual truth." Scientists, artists and writers have all reported such experiences. Delirium of fever can produce tactile or musical hallucinations as well.
Toxic psychosis appears during withdrawal from drugs or alcohol, a situation well-described in Evelyn Waugh's novel The Ordeal of Gilbert Penfold. While writing it, Waugh continued his drinking habit, and took heavy doses of sleeping drugs as well. Penfold "is not 'allowed' to see the speaker" of his auditory hallucinations, lest the delusion be shattered. Guy de Maupassant, who suffered from syphilis, began to see a double of himself; he wrote about this in "Le Horla."
Sacks describes such elaborate deliria and psychoses as "volcano-like eruptions from the 'lower' levels of the brain." Yet, he points out, they are also "shaped by the intellectual, emotional and imaginative powers of the individual" as well as "the culture in which he is embedded."
Normal people commonly experience hypnagogic hallucinations, either just before falling asleep or immediately on waking. However, these are seen with the mind's eye, rather than being projected into external space. Other hallucinations may accompany narcoleptic syndrome, a sleep disorder. One patient, diagnosed with this condition only in middle age, became convinced that her earlier apparent experiences of paranormal phenomena had actually been caused by the narcolepsy. Sacks suggests that "the folklore of every culture includes supernatural figures that behave in similar ways," adding that "such myths and beliefs are...narratives for a nocturnal experience which is common, real, and physiologically based."
Flashbacks are "profound and sometimes delusional states that can go with post-traumatic hallucinations." For example, a war veteran may suddenly "be convinced that people in a supermarket are enemy soldiers" and "open fire on them." It is fortunate that though potentially deadly, this "extreme state of consciousness is rare." It is interesting to note that "PTSD seems to have an even higher prevalence and greater severity following violence or disaster that is man-made," while "natural disasters...seem somehow easier to accept." It is also noteworthy that the people who suffer from PTSD and hallucinations are those who have locked away their horrible memories, rather than attempting to consciously remember, accept and integrate them.
Sometimes, groups of people experience mass hallucinations. This may explain events like the Salem witch trials and the witchcraft stories of the Middle Ages. Sacks feels that these kinds of events may possibly be explained by ergot poisoning, which may have induced the hallucinations suffered by an entire population.
A century ago, William James lectured on exceptional mental states. Discussing trances where mediums channeled voices of dead people, he discussed the mental states that produced them. An observer at many seances, he felt mediums were not charlatans, but people who entered altered states of consciousness that generated hallucinations. As Sacks says, "meditative or contemplative techniques...have been used in many religious traditions to induce hallucinatory visions."
In early developmental stages, many children hallucinate imaginary playmates and interact with them. This is both normal and common.
Electrical stimulation in the cortex, as well as severe blood loss, can induce out-of-body experiences. When he suffered a brief cardiac arrest after being struck by lightning, New York surgeon Tony Cicoria clearly remembers experiencing a departure from his body and his subsequent return.
Swedish botanist Carl Linnaeus experienced the doppelganger phenomenon, an autoscopic hallucination that made him feel his other self was strolling beside him in the garden, mimicking his movements. In an "even stranger and more complex form of hallucinating oneself," a person can interact with his double and even become confused about which is the original. The strength of this impression is illustrated by the following anecdotes. One patient, though at a logical level he knew the double was a hallucination, felt compelled to pull up a chair for him. Another enjoyed watching his double mow the lawn, reminding him of the duty he himself was avoiding.
The Other is also a literary archetype that taps into a certain vein of horror, as in the case of Edgar Allen Poe's "William Wilson," R.L.Stevenson's "Dr. Jekyll and Mr. Hyde," and Oscar Wilde's The Picture of Dorian Grey."
A phantom limb is a hallucination "more like a memory than an invention." Phantom limb pain can be experienced even by people born with missing limbs. This fact is well-illustrated by a child who learned to count on phantom fingers she'd never had. Phantom limbs can "enter" a prosthesis, or become grotesquely foreshortened, like a hand springing from the shoulder.
Until neuroscientist V.S. Ramachandran found a way to treat it, phantom limb pain was an intractable condition. Ramachandran tricks the brain with a simple box that uses the mirror image of the normal limb to make the missing limb seem visible. His remarkable experiments have helped patients use mirror boxes to influence phantom limbs. It is now evident that "the brain's representation of the body can be fooled simply by scrambling the inputs from different senses."
Common hallucinations that most people experience follow dental anesthesia. While the facial nerves remain frozen, we sense grotesque swelling, deformity or displacement of the cheek or tongue. While freezing lasts, this sensation persists, even as we see in the mirror that it isn't so.
Quadriplegics may have a particular challenge: a phantom body that is "unstable and prone to distortions and deformations." One patient reported her technique for reversing these by taking "visual sips" of her body's appearance while passing a mirror in her wheelchair.
Perhaps the most bizarre hallucination is the conviction that one's limb is not one's own. A man with a damaged right parietal lobe became so deeply estranged from his own leg that he refused to believe it belonged to him, and pushed it out of bed. Naturally, he fell out along with it. Yet in spite of the evidence, astonishingly, he continued to insist that the leg was not his own.
Humans, says Dr. Oliver Sacks, need to "transcend, transport, escape...meaning, understanding, and explanation." Whether or not it is literally true, some people have direct experiences of the presence of God or an overwhelming force for good. Their religious feelings, rather than being mere intellectual concepts, are realities that are apprehended directly, as William James has also said. Sacks adds that the the animal sense of "'the other,' which may have evolved for the detection of threat, does not have to be negative. On the contrary, it "can take on a lofty, even transcendent function, as a biological basis for religious passion and conviction."