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Posts Tagged ‘Oliver Sacks’

09 JULY, 2014

Visionary Neurologist Oliver Sacks on What Hallucinations Reveal about How the Mind Works


“We see with the eyes, but we see with the brain as well.”

While our delusions may keep us sane, hallucinations — defined as perceptions that arise independently of external reality, as when we see, hear, or sense things that aren’t really there — are an entirely different beast, a cognitive phenomenon that mimics mysticism and has no doubt inspired mystical tales over the millennia. In the 18th century, Swiss lawyer-turned-naturalist Charles Bonnet, the first scientist to use the term evolution in a biological context, turned to philosophy after deteriorating vision rendered him unable to perform the necessary observations of science. Blindness eventually gave him a special form of complex visual hallucinations, known today as Charles Bonnet syndrome, but he was otherwise fully lucid and marveled, as a cognitive scientist might, at “how the theater of the mind could be generated by the machinery of the brain.”

Some 250 years later, pioneering neurologist Oliver Sacks (b. July 9, 1933) — who has previously explored the necessary forgettings of creativity and how music impacts the mind — picked up Bonnet’s inquiry in his immeasurably fascinating book Hallucinations (public library). In this TED talk based on the book, Sacks draws on his extensive clinical experience of working with patients, illuminating that astounding “theater of the mind” to shed light on what hallucinations reveal about how the mind works.

We see with the eyes, but we see with the brain as well. And seeing with the brain is often called imagination. And we are familiar with the landscapes of our own imagination, our inscapes. We’ve lived with them all our lives. But there are also hallucinations as well, and hallucinations are completely different. They don’t seem to be of our creation. They don’t seem to be under our control. They seem to come from the outside, and to mimic perception.

In the book, Sacks offers a detailed definition of hallucinations, contrasting them with regular perception and peering into their promise for better understanding the brain and the human mind:

When the word “hallucination” first came into use, in the early sixteenth century, it denoted only “a wandering mind.” It was not until the 1830s that Jean-Étienne Esquirol, a French psychiatrist, gave the term its present meaning — prior to that, what we now call hallucinations were referred to simply as “apparitions.” Precise definitions of the word “hallucination” still vary considerably, considerably, chiefly because it is not always easy to discern where the boundary lies between hallucination, misperception, and illusion. But generally, hallucinations are defined as percepts arising in the absence of any external reality— seeing things or hearing things that are not there.

Perceptions are, to some extent, shareable — you and I can agree that there is a tree; but if I say, “I see a tree there,” and you see nothing of the sort, you will regard my “tree” as a hallucination, something concocted by my brain or mind, and imperceptible to you or anyone else. To the hallucinator, though, hallucinations seem very real; they can mimic perception in every respect, starting with the way they are projected into the external world.


When you conjure up ordinary images— of a rectangle, or a friend’s face, or the Eiffel Tower —the images stay in your head. They are not projected into external space like a hallucination, and they lack the detailed quality of a percept or a hallucination. You actively create such voluntary images and can revise them as you please. In contrast, you are passive and helpless in the face of hallucinations: they happen to you, autonomously — they appear and disappear when they please, not when you please.


Hallucinations are “positive” phenomena, as opposed to the negative symptoms, the deficits or losses caused by accident or disease, which neurology is classically based on. The phenomenology of hallucinations often points to the brain structures and mechanisms involved and can therefore, potentially, provide more direct insight into the workings of the brain.

Hallucinations, which goes on to explore how advances in neuroimagining in the last few decades have greatly enhanced our understanding of hallucinations and the brain, is a mind-bending read in its entirety. Complement it with Sacks on the psychology of plagiarism.

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04 FEBRUARY, 2013

Neurologist Oliver Sacks on Memory, Plagiarism, and the Necessary Forgettings of Creativity


“Memory is dialogic and arises not only from direct experience but from the intercourse of many minds.”

“Memory is never a precise duplicate of the original… it is a continuing act of creation,” researcher Rosalind Cartwright reminded us in her fascinating treatise on the science of dreams. “The biggest lie of human memory is that it feels true,” Jonah Lehrer wrote shortly before being engulfed a maelstrom of escalating accusations of autoplagiarism and outright fabulation. Yet while we already know that memory is not a recording device, the exact extent of its fallibility eludes — often, quite conveniently — most of us.

In his recent New York Review of Books essay, legendary neurologist Oliver Sacks tackles precisely that, exposing the remarkable mechanisms by which we fabricate our memories, involuntarily blurring the line between the experienced and the assimilated:

It is startling to realize that some of our most cherished memories may never have happened — or may have happened to someone else. I suspect that many of my enthusiasms and impulses, which seem entirely my own, have arisen from others’ suggestions, which have powerfully influenced me, consciously or unconsciously, and then been forgotten.

One phenomenon Sacks argues is particularly common — if not adaptive — in the creative mind is that of autoplagiarism:

Sometimes these forgettings extend to autoplagiarism, where I find myself reproducing entire phrases or sentences as if new, and this may be compounded, sometimes, by a genuine forgetfulness. Looking back through my old notebooks, I find that many of the thoughts sketched in them are forgotten for years, and then revived and reworked as new. I suspect that such forgettings occur for everyone, and they may be especially common in those who write or paint or compose, for creativity may require such forgettings, in order that one’s memories and ideas can be born again and seen in new contexts and perspectives.

Citing a number of case studies where false memories of fictitious events were “implanted” in people’s minds, Sacks explores unconscious plagiarism, something Henry Miller poetically probed and Mark Twain eloquently, if unscientifically, addressed in his famous letter to Helen Keller. Sacks writes:

What is clear in all these cases — whether of imagined or real abuse in childhood, of genuine or experimentally implanted memories, of misled witnesses and brainwashed prisoners, of unconscious plagiarism, and of the false memories we probably all have based on misattribution or source confusion — is that, in the absence of outside confirmation, there is no easy way of distinguishing a genuine memory or inspiration, felt as such, from those that have been borrowed or suggested, between what the psychoanalyst Donald Spence calls ‘historical truth’ and ‘narrative truth.’


There is, it seems, no mechanism in the mind or the brain for ensuring the truth, or at least the veridical character, of our recollections. We have no direct access to historical truth, and what we feel or assert to be true (as Helen Keller was in a very good position to note) depends as much on our imagination as our senses. There is no way by which the events of the world can be directly transmitted or recorded in our brains; they are experienced and constructed in a highly subjective way, which is different in every individual to begin with, and differently reinterpreted or reexperienced whenever they are recollected. . . . Frequently, our only truth is narrative truth, the stories we tell each other, and ourselves—the stories we continually recategorize and refine. Such subjectivity is built into the very nature of memory, and follows from its basis and mechanisms in the human brain. The wonder is that aberrations of a gross sort are relatively rare, and that, for the most part, our memories are relatively solid and reliable.

Sacks concludes:

We, as human beings, are landed with memory systems that have fallibilities, frailties, and imperfections — but also great flexibility and creativity. Confusion over sources or indifference to them can be a paradoxical strength: if we could tag the sources of all our knowledge, we would be overwhelmed with often irrelevant information.

Indifference to source allows us to assimilate what we read, what we are told, what others say and think and write and paint, as intensely and richly as if they were primary experiences. It allows us to see and hear with other eyes and ears, to enter into other minds, to assimilate the art and science and religion of the whole culture, to enter into and contribute to the common mind, the general commonwealth of knowledge. This sort of sharing and participation, this communion, would not be possible if all our knowledge, our memories, were tagged and identified, seen as private, exclusively ours. Memory is dialogic and arises not only from direct experience but from the intercourse of many minds.

In a rare act of defiant reliability, my own memory brought to mind a footnoted passage in Sacks’s mind-bendingly excellent recent book, Hallucinations, where he explores memory further:

We now know that memories are not fixed or frozen, like Proust’s jars of preserves in a larder, but are transformed, disassembled, reassembled, and recategorized with every act of recollection.

In a footnote, he adds:

For [researchers] in the early twentieth century, memories were imprints in the brain (as for Socrates they were analogous to impressions made in soft wax) — imprints that could be activated by the act of recollection. It was not until the crucial studies of Frederic Bartlett at Cambridge in the 1920s and 1930s that the classical view could be disputed. Whereas Ebbinghaus and other early investigators had studied rote memory — how many digits could be remembered, for instance — Bartlett presented his subjects with pictures or stories and accounts of what they had seen or heard were somewhat different (and sometimes quite transformed) on each re-remembering. These experiments convinced Bartlett to think in terms not of a static thing called ‘memory,’ but rather a dynamic process of ‘remembering.’ He wrote:

Remembering is not the re-excitation of innumerable fixed, lifeless and fragmentary traces. It is an imaginative reconstruction, or construction, built out of the relation of our attitude towards a whole active mass of organized past reactions or experience. . . . It is thus hardly ever really exact.

Could it be, then, that the very fallibility of memory is essential to our combinatorial creativity and to the mechanics of the slot machine of ideation? To steal like an artist might be, after all, the default setting of the brain.

Oliver Sacks portrait by John Midgley via Wired

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