What exactly is a hallucination? How does it differ from imagination or a lucid dream? What can we learn about the brains functionality during a hallucinatory experience?
These were just some of the questions renown biologist/neurologist, Oliver Sacks (1933), and award-winning journalist, John Hockenberry (1956), attempted to answer last Friday night at NYC’s Great Hall at The Cooper Union. The discussion, presented by the World Science Festival, was centered around Oliver Sacks’ new book, released on November 6th, aptly titled Hallucinations.
Let’s begin by defining a hallucination. According to the dictionary, it’s “an experience involving the apparent perception of something not present”. Oliver Sacks would add that it’s an experience that is often startling to the person experiencing it because of how absolutely real hallucinations seem to appear, and because no one else around seems to “agree with them”.
For example, when Hockenberry was a young man hitchhiking on the Pennsylvania Turnpike, he was involved in a terrible accident that left him paralyzed from the mid-chest down. When he described the accident in full detail, he mentioned a remarkable hallucination that he personally experienced – that he was convinced to be absolutely real – only it wasn’t. The hallunation occurred when he woke up from the accident, while he was being helped. Whether it was because of the accident or not, he didn’t say but it’s very likely, he simply remembers watching everything take place without realizing it was happening to him. He has been paralyzed ever since.
According to Sacks, there are numerous types of hallucinations that can occur, and they may affect any sensory modality; visual, auditory, olfactory, gustatory, tactile, or other. The affected person tends to have a heightened level of brain activity as different hallucinations engage different parts of the brain. By monitoring a person’s brain activity, neurologists can guess what types of hallucinations are likely being experienced.
There are those who see vivid faces, landscapes or animals. There are also people who see shapes or patterns instead – Sacks being one of them. He points out that, while there are some patterns among what people could see, what they tend to see is affected by their individual backgrounds. For example, seeing miniature people is one type of hallucination, but depending on the person’s cultural background, the miniature people may be leprechauns, dwarfs or fairies.
It turns out that many elderly people experience hallucinations. While some of these false percepts are extremely frightening, others are surprisingly comforting. For instance, when someone experiences the loss of a spouse, a hallucination of that person may be a coping mechanism.
Sacks’ own forays into the various worlds of perception were predominantly the results of his hallucinatory launch pad, or as Hockenberry put it “controlled substances”. By inducing his hallucinatory experiences, Sacks was inspired to clinically test his ideas and explore altered states of perception – something he insists he hasn’t really done since the 1960’s.
Yet, these distant adventures into Alice’s world sparked many of the ideas Sacks pursued throughout his life and career. He has contributed much to a rich cultural history and contemporary science of the hallucinatory experience. Check out Hallucinations, if not for the science, at the very least for his impressively approachable writing, especially about the color Indigo, trust us, it’s a good.
Oliver Wolf Sacks, CBE (born 9 July 1933), is a British biologist, neurologist, writer, and amateur chemist who has spent the major portion of his career in the United States.