Stuff our brain makes up

kw: book reviews, nonfiction, psychology, neuroscience, hallucination

To hallucinate is to be human…and, perhaps, to be any creature with a mind. As we read in Hallucinations by Oliver Sacks, a great many stresses and neurological disorders can lead to sensing (any of the "5 senses" may be involved) things that aren't there, but for many of us, so can a great many rather prosaic matters. For example, many people are like me: almost any time I can close my eyes and I will either see things—including persons—or hear voices that aren't there. Particularly when I am sleepy, these phantasms can be quite detailed: I'll either see entire scenes being enacted or hear entire conversations (though I can seldom understand the words), or music, and sometimes sight and sound go together. Also when I am sleepy or tired, I don't necessarily have to close my eyes to hallucinate. It is likely that these kinds of things happen at times for most of us. (I was once asked why I rarely listen to music. I replied that I have a sound track running almost all the time.)

Hallucinations could be considered both a travelogue and a catalog of hallucinatory perceptions. Dr. Sacks has migraine auras; he has experimented with sundry drugs; he has suffered griefs and stresses that led to several hallucinatory episodes. While many disease syndromes, from high fevers to Parkinsonism, lead to hallucinations, I was particularly interested in the more "normal" cases. It seems that the brain's pattern matching and recognition systems easily go into overdrive, as many of us experience when we look at clouds and see all kinds of fantasies. Static images get "over-recognized" rather easily. I have a painting of a seascape, with waves and rocks; one of the rocks one day looked just like a jaguar's head to me, and I can't see it any other way now. But we also experience things for which there is no apparent external trigger. Perhaps it is the lack of a trigger that triggers them, such as closing one's eyes.

By the way, the author mentions tinnitus, or "ringing in the ears" as a kind of hallucination caused by damage to the inner ear, and the brain hallucinates the sounds it is not receiving from the organ. This may be so in some cases, but certainly not all. I have low-level tinnitus, which gets louder if a pull my head back a certain distance. An audiologist used a tiny microphone in my ear to listen in, and said that pulling my head back changed the shape of the middle ear, which amplified the sound. The cause is the damaged hair cells vibrating in response to random noise (Brownian motion), not being damped as is normally the case. The inner ear may be a super-regenerative amplifier, which I'll discuss in a moment.

It may be that the only time most of us are free of hallucinations is when we are in a most ordinary state, not bored, not over-engaged, just "doing something" that fits well within our comfort zone, mentally and emotionally. I like the concept of the comfort zone, particularly in this context. Its boundary may be quite firm for some of us, and rather more nuanced for others. In my case, I think of the boundary as a wide zone of gradually increasing stress, and throughout most of this range any shift can release a mild hallucination of some sort. Thus the tendency to hallucinate in this "normal" way follows a sort of spectrum.

I think of a mechanical/electronic example. A kind of radio receiver, used in older CB radios, is "super-regenerative". It has three circuits in its detector portion. One is an extra-sensitive amplifier that will oscillate and almost blow itself out when any signal of the right frequency appears, including noise. It has extremely high positive feedback, but the key is that it "pops" faster the stronger the input signal. The second is a squelch circuit that allows the amplifier to "go crazy" for about 1/20,000th of a second, then very briefly cuts its power. The amount of squelch can be set by the operator. The third measures the maximum level achieved during each tiny time slice, and turns that series of measurements into an audio signal. So you can think of a hallucinating brain as a super-regenerative receiver with the squelch set too low.

A characteristic of most hallucinations is that you know it. A hallucination taken as real is a delusion. One question raised a few times in the book is whether the human tendency to religious faith is based entirely on hallucinations. Of course, to a total rationalist, all religion is delusional. But total rationalists are quite rare. According to Julian Jaynes (see The Origin of Consciousness in the Breakdown of the Bicameral Mind), half our brain informed the other half of its sensings and learnings via hallucinations that were thought to embody the voices or appearances of deities. Further evolution caused these two functions to become better integrated. Some say the tendency to generate divine apparitions and voices are a remainder of the bicameral mind, leading to every form of religious experience. I personally think that is an over-interpretation, and that there really is a God, but I'll forego theology in this review.

Hallucinations of all kinds are a class of experience that stands alongside dreams and imagination. They resemble dreams but can be much more detailed. Some dreams can be directed; this is called lucid dreaming. Hallucinations can't be directed, and usually play out as though the hallucinator is a spectator in someone else's theater. Imagination is nearly always directed but typically lacks the apparent veracity of a hallucination. We imagine something and may even speak of "seeing it in the mind's eye", but it doesn't appear to project into the world outside the way a hallucination does. Hallucination is also related to synesthesia, and perhaps this is its closest cousin. A synesthete might see colors attached to musical notes or printed numbers or letters; or to be able to taste the sound of certain words or songs.

But hallucination is more than mixed perception. It is perception without a perceived object, a result that is quite different from the stimulus that might produce it. For example, in a healthy person, grief can trigger the sight and/or sound of the lost loved one. This kind of hallucination is most directly related to a perceived object, or the memory of one. But the "sleepy-time" hallucinations I have aren't based on any proximal object, nor memory, except, I suppose, my general fund of memories about prior events. Thus, they might be waking dreams, though they differ from dreams during sleep, which are usually accompanied by a feeling of purpose. Hallucinations are typically purposeless.

I had a great time reading an earlier book by Oliver Sacks (reviewed in May). Hallucinations was a bit harder to read through. The writing is often more analytical, written at a higher level, and perhaps a bit more detailed at times than I had tolerance for. However, I don't want to commit the error of the king who told Mozart, "There are too many notes." Mozart rightly replied (so it is reported), "Majesty, which notes should have been left out?" This book can be read with profit by anyone, and will provide particular comfort to those who may be seeing or hearing "things", and fear they are crazy. No, you aren't crazy if you know your hallucination from what is really "out there". Or, if you are crazy, then so are we all.