Hallucinations - Oliver Sacks UPDATE - 10-Feb-13: There's an essay in the Feb. 21, 2013 issue of the NYRB by Sacks. The telling paragraph is this:

There is...no mechanism in the mind or the brain for ensuring the truth...of our recollections. We have no direct access to historical truth, and what we feel or assert to be true...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 being 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.


If there is one thing I’ve learned from my readings in the science of the mind, it’s that the brain is most definitely not a reliable organ of perception. If you don’t believe me, believe Oliver Sacks, who has some experience with brain science. In Hallucinations he explores the wide variety of delusional perceptions humans are prey to – and not alone humans who’ve suffered trauma or are in a situation where you might expect delusions (like sensory deprivation or drug use). Perfectly healthy people are susceptible as well, including myself.

At times, when I’m on the cusp of going to sleep and I’m reading in bed, I’ll hallucinate a page that doesn’t exist. I shake my head and come fully awake, and the illusory page will disappear but for that brief time, I will have been reading a perfectly legible and coherent story. Sometimes it will have some relationship to what I’m reading – characters will be the same; there will be some connection to the plot – but at other times, there will be none. I’ve also noticed that I’m prone to an olfactory hallucination most likely brought on by the fact that I currently live with six cats. Sometimes, I smell cat dootie (spelling?) when it doesn’t exist. It won’t happen when I’m in the room with the litter boxes so I know it’s not coming from there, but occasionally I’ll be sitting at the computer or come into a room and “smell” urine or kaka. When I search for its source, I can’t find it – no wet spots, no turds, and (once I’ve begun actively searching) no smell.

And there’s my friend, who suffers from migraines. When I asked her if she hallucinated before a headache, she described exactly what other migraine sufferers describe in Chapter 7, “Patterns: Visual Migraines.” She also described losing half of her visual field – i.e., if she were looking at me, half of me would disappear; an experience I can’t even begin to imagine.

The book is a collection of anecdotes. Sacks likes to tell stories but – in this book, at least – largely steers clear of asking “why,” which is why I’m giving this book two stars.

The stories are interesting, however.

One of my favorites is one he relates about Michael Shermer. For those who don’t know who Shermer is, he’s the founding publisher of Skeptic magazine, executive director of the Skeptic Society and a prolific author, including books on brain science. He’s also a marathon runner and triathlete. During one competition, he had reached a point of severe dehydration and utter exhaustion and hallucinated that he was abducted by aliens, losing 90 minutes of consciousness. It happened that the “aliens” were his support crew, who had forced him to stop running, take some fluids and rest.

I also better understand the guests who show up on Coast to Coast AM with George Nouri, which I listen to on the drive home from work most nights. Most of the guests who claim to have seen, smelt and/or talked to angels, aliens, demons, ghosts, Loch Ness monsters, sasquatch, Star Children, etc., did.

And the brain’s delusional propensity would also explain the astonishing and contradictory variety of religious revelations.

I’d recommend Hallucinations as an entertaining, if rather hollow, diversion, but if you’re more interested in the why’s and how’s of brain science, this is not the book for you.