Before Christmas I had the pleasure of reading Oliver Sacks’s new book Hallucinations.
Like his other books, this is extremely readable with vivid accounts of his patients’ symptoms leading to a tentative neurological explanation of their often bizarre experiences. In this case I was pleased to find that I had myself experienced a common form of visual hallucination. A few years ago I fell (in trying to catch a frisbee sailing away from my hand) and banged the back of my head. Shortly afterwards half my visual field was filled with wobbly black and white hexagons. I realized I could not drive home with these patterns blocking out half the motorway. By the next day they had gone but in the weeks following I occasionally had the illusion of a large red hexagon taking over my visual field. Continue reading