In 1864, a peculiar book called "Spectropia" offered Victorian readers a scientific way to summon ghosts. As the Smithsonian reports, author J.H. Brown created this "toy book" to combat what he called "the absurd follies of Spiritualism" during an era when séances and spirit mediums were gaining popularity.
Neuroscientist Tedi Asher explained how the book worked: "if a person stared at one of the book's images under a strong light source for about 20 seconds and then gazed at a blank wall in a darkened room, a version of that image in inverted colors appeared."
While Brown intended the book as a serious weapon against supernatural beliefs, publishers marketed it as entertainment. "Ghosts everywhere," promised one ad, offering "ghosts of all sizes, all styles, all colors, at 60-second notice" for just $1 (about $20 today).
Did it succeed in dispelling ghost beliefs? Not exactly. England's Birmingham Gazette noted at the time, "When one delusion is laid bare, a large section of the public will rather resent than approve any attempt to undeceive them." Sound familiar?
Try it yourself:
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