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Why is it that when I rub my eyes I see psychedelic op-art patterns? Could it be the result of too many grueling hours in art-history classes? --Jackie Russow, Chicago

We must have been in the same class, kid, because I see the patterns too. So does everybody. For best results press firmly on both eyes with the heels of your palms. After several seconds your field of vision will be filled with a kaleidoscopic array of geometric patterns. If you'd made a poster out of it in the 60s you'd have made millions.

You'd probably guess the patterns vary with the individual, but they don't. In 1942 University of Chicago researcher Heinrich Kluver pointed out there are just four basic patterns: (1) grating, lattice, fretwork, filigree, honeycomb, or chessboard; (2) cobweb; (3) tunnel, funnel, alley, cone, or vessel; and (4) spiral. Heinrich noticed the patterns while hallucinating on mescaline--you know what party animals those U. of C. guys are--but they can be triggered by everything from migraine to hand pressure to petit mal epilepsy.

Where do the patterns come from? It was once thought they had something to do with the nerves or blood vessels of the retina, but many researchers today think it all happens in the visual cortex, the brain's visual processing center. U. of C. neurobiologist Jack Cowan has crammed a scholarly paper with more equations than Cecil feels is decent to show that . . . well, frankly I'm not sure what it shows, except maybe that somebody has gotten into Heinrich Kluver's leftover mescaline supply. But the gist of it is that random nerve firing, such as that caused by hand pressure, will produce "stripes" in the cortex that may be perceived as spirals.

British psychologist Susan Blackmore has proposed that since there are more cortical nerve cells representing the center of the visual field than the edges, random firing will produce a "floating toward a light at the end of the tunnel" effect. This is commonly seen in near-death experiences, a topic we have discussed in the past. Checkerboards and honeycombs they're still working on; we can't rule out the possibility that it all comes from staring at the back of too many Rice Chex boxes on too many bleary mornings. But more likely it reflects some physiological characteristic of the brain.

I have heard many times that smoking commercially available filtered clove cigarettes is "ten times worse for your lungs than normal cigarettes." I suspect this is just an urban legend, but if it is true maybe I should quit smoking cloves. Are cloves worse than other cigarettes? --Summers Henderson

The "ten times worse" figure is probably an exaggeration, but this is no urban legend. At least two teenagers died after smoking clove cigarettes during the clove craze of the early 1980s. Five others were hospitalized and 250 others reported breathing difficulties, including coughing up blood.

Called "kreteks," clove cigarettes are imported from Indonesia and were first brought to California by Australian surfers. Typically they're a 40-60 mix of shredded clove buds and tobacco. Sales rose from 15 million in 1980 to 150 million in 1984 but then plummeted following reports about health problems, including a warning from the American Lung Association. Clove-cigarette importers claimed that the media were whipping up antikretek hysteria, pointing out that 80 billion had been sold worldwide in 1984 and that Indonesians had been smoking them for a century without massive loss of life (at least due to smoking kreteks).

But we're not talking candy cigarettes here. Kreteks produce more tar, nicotine, and carbon monoxide than ordinary cigarettes. Little research has been done on eugenol, the active ingredient in clove cigarettes, but there is reason to believe it promotes lung infections or allergic reactions in vulnerable individuals. One of the two clove fatalities involved somebody with a cold; the other victim had a history of severe allergies. Part of the original appeal of clove cigarettes was that they were healthier than the all-tobacco variety; clearly that's not the case.

Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.

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