There Are Four Lights

Oh how I luvs the Bad Astronomer. I believe I first came across Dr. Phil Plait’s astronomy blog when I was searching the interwebs to check up on a claim by some astrology proponents. It actually wasn’t that long ago when I got my first taste of new agers trying to make astrology sound sciency. I was pretty amazed at how easy it is to disprove all the pseudoscience claims. Thus, began my journey into the world of scepticism.

Though I’m just a hobbyist astronomer, I can turn into a bit of an astronomonster when the subject of astrology is brought up. There is just so much that is wrong about astrology. The first major hint that there might be something wrong with this kind of model is that it was invented by humans who thought the universe was geocentric. That’s basically all it takes to shatter astrology: discovering that our solar system revolves around the sun. But new agers don’t trouble themselves with silly things like laws of physics. Too bad, because Dr. Phil does such a nice job of explaining!

If you do manage to convince them that astrology can’t possibly work (I’ve never been successful), the last argument is that their experience in using astrology works for them. Ah, mon amie, it’s confirmation bias and the Forer effect that create the illusion that astrology works. “The Forer effect refers to the tendency of people to rate sets of statements as highly accurate for them personally even though the statements could apply to many people.” The personality models of astrology are all highly generalized so that each zodiac has pretty much the same chance of describing anyone, regardless of when they were born. It’s simple; the personality models of the zodiac are highly generalized and the personalities of people are highly complex. Of course you’re going to get a match.

It’s really simple to test astrology to see if it actually works in describing people’s personalities based on the month they were born. You simply take the traits each zodiac proposes, but then blind what zodiac (aka, birth month) the set of traits is from, and have people rate how accurately it describes them. If people end up highly rating or being matched with the ‘correct’ zodiac at a rate no better than chance, then it’s clear the model doesn’t work as it claims. This is exactly what happens each and every time astrology is tested.

Confirmation bias is the trick behind making most forms of divination, including astrology, ‘work’. Basically, it’s when we count the hits and not the misses. We do this often because we’re pattern seeking creatures. The example I use most often to describe confirmation bias is the myth that more accidents/births/craziness happens during a full moon. This is statistically untrue; when you compare lunar cycles to rates of crime/accidents/births etc. there are no relationships. But then why do so many reputable sources, like nurses and police officers, swear that this myth is true? It’s because they are just going by the memory of their own experience; they’re only recalling the times where a full moon matched up with a crazy night, and made no mental note of those crazy nights where there was a quarter moon or crescent. This happens in astrology too; we remember the times when the model did work, and don’t make a connection when it doesn’t. We may ignore the times when we met someone who didn’t match up very well with their zodiac, or just focus on the traits of their zodiac that do match with them.