The fracas over the Beatles purported backward messages — or backmasking, as it's called — led to the "discovery" of many more messages in songs, including those of Led Zeppelin, Styx, and Queen. In the 1980s, some politicians practically tripped over themselves to find examples of secret satanic messages in pop songs. For an example, listen to Queen's "Another One Bites The Dust" played backward in this video. If you're not familiar with what the message is supposed to be, you probably won't hear anything unusual.

Now, scroll to the bottom of this article, read the message Queen fans think you should be hearing, then scroll back up and listen again. What do you hear? (You'll never unhear it again. You're welcome.)

What's going on? There's nothing actually encoded in the reversed audio. Your brain just processes speech in a wholly unique way — "top-down," as a 2006 study on the subject calls it. You don't just hear speech as sound; your brain first categorizes it as something special (This is speech! There's information here!), then uses context clues and known information to decipher what that speech is saying.

When you found out what the backward Queen lyrics were supposed to be saying, it "primed" your brain to hear the unintelligible noise as speech, and to call on new information about what the speech was saying. The next time around, it used all of that information to interpret the noises in a brand new way. As a result, you actually heard a message.

A 1981 study published in the journal Science is a perfect example of the speech-primed brain at work. Try it yourself by listening to the sound clips below (before we spoil it all by letting your brain in on the secret). What do you hear?

The clips above are examples of "sine wave speech." It's real speech, artificially degraded so that any evidence of a message is lost and only certain frequencies remain. In the 1981 study, one group of volunteers were first asked to listen to sound clips like those and describe what they heard (like you did just now). Most people said things like "science fiction sounds," or "animal cries." Another group of volunteers were informed that they would hear "a sentence produced by a computer," and asked to write the sentence down as well as they could. Two-thirds of listeners were able to write down at least a few words correctly, and about a third correctly transcribed the entire sentence. A final group was told what the sentence was, and just asked to say whether or not they could hear and understand it. Almost all of the listeners were "very confident" they could.

This shows how robustly your brain is wired for language. Over millions of years of evolution, the human brain developed in a way that valued the sound of speech over all other noises — even things that could kill it, like a lion's roar or the rumble of a landslide. Technology has only made communication faster and easier, but for our brains, nothing compares to the spoken word.

(The message in Queen's "Another One Bites The Dust" is "It's fun to smoke marijuana.")

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For a deeper look at the weirdness of the human brain, check out "Quirkology: How We Discover the Big Truths in Small Things" by psychology researcher Richard Wiseman. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.