On April 27, 1982, members of the California Assembly’s Consumer Protection and Toxics Committee gathered in Sacramento to hear Robert Plant endorse Satan. This was not a straightforward testimonial. For one thing, the Led Zeppelin frontman wasn’t actually in attendance. Also, his pro-devil paeans could only be heard when you played “Stairway to Heaven” backwards.

After circulating pamphlets with the “backward masked” declarations spelled out, that’s precisely what Assemblyman Phillip Wyman and panel witness William H. Yarroll II did. The relevant portion of the eight-minute classic was first played forward for committee members and then reversed. Here’s what Wyman claimed could be heard: “I sing because I live with Satan. The Lord turns me off. There’s no escaping it. Here’s to my sweet Satan.” Yarroll, who identified himself as a “neuroscientist,” noted that a teenager need only listen to “Stairway to Heaven” three times before these backward messages were “stored as truth.”

It wasn’t just Plant reverse-singing Satan’s praises, either. According to Yarroll, bands ranging from Styx to the Beatles also had secret backmasked messages hidden in their music—messages that, in the words of legislative proposal A.B. 3741, had the power to “manipulate our behavior without our knowledge or consent and turn us into disciples of the Antichrist.”

As the bill’s sponsor, Wyman wanted mandatory warning labels on all rock albums containing these morally dubious backward messages. “Suppose young people have heard ‘Stairway to Heaven’ two or three hundred times and there has been implanted in their subconscious mind pro satanic messages or incantations?” he told Terry Drinkwater the following day on a CBS Evening News segment. Indeed, this was the truly insidious part of backmasking. Even though you had to play records in reverse to decipher the occultic messages, they could still subliminally imprint themselves upon young teen minds when played in the standard direction.

During the same news segment, Yarroll described how the brain unscrambles a backward masked message: “We have it stored in the unconscious as a truth image,” he said, “and as the creative unconscious side of the brain does, it goes through scanning the unconscious brain to go about and bring those truth images to the surface and make them reality for us.”

After calling the issue “exciting and interesting,” committee chairman Sally Tanner (D-El Monte) delayed an official vote until the music industry and band members could weigh in on the matter. That day never came. But the national panic surrounding subliminal satanic messages in rock music was about to reach fever pitch.

In the early ’70s, backmasking—or the practice of recording vocals and instruments backwards and then reinserting them into the forward mix of a song—was something a music savvy (and possibly stoned) Beatles fan might bring up. A decade later, it had become a cause célèbre for conservative religious leaders, school teachers, parents, and even politicians. Whether it was the reversed voice of Freddie Mercury declaring “it’s fun to smoke marijuana” on “Another One Bites the Dust” or Styx imploring Satan to “move through our voices” on “Snowblind,” there seemed to be mounting evidence that rock music was literally becoming a mouthpiece for the devil.

Believers held record-smashing parties, appeared on popular TV talk shows, wrote books, formed watchdog groups, and, perhaps most importantly, called their government representatives to warn them.

By 1982, state and federal legislation was being introduced at a steady clip to combat rock and roll’s hidden satanic agenda. Two weeks after the California Assembly hearing in Sacramento, California congressman Robert Dornan introduced H.R. 6363 to the House. Also known as the “Phonograph Record Backward Masking Labeling Act,” the bill aimed to do the same thing as Wyman’s A.B. 3741, only on a national level.

Some of the books that would “expose the sinister nature of rock and roll music”. Courtesy Amazon

While it would ultimately be shuffled off to the Subcommittee on Commerce, Transportation and Tourism to die, other bills—including one in Arkansas a year later—were passed unanimously by both house and senate members (then-Governor Bill Clinton ultimately vetoed that one).

For its own part, the music industry responded with a bemused skepticism. Styx’s James Young called the whole idea of satanic backmasking a hoax perpetrated by religious zealots, and refused to attend any meeting or hearing where the topic was discussed. Then there was Bob Garcia of A&M Records, who declared, “it must be the devil putting these messages on the records because no one here knows how to do it.” A spokesman for Led Zeppelin’s record label, Swan Song Records, issued just one statement in response to the “Stairway to Heaven” satanic allegations: “Our turntables only rotate in one direction.”

Taken as a whole, these reactions only stoked the righteous (and possibly entrepreneurial) fires of religious leaders like pastor Gary Greenwald, who started holding backmasking seminars all over the country. Soon, books like Backward Masking Unmasked, Dancing With Demons, and The Devil’s Disciples: The Truth About Rock, were exposing “the sinister nature of rock and roll music,” while watchdog organizations like Parents Against Subliminal Seduction (P.A.S.S.) tried to block rock concerts at various venues.

The problem, as you may have already guessed, was that the whole thing was a bunch of diabolical tihsllub.

Let’s pause here to do something most satanic backmasking proponents never did during the controversy: distinguish between real engineered backmasking and the majority of messages people thought they were hearing during the ’70s and ’80s. The former is a technique that dates back to the advent of recorded music. The latter is the result of what psychologists call pareidolia (more on that in a bit), and is simply the brain’s attempt to make sense of the gibberish that results from phonetic reversals.

“Recording things backwards really began when the field of sound recording began,” says Alex Case, president of the Audio Engineering Society. After Thomas Edison’s invention of the phonograph in 1877, there was rampant experimentation both with recorded speech and music. “It’s clear that part of the sales pitch when they were selling wax cylinder recorders would be to record someone speaking and then play it backwards for them,” says Case. Fittingly, the phrase “mad dog” (“goddamn” in reverse) seems to have been a crowd favorite.

Real backmasking—intentional backwards music or speech in musical compositions—began to come into vogue during the 1940s with experimental composers like Pierre Schaeffer. Playing records (and later, tapes) backwards was, according to Case, a way for musicians and composers to fool around with timbre and produce new and distinct sounds.

By most accounts, that’s precisely what attracted the Beatles to the practice. The band famously used backward instrumentation, including a backward guitar solo, on their 1966 album Revolver. “Rain,” the B-side of “Paperback Writer,” has what is believed to be the first backward masked message in a pop song. Its coda is a backwards version of the song’s first line: “When the rain comes, they run and hide their heads.”

Yet while the Beatles may have popularized the practice, the satanic backmasking scare of the 1980s required more than just the willful misrepresentation of a decades-old musical trend. It also needed some good old fashioned pseudoscience.

A drive-in movie theater in Fort Lee, New Jersey just happened to provide a perfect junk science laboratory. Over the course of six weeks in 1957, unsuspecting filmgoers were the subjects of a grand marketing experiment. Using a special high-speed projector, researcher and social psychologist James Vicary inserted the words “drink Coke” and “eat popcorn” into movies that summer. Invisible to the human eye, each message lasted for 1/3,000th of a second and was repeated in five-second intervals during films on alternating nights.

By the end of the six weeks, Vicary claimed 45,699 people had been subjected to his subliminal inducements. He also claimed that popcorn and Coke sales went up 57.5 and 18.1 percent, respectively. At a press conference held later that same year, Vicary described the results of this now infamous study to help boost interest in his new “Subliminal Projection Company,” an attempt to commercialize what he called a major breakthrough in subliminal advertising. The public and press went bonkers, and not in a good way.

The first sentence of an influential op-ed responding to the press conference by journalist Norman Cousins read: “Welcome to 1984.” He, like many others, wondered what such a technology could mean not just for advertisers who wanted to sell us stuff, but also for governments seeking to steer public sentiment.

For its own part, the FCC almost immediately threatened to suspend the broadcast license of any company that dared use Vicary’s machine. In the years following the experiment, the CIA started looking into the “operational potential of subliminal perception” (they found it “exceedingly limited”), and authors like Wilson Bryan Key began cranking out books such as Subliminal Seduction, which claimed that sexual images (and the actual word “sex”) were being hidden in hundreds of ads.

But when the Canadian Broadcasting Corporation tried to replicate Vicary’s claims by subliminally flashing the message “Call now” during a popular Sunday night program, there was no increase in phone calls. The station later told viewers they had inserted a message and asked them to guess what it might have been. Almost half of the roughly 500 viewers claimed to have been made hungry or thirsty during the show, which aired during dinner time.

James Vicary sought to prove that “subliminal advertising” was effective, by flashing the words “drink Coke” during a film. Steve Snodgrass/CC BY 2.0

Vicary’s study was clearly on the public’s mind, which was problematic because it was completely made up. From the beginning, Vicary refused to release key details about his study. Not only was there never any independent evidence to support his claims about the effectiveness of subliminal advertising, years later, Vicary admitted he had done only enough research to file a patent for his machine, and actually had collected barely any data. Even worse, his machine didn’t seem to work half the time once people did try to test it.

Of course, none of that mattered by the late ’70s and early ’80s. Subliminal messaging was being used in self-help tapes, in department store Muzak to ward off shoplifters, and, if you believed Key, to sell the American public lots and lots of booze and cigarettes.

Fast-forward 25 years, when two psychologists from the University of Lethbridge in Alberta, Canada decided to figure out why so many of their neighbors to the south were hearing devilish incantations in their rock music. After being contacted by a skeptical local radio DJ who had attended one of pastor Gary Greenwald’s backmasking talks, John Vokey and his colleague Don Read agreed to come up with a series of experiments that would directly address the idea of subliminal satanic messages.

The psychologists decided to start their study by recording a few simple passages from Lewis Carroll’s Jabberwocky and the 23rd Psalm. They wanted to find out whether the content of backward messages had any measureable influence on a listener, consciously or otherwise. They also wanted to see if the alleged backward messages people were hearing in rock music were perhaps more about active construction on the listener’s part and less about a devious satanic plan to corrupt young people.

After each passage was recorded forward in a few languages, Vokey and Read re-recorded them backward and played them for 65 test subjects. They found that the participants could discern things like the sex of the speaker with 98.9 percent accuracy when the passages were played backwards. Subjects also displayed a better-than-chance ability to detect the language of the backwards messages.

But when it came to deriving any kind of meaning from the passages, things didn’t go as well. Another series of tests asked subjects to categorize the content of the backwards messages as a nursery rhyme, Christian, satanic, or pornographic. The results were no greater than chance, and the meaning of the backwards messages didn’t appear to have been understood at any level, says Vokey.

In a final experiment, the two psychologists listened to the backwards passages themselves and came up with some real sounding phrases hidden within them. They found the following: “Saw a girl with a weasel in her mouth,” “snatched her nips,” and, to their delight, “I saw Satan.” Listen below:

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“It wasn’t as easy as it sounds,” says Vokey. “We had to drink a lot of beer to create those messages.” The two psychologists also invented control messages that didn’t fit the phonological patterns of the samples. Just as Vokey predicted, when subjects were instructed to listen for the phrases, they were unable to hear the control messages but were successful in detecting the phonologically plausible ones at a rate of 84.6 percent. Mind you, this was only after the phrases had been provided to them.

As Vokey and Read noted in their now famous article about the study, “Subliminal Messages: Between the Devil and the Media,” this suggested you really could induce people to hear messages that weren’t there so long as they were plausible-sounding interpretations.

How was this relevant to the satanic backmasking scare? Well, for one critical reason: Believers were almost always providing the alleged backward masked phrases before having others listen to them. It’s what happened at the 1982 California Assembly hearing, and it was the MO for religious leaders like Greenwald.

In what has become a staple of modern Intro to Psych perception lectures, professors will often play these backmasked songs or similar garbled and distorted messages. When students aren’t given any guidance, almost all of them struggle to make sense of the gibberish. Once supplied with a phonetically plausible phrase, however, suddenly they can’t hear anything but that phrase.

This is what psychologists call pareidolia. For the same reason some of us see faces on Mars and Jesus in toast, we also can be led to hear things that aren’t there. Our brains are exceptional pattern recognition machines, particularly when comes to sound and vision. Often, all it takes is a little priming to get things rolling.

As many have noted, one of the many delicious ironies of the ’80s backmasking panic is that it actually helped rekindle the practice in popular music. As rock bands began to regularly get accused of hiding secret satanic messages in their records, they figured: why not start putting real messages in them? Many of these were sarcastic rebuttals to the backmasking controversy itself.

On ELO’s fifth studio album, Face the Music, you can find this tongue-in-cheek message at the start of the song “Fire on High”: “The music is reversible, but time is not. Turn back, turn back, turn back.”

Pink Floyd had some fun on The Wall’s “Empty Spaces,” as well. When played backwards, you can hear Roger Waters say: “Congratulations. You have just discovered the secret message. Please send your answer to old pink, care of the funny farm.”

Although the moral panic started to subside by the end of the ’80s (less because of the scientific discrediting of subliminal messages and more because records and cassettes gave way to CDs), musicians continued to play around with backward masking throughout the ‘90s and early aughts. Today, perhaps because most of us stream the music we listen to, hiding backwards messages in songs seems both quaint and pointless.

Yet while Satan abandoned his plans to corrupt America’s youth through rock and roll, a devil-may-care attitude towards science is keeping the belief in subliminal messages alive and well. Earlier this fall, author and journalist Ahmet Altan and his brother were arrested in Turkey. The charge? Sending out “subliminal messages suggestive of a coup attempt” during a TV appearance. Both men will stand trial “for trying to overthrow the government or prevent it from carrying out its duties.”

Backwards music may have fallen out of fashion, but backwards thinking is alive and well.