At 6 o’clock on Christmas Eve, 1954, a small group of people gathered on the street outside Dorothy Martin’s home in Oak Park, Illinois, singing Christmas carols and waiting. But this was no symbolic vigil; they weren’t waiting for the birth of baby Jesus. They were waiting to depart the Earth, and 200 more people had come to watch them wait.

A day earlier, Martin had received a message telling her the group was to wait at that place, at that time, for a flying saucer to land. They waited for 20 minutes for the “spacemen” to pick them up, as the message had promised. When none arrived, they went back inside.

This wasn’t the first time they were disappointed. It was the fourth.

It all started with a prophecy that a massive flood was coming on December 21, 1954. The message was just one of many that Martin, who was involved in Scientology and interested in flying saucers, claimed to receive from beings she called the Guardians.

“I felt a kind of tingling or numbness in my arm, and my whole arm felt warm right up to the shoulder,” she said, describing the way she would receive the messages. “Without knowing why, I picked up a pencil and a pad that were lying on the table near my bed. My hand began to write in another handwriting. I looked at the handwriting and it was strangely familiar, but I knew it was not my own. I realized that somebody else was using my hand.” The flood warning, like all the others, had flowed through her as she wrote it out, her arm possessed by these otherworldly beings.

With warnings of the coming tide came the promise that she and the other believers would be rescued by the Guardians before the flood came, on December 17. One of her most ardent supporters was Charles Laughead, a staff doctor at Michigan State in East Lansing, Michigan, who was asked to resign his position for teaching his beliefs and upsetting students. (In a Chicago Tribune article from the time, he maintained that he was fired.)

But a few of the other believers who would end up singing carols with Martin on Christmas Eve weren’t actually believers at all. They were scientists.

A team of researchers from the University of Minnesota studying social movements had learned of Martin earlier that year, and considered her and her followers a perfect field study. They began spending time with Martin in October, eventually earning her confidence, and watched how she and her followers dealt with disappointment over the next several months as their predictions repeatedly failed to pan out.

Three of the Minnesota researchers, Leon Festinger, Henry Riecken, and Stanley Schachter, recounted the believers’ story in detail in their book When Prophecy Fails, published nearly 60 years ago on January 1, 1956. The experiences of Martin and the other believers were influential on Festinger’s theory of cognitive dissonance.

According to the book, the spacemen’s arrival was originally scheduled for 4 o’clock on December 17. The believers removed all the metal from their bodies, “an act considered essential before one might safely board a saucer,” the authors write, and went out into Martin’s backyard, scanning the skies. Ten minutes went by, and then Martin, who is given the pseudonym Marian Keech in the book, “abruptly … returned to the living room.” Others trickled away, and the last believers went back inside by 5:30.

In the house, they discussed what went wrong, eventually landing on the explanation that it must have just been a practice session. “The saucers would indeed land when the time was ripe, but everyone had to be well trained, ‘well-drilled actors,’ so that when the real time arrived, things would go smoothly,” the book reads. “The spacemen were not testing their faithfulness, but were simply unwilling to leave any possibility that their human allies would make a mistake.”

Faced with evidence that directly contradicted their beliefs, the group experienced cognitive dissonance—two thoughts that are inconsistent. This is uncomfortable, and the natural instinct is to try to make it go away. People can do that in a few different ways: by trying to forget about the dissonant things, by changing their minds, or by looking for new information that gets rid of the contradiction.

Sometimes this can mean, as the alien-less Christmas demonstrated, people can react to evidence against their beliefs by leaning in to those beliefs even more. At midnight, when the 17th became the 18th, Martin claimed to receive a message that the flying saucer was coming right then and everybody had to get on board or be left behind. For her followers, this new message served as confirmation that they had been right to believe. They scrambled outside, being sure to remove any remaining metal from their persons.

“We got back outside again and Edna took me aside and said, ‘How about your brassiere? It has metal clasps, doesn’t it?’” one of the observers reported. “I went back in the house and took my brassiere off. The only metal on me was the fillings in my teeth and I was afraid someone would mention those.”

They waited until 2 a.m. this time. Still no spacemen.

But the next day, the Guardians reassured Martin with a long message that repeatedly stated: “I have never been tardy; I have never kept you waiting; I have never disappointed you in anything.”

At midnight on the 21st, the scene played out again. This time, nobody but the five observers wanted to talk afterwards about what had happened. And then came the Christmas Eve disappointment, which had so many witnesses because the believers had sent out a press release about it. By this point, the cognitive dissonance was strong, as evidenced by this (condensed) conversation between Laughead (given the pseudonym Thomas Armstrong in the book) and a news reporter after the Christmas Eve debacle:

Newsman: Dr. Armstrong, I wanted to talk to you with reference to this business about—you know—your calling the paper to say you were going to be picked up at 6 o’clock this evening. Ahh, I just wanted to find out exactly what happened. ... Didn’t you say they sent a message that you should be packed and waiting at 6 p.m. Christmas Eve?

Armstrong: No.

Newsman: No? No, I’m sorry, sir. Weren’t the spacemen supposed to pick you up at 6 p.m.?

Armstrong: Well, there was a spaceman in the crowd with a helmet on and a white gown and what not.

Newsman: There was a spaceman in the crowd?

Armstrong: Well, it was a little hard to tell, but of course at the last when we broke up, why there was very evidently a spaceman there because he had his space helmet on and he had a big white gown on.

Newsman: And what did he say? Did you talk to him?

Armstrong: No, I didn’t talk to him.

Newsman: Didn’t you say you were going to be picked up by the spacemen?

Armstrong: No.

Newsman: Well, what were you waiting out in the street for singing carols?

Armstrong: Well, we went out to sing Christmas carols.

Newsman: Oh, you just went out to sing Christmas carols?

Armstrong: Well, and if anything happened, well, that’s all right, you know. We live from one minute to another. Some very strange things have happened to us and—

Newsman: But didn’t you hope to be picked up by the spacemen? As I understand it—

Armstrong: We were willing.

Newsman: Uhuh. Well, how do you account for the fact that they didn’t pick you up?

Armstrong: Well, as I told one of the other news boys, I didn’t think a spaceman would feel very welcome there in that crowd.

Newsman: Oh, a spaceman wouldn’t have felt welcome there.

Armstrong: No, I don’t think so. Of course, there may have been some spacemen there in disguise, you know. We couldn’t see. I think—I think that’s quite possible.

Perhaps the most powerful example of trying to reaffirm beliefs after these disappointments was on Christmas Day, when a new observer affiliated with the researchers showed up on Martin’s doorstep, attempting to gain entry into the group. Suspecting that this new visitor may be a spaceman, Martin and Laughead questioned him intensely, asking him to tell stories and seating him at a place of honor at the dinner table. But the next day, Martin got fed up, asking him, “Are you sure that you have no message for me? Now that we are alone, we can talk.”

“The experiences of this observer well characterize the state of affairs following the Christmas caroling episode—a persistent, frustrating search for orders,” Festinger and his co-authors write. After this, the believers began to disperse, leaving Martin’s home for their own, though not all of them lost their faith. Martin did not—in fact, she went on to found the Order of Sananda and Sanat Kumara (the names of two of the Guardians), calling herself “Sister Thedra.”

The lesson the researchers learned from all this, as they wrote in the introduction to When Prophecy Fails: “A man with a conviction is a hard man to change.” And when that conviction is as important as the promise of salvation coming from the sky, “it may even be less painful to tolerate the dissonance than to discard the belief and admit one had been wrong.”