Harold Camping is not the first religious prophet to have missed a deadline. One of psychology’s most exciting, famous and odd experiments tells us what will happen next — and why.

On the night of Dec. 20, 1954, 15 people sat in tense anticipation in the living room of a Chicago housewife named Dorothy Martin. They were awaiting the fulfillment of Martin’s end-days prophecy. A spaceman from the planet Clarion was to knock on the door at precisely midnight. They would be taken by car to a rendezvous with a flying saucer, where each would identify him or herself using a passport Martin had prepared. Each of the group members had removed all metal objects from their pockets and clothing, and rehearsed the special call-and-response routine that would be required of them as they boarded the saucer. Martin and nine others in the room believed that the saucer would whisk them to Clarion or another out-of-the-way location from where they could safely witness the destruction of Earth by flood.

The visitor was to arrive at precisely midnight, and as the hour approached, a mood of elation began to fill the room. Imagine. A new world order was about to be initiated, one that would transform a selected group of ordinary mortals into angelic beings living a life full of joy and free of suffering. Not only that, but those in the group who had been publicly ridiculed and humiliated would at last be vindicated, as they were elevated in glory above the nonbelieving multitudes.

As the hour approached, the telephone had been ringing continuously with reporters, curiosity seekers and true believers seeking updates. But the members now ignored all calls. It no longer mattered what the media reported, and it was too late to initiate new members. The hour was at hand.

I’m able to relate this precise, minute-by-minute account to you because — unknown to the rest of the group — five of them were researchers associated with a rising star in a (then) new field of social science called social psychology. Leon Festinger was the young professor’s name, and he was about to cement his reputation with the invention of a new theory of human behavior called cognitive dissonance.

Festinger and his colleagues had infiltrated the group and recorded their activities over the weeks and months before the night of the expected visit. They had gotten to know Martin and her followers, and were convinced that this was not a con game to exploit people’s gullibility but an earnest belief held by all members. They had witnessed and recorded the group’s reactions to other false starts — earlier expectations and disappointments when the Clarion visitors had failed to arrive — and noticed how they dealt with these.

Let me describe to you Festinger’s idea, and you can see why the crisis shaping up at Martin’s Chicago home in 1954 would provide the ideal proving ground.

Cognitive dissonance describes a condition of mental and emotional suffering (or dissonance) in which someone holds two competing views about something important to him or her. Do you know anyone who still smokes? Greater awareness of the dangers of smoking has created serious dissonance in smokers between the cognitions “I am a smoker” and “smoking can kill me.” Many people reduce the dissonance by quitting. But if you know any smokers, you’ve probably been exposed to the kinds of cognitions Festinger predicted with his theory: People are driven toward reducing dissonance by fabricating a compensating rationalization and trying to get people around them to buy into it. “Everybody’s got to die sometime,” would be a typical rationale for smoking, reflecting a belief that something is going to kill me, so it might as well be smoking. Or, less fatalistically, “smoking keeps me from overeating” or “it reduces my anxiety.”

Festinger was particularly interested in situations where a) someone had gone out on a limb by announcing his or her belief publicly; b) he or she had been ridiculed or otherwise taken flack for this belief; and c) a “disconfirming event” had made it all but impossible to continue to hold to the unmodified original belief. His prediction was that, rather than giving up the notion, the believer would become even more convinced of it and invent an explanation that reconciled the belief with the disconfirming event. Since Festinger was confident that there would be a disconfirming event in Martin’s case, he had decided immediately after reading a news account to infiltrate her inner circle and be present when the disconfirming moment arrived.

Festinger’s own later account of the minutes leading up to the appointed hour captures the intensity of the moment well: “These (last) four minutes passed in complete silence except for a single utterance. When the clock on the mantel showed only one minute remaining before the guide to the saucer was due, (Dorothy) exclaimed in a strained, high-pitched voice, ‘And not a plan has gone astray!’ The clock chimed 12, each stroke painfully clear in the expectant hush. The believers sat motionless.”

On May 13 of this year, Camping’s followers took out a full-page ad in USA Today announcing “Judgment Day Begins with an Earthquake on May 21, 2011.” Along with the 2,000 or so paid-advertising billboards, this publicity fulfilled one of Festinger’s requirements for a truly momentous bout of cognitive dissonance: an unequivocal public commitment to an outcome that would inevitably be disconfirmed. Obligingly, Camping reveals not an iota of doubt in a May 11 email interview. Responding to the interviewer’s obvious skepticism, he insists, “It. Is. Going. To. Happen.”

As May 21 arrived, Camping had one advantage over Martin sitting in her Chicago home in 1954. He had the wiggle room you get the first time you announce the precise date and time of your apocalypse. These calculations are complicated, and mistakes can understandably be made pinpointing dates from biblical verses. But, unfortunately for Martin, she had seriously drawn down her account balance of credibility with the group when the spaceman had failed to arrive on two previous nights. When the clock in her living room continued ticking loudly after the appointed moment with no spaceman in evidence, her group was in a state of silent emotional turmoil close to despair. They sat speechless for a long time, and then spent several desperate hours trying to reconcile their beliefs with the night’s events.

Dr. Thomas Armstrong, a physician and flying saucer expert who had emerged as a leader early on, may have spoken for all the assembled when he declared, “I’ve cut every tie. I’ve burned every bridge. I’ve turned my back on the world. I can’t afford to doubt. I have to believe.” This, in the face of the irrefutable disconfirmation of the evening’s events, describes exactly what Festinger had in mind when he talked about cognitive dissonance. Festinger’s prediction was that some new explanation would emerge to reduce the dissonance.

At about 4 o’clock that morning, with the group — including Festinger’s team — still assembled and struggling to understand what had happened, Martin received a psychic message from The Guardians, the putative organizers of the flying saucer rescue mission. In jubilant language and with biblical diction, the message indicated that, by their faith and prayers, the little group had flooded the Earth with God’s grace and caused him to commute his sentence of destruction. The cataclysm had been avoided. Festinger’s prediction of a dissonance-reducing explanation was fulfilled.

When Camping’s earthquake failed to materialize, he also provided a dissonance-reducing explanation. He had miscalculated the dates. Make no mistake, Camping announced, the “spiritual” judgment day had occurred exactly as planned on May 21, but due to some previously misunderstood technical mechanics, the actual earthquake and flood will occur on Oct. 21. Dissonance averted. Or at least delayed.

Interestingly, unlike Martin, Camping is reducing his evangelizing and proselytizing for the duration of Earth’s existence. Camping’s media empire of radio networks will just play music and programs until Oct. 21, according to a report in the Christian Science Monitor.

In academic circles, Festinger’s Martin experiment was received skeptically at first. But there can be no argument that it clearly and dramatically demonstrated his theory. Since it was introduced in the 1950s, cognitive dissonance has become a mainstream theory of social psychology. It has been expanded and refined, and applied usefully to illuminate human behavior in many domains.

It explains, for instance, why members of a college fraternity with difficult initiation rights are more loyal and value their membership more highly than brothers in less demanding fraternities. “I worked hard to get in” is dissonant with “it’s no better than any other group,” so I reduce the dissonance by believing in the superiority of my group. Similarly, brand marketers understand that a claim of high quality in a product is cognitively dissonant with a low price, and are therefore very careful in managing public perception when they discount their products.

In a recent paper, Richard Eibach and Steven Mock theorized that cognitive dissonance causes parents to significantly overstate the joys of parenthood, both to themselves and others, as a direct result of their dissonant experience of the cost-benefit differential. (If it costs this much, I must really like it!) Festinger’s theory helps explain anomalies in the way judges make decisions in court, people behave in traffic and consumers make buying decisions, to mention just a few. Cognitive dissonance today is a widely used term employed by politicians, economists, corporate chieftains — even TV comedians.

In working with couples and individuals, therapists sometimes use cognitive dissonance to assist clients making difficult life choices. I have used it with clients struggling with conflicting desires about having an affair, for instance. For many of these people, the belief that, “I would never deliberately hurt my spouse. That’s not who I am,” conflicts disturbingly with, “I’m about to embark on an affair that would hurt my spouse terribly.” These are dissonant ideas that can elicit highly creative attempts to reduce dissonance. “He’ll never find out,” is one. More imaginatively, “she wouldn’t really mind; she just doesn’t want to know.” Or, “everybody does it,” following Festinger’s notion that the more people who buy into our idea or behavior, the less dissonance we experience.

Eric Anderson, writing last year in the Journal of Social and Personal Relationships, called this dissonance the “Monogamy Gap.” Exploring this gap between conflicting beliefs with clients considering an affair can produce dramatic results, as they confront the question of who they really are, and what they truly believe.

Even more obvious is the dissonance that normally loving and affectionate couples have when they are in conflict. The angry, “he always (e.g. gets his way)” and “she never (e.g. does anything for me)” character attacks with which couples indict each other are inconsistent with both a belief and a behavior: the belief that their partner is at least a pretty good person, and the behavior of staying in the relationship year after year. (To a friend who is complaining bitterly about a spouse, just ask this question, “Why do you stay with such a terrible person, anyway?”) Confronting this inconsistency during a fight can create a very productive confusion, as partners recognize their own responsibility for their choices in how they characterize their partners.

It will be fascinating to see what Camping does after the disconfirming events of Oct. 21. Based on Festinger’s theory, I have a prediction: Camping’s dissonance-reducing explanation on that date will a) not be another temporary delay. As Martin realized, you can do that only so often. Nor b) will there be any admission that he was wrong about his original prediction of a Judgment Day on May 21. Rather, he will come out with a complex and unintelligible (to regular people) reinterpretation of biblical sources that sticks to the May 21 date, while reconciling it somehow to the undeniable fact that we are still around, and still alive to ponder the incomprehensible power of the human mind to grip tightly to concepts about ourselves and our world in the face of overwhelming evidence to the contrary.

— Russell Collins, Psy.D., is a Santa Barbara psychotherapist and divorce mediator. Click here for more information.