Social psychologist Leon Festinger infiltrated a flying saucer doomsday cult in the late 1950s. The members of this cult had given up everything on the premise that the world was about to self destruct and that they, because of their faith, would be the sole survivors. In the lead up to the fateful day, the cult shunned publicity and shied away from journalists. Festinger posed as a cultist and was present when the space ship failed to show up. He was curious about what would happen. How would the disappointed cultists react to the failure of their prophecy? Would they be embarrassed and humiliated? What actually happened amazed him.

Now, after the non-event, the cultists suddenly wanted publicity. They wanted media attention and coverage. Why? So they could explain how their faith and obedience had helped save the planet from the flood. The aliens had spared planet earth for their sake - and now their new role was to spread the word and make us all listen. This fascinated Festinger. He observed that the real driving force behind the cultists' apparently inexplicable response was the need, not to face the awkward and uncomfortable truth and 'change their minds', but rather to 'make minds comfortable' - to smooth over the unacceptable inconsistencies.

Festinger coined the term 'cognitive dissonance' to describe the uncomfortable tension we feel when we experience conflicting thoughts or beliefs (cognitions), or engage in behavior that is apparently opposed to our stated beliefs. What is particularly interesting is the lengths to which people will go to reduce the inner tension without accepting that they might, in fact, be wrong. They will accept almost any form of relief, other than admitting being at fault, or mistaken. Festinger quickly realized that our intolerance for 'cognitive dissonance' could explain many mysteries of human behavior.

In a fascinating experiment Festinger and his colleagues paid some subjects twenty dollars to tell a specific lie, while they paid another group of subjects only one dollar to do the same. Those who were paid just one dollar were far more likely to claim, after the event, that they had actually believed in the lie they were told to tell. Why? Well, because it's just so much harder to justify having done something that conflicts with your own sense of being 'an honest person' for a mere pittance. If you get more money, you can tell yourself: 'Yeah, I lied, but I got well paid! It was justified.' But for one dollar? That's not a good enough reason to lie, so what you were saying must have been true in the first place, right?

Emotional factors influence how we vote for our politicians much more than our careful and logical appraisal of their policies, according to Drew Westen, a professor of psychiatry and psychology. This may come as little surprise to you, but what about when we learn that our favored politician may be dishonest? Do we take the trouble to really find out what they are supposed to have done, and so possibly have to change our opinions (and our vote), or do we experience that nasty cognitive dissonance and so seek to keep our minds comfortable at the possible cost of truth?

Cognitive dissonance is essentially a matter of commitment to the choices one has made, and the ongoing need to satisfactorily justify that commitment, even in the face of convincing but conflicting evidence. This is why it can take a long time to leave a cult or an abusive relationship - or even to stop smoking. Life's commitments, whether to a job, a social cause, or a romantic partner, require heavy emotional investment, and so carry significant emotional risks. If people didn’t keep to their commitments, they would experience uncomfortable emotional tension. In a way, it makes sense that our brains should be hard-wired for monitoring and justifying our choices and actions - so as to avoid too much truth breaking in at once and overwhelming us.

I guess we can't really develop unless we start to get a grip and have some personal honesty about what really motivates us. This is part of genuine maturity. If I know I am being lazy, and can admit it to myself, that at least is a first step to correcting it. If, however, I tell myself it's more sensible to wait before vacuuming, then I can go around with a comfortable self-concept of 'being sensible' while my filthy carpets and laziness remain unchanged. Cognitive dissonance can actually help me mature, if I can bring myself, first, to notice it (making it conscious) and second, to be more open to the message it brings me, in spite of the discomfort. As dissonance increases, providing I do not run away into self-justification, I can get a clearer and clearer sense of what has changed, and what I need to do about it.

And then I can remember what Darwin had to say about who will survive...

Easter Island, or Rapu Nui as it is known locally, is home to several hundred ancient human statues - the moai. After this remote Pacific island was settled by the Polynesians, it remained isolated for centuries. All the energy and resources that went into the moai - some of which are ten metres tall and weigh over 7,000 kilos - came from the island itself. Yet when Dutch explorers landed in 1722, they met a Stone Age culture. The moai were carved with stone tools, then transported for many kilometres, without the use of animals or wheels, to massive stone platforms. The identity of the moai builders was in doubt until well into the twentieth century. Thor Heyerdahl, the Norwegian ethnographer and adventurer, thought the statues had been created by pre-Inca peoples from Peru. Bestselling Swiss author Erich von Daniken believed they were built by stranded extraterrestrials. Modern science - linguistic, archaeological and genetic evidence - has definitively proved the moai builders were Polynesians, but not how they moved their creations. Local folklore maintains that the statues walked, while researchers have tended to assume the ancestors dragged the statues somehow, using ropes and logs.

When the Europeans arrived, Rapa Nui was grassland, with only a few scrawny trees. In the 1970s and 1980s, though, researchers found pollen preserved in lake sediments, which proved the island had been covered in lush palm forests for thousands of years. Only after the Polynesians arrived did those forests disappear. US scientist Jared Diamond believes that the Rapanui people - descendants of Polynesian settlers - wrecked their own environment. They had unfortunately settled on an extremely fragile island - dry, cool, and too remote to be properly fertilised by windblown volcanic ash. When the islanders cleared the forests for firewood and farming, the forests didn’t grow back. As trees became scarce and they could no longer construct wooden canoes for fishing, they ate birds. Soil erosion decreased their crop yields. Before Europeans arrived, the Rapanui had descended into civil war and cannibalism, he maintains. The collapse of their isolated civilisation, Diamond writes, is a ’worst-case scenario for what may lie ahead of us in our own future’.

The moai, he thinks, accelerated the self-destruction. Diamond interprets them as power displays by rival chieftains who, trapped on a remote little island, lacked other ways of asserting their dominance. They competed by building ever bigger figures. Diamond thinks they laid the moai on wooden sledges, hauled over log rails, but that required both a lot of wood and a lot of people. To feed the people, even more land had to be cleared. When the wood was gone and civil war began, the islanders began toppling the moai. By the nineteenth century none were standing.

Archaeologists Terry Hunt of the University of Hawaii and Carl Lipo of California State University agree that Easter Island lost its lush forests and that it was an ‘ecological catastrophe' - but they believe the islanders themselves weren’t to blame. And the moai certainly weren’t. Archaeological excavations indicate that the Rapanui went to heroic efforts to protect the resources of their wind-lashed, infertile fields. They built thousands of circular stone windbreaks and gardened inside them, and used broken volcanic rocks to keep the soil moist. In short, Hunt and Lipo argue, the prehistoric Rapanui were pioneers of sustainable farming.

Hunt and Lipo contend that moai-building was an activity that helped keep the peace between islanders. They also believe that moving the moai required few people and no wood, because they were walked upright. On that issue, Hunt and Lipo say, archaeological evidence backs up Rapanui folklore. Recent experiments indicate that as few as 18 people could, with three strong ropes and a bit of practice, easily manoeuvre a 1,000 kg moai replica a few hundred metres. The figures’ fat bellies tilted them forward, and a D-shaped base allowed handlers to roll and rock them side to side.

Moreover, Hunt and Lipo are convinced that the settlers were not wholly responsible for the loss of the island’s trees. Archaeological finds of nuts from the extinct Easter Island palm show tiny grooves, made by the teeth of Polynesian rats. The rats arrived along with the settlers, and in just a few years, Hunt and Lipo calculate, they would have overrun the island. They would have prevented the reseeding of the slow-growing palm trees and thereby doomed Rapa Nui’s forest, even without the settlers’ campaign of deforestation. No doubt the rats ate birds’ eggs too. Hunt and Lipo also see no evidence that Rapanui civilisation collapsed when the palm forest did. They think its population grew rapidly and then remained more or less stable until the arrival of the Europeans, who introduced deadly diseases to which islanders had no immunity. Then in the nineteenth century slave traders decimated the population, which shrivelled to 111 people by 1877.

Hunt and Lipo’s vision, therefore, is one of an island populated by peaceful and ingenious moai builders and careful stewards of the land, rather than by reckless destroyers ruining their own environment and society. ‘Rather than a case of abject failure, Rapu Nui is an unlikely story of success’, they claim. Whichever is the case, there are surely some valuable lessons which the world at large can learn from the story of Rapa Nui.