Some scientists visited a New Guinea tribe that believed their world ended at the nearby river. After several months one of the scientists had to cross the river to leave. When the scientist was safely across he waved, but the tribesmen did not respond. They said they didn’t see him as nothing existed beyond the end of the world. Their entrenched patterns of belief about where the world ended distorted their perception of reality.
The New Guinea people disregard things which do not fit into the way they were taught to view reality and make them into something consistent with their beliefs. They see what they expect to see.
Take a look at these two tables. Which one of them do you think is longer, and which one is wider?
It might be hard to believe, but the two tables have the exact same dimensions! Measure both table surfaces with a ruler and prove it to yourself. Why, then, does the table on the left look elongated, while the table on the right appears to have a wider width? The illusion of two tables was first discovered by Stanford University’s Roger Shepard in 1981.
It comes down to how we perceive the scene. Accustomed as we are to photography and Western art, we automatically interpret the scene as three-dimensional. The concept of perspective, first mastered by artists during the Renaissance, is one we encounter in our everyday lives, and our brains automatically assume that the further away an object is from us, the smaller it will be. To compensate, our brain interprets and “lengthens” lines that appear to be pointing away from us into the distance. In this scene, the interpretation made by our brain extends the length of the table on the left by making it appear longer and the shorter side of the right-hand table by making it appear wider. Our brain constructs what we perceive based on our past experiences rather than what is there.
People tend to think of perception as a passive process. We see, hear, smell, taste or feel stimuli that impinge upon our senses. We think that if we are at all objective, we record what is actually there. Yet perception is demonstrably an active rather than a passive process; it constructs rather than records “reality.” Perception implies understanding as well as awareness. It is a process of inference in which people construct their own version of reality on the basis of information provided through the five senses.
THE CLASSIC TEASER OF THE MIRROR
Noble laureate physicist, Richard Feynman, wrote about the classic teaser of the mirror. Why, Feynman wondered, does a mirror seem to invert left and right but not top and bottom? That is, why are the letters of a book backward but not upside down, and why would Feynman’s double behind the mirror appear to have a mole on the wrong hand?
Imagine yourself standing before the mirror, he suggested, with one hand pointing east and the other west. Wave the east hand. The mirror image waves its east hand. Its head is up. Its west hand lies to the west. Its feet are down. Everything’s really all right.
The problem is on the axis running through the mirror. Your nose and the back of your head are reversed: if your nose points north, your double’s nose points south. The problem now is psychological. We think of our image as another person. We cannot imagine ourselves “squashed” back to front, so our brains imagine ourselves turned left and right, as if we had walked around a pane of glass to face the other way.
It is in this psychological turnabout the brain makes that make us believe that left and right are switched. This is another example that shows the extraordinary extent to which the information obtained by an observer depends upon the observer’s own assumptions and preconceptions. We cannot imagine our image squashed so we construct a reality that assumes an image of ourselves as if we walked around the pane of glass.
THE WAR OF GHOSTS THOUGHT EXPERIMENT
Read the following story. Wait a few minutes. Then write what you remember about the story. You might also want to try it with a friend. Ask a friend to read the story, wait a few moments, and then ask your friend to retell it to you from memory. Compare the stories to see the results.
THE STORY. One night two young men from Egulac went down to the river to hunt seals and while they were there it became foggy and calm. Then they heard war cries, and they thought: “Maybe this is a war party”. They escaped to the shore, and hid behind a log. Now canoes came up, and they heard the noise of paddles, and saw one canoe coming up to them. There were five men in the canoe, and they said: “What do you think? We wish to take you along. We are going up the river to make war on the people.”
One of the young men said, “I have no arrows.” “Arrows are in the canoe,” they said. “I will not go along. I might be killed. My relatives do not know where I have gone. But you,” he said, turning to the other, “may go with them.”
So one of the young men went, but the other returned home. And the warriors went on up the river to a town on the other side of Kalama. The people came down to the water and they began to fight, and many were killed. But presently the young man heard one of the warriors say, “Quick, let us go home: that Indian has been hit.” Now he thought: “Oh, they are ghosts.” He did not feel sick, but they said he had been shot.
So the canoes went back to Egulac and the young man went ashore to his house and made a fire. And he told everybody and said: “Behold I accompanied the ghosts, and we went to fight. Many of our fellows were killed, and many of those who attacked us were killed. They said I was hit, and I did not feel sick.” He told it all, and then he became quiet. When the sun rose he fell down. Something black came out of his mouth. His face became contorted. The people jumped up and cried.
He was dead.
Now look away from the story. Wait a few minutes. Now write the story as you remembered it. How did your stories compare?
This story was used by British psychologist, Sir Frederic Bartlett, in his experiments in perception. He asked people to read the story which was unfamiliar to them and then later asked them to write what they remembered. He found that when they recalled the story, they had changed it to fit their existing knowledge, and it was this revised story which then became incorporated into their memory. He demonstrated that existing conceptual patterns of knowledge, beliefs, and theories absorb unfamiliar new experiences and re-interpret them to fit with what they know.