Köhler found that a chimpanzee can imitate only those intelligent acts of other apes that it could have performed on its own. Persistent training, it is true, can induce it to perform much more complicated actions, but these are carried out mechanically and have all the earmarks of meaningless habits rather than of insightful solutions. The cleverest animal is incapable of intellectual development through imitation. It can be drilled to perform specific acts, but the new habits do not result in new general abilities.

Comparative psychology has identified a number of symptoms that may help to distinguish intelligent, conscious imitation from automatic copying. In the first case, the solution comes instantly in the form of insight not requiring repetition. Such a solution pertains to all characteristics of intellectual action. It involves understanding the field structure and relations between objects. On the contrary, drill imitation is carried out through repeating trail-and-error series, which show no sign of conscious comprehension and do not include understanding the field structure. In this sense, it can be said that animals are unteachable.

In the child’s development, on the contrary, imitation and instruction play a major role. They bring out the specifically human qualities of the mind and lead the child to new developmental levels. In learning to speak, as in learning school subjects, imitation is indispensable. What the child can do in cooperation today he can do alone tomorrow. Therefore the only good kind of instruction is that which marches ahead of development and leads it; it must be aimed not so much at the ripe as at the ripening functions.

– Lev Vygotsky, Thought and Language

When there is light on our planet, it comes from the sky, not from earth.  Our vision knows this perfectly  even though it was not until a few years ago that the psychologist Vilyanur Ramachandran, from the University of California, San Diego, came up with these splendid examples.  The actual effect of the direction of the light determining whether we see shapes as concave or convex was described by David Brewster in the 1800s.

We can thank the Danish psychologist Edgar Rubin for the figure above, or more correctly, the American photographer Zeke Berman’s elaboration of Rubin’s vase, a double image initially conceived by Rubin in 1915.  You can choose to see black vases-with the white faces as background.  Or you can see the faces-and then the black cases become background.  You can choose to see one as the shape, the other as the background.  But you cannot choose both of them simultaneously   You distinguish between signal and noise. Again it is not the raw data that you see; you see an interpretation  and only one interpretation at a time.  Berman’s version of the Rubin vases is not a drawing. He used silhouettes of real faces.  The figure above is a drawing inspired by Berman.

– Tor Nørretranders, The User Illusion