Kohler's work on insight learning

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The Animal Mind

by J.L Gould & C. G. Gould

Wolfgang Kohler, a psychologist trained at the University of Berlin, was working at a primate research facility maintained by the Prussian Academy of Sciences on Tenerife in the Canary Islands when the First World War broke out. Marooned there, he had at his disposal a large outdoor pen and nine chimpanzees of various ages. The pen, described by Kohler as a playground, was provided with a variety of objects-"toys"-including boxes, poles, and sticks, with which the primates could experiment.

Kohler set the chimps a variety of problems, each of which involved obtaining food that was not directly accessible. In the simplest, food was put on the other side of a barrier. Dogs and cats in previous experiments faced with the food in order to reach it, or to move away from the goal to circumvent the barrier. The chimps, on the other hand, presented with an apparently analogous situation, set off immediately on the circuitous route to the food.

But it turns out that the other animals that had apparently failed this same test were not so stupid after all. The earlier experiments that psychologists had run on dogs and cats differed from Kohler's on chimps in two important ways: first, the barriers were not familiar to the pets, and thus there was no opportunity for using any latent learning, whereas the chimps were well acquainted with the rooms used in Kohler's tests. And second, whereas the food remained visible in the dog and cat experiments, in the chimp test the food was tossed out the window (after which the window was shut) and fell out of sight. Indeed, when Kohler tried the same test on a dog familiar with the room, the animal (after proving to itself that the window was shut), took the shortest of the possible indirect routes to the unseen food.

In fact, the ability to select an indirect (or even novel) route to a goal is not restricted to rats, chimps, and dogs; at least some insects routinely perform similar feats. What possessing this ability actually says about the underlying cognitive processing will become clearer when we look at navigation by chimps in a later chapter. For now, the point is that the chimpanzees' abilities to plan routes are not as special as they looked at the time.

Some of the other tests Kohler is justly famous for are preserved on film. In a typical sequence, a chimp jumps fruitlessly at bananas that have been hung out of reach. Usually after a period of unsuccessful jumping the chimp apparently becomes angry or frustrated, walks away in seeming disgust, pauses, then looks at the food in what might be a more reflective way, then at the toys in the enclosure, then back at the food, and then at the toys again. Finally the animal begins to use the toys to get at the food.

The details of the chimps' solutions to the food-gathering puzzle varied. One chimp tried to shinny up a toppling pole it had poised under the bananas; several succeeded by stacking crates underneath, but were hampered by difficulties in getting the centers of gravity right. Another chimp had good luck moving a crate under the bananas and using a pole to knock them down. The theme common to each of these attempts is that to all appearances the chimps were solving the problem by a kind of cognitive trial and error, as if they were experimenting in their minds before manipulating the tools. The pattern of these behaviors-failure, pause, looking at the potential tools, and then the attempt-would seem to involve insight and planning, at least on the first occasion