This brief excerpt on Kohler's research is from the book:
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 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 including boxes, poles, and
sticks, with which the primates could experiment.
Kohler constructed a variety of problems for the chimps, each of which involved
obtaining food that was not directly accessible. In the simplest task, food was put on the
other side of a barrier. Dogs and cats in previous experiments had faced the barrier in
order to reach the food, rather than moving away from the goal to circumvent the barrier.
The chimps, however, presented with an apparently analogous situation, set off immediately
on the circuitous route to the food.
It is important to note that the dogs and cats that had apparently failed this test
were not necessarily less intelligent than the chimps. The earlier experiments that
psychologists had run on dogs and cats differed from Kohler's experiments on chimps in two
important ways. First, the barriers were not familiar to the dogs and cats, and thus there
was no opportunity for using latent learning, whereas the chimps were well acquainted with
the rooms used in Kohler's tests. 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.
The ability to select an indirect (or even novel) route to a goal is not restricted to
chimps, cats, and dogs. At least some insects routinely perform similar feats. The
cognitive processing underlying these abilities 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 unique as they appeared at the time.
Some of the other tests that Kohler is known 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 Kohler's 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
their 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.
Photos
and captions from The Mentality of Apes
click on each image to see larger version
Read Kohler's Introduction to the Mentality of Apes
Kohler's objections to Thorndike's approach to Animal Intelligence
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