Soon after however, Köhler was named the second director of the newly established Primate Station on the island of Tenerife off the west coast of Africa. The station had been established so that “the behavior of the chimpanzee, gorilla, orangutan, and gibbon would be studied and compared, permitting a better evaluation of these animals on an evolutionary scale” (Teuber, 1994, p. 552). Tenerife was picked because of its relatively constant weather and its nearness to Cameroon, then a German colony, and a place were apes could be captured in the wild for study under more controlled conditions. The apes had preceded the arrival of the first director, Eugen Teuber. Upon his arrival he quickly found and developed a site, hired an animal keeper, and began filmed observational studies. Teuber’s research focused on the animal’s emotional behavior and their communication abilities. However, once Köhler arrived, he and Teuber began studying the ape’s cognitive abilities. Working together, they set up a fruit basket that was suspended in the air by means of a rope and pulley. At the end of the rope, a large ring hooked onto a tree limb held the fruit in place. Köhler hoped that the apes would examine the rigging of the basket and simply unhook the ring and get the fruit. That never happened. Instead, a chimpanzee named Sultan learned to dislodge the fruit from the basket by vigorously shaking the rope and causing the fruit to fall to the ground. Quickly, Köhler realized that his initial experiment was too complicated. Figure 12.x shows a schematic view of the problem. It was drawn by Köhler’s first wife, Thekla.

--------------Insert Figure 12.x about here [Fruit basket experiment]---------------

After Teuber left for home and because Köhler believed he, too, only had a year to conduct his research, he quickly went to work. He could not foresee or imagine that he would end up staying on Tenerife for nearly six years. The outbreak of World War I in August 1914 was the event that led to his long sojourn on the island.

Following the failure of the fruit basket experiment, Köhler devised simpler tests for his animals. He provided them with wooden crates that they could move and stack. Later, he hung a banana out of reach, from the netting that formed the roof of the animal enclosure. Sultan, later judged the smartest of the station’s apes, solved the problem in about five minutes. But, his solution was unlike any previously described example of animal learning. Unlike Thorndike’s cats, for instance, he showed no evidence of trial-and-error learning. Instead, Sultan first attempted to retrieve the banana by jumping up for it. When that failed, he quit trying for a short period. Then, he jumped up, grabbed a box, and placed it directly under the banana. Now, he was close enough to jump up and grab it. From that point on, getting the banana was accomplished in the same way. Köhler named this type of learning as insight learning. It was characterized by the sudden appearance of a solution after a period of quiescence. Köhler interpreted Sultan’s

Marginal Definition: Insight Learning-a type of learning in which a solution to a problem appears suddenly, usually after a period of time has passed since the problem was first presented.

solution in Gestalt terms. He believed that Sultan had reorganized the problem cognitively. The ape had somehow realized that putting the box right under the banana was the solution. Köhler devised other similar tests including hanging the banana higher so that boxes had to be stacked upon each other in order to retrieve the banana, tests

---------------Insert Figure 12.x about here [Chimpanzees and stack of boxes]---------------

involving the use of sticks to retrieve food items, and detour tasks. He also compared the behavior of his apes to that of dogs, chickens, and a young child. Another test he used demonstrated the phenomenon of transposition. He used chickens first and chimpanzees later. The chickens first learned to discriminate between two gray boxes, learning to

Marginal Definition: transposition-learning the relationship between two stimuli and subsequently transferring that learning to other pairs of stimuli.

choose the lighter shade. Next, Köhler tested them with the original light gray box and a newer one colored an even lighter gray. The chickens now chose the new lighter shade. Chimpanzees showed the same pattern, only the stimuli varied in size not in color. He concluded that both species had learned a relationship because neither picked the original training stimulus. Thus, he used Gestalt psychology to interpret his animal learning experiments. He believed he had demonstrated that his apes had exhibited intelligent behavior, a radical concept at the time. Remarkably, he wrote up his results and had them published while still at Tenerife, while war raged in Europe. His book, The Mentality of the Apes, was published in German in 1917 and in English in a few years later (Köhler, 1925). Although the book made him world famous, he left animal research behind after his return to Germany.