Wolfgang Koehler demonstrated that chimpanzees could solve problems by applying insight. His research showed that the intellectual gap between humans and chimpanzees was much narrower than previously thought. The work was revolutionary when originally published in 1917 in German, but it was largely ignored for decades because it violated the conventional wisdom that animal behavior is simply the result of instinct or conditioning.

Wolfgang Khler

int: Introduction; 1: Roundabout methods 1; 2: The use of implements; 3: The use of implements-(cont.) Handling of Objects 1; 4: The making of implements; 5: The making of implements-(cont.); Building; 6: Detours round separate intervening objectives; 7: "Chance" and "imitation"; 8: The handling of forms