Ethology:

Frans de Waal, Chimpanzee Politics, 1982:

"The greatest difference between ethology and psychological behavioral study of animals lies in ethology's strong emphasis on spontaneous behavior in the natural environment, or at least under the most natural conditions possible. Ethologists do conduct experiments, but never completely detached from their fieldwork. They are first and foremost patient observers. This attitude of waiting to see what the animals do of their own accord, instead of encouraging a particular kind of behavior for experimental purposes, also characterizes our research in Arnhem."