To err is human. At times we misconceive and/or misperceive situations. Our brain has built-in cognitive biases. And we also have confirmation biases that we are usually unaware of. For this reason the blind experiment has become fundamental to the scientific method.
An anthropologist cannot be a participant-observer of any people without that participation having some effect on the behavior being observed. You see, if a chemist was able to become a molecule in order to be a participant-observer in the chemical process of a compound while observing it, then his observation would be disputable because of the unknown ways he (as a molecule in the mixture) had influenced the outcome. The same would apply to the anthropologist studying any human group. And this would also apply to the study of non-human animals.
The Clever Hans effect is another reason that studies of non-human animal behavior is disputable should the animal observed happened to be or have been able to observe the observer. And this is especially true concerning our closest non-human relatives, i.e., the Chimpanzee.
Ethologist Konrad Lorenz argued in 1949 that infantile features triggered nurturing responses in adults and that this was an evolutionary adaptation which helped ensure that adults would care for their offspring, thereby contributing to the survival of the species. In other words, we have a cognitive bias which has been called “the Kewpie doll effect” (see also Neoteny). Now, taking into consideration both the Kewpie doll effect and the Clever Hans effect, should the physical features of the domesticated silver fox be considered purely the result of selecting out the most docile animals without taking into consideration that those animals could have been reacting to clues picked up from the human observer? No. Reacting to subtle clues displayed by the observer could have determined the aggressiveness or nonagressiveness of the foxes. And the human could have been selecting as a result of the degree of “cuteness” (the term used by Konrad Lorenz). Thus the degree of aggression displayed by the foxes could have been a response to the human cognitive bias for “cuteness” instead of a purely genetic mechanism.