Pfister's hen is wearing prism's to deviate light. The experiment set out to find if the chicken, like humans, is able to correct an upside down world. It is. However, as a friend asked, is that a good or a bad sign, or can the chicken be considered smarter if it does it more quickly than us humans? Animals were used extensively in experimental research on the physiology of perception. In the literature from the 1950s and 1960s which I have been consulting those animals are always treated as 'things', as soulless non-entities. Yet maybe some animals showed some enthusiasm for the tasks. Others, so much is sure, were made to suffer in the name of progress. Whichever way, once you start thinking about it, it is strange that their agency as beings is so completely absent from literature (a nod to Fahim Amir whose work on doves stimulated my thoughts). Let's demand a Nobel price for animal researchers. This researcher chicken is from Gregory, Eye and Brain, first published 1966. The image is quoted in the context of this article on Art as Visual Research .