I was reading this question, and it reminded me of something interesting I had once stumbled upon, although for the life of me I cannot remember where.
I think it may have been a book (perhaps a lecture on YouTube or an article) but I remember certainly that it was by a philosopher/cognitive scientist of a distinctly 'Turing bent' (Dennett, Pinker or some such). The author (resp. lecturer)'s contention was that certain experiments concerning chickens and cages indicated that, by virtue of their non-resistance to (indeed eagerness toward) captivity, chickens did not experience 'high order suffering' as equated with a frustration of desire.
Now perhaps I am remembering the argument through somewhat rose-tinted spectacles, but I remember the design of the experiment as 'ruling out' or at least reasonably discounting a sort of Stockholm syndrome on the part of the subjects, but google reveals only an untrackdownable 1980 reference to Dawkins (mentioned in the linked page- a find-search for 'Dawkins' will track it down) in which caged hens initially preferred cages to runs whenb given the choice.
Is this just a false memory? Perhaps Dawkins' deeply unconvincing experiment is the most convincing out there. Has anyone seen or heard anything similar? Can anyone put a stop to the repeated kicking of myself that has followed my failing to jot down the reference in the first place?