Excellent article but, certainly not conclusive as the RSPCA spokesperson stated. However, the article points out the difference between pain as experienced by humans and response to negative stimuli as part of a survival tactic. I think I would find myself supporting the latter. I have caught the same fish in a few minutes on the same fly. Bluegills and greens are not even Pavlovian enough to avoid negative stimuli. Of course, the animal rights folks might say this is a feeding urge overcoming a safety need (which takes us to Maslow). Anthropomorphizing is a dangerous thing to do when dealing with wildlife.