 Much of the research that is of direct relevance to the treatment of human pain, including on the efficacy of analgesics and anesthetics, is conducted on rats and other animals. The validity of this research depends on the similar mechanisms  involved[1]  and to many it seems arbitrary to deny that injured rats, who respond well to opiates for example, feel  pain.[2]  Likewise, much of the basic research that is of direct relevance to understanding human visual consciousness has been conducted on the very similar visual systems of monkeys.  Monkeys whose primary visual cortex is damaged even show impairments analogous to those of human blindsight patients (Stoerig &amp; Cowey 1997) suggesting that the visual consciousness of intact monkeys is similar to that of intact humans.  Scientific demonstrations that members of other species, even of other phyla, are susceptible to the same visual illusions as we are (e.g., Fujita et al. 1991) suggesting that their visual experiences are similar.