This video was brought to my attention last night, and it seems to have gone viral with everyone getting excited that this video demonstrates that cats are fooled by illusions just like we are. A common thing people say is that we can reasonably infer that the cat is “seeing things”. The most glaring problem with this “demonstration” is that the paper is placed on a soft couch. If you notice, as the cat paws the paper, it makes the paper move. This self-induced movement changes not only the lighting patterns on the paper but makes the patterns themselves move, which is obviously attention-grabbing. As the cat bats down one “hill” on the paper, another “hill” pops up which immediately attracts attention. I’ve seen my own cat do this with blank pieces of paper or newspaper. Because it’s impossible from this video alone to determine whether the cat was reacting to self-induced movements or “illusory” movements, it’s completely inconclusive whether or not this cat is really seeing things. A better demonstration would be if the printed illusion was laminated flat against a hard and smooth surface, so the cat would not be able to self-deform the pattern and induce movement. My guess is that the experiments would be similarly inconclusive and difficult to interpret.
I am not aware of any scientific attempt to determine whether cats really see things. This is probably because most level-headed experimentalists understand there is a deep epistemological problem in trying to make inferences about the private mental states of animals that are incapable of giving verbal reports about their experience in terms we can make sense of. A scientist could only ever tentatively make such inferences on the basis of analogy, but since cats can’t talk to us, we must make these analogical inferences about their visual qualia from strictly physical cues as measured by physical measuring instruments. But therein lies the problem: how do we know we made the right inference about “what-it-it’s-like” to be a cat based purely on the read-outs of our physical instruments e.g. electrical recordings of neuronal activity? This problem about an “inferential gap” is similar to familiar philosophical chestnuts such as the “explanatory gap” or “problem of inverted qualia” , which in turn are related to that much older chestnut: the “Problem of Other Minds”.
As far as I know, there is no solution to these problems that doesn’t involve some kind of handwaving appeals to intuition, circular reasoning, or wishful thinking. One thing to do is deny foundationalism and the loosen our standards for what counts as knowledge such that our blind inference about the cat’s visual qualia becomes something more secure and less troublesome when we ask the pesky skeptical questions. There is nothing wrong in principle with inferential reasoning and analogical bootstrapping because we will always run into these sorts of worries when trying to make sense of the unknown in terms of the known through an iterated extension of our properly basic knowledge. But some bootstrapping extensions are more reasonable than others. In terms of Otto Neurath’s analogy of repairing a boat while out at sea, some repairs will keep us afloat but others will sink us. A good extension is when scientists turn their newly calibrated instruments on these unknown domains and they can make sense of the unfamiliar readings in terms that overlap with familiar domains of extension where the experimental results are robust and reliable.
So why can’t we “extend” our knowledge to the unknown domain of visual qualia in nonhuman animals? The crucial disanalogy is that in the natural sciences the successful extension of the concept is done by using reliable instruments that work using known means and provide reliable, replicable data in familiar domains. Moreover, if different versions of the same instrument made by different scientists gave similar data we would have a good reason to be confident that this instrument would be a good “base” upon which to extend our knowledge. But as far as I’m aware, we haven’t got a clue how to build a “qualia-scope”. What materials would such a device be made of? Why those materials and not others? What physical quantities would it be designed to respond to? Why those quantities and not others? What theory can we appeal to to justify a decision to use some quantities over others?