Yesterday I noted how many of the Hominidae pass the "mirror test"; orangutans, chimpanzees, bonobos, and humans all are able to recognize themselves in a mirror. Gorillas, however, fail the test. Why should this be? The following video might give us a clue;
The juvenile in the baboon is scared as soon as it sees itself in the mirror, and this makes sense because direct eye contact is considered aggressive in baboons, just as it is in gorillas. The key to passing the mirror test is the ability to look at the image in the mirror long enough to match up the movements and realize that the image is really a reflection of the animal itself; many animals cannot figure out that the reflection is not another animal (many animals act aggressively towards their reflection), and if they can't watch long enough to figure this out they will fail. This very simple reason presents us with a flaw in the test that will bias our results towards particular animals that are not as scared by direct eye contact, and circumstantial evidence suggests that gorillas have the capacity for self recognition even if the test is flawed. The famous female gorilla Koko, raised in a way where eye contact was not reinforced as being aggressive, passed the test, and while there are some who doubt what Koko can tell us about primate cognition the fact that she can recognize herself in the mirror (and tell us that she does via sign language) is compelling.
What, then, about other animals? Does a dog lack a sense of self because it doesn't pass the test? Not at all, and in this case a negative result does not mean that the animal lacks a sense of self. Creating alternate tests that use the animals primary senses (perhaps smell in canines) is the difficult part, especially since our own species (Homo sapiens) is so visually-oriented. Likewise, what are we to make of animals like Capuchin monkeys (Cebus sp.) that can use mirrors to look for objects that they can't otherwise see but don't seem to recognize themselves? Overcoming out own biases is going to be the most difficult part in such tests.
Just as well, laboratory tests are not the final answer to animal cognition and behavior; behavior must be studied and understood in the wild as well as in the lab if we are to truly make sense of it. Take, for instance, the belief that passerine birds ("songbirds" as they're commonly known) learn their songs entirely from their fathers and duplicate them dutifully when they disperse. Lab studies seemed to suggest this idea, but studies in the wild showed that some songbirds switch over to the local dialect when they settle in a new area; they sing their fathers songs if they haven't heard the local version, but once they've learned the local version they stop singing it the way they learned it from their father. This does not mean that the lab studies were worthless, but only that they can only truly make sense if we understand learning and behavior as it exists in wild populations. So it is, too, with the mirror test; once we know an animal has a sense of self, what does that tell us about the behavior of those animals in the wild? It's not simply a matter of closing the gap between man and beast, but understanding the utility and evolution of cognition and intelligence in various groups of animals. Volumes upon volumes have been written on these topics, but for now I simply wish to convey a sense of caution in interpreting results that might seem all-too-clean-cut on the surface.
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I typed the following, then realized it's not very relevant, but:
based on little data (the few photos I've seen on the net),
and considering that smooth water is the only reflective surface typically seen by non-human tetrapods, and that hominoids have poor olfaction and are visually oriented,
orang mother and attached infant wade in smooth water bipedally
(Borneo marsh photo)
bonobo mother and attached infant wade in smooth water bipedally
(Plankendaal zoo moat photo)
human mother and attached infant wade in smooth water bipedally
(common photos)
gorilla mother sets infant in grass, then wades in smooth water bipedally using wading/measuring stick
(Ndoki swamp, Congo photos)
capuchins in mangroves use oyster shells to open other oysters
where shell interior and water surface are both reflective
(ref at sci.anthro.paleo google group)
Actually, it is common for animals in the wild to see their own reflections. Drink directly from a pool of still water during daylight and it is hard to miss seeing your mirror image. On seeing themselves, do animals usually freak out? No.
Given the normalcy of seeing one's reflection in still water while drinking, it might actually startle a primate to see his reflection in something that isn't water, such as a hand-held mirror.
Has anyone tried testing gorillas with a mirror at the bottom of a bucket of drinking water?
Regarding eyes and agression, of course one of the problems with a mirror is that when you are looking at your eyes, your eyes are looking right back at you.
I wonder what would happen with a video camera and a flat-screen TV or monitor, where the two were offset? Then you won't get the eye-looking-into-eye effect. As a human it sometimes takes me a bit of time (usually in an electronics store) to figure me out, but I suspect that's because I'm used to seeing my reversed image from a mirror.
Here's an interesting synchronicity.
I just started reading "Merle's Door" by Ted Kerasote, which is a book about a dog he had. Early on, shortly after meeting the dog just before a river rafting trip, he describes passing through canyon walls. He admits that he may be anthropomorphicizing, but here's what he describes upon entering:
So, there may be different kinds of mirrors, with certain ones more suited to individual species.