The news have been full these days with the reports of magpies being able to recognize themselves in the mirror. While this is an interesting, even exciting feat in and of itself, I was more amused by the fact that all animals which recognize themselves in a mirror can be observed doing what is called "contingency testing". The authors of the original paper describe this operant behavior in the following way:This is, of course, the type of spontaneous behavior one would generate to find out what portion of the currently perceived scene is actually caused by the individual. Animals with a concept of 'self' use the operant reafference principle to find out if it really is themselves they perceive in the mirror. You generate behavior in such an erratic way that only you could be the source of any contingent sensory feedback (visual feedback as in the case of the mirror). Until this study, only a few animal species have been reported to recognize themselves in the mirror so far, 4 great apes, bottlenose dolphins and Asian elephants. All of these animals do this contingency testing. Of course, we humans are no exception to this rule. Probably the most iconographic scene exemplifying this behavior is the mirror scene in the movie "Duck Soup" where Groucho Marx is doing the testing. I've put magpie Gerti (video from the original paper) and Groucho side by side for a comparison: