for those that aren't aware, this is a psychological test (of somewhat dubious value) to determine self-awareness. it clearly demonstrates what is becoming a widely held consensus: elephants are smarter than chimps. beside that, it's pretty much expected behaviour, with the exception of the gorilla, who would actually be expected to "get it" pretty fast. but gorillas demonstrate variation like every other species. it looks like this particular gorilla is not the hardest chest in the forest.