Okay, so Morgan was a bit taken aback. And about seven years later, after he wrote the first version of the Introduction to Comparative Psychology, he was taken aback because people were attributing to him that animals had no intelligence. That because you should always favor the more parsimonious explanation, and because we should always be careful about attributing human traits to animals when we're explaining their behavior. That they were saying animals were never intelligent, and that animals and humans were totally different. And there was the gulf between the two that could never be covered. So what he wrote in his second version of his book, seven years later, he added to his Canon by saying, to this however, it should be added, lest the range of the principle be misunderstood. That the canon by no means excludes the interpretation of a particular activity in terms of the higher processes, if we already have independent evidence of the occurrence of these higher processes in the animal under observation. And so what he's trying to say here is that if we did an experiment and actually rule out the parsimonious or simple explanation, we can then accept the more complex explanation. Or the more sophisticated flexible cognitive solution as the internal process that the animal's using to solve the problem. And he would be happy to know, having written this revision, that we now know. There's been some brilliant work by Thomas Zentall's research group in Kentucky University showing that dogs can actually learn very rapidly to open doors and to open gates. Remember the example of Morgan's dog learning to open the gate where he had to use trial and error, and he concluded that it clearly wasn't very sophisticated cognition. But the key thing about that was, Morgan's dog was on his own. He learned it completely independently, without watching anyone else. But when you show a dog the solution to opening a new door that they've never opened before, it ends up. What Thomas Zentall found in Kentucky, is that dogs in one or even two trials learn to open a new door and copy the method that they see someone else demonstrate to them. So, a dog on its own, Morgan was right, very simple explanation. A dog with someone else to watch, it's a different story. So that's the exciting thing about experiments. You can find that simple explanations explain behavior in places that you didn't think that it was a simple explanation. Or, it can actually be a complicated cognitive explanation that's allowing for an animal to solve interesting problems. Okay, so to summarize and to wrap up, why experiments? Why do we need these experiments? Why can't we just watch animals do what they do and become experts in how their minds work? And the reason is, cognition involves internal processes. Only experiments can reveal the inner working of the animal mind and help us understand which different mechanism is helping them solve a different problem. The same or similar appearing behavior can be the result of very different cognition. And simple explanations often can explain animal problem solving and are given priority until they are ruled out with experiments. Careful experiments also often rule out parsimonious explanations though and favor the existence of sophisticated cognition in animals. And so that's the fun is, how is it that animals are actually solving the problems that we think are interesting to explain?