Animal research in this area began perhaps with the uncertainty response noticed by Tolman in the 1920s. His rats seemed to hesitate before a difficult task as reflected in their “lookings or runnings back and forth.”36 This was most remarkable, since at the time animals were thought to simply respond to stimuli. Absent an inner life, why be in turmoil about a decision? Decades later the American psychologist David Smith gave a bottlenose dolphin the task to tell the difference between high and low tones. The dolphin was an eighteen-year-old male named Natua, in a pool at the Dolphin Research Center in Florida. As in Tolman’s rats, Natua’s level of confidence was quite manifest. He swam at different speeds toward the response, depending on how easy or hard it was to tell both tones apart. When they were very different, the dolphin arrived with such speed that his bow wave threatened to soak the electronics of the apparatus. They had to be covered with plastic. If the tones were similar, though, Natua slowed down, waggled his head, and wavered between the two paddles that he needed to touch in order to indicate a high or low sound. He didn’t know which one to pick. Smith decided to make a study of Natua’s uncertainty, mindful of Tolman’s suggestion that it might reflect consciousness. The investigator created a way for the animal to opt out. A third paddle was added, which Natua could touch if he wanted a fresh trial with an easier distinction. The tougher the choice, the more Natua went for the third paddle, apparently realizing when he had trouble coming up with the right answer. Thus the field of animal metacognition was born.37
Investigators have essentially followed two approaches. One is to explore the uncertainty response, as in the dolphin study, while the other is to see if animals realize when they need more information. The first approach has been successful with rats and macaques. Robert Hampton, now a colleague at Emory University, gave monkeys a memory task on a touchscreen. They would first see one particular image, say a pink flower, then face a delay before being presented with several pictures, including the pink flower. The delay varied in length. Before each test, the monkeys had the choice to either take it or decline it. If they took the test and correctly touched the pink flower, they gained a peanut. But if they declined, they only got a monkey pellet, a boring everyday food. The longer the delay, the more the monkeys declined taking the test despite its better reward. They seemed to realize that their memory had faded. Occasionally, they were forced to take a trial without a chance of escape. In those cases they fared rather poorly. In other words, they opted out for a reason, doing so when they couldn’t count on their memory.38 A similar test with rats gave similar results: the rats performed best on tests that they had deliberately chosen to take.39 In other words, both macaques and rats volunteer for tests only when they feel confident, suggesting that they know their own knowledge.
A rhesus macaque knows that food has been hidden in one of four tubes, but he has no idea which one. He is not allowed to try every tube and will get only one pick. By bending down to first peek into the tubes, he demonstrates that he knows he doesn’t know, which is a sign of metacognition.
The second approach concerns information seeking. For example, jays placed at peepholes were given an opportunity to watch food—waxworms—being hidden before they were allowed to enter the area to find it. They could look through one peephole to see an experimenter put a waxworm in one of four open cups, or they could look through another to see another experimenter with three covered cups plus one open one. In the second case, it was obvious where the worm would end up. Before entering the area to find the worm, the birds spent more time watching the first experimenter. They seemed to realize that this was the information they needed most.40
In monkeys and apes, the same sort of test has been done by having them watch an experimenter hide food in one of several horizontal pipes. Obviously, the primates remembered where he had put the food and confidently selected the correct pipe. If the food hiding had taken place in secret, however, they were not sure which pipe to pick. They peeked into the pipes, bending down to get a good look, before selecting one. They realized that they needed more information to succeed.41
As a result of these studies, some animals are now believed to track their own knowledge and to realize when it is deficient. It all fits Tolman’s insistence that animals are active processors of the cues around them, with beliefs, expectations, perhaps even consciousness. This viewpoint being on the rise, I asked my colleague Rob Hampton about the state of affairs in this field. The two of us have offices on the same floor of Emory’s psychology department. While sitting in mine, we first watched the video of Lisala carrying her huge rock. Like a real scientist, Rob immediately began to imagine how to turn this situation into a controlled experiment by varying the locations of the nuts and the tools, even though for me the beauty of the whole sequence was Lisala’s spontaneity. We had nothing to do with it. Rob was impressed.
I asked him if his work on metacognition had been inspired by the dolphin study, but he rather saw this as a case of convergent interests. The dolphin study did come out first, but it wasn’t about memory, which was Rob’s focus. He was inspired by the ideas of Alastair Inman, a postdoc in Sara Shettleworth’s Toronto lab, where Rob worked at the time. Alastair wondered about the cost of memorizing things. What is the price of holding information in mind? He set up an experiment on pigeon memory that was similar to the metacognition test for monkeys that Rob developed.42
When I asked what he thought of people who draw a sharp line between humans and other animals, such as Endel Tulving’s shifting definitions, Rob exclaimed: “Tulving! He loves to do that. He has done a great service to the animal research community.” Tulving says those things, Rob believes, because he thinks it’s fun to set a high bar. He knows that others will go after it, so he pushes them to come up with clever experiments. In his first monkey paper, Rob thanked Tulving for his “incitement.” Meeting the senior scientist not long thereafter at a conference, Tulving told Rob, “I have seen what you wrote, thank you!”
For Rob, the big question in relation to consciousness is why we actually need it. What is it good for? After all, there are lots of things we can do unconsciously. For example, amnesic patients are able to learn without knowing what they have learned. They may learn to make inverse drawings guided by a mirror. They acquire the hand-eye coordination at about the same rate as any other person, but every time you test them, they’ll tell you that they’ve never done it before. It is all new to them. In their behavior, though, it is obvious that they have experience with the task and have acquired the required skill.
While consciousness has evolved at least once, it is unclear why and under which conditions. Rob considers it such a messy word that he is reluctant to use it. He adds, “Anyone who thinks they have solved the problem of consciousness hasn’t been thinking about it carefully enough.”
Consciousness
When in 2012 a group of prominent scientists came out with The Cambridge Declaration on Consciousness, I was skeptical.43 The media described it as asserting once and for all that nonhuman animals are conscious beings. Like most scientists studying animal behavior, I really don’t know what to say to this. Given how ill-defined consciousness is, it is not something we can affirm by majority vote or by people saying “Of course, they are conscious—I can see it in their eyes.” Subjective feelings won’t get us there. Science goes by hard evidence.
But in reading the actual declaration, I calmed down, because it is a reasonable document. It doesn’t actually claim animal consciousness, whatever that is. It only says that given the similarities in behavior and nervous systems between humans and other large-brained species, there is no reason to cling to the notion that only humans are conscious. As the document puts it, “The weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness.” I can live with that. As you can see from this chapter, there is sound evidence that mental processes associated with consciousness in humans, such as how we relate to the past and future, occur in other species as well. Strictly speaking, this doesn’t prove consciousness, but science is increasingly favoring continuity over discontinuity. This is certainly true for comparisons between humans and other primates, but extends to other mammals and birds, especially since bird brains turn out to resemble those of mammals more than previously thought. All vertebrate brains are homologous.
Although we cannot directly measure consciousness, other species show evidence of having precisely those capacities traditionally viewed as its indicators. To maintain that they possess these capacities in the absence of consciousness introduces an unnecessary dichotomy. It suggests that they do what we do but in fundamentally different ways. From an evolutionary standpoint, this sounds illogical. And logic is one of those other capacities we pride ourselves on.
8 OF MIRRORS AND JARS