Clever Hans in Reverse
So why did we at first reach the wrong conclusion about animal perspective taking, and why has it happened so many times before and since? Claims about absent capacities range from the idea that primates do not care about the welfare of others, do not imitate, or even fail to understand gravity. Imagine this for flightless animals that travel high above the ground! In my own career, I have faced resistance to the notion that primates reconcile after fights or console those who are distressed. Or at least I heard the counterclaim that they do not truly do so—as in, they do not “truly imitate” or “truly console”—which immediately gets one into debates about how to distinguish what looks like consolation or imitation from the real thing. At times, the overwhelming negativity got to me, as an entire literature burgeoned that was more excited about the cognitive deficits of other species than about their actual accomplishments.32 It would be like having a career adviser who all the time tells you that you are too dumb for this or too dumb for that. What a depressing attitude!
The fundamental problem with all these denials is that it is impossible to prove a negative. This is no minor issue. When anyone claims the absence of a given capacity in other species, and speculates that it must therefore have arisen recently in our lineage, we hardly need to inspect the data to appreciate the shakiness of such a claim. All we can ever conclude with some certainty is that we have failed to find a given skill in the species that we have examined. We cannot go much further than this, and we certainly may not turn it into an affirmation of absence. Scientists do so all the time, though, whenever the human-animal comparison is at stake. The zeal to find out what sets us apart overrides all reasonable caution.
Not even with regard to the Monster of Loch Ness or the Abominable Snowman will you ever hear anyone claim to have proven its nonexistence, even though this would fit the expectations of most of us. And why do governments still spend billions of dollars to search for extraterrestrial civilizations while there is no shred of evidence to encourage this quest? Isn’t it time to conclude once and for all that these civilizations simply don’t exist? But this conclusion will never be reached. That respected psychologists ignore the recommendation to tread lightly around absent evidence is most puzzling, therefore. One reason is that they test apes and children in the same manner—at least in their minds—while coming up with contrary results. Applying a battery of cognitive tasks to both apes and children and finding not a single result in the apes’ favor, they tout the differences as proof of human uniqueness. Otherwise, why didn’t the apes fare better? To understand the flaw in this logic, we need to go back to Clever Hans, the counting horse. But instead of using Hans to illustrate why animal capacities are sometimes overrated, this time we are concerned with the unfair advantage that human capacities enjoy.
The outcome of ape-child comparisons themselves suggests the answer. When tested on physical tasks, such as memory, causality, and the use of tools, apes perform at about the same level as two-and-a-half-year-old children, but when it comes to social skills, such as learning from others or following others’ signals, they are left in the dust.33 Social problem solving requires interaction with an experimenter, however, whereas physical problem solving does not. This raises the possibility that the human interface is key. The typical format of an experiment is to let apes interact with a white-coated barely familiar human. Since experimenters are supposed to be bland and neutral, they do not engage in schmoozing, petting, or other niceties. This doesn’t help make the ape feel at ease and identify with the experimenter. Children, however, are encouraged to do so. Moreover, only the children are interacting with a member of their own species, which helps them even more. Nevertheless, experimenters comparing apes and children insist that all their subjects are treated exactly the same. The inherent bias of this arrangement has become harder to ignore, however, now that we know more about ape attitudes. A recent eye-tracking study (which precisely measured where subjects looked) reached the unsurprising conclusion that apes consider members of their own species special: they follow the gaze of another ape more closely than they follow the human gaze.34 This may be all we need to explain why apes fare poorly on social tasks presented by members of our species.
There are only a dozen institutes that test ape cognition, and I have visited most of them. I have noticed procedures in which humans barely interact with their subjects and ones in which they have close physical contact. The latter can safely be done only by those who raised the apes themselves or have at least known them since infancy. Since apes are much stronger than we are and have been known to kill people, the up-close-and-personal approach is not for everyone. The other extreme derives from the traditional approach in the psychology lab: carrying a rat or a pigeon into a testing room with as little contact as possible. The ideal here is a nonexistent experimenter, meaning the absence of any personal relation. In some labs apes are called into a room and given only a few minutes to perform before they are sent out again without any playful or friendly contact, almost like a military drill. Imagine if children were tested under such circumstances: how would they fare?
At our center in Atlanta, all our chimps are reared by their own kind and so are more ape-than human-oriented. They are “chimpy,” as we say, relative to apes that have a less social background or were raised by humans. We never share the same space with them, but we do interact through the bars, and we always play or groom before testing. We talk to them to put them at ease, give them goodies, and in general try to create a relaxed atmosphere. We want them to look upon our tasks as a game rather than as work, and certainly never put them under pressure. If they are tense because of events in their group, or because another chimp is banging on the outside door or hooting his lungs out, we wait until everyone has calmed down, or we reschedule the test. There is no point testing apes who are not ready. If such procedures are not followed, apes may act as if they don’t understand the problem at hand, whereas the real issue is high anxiety and distraction. Many negative results in the literature may be explained this way.
The methodology sections of scientific papers rarely offer a look in the “kitchen,” but I think it is crucial. My own approach has always been to be firm and friendly. Firm, meaning that we are consistent and don’t make capricious demands but also don’t let the animals walk all over us, such as when they only want to play around and get free sweets. But we are also friendly, without punishment, anger, or attempts to dominate. The latter still happens all too often in experiments and is counterproductive with such headstrong animals. Why would an ape follow the points and prompts of a human experimenter whom he sees as a rival? This is another potential source of negative outcomes.