Yet during my student days, behaviorism still ruled supreme, at least in psychology. Luckily for me, the professor’s pipe-smoking associate, Paul Timmermans, regularly took me aside to induce some much-needed reflection on the indoctrination I was being subjected to. We worked with two young chimpanzees who offered me my first contact with primates apart from my own species. It was love at first sight. I had never met animals that so clearly possessed a mind of their own. Between puffs of smoke, Paul would ask rhetorically, with a twinkle in his eyes, “Do you really think chimps lack emotions?” He would do so just after the apes had thrown a shrieking temper tantrum for not getting their way, or laughed their hoarse chuckles during roughhousing. Paul would also mischievously ask my opinion about other taboo topics, without necessarily saying that the professor was wrong. One night the chimps escaped and ran through the building, only to return to their cage, carefully closing its door behind them before going to sleep. In the morning, we found them curled up in their straw nests and would not have suspected a thing had it not been for the smelly droppings discovered in the hallway by a secretary. “Is it possible that apes think ahead?” Paul asked when I wondered why the apes had closed their own door. How to deal with such crafty, volatile characters without assuming intentions and emotions?
To drive this point home more bluntly, imagine that you wish to enter a testing room with chimpanzees, as I did every day. I would suggest that rather than rely on some behavioral coding scheme that denies intentionality, you pay close attention to their moods and emotions, reading them the way you would any person’s, and beware of their tricks. Otherwise, you might end up like one of my fellow students. Despite the advice we gave him of how to dress for the occasion, he came to his first encounter in a suit and tie. He was sure he could handle such relatively small animals, while mentioning how good he was with dogs. The two chimps were mere juveniles, only four and five years old at the time. But of course, they were already stronger than any grown man, and ten times more cunning than a dog. I still remember the student staggering out of the testing room, having trouble shedding both apes clinging to his legs. His jacket was in tatters, with both sleeves torn off. He was fortunate that the apes never discovered the choking function of his tie.
One thing I learned in this lab was that superior intelligence doesn’t imply better test outcomes. We presented both rhesus monkeys and chimpanzees with a simple task, known as haptic (touch) discrimination. They were to stick their hand through a hole to feel the difference between two shapes and pick the correct one. Our goal was to do hundreds of trials per session, but whereas this worked well with the monkeys, the chimps had other ideas. They would do fine on the first dozen trials, showing that the discrimination posed no problem, but then their attention would wander. They’d thrust their hands farther so as to reach me, pulling at my clothes, making laughing faces, banging on the window that separated us, and trying to engage me in play. Jumping up and down, they’d even gesture to the door, as if I didn’t know how to get to their side. Sometimes, unprofessionally, I would give in and have fun with them. Needless to say, the apes’ performance on the task was well below that of the monkeys, not due to an intellectual deficit but because they were bored out of their minds.
The task was just not up to their intellectual level.
The Hunger Games
Are we open-minded enough to assume that other species have a mental life? Are we creative enough to investigate it? Can we tease apart the roles of attention, motivation, and cognition? Those three are involved in everything animals do; hence poor performance can be explained by any one of them. With the above two playful apes, I opted for tedium to explain their underperformance, but how to be sure? It takes human ingenuity indeed to know how smart an animal is.
It also takes respect. If we test animals under duress, what can we expect? Would anyone test the memory of human children by throwing them into a swimming pool to see if they remember where to get out? Yet the Morris Water Maze is a standard memory test used every day in hundreds of laboratories that make rats frantically swim in a water tank with high walls until they come upon a submerged platform that saves them. In subsequent trials, the rats need to remember the platform’s location. There is also the Columbia Obstruction Method, in which animals have to cross an electrified grid after varying periods of deprivation, so researchers can see if their drive to reach food or a mate (or for mother rats, their pups) exceeds the fear of a painful shock. Stress is, in fact, a major testing tool. Many labs keep their animals at 85 percent of typical body weight to ensure food motivation. We have woefully little data on how hunger affects their cognition, although I do remember a paper entitled “Too Hungry to Learn?” about food-deprived chickens that were not particularly good at noticing the finer distinctions of a maze task.5
The assumption that an empty stomach improves learning is curious. Think about your own life: absorbing the layout of a city, getting to know new friends, learning to play the piano or do your job. Does food play much of a role? No one has ever proposed permanent food deprivation for university students. Why would it be any different for animals? Harry Harlow, a well-known American primatologist, was an early critic of the hunger reduction model. He argued that intelligent animals learn mostly through curiosity and free exploration, both of which are likely killed by a narrow fixation on food. He poked fun at the Skinner box, seeing it as a splendid instrument to demonstrate the effectiveness of food rewards but not to study complex behavior. Harlow added this sarcastic gem: “I am not for one moment disparaging the value of the rat as a subject for psychological investigation; there is very little wrong with the rat that cannot be overcome by the education of the experimenters.”6
I was amazed to learn that the nearly century-old Yerkes Primate Center went through an early period in which it tested food deprivation on chimpanzees. In the early years, the center was still located in Orange Park, Florida, before it moved to Atlanta, where it became a major institute for biomedical and behavioral neuroscience research. While still in Florida, in 1955, the center set up an operant conditioning program modeled on procedures with rats, including a drastic reduction in body weight and the replacement of chimp names with numbers. Treating apes as rats proved no success, however. Due to the gigantic tensions this program engendered, it lasted only two years. The director and most of the staff deplored the fasting imposed on their apes and constantly argued with the hard-nosed behaviorists who claimed that this was the only way to give the apes “purpose in life,” as they blithely called it. Expressing no interest in cognition—the existence of which they didn’t even acknowledge—they investigated reinforcement schedules and the punitive effect of time-outs. Rumor had it that staff sabotaged their project by secretly feeding the apes at night. Feeling unwelcome and unappreciated, the behaviorists left because, as Skinner later put it, “tender-hearted colleagues frustrated [their] efforts to reduce chimpanzees to a satisfactory state of deprivation.”7 Nowadays, we would recognize the friction as about not just methodology but also ethics. That creating morose, grumpy apes through starvation was unnecessary was clear from one of the behaviorists’ own attempts with an alternative incentive. Chimpanzee number 141, as he called him, successfully learned a task after each correct choice was rewarded with an opportunity to groom the experimenter’s arm.8