JB: Let's talk about what you do in your job.
HAUSER: My day job involves a couple of different strands. One of the most novel aspects of my work is that unlike researchers who restrict themselves to field studies, people like Jane Goodall, or Robert Seyfarth, Dorothy Cheney, where most of the work is done in the wild, with animals living in their natural conditions, occasionally maybe an experiment in captivity, my own work combines at least four different kinds of approaches to finding out what animals know, think, and represent.
The first is field studies. I go into the wild places like Puerto Rico where there's a wild population of rhesus monkeys, or Africa and look at chimpanzees in Uganda or vervet monkeys in Kenya, and I use my studies in the wild to understand what kinds of problems shaped the design features of the brains of those animals in their natural habitat. Watching what they do will tell us what particular problems their brains need to solve. The same logic applies to humans of course, and is one reason why the study of the human mind must not be restricted to studies in the laboratory. We need to figure out what kinds of problems humans confronted in their past and that are recurring problems to understand how our own minds were sculpted by the forces that we have confronted. We take that same approach and we apply it to animals as well. In the wild, vervet monkeys in East Africa confront a wide array of predator, as the biologists Peter Marler, Thomas Struhsaker, Dorothy Cheney and Robert Seyfarth have documented. In response to these predators, which have very different hunting styles, they have evolved a unique alarm call system, where different kinds of calls appear to refer to different kinds of predators. We would never have uncovered that particular phenomenon if we had studied these animals in captivity where there are no predators. So I go to the field, I watch what animals do naturally, and then I come back to the lab where we can gain more experimental control and ask specific questions about their cognitive ability.
In the lab, for example, we would take the fact that animals seem to discriminate all sort of objects in their world, and ask them what features are relevant to that kind of discrimination. To give one example, we now have 30 years of studies showing that animals use tools. They use objects to extract food from their environment. But what none of these studies have ever shown is the kinds of representations that the animals bring to the task of tool use. Now here's the question: for humans we know that when we have an artifact like a tool there are certain features of the object that are relevant to the tool, and certain features that are irrelevant. A simple example is that most dishwashers are white, but if we came into our home and found a dishwasher that was rainbow colored we wouldn't say "That's no good. Can't do my dirty dishes in that thing". We know that color is an irrelevant feature of what makes a good dishwasher as opposed to a bad dishwasher. The question then becomes, when we see animals, for example chimpanzees in the wild using stones to crack open nuts, if we presented them with a stone as opposed to a sledge hammer, would they see that the sledge hammer has better design features for the task than does the stone? Would they prefer the sledge hammer? Would they realize that if we painted the stone red it wouldn't make any difference at all to its functionality? So what we've done is we've taken that problem, gone into the lab, and systematically manipulated all features of the objects, both relevant and irrelevant, to see whether animals make a decision based on those features. When we run those experiments we see that animals are, in fact, quite sensitive to the functionally relative features, ignoring differences that have no impact on the task. We can take a problem from the wild and bring it into the lab, and systematically assess how the representation is actually operating in the animal's mind.