Daniel Haun of the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands, and his colleagues began by testing 12 Dutch adults and 12 roughly eight-year-old children. The team compared them with a similar number of adults and eight-year-olds of the Haikom, a Khoisan hunter-gatherer people in Namibia. A key difference in their languages lies in how they describe space. The Dutch, like most Europeans, rely on so-called egocentric constructions, wherein a space is described from the point of view of the speaker. For example, "The ball is to the left of the tree." The Haikom, on the other hand, typically rely on so-called absolute constructions, wherein a space is described from a viewer-independent directional system. For example, "The ball is to the north of the tree."
The subjects watched as a researcher facing them hid a block under one of five cups; they then attempted to find a similar block under five other cups in front of them. But where their block might be found varied: In the egocentric testing condition, if the researcher placed the block under the leftmost cup closest to him, then it would be found in the leftmost cup closest to the participant. In the object-centered testing condition, the blocks maintained the same relationship to a so-called landmark, such as the experimenter or the screen separating the two sets of cups. Finally, in the geocentric testing condition, if the block was hidden under the northwestern cup facing the researcher, then its counterpart could be found under the northwestern cup facing the subject.
Each subject faced each condition 10 times, and as expected, the Dutch of all ages performed better under relative conditions whereas the Haikom of all ages fared better under geocentric conditions (although the Haikom adults did not do very well under any conditions). "Even though the test might be strange for the Haikom, they still show understanding of the problem and prefer to solve it one way more than another," Haun notes. "The interesting thing that differs between our culture and theirs is the directionality of that preference."
But Haun also extended this experiment to determine if our closest relatives--the great apes--shared an innate preference for one strategy or another. Testing the great apes against 12 German children nearing five years of age, the researchers found that all performed best when the hidden block was found under a cup that maintained the same spatial relationship to the surrounding environment. In fact, only the six orangutans tested performed better than chance in the egocentric condition. Haun concludes that "all genera prefer environment- to self-centered processing of spatial relations" in the paper presenting the findings published online this week in Proceedings of the National Academy of Sciences USA.
Of course, questions remain such as how European language might override an innate preference and why the Haikom adults did not fare better as a result of adhering more closely to this bias. "I think it again has to do with the fact that abstract testing situations are an everyday thing for Europeans and a very strange thing for Haikom," Haun explains. "So here is my prediction: if we tested another culture, with equally limited standardized schooling but egocentric spatial language, they should perform worse than the Haikom. I'll get to it right away." For example, Haun might test the speakers of Kgalagadi, a Bantu language, spoken by people living within a few hundred kilometers of the Haikom. But the answer may not be as simple as one or the other: "I think that both other hominid species and our own likely have several different ways to conceptualize space, which co-exist," notes psychologist Nora Newcombe of Temple University. "For Homo sapiens language tips the balance as to what meaning is emphasized and what meaning is believed to be intended in these testing situations."
"What we need to resolve the debate are experiments that disclose the level of flexibility in our own and other species as a function of task variation," she adds. The simple fact that English readers can parse this discussion of the various spatial strategies involved means we must be able at least to comprehend and employ the different approaches, as is true for most other language speakers. And that might be the universal ability the researchers set out to find: "I will start looking for things which are unique to humans amongst the great apes and universal across cultures," Haun notes. "Universality is very hard to prove, but I'll do my very best."