EDGE 3rd Culture: Marc Hauser: Animal Minds - Page 3
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Imagine an open stage, a screen comes up that blocks the stage, and now what happens is one object goes behind the stage, followed by a second object. Let's call them Mickey Mouse 1 and Mickey Mouse 2. In our minds we are representing two Mickey Mouse objects. When the screen is removed, we expect to see two Mickey Mouse objects. If we see three, or we see one, that would be a violation because nothing should have been added to what was going on behind the stage. It turns out that at the age of about four to five months, human infants look longer when they see an outcome of three objects, or one object, as opposed to the two objects that they appear to expect. This is at a very young age. We have run the same exact experiment with two different non-human primate species, rhesus monkeys living wild on the island of Cayo Santiago, Puerto Rico, as well as a primate called the cotton-top tamarin living in my lab at Harvard. We have found exactly the same results as the psychologist Karen Wynn found with human infants. These results raise the important question of whether the representation of number is innate. This question is important for our understanding of the mechanisms underlying developmental and evolutionary change, and also, for our understanding of the relationship between language and thought. In fact, because animals lack language, studies of their mental representations provides a beautifully clear method for exploring under what conditions language is necessary for thought and under what conditions it contributes and enriches our thoughts.

JB: Gregory Bateson said that humans can't hold more than 7 of anything in their minds.

HAUSER: What seems to be occurring with studies of human infants and animals that involve spontaneous representation of number is more on the order of four. Four seems to be the limit of what we can actually enumerate spontaneously without a mechanism that encodes each object with a particular symbol, like an Arabic numeral. Very much in parallel with some of the findings that people like Stanislas Dehaene have produced recently, we are now finding that there are some core principals that non-human animals and infants bring to the table of numerosity, which then become elaborated through both language and culture, through education and through our capacity for language. What becomes interesting is to do comparative studies on human infants and non-human animals to see at what point they diverge in their capacities. We know of course at some point humans are able to do calculus, become bankers, do their taxes, and non-human animals are not able to do that. That's not interesting. What is interesting is what happens during the course of development that separates a human child from a non-human animal. By identifying the divergence point we are able to show what cognitive ability developed in the child which failed to evolve in non-human animals. The elegance of this work is that we're now beginning to pinpoint processes that emerge during development in the human child that either have evolved in other animals or have failed to evolve. By identifying both the similarities and differences we begin to pick up a pattern of evolution which is truly unique in terms of our understanding of both our own species and the unique attributes of other species.