Wednesday, August 31, 2005

CogBlogGroup: Tomasello, Ch. 2, Part 2: The Human Ratchet

The third section of Chapter 2, beginning on p. 37, is where Tomasello really begins the book. Up to this point, he's been arguing that his hypothesis is viable, based on the differences in human and nonhuman primate social cognition. Now he begins to show what his hypothesis can give us. And he doesn't start small. He goes straight to language and mathematics, to of the most striking human achievements. And along the way, he takes a stand that, in my view, makes this an excellent book. But I will get to that in a moment. First, let's look at the ratchet effect and the sociogenesis of language and mathematics.

By page 37, Tomasello feels that he's given us enough evidence to convince the convinceable that one of the major cognitive differences between humans and nonhuman primates lies in our ability to understand others as intentional agents like ourselves. This understanding makes possible, among other things, imitative learning, and as he puts it, imitative learning gives us the ability to learn new behaviors by understanding the goals of the behavior, allowing us to "faithfully [preserve] newly innovated strategies" (p. 40, and this in turn puts us "into a new cognitive space" (p. 39). This placement into a new cognitive space is important, because creativity is dependent on existing knowledge. Innovations always need something to build on, and by learning more than mere associations through social interactions, we are provided with the building blocks for further innovations. A tool one person makes can be improved upon by the person who learns to use that tool from her, and then that tool can be improved upon, and so on, and so on, until our knowledge-base grows to the point at which we get the sorts of technological explosions that humans have seen over the last few millennia, and over the last century in particular. This process is further enhanced by the ability to work in direct collaboration with others, in essence pooling our knowledge resources, and producing even better innovations. The process of learning and then improving upon the innovations of those who come before us is the ratchet effect, and the two types of cooperation that I described, building, individually, on something that someone else has created, and building on something in direct collaboration with another individual, Tomasello calls virtual and simultaneous collaboration.

As an example of virtual collaboration, Tomasello uses the development of the collections of linguistic symbols and constructions that make up individual languages. While children initially learn fairly exact copies of the symbols and constructions that their parents use, languages develop over time, meaning that as new individuals learn them, they make alterations (most often unconsciously, I'm sure) that end up making those symbols and constructions more efficient for speech and communication. On pages 43 and 44, he gives several examples of how English expressions have become more efficient over time, usually through shortening the expressions (by removing redundancies, e.g.). This is just sort of collaborative construction process that the model of Hutchins and Hazelhurst simulates. Their model shows just how powerful such collaboration is in the creation of a shared system of linguistic symbols. For instance, their model shows how different systems of symbols can develop by dividing agents into groups that can only collaborate with other members of their groups.

While there are many languages, language itself is shared by all human cultures. This may be, as Tomasello notes, because some aspects (perhaps its underlying structure) of language are innate. This is the Chomskyan position, and Tomasello is quick to point out that his hypothesis is not inconsistent with some versions of that position (he mentions the principles and parameters approach, which I briefly described here). But it is also consistent with the creation of a simple symbol system by our earliest human ancestors some 250,000 years ago. Out of this system, all languages would develop through the sort of collaboration Tomasello as well as Hutchins and Hazelhurst describe. Similarities across languages in their structure, which are fairly common as linguists will tell you, could then be a product of the fact that languages develop to work with existing cognitive and physical (e.g., the anatomy of the vocal tract) mechanisms.

After language, Tomasello describes how the sociogenesis of mathematics might have worked. Mathematics, unlike language, is not universal, and while some have posited that we have innate arithmetical abilities (the addition and subtraction of small numbers, specifically), few have argued that we have a complex mathematical cognition module. Instead, mathematical knowledge develops using existing cognitive mechanisms, and only to the extent that it is needed in a particular culture. As cultures develop more complex economic, architectural, and technological systems, mathematical knowledge grows more complex. And often, particularly at the highest levels, mathematics develops through the simultaneous collaboration of small groups of individuals (people we would call mathematicians). Each innovation along the way is built upon previous innovations, and thus the development of mathematics is a particularly impressive example of the ratchet effect.

After the discussion of language and mathematics as examples of the power of sociogenesis, Tomasello moves on to human ontogeny (human development), and he begins this discussion, which will comprise the bulk of Chapter 3, with a philosophical discussion. And I must say that this short discussion (in the subsection titled "Philosophical Nativism and Development," beginning on p. 48) is one of the main reasons I like this book so much, and why I think it's a very good first book for the reading group. This is because he touches on one of the foremost debates in cognitive science: the nativism vs empiricism debate. Since its inception in the mid-1950s, cognitive science has been dominated by a few far-reaching debates, the most famous of which being the imagery debate, connectionist vs symbolic architecture, and nativism vs empiricism (there has also been a debate over the use of similarity-based vs rule-based processes within the symbolicist camp, but this is more local and technical, and therefore less famous). The imagery debate was an incredibly heated debate in the 1970s over whether representational primitives (the building blocks of all representations) were images or propositions. This debate died out in the early 80s, with most cognitive scientists deciding that both images and propositions both comprised our representational primitives, but with an emphasis on propositions. Recently, the debate has been making a comeback, largely due to the work of Larry Barsalou, who argues that most or all of our representations are images (which need not be visual, I should add). The connectionist vs symbolic architecture debate, which took off in the 1980s (perhaps because people were sick of the imagery debate) has been equally heated, and concerns the ways in which our brains process information. Do they do so using syntactic processes (rules) operating over discrete symbols (symbolic representations), or do they use analog representations that allow for similarity-based pattern recognition, as in connectionist models? Despite more than two decades of fighting, neither side has one out yet, and I wouldn't be surprised if this debate ended in a compromise like the one that initially ended the imagery debate.

But the nativism vs empiricism debate has been a part of cognitive science since its birth, and probably isn't going away anytime soon. As you probably know, cognitive science was born out of a revolt against behaviorism. Behaviorism was a particularly strong version of empiricism, in which all, or virtually all behavior was learned through associations. Many of the cognitive revolutionaries rebelled against empiricism as they rebelled against behaviorism. The most famous of these is, of course, Noam Chomsky, whose nativist theory of language has dominated linguistics and cognitive science in general for nearly 50 years. But empiricism didn't die with behaviorism. So for those same 50 years, people have debated whether pretty much every particular cognitive ability and process is innate or learned. For the most part, cognitive scientists now believe that some processes are innate, and some are learned, and no one is a strict nativist or empiricist (except Jerry Fodor, who is a strict nativist, believing that even concepts are innate). But there are still local debates over innateness, and in most cases, a particular cognitive ability is thought to be either innate or learned, with no middle ground.

This is where Tomasello takes issue with the way cognitive scientists view the mind. He argues that this either/or way of approaching things is bad biology, and it's not very useful either. Very few of our cognitive abilities are present, in their entirety, at birth (though if they are, or even if primitive versions are available early in infancy, nativists will argue that they are innate). Instead, these abilities develop over time and through our interactions with our environment. And this, Tomasello believes, is what we should be trying to understand: how these abilities develop ontogenetically. Trying to decide whether the abilities are innate or not doesn't help us in that task, unless it is directed at attempting to understand that development. I think this is a very important message, and one that I obviously haven't fully taken to heart (in a paragraph in this post, I've taken an either/or perspective, even). But it is a message that we cognitive scientists must learn if we're going to be able to use the study of our cognitive development to fully understand human cognition.

Now, I can't say that I find Tomasello's approach to the study of development entirely satisfying. His approach is to divide learning into two types: individual and cultural. Individual learning occurs through insight that we gain while interacting with our environment on our own, while cultural learning occurs through collaborative interactions with other individuals. This may be a fruitful approach experimentally, in that it may be important to control either individual or cultural factors, to the extent that it is possible, in order to understand particular factors in cognitive development. But in practice, and certainly in actual development, I'm not sure it's really possible to separate the two. Sure, human children are occasionally alone (some more than others), but for the most part, our development takes place in a rich social environment, and while not all of our interactions with that environment are collaborative, they are all impacted by culture. Where does cultural learning end, and individual learning begin? I'm not sure cognitive science can provide an answer to that question, or that it needs to.

Still, I think Tomasello's general approach, which is to focus on development, be it individual or cultural, is the right one. God knows how many hours of research and pages in journals have been wasted arguing over whether a particular cognitive ability is innate, and with little insight into the ability itself coming of it. If we focus on development, we can gain great insight into the different aspects of those individual abilities. The book chapter on causal reasoning in infants that I linked in the last post on Tomasello (it's here, if you didn't read it then) is a great example of this. By looking at the stages of the development of infants' concepts of causation, the authors show us different aspects that are contained in our fully developed causal reasoning. Of course, if you read the chapter through, you'll notice that the authors end up taking a stand on one side of the nativism-empiricism debate, which is unnecessary, but old habits die hard. Fortunately, that wasn't the main focus of the chapter, and as a result, their review of the developmental research is enlightening.

In the next chapter, Tomasello will focus exclusively on development. He'll occasionally mention nativist and empiricist theories, and I must admit that at times it looks like he's taking a distinctly empiricist position, even if he believes that doing so is unproductive. But for the most part, his focus is on the developmental sequences in cognitive development. I hope his approach will serve as a model for all of those cognitive scientists who are stuck in mostly fruitless debates over innateness.


Blar said...

Individual learning occurs through insight that we gain while interacting with our environment on our own, while cultural learning occurs through collaborative interactions with other individuals. ... But in practice, and certainly in actual development, I'm not sure it's really possible to separate the two.

Tomasello discusses, and basically accepts, your critique (on pp. 52-53). He says that it is still a distinction worth making, and gives two reasons. First, it's useful for figuring out how humans are different from all other primates. My view on that is that I'll accept the distinction for the purposes of this one book, since the puzzle that he is looking at and the argument that he is making really depend on making some distinction of this sort. However, I don't see that argument as giving us much of a reason to carry the distinction into other aspects of cognitive science. His second argument in favor of the distinction is that "it helps to capture what is perhaps the fundamental dialectical tension in human cognitive development: the tension between doing things conventionally ... and doing things creatively" (p. 53). I see the importance of the conventional/creative tension (which appears throughout history as conservatives vs. progressives, or revolutionaries vs. gradualists, or in some other guise), but I'm still withholding judgment on the relevance of his cultural vs. individual distinction to this tension.

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