But with the theory theory, and the corresponding psychological essentialism view of concepts, came a recognition that concept names might be important. Since concepts are treated as embedded in a larger knowledge structure, and according to psychological essentialism, concept names refer to underlying essences (ala Putnam), whether they exist or not, it made sense to treat names as unique among category features, if they could be treated as features at all. If this is true, then concept names should be treated as of a different kind than other features of concepts.
Concept researchers took heart, and finally went out and sought data about the relationship between names and other features. For example, Yamauchi and Markman1 used the classic classification paradigm, in which participants are given features and asked to infer the category label, and a variation of that paradigm, in which participants are given the category label and some features, and asked to infer a missing feature. If labels are just like any other features, then the variation (called the "inference task," perhaps unwisely, since both tasks involve an inference), then participants should perform similarly in both tasks. However, if labels are different from other features, then when participants are given the label, the sorts of inferences they make should be diferent. Yamauchi and Markman's experiments showed that people do in fact treat the label differently. When the label is present, participants infer category-typical features more often, even when the other features they are given are more similar to the features of contrast categories. For instance, if the prototype of category A is
1 1 1 1and the prototype of category B is
0 0 0 0where 1's and 0's represent the value on a particular feature dimension (e.g., 1=tall and 0=short), and participants receive the category label A, along with three features, 0 0 0, they are more likely to infer that the fourth feature will be a 1, even though the three 0's makes the instance about which they are making an inference more similar to the prototype of category B. In other words, given the implication of category membership that comes with the presence of the category name, people will infer category-typical features when the label is present, even when all of the other information seems to contradict this inference. This finding is a blow both to similarity-based views in general and their belief that labels are just ordinary features.
In developmental research, similar results have been found. For instance, in one study2, children were presented with information about a person (e.g., she eats a lot of carrots), and then either given a label (e.g., "She is a carrot-eater") or a sentence that confirms that information ("She eats carrots whenever she can"). The results showed that children were much more likely to make inferences about a person when given a label, and that they believed the traits implied by the label were much more stable than when they were attributed to the person without the label. Thus, children think that a carrot-eater is much more likely to be eating carrots at some later date than someone who just eats carrots whenever she can. Once again, it appears that concept names, and their implications of category membership, are influencing the inferences that people will make about instances, and furthermore, that the importance of names develops fairly early in childhood (the children in the study were between 5 and 7).
The Markman and Yamauchi studies used artificial categories that were designed to be like natural kinds (complete with bug-like pictures), and the carrot-eater studies used trait concepts applied to humans. It is reasonable to assume that people are essentialists about natural kinds, and perhaps even human personalities, but what about artifacts? Putnam's "Twin Earth" thought experiment, and the original claims of psychological essentialism, are difficult to apply to artifacts. Water can be said to have an essence (its chemical composition, H2O), but what is the essence of a chair? If artifacts don't have essences, are artifact labels more like the labels of natural kinds and human traits, or are they more like other artifact features? Paul Bloom3 has recently argued that psychological essentialism does apply to artifacts. People treat the intentions of the author (or creator) as the essence of artifacts. This explains why certain objects are treated as members of artifact categories despite being highly dissimilar from other members of that category (e.g., bean bag chairs). Conducing experiments similar to the Yamauchi and Markman and carrot-eater studies on artifacts might help to confirm Bloom's view.
Or maybe not. Do labels really refer to essences? A recent review of the developmental literature has shown that concept names have much more influence on children's reasoning about artifacts than about natural kinds, with human traits being somewhere in between the two4. This is the opposite of what we would expect from traditional essentialist theories. Furthermore, in a now imfamous study, Barbara Malt has shown that people's use of the name "water" is not consistent with their essentialist intuitions about water5. She asked people about their beliefs about the amount of water in different kinds of liquids, and showed that such beliefs were not correlated with their use of the label "water." For instance, tea and lemonade were believed to have a much higher water (as in H2O) content than a natural lake, but the liquid in lakes is referred to as water, while lemonade and tea are referred to as, well, "lemonade" and "tea." If this is the case, then psychological essentialism may ot explain the importance of names, and the importance of names in artifacts may not provide evidence of psychological essentialism about artifacts.
What are names, then? Clearly they are important, but why? What information do they carry with them that other features do not? If labels do not refer to underlying essences, how do we explain their deep connection to category membership, as demonstrated in the inference and carrot-eater studies? My own suspicion is that names are closely connected to the position that a concept takes in a larger relational system. Thus, names not only provide information about typical features and essences (such as function for artifacts and chemical composition or genetic make up for natural kinds), but also how a concept differs from related concepts, and how it fits into our knowledge base. I think of names as sort of like suitcases that are held in the hands of relations. When names are used, the suitcases can be unpacked, and out will flow all sorts of relational information. Many names may even be empty suitcases, telling us little more than where a concept is situated in a relational system. It is in these cases that people hold strong essentialist intuitions, but when queried, are unable to express what the essences of such concepts may be. Such appears to be the case for concepts like GAME, for instance. The position of the suitcase itself is all of the information we really have about the concept. Any inferences we make will have to come from that. Of course, there's no direct empirical evidence for my view, but there's not much direct empirical evidence for other views of names either, since the essentialist theory of names has been called into question. So, mine's as good as anyone elses, from an empirical standpoint.
1 Yamauchi, T., & Markman, A.B. (2000). Inference using categories. Journal of Experimental Psychology: Learning, Memory, and Cognition, 26, 776-795.
2 Gelman, S.A., & Heyman, G.D. (1999). Carrot-eaters and creature believers: The effects of lexicalization on children's inferences about social categories. Psychological Science, 10(6), 489-493.
3Bloom, P. (1996). Intention, history, and artifact concepts. Cognition, 60(1), 1-29.
4Diesendruck, G. (2003). Categories for names or names for categories? The interplay between domain-specific conceptual structure and language. Language and Cognitive Processes, 18(5-6), 759-787.
5Malt, B.C. (1994). Water is not H2O. Cognitive Psychology, 27, 41-70.