What makes a word?

Abstract

What makes a word? Eliana Colunga (eco1unga@cs.indiana.edu) Department of Psychology; 1101 East 10th Street Bloomington, IN 47405-7007 USA Linda B. Smith (smith4@indiana.edu) Department of Psychology; 1101 East 10th Street Bloomington, IN 47405-7007 USA Abstract Words seem to have a special status among percep- tual signals. The developmental evidence, however, suggests that words become special. Woodward and Hoyne (1999) showed that 13-month-olds readily as- sociate both words coming from the experimenter’s mouth and non-linguistic sounds coming from a hand-held noisemaker, with object categories. In contrast, 20-month-olds associate words but not non-linguistic sounds with object categories. Wood- ward and Hoyne suggest that words become privi- leged as possible names; that the forms a name can take are open at the beginning and become more restricted with development. Are children learning what forms count as words? If so, just what defining features are they learning? This paper presents an associationist account of this developmental trend and tests this explanation in two experiments with 20-26-month-old children. Introduction Words seem to have a special status among percep- tual signals. Having a label for an object changes the way it is categorized for both adults and chil- dren. For example, when asked to generalize an object name to new instances, children and adults generalize by shape. However, when asked to find an object that “goes with” another, they choose by overall similarity (Landau, Smith & Jones, 1988; Imai & Gentner, 1997). A label also makes children’s choices shift from thematic to taxonomic (Waxman, 1997) and from surface to more conceptual similari- ties (Keil, 1989) . As Waxman said, words work like invitations to form categories; words are category names. But what makes a word? How do children know whether a particular sound is a category label? One finding critical to this issues was reported by Woodward and Hoyne (1999) . They presented children with two novel objects and labeled one of them (the target object). In the Word condition they paired the target object with a word (“this is a toma”); in the Sound condition they paired the target object with a non-linguistic sound, such as a tone. Children were then asked to “get the toma” or “get the l tone g” to test whether they had as- sociated the “label” (toma or l tone g) with the object. They asked: Do children treat only words as possible names or do they also accept tones as pos- sible names? Their results indicate that the answer to this question depends on the developmental level of the child. Thirteen month-old infants will asso- ciate both a word and a non-linguistic sound with a target object. In contrast, 20-month-old children will associate a word to a target object, but not a non-linguistic sound. Namy & Waxman (1998) have similar results for 18- and 26-month-olds contrasting words and gestures. While the younger children will associate both a novel word and a novel gesture with a target object (object category) the older children will only associate the word to the object, and not the gesture. Both teams of researchers suggest that older chil- dren do not associate non—words with the objects because older children know that non—words are not possible names. The idea is that words become priv- ileged as possible names; that the forms a name can take are open at the beginning and become more restricted with development. But how do words be- come names and thus privileged? What determines what counts as a name? In this paper we attempt to answer these ques- tions. First we offer a mechanistic explanation of this developmental trend. Then we present two ex- periments that test our explanation. An associationist account We propose that words become privileged as cate- gory names because of the special way in which they correlate with object categories. In the experience of a child, many events may co-occur with attention to objects. For example, objects may co-occur with ex- pressions such as “lookl”, gestures such as pointing, words related or unrelated to the object, noises, ac- tions related or unrelated to the nature of the object, and so on. However, of all these events, words (as object names) correlate in a way that makes them especially good predictors for category membership. By our account, there are two properties that make words good candidates for becoming privileged as names. The first property is predictiveness or cue validity. There is one name (more or less) that goes with one category (more or less). Thus, the name of