The Principle of Mutual Exclusivity in Word Learning: To Honor or Not to Honor? Author(s): Terry Kit-fong Au and Mariana Glusman Source: Child Development, Vol. 61, No. 5 (Oct., 1990), pp. 1474-1490 Published by: Wiley on behalf of the Society for Research in Child Development Stable URL: http://www.jstor.org/stable/1130757 . Accessed: 27/09/2013 01:58

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This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions The Principle of Mutual Exclusivity in Word Learning: To Honor or Not to Honor?

Terry Kit-fong Au and Mariana Glusman Brown University

Au, TERRYKIT-FONG, and GLUSMAN,MARIANA. The Principle of Mutual Exclusivity in WordLearn- ing: To Honor or Not to Honor? CHILDDEVELOPMENT, 1990, 61, 1474-1490. Accordingto Markman and Wachtel,children assume that nouns pick out mutuallyexclusive object categories,and so each object should have only one categorylabel. While this assumptioncan be useful in word learning,it is not entirely reliable. Therefore, children need to learn when to and when not to make this assumption. 6 studies examined whether knowledge about hierarchicalorganization of categories and about cross-languageequivalents for object labels can help children limit their use of this assumptionappropriately. These studies revealed thatadults as well as childrenresisted assigning 2 novel names to the same object in some situations.By age 4, children also seemed to know enough about categorizationto accept 2 names for an object if the names picked out categoriesfrom different levels of a hierarchy(e.g., animal and lemur) but not if they picked out categories from the same level (e.g., lemur and seal). Moreover,monolingual as well as bilingual children seemed to know enough about languages to accept 2 names for the same object if the names clearly came from different languages. Together, these findings suggest that even preschoolchildren can make use of knowledge about language and categorizationto fine tune the mutual exclusivity assumptionin order to use it effectively in word learning.

For any finite amount of information Gelman, 1988), an object part (Markman & about a new word meaning, there will be nu- Wachtel, 1988), or a thematic relation (Bauer merous hypotheses consistent with it (Pierce, & Mandler, 1989; Markman & Hutchinson, 1957; Quine, 1960). How is it, then, that chil- 1984; Waxman & Gelman, 1986). Markman dren often manage to settle on the correct hy- and Hutchinson (1984) argued that such a pothesis? One possibility is that children preference reflects the taxonomic constraint have many reasonable beliefs about word children place on noun meanings (see Nel- meanings, and such beliefs help them rule son, 1988, for a critique). out numerous incorrect hypotheses and settle Another belief about word meanings that on the correct one (Brown, 1957; Clark, 1983; children seem to hold is that words pick out Goodman, 1955; Keil, 1979; Landau & Gleit- mutually exclusive categories (Markman & man, 1985; Macnamara, 1982; Markman & Wachtel, 1988; Merriman & Bowman, 1989). Hutchinson, 1984; Markman & Wachtel, Each object, then, should have only one cate- 1988). gory label. How might the mutual exclusivity Imagine that a child saw two toys-a dog assumption help children induce a new word and a lemur-and heard, "Look at the meaning? Suppose a child who knew dog lemur!" The new term could have referred to heard "Look at the lemur!" in the presence of "pair of animals," "friends," "fur," "stripes," a dog and a lemur. If the child assumed that "tail," as well an object such as "lemur" or dog and lemur picked out two mutually ex- "animal." Nonetheless, in this kind of context, clusive categories-and hence something children often interpret a new word as an ob- could not be both a dog and a lemur-the ject-category label rather than as a label for a child could figure out which animal was be- color or substance (Au, 1985, 1990; Baldwin, ing named. That is, the child might reason 1989; Clark, 1973; Dockrell & Campbell, that since the dog was a dog and hence could 1986; Soja, Carey, & Spelke, 1985; Taylor & not also be a lemur, the lemur had to be the

We are gratefulto the children,teachers, and parentsof Brown-FoxPoint Day-CareCenter, the Children's Center of Pawtucket,Joslin Day-CareCenter, PawtucketDay Nursery,and Pied Piper Nursery School for their cooperation.We thank Judith-AnneLarsen, GregoryMurphy, and three anonymousreviewers for their helpful and extensive commentson the manuscript.Jennifer DeWitt, Kristi Erdal, Denise Laframboise,and Allison Sidle offered valuable help in data collection. This work was supported in part by BRS Grant5-27350 from Brown University. Requests for reprints should be sent to TerryK. Au, Departmentof Psychology,Brown University, Providence, RI 02912. [Child Development, 1990, 61, 1474-1490. ? 1990 by the Society for Researchin Child Development, Inc. All rights reserved.0009-3920/90/6105-0004$01.00]

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions Au and Glusman 1475 referent for the novel term. Indeed, several and preschool children (Gelman, Wilcox, & studies have shown that young children tend Clark, 1989; Macnamara, 1982; Mervis, 1987). to apply new names to unnamed objects Finally, a child might restrict generalization (Dockrell & Campbell, 1986; Golinkoff, of a word by avoiding things that are referents Hirsh-Pasek, Lavallee, & Baduini, 1985; of other words. This effect is closely related to Hutchinson, 1986; Markman & Wachtel, the second one, except that it concerns initial 1988; Merriman & Bowman, 1989; Vincent- decisions about whether a name applies to an Smith, Bricker, & Bricker, 1974). object, whereas the second effect concerns revisions of these decisions. Merriman and According to Markman and Wachtel Bowman (1989) found that, around (1988; mutual by age 3, Markman, 1989), exclusivity children to avoid would be a reasonable for chil- begin generalizing two con- assumption trastive nouns dren to make because most of the words chil- (e.g., spoon andfork) to objects that have properties characteristic of each dren hear tend to name mutually exclusive (e.g., a hybrid spoon-fork). categories. For example, chair, table, spoon, and cup denote mutually exclusive catego- Although the mutual exclusivity assump- ries, and so no object can have more than one tion can be useful, it has to be suspended of these names. Similarly, cat, dog, horse, sometimes so that children can learn names and cow also denote mutually exclusive cate- for overlapping categories. Indeed, by age 3 gories. Markman and Wachtel also noted that or 4, children can suspend this assumption the most useful kinds of category tend to be when there is compelling evidence that a mutually exclusive. Since richly structured new word (e.g., animal) overlaps in meaning categories such as "dog," "cat," "boat," and with a familiar word (e.g., dog). For example, "car" provide much correlated information "achild who thinks that her pet cannot be both about an object, to be a member of more than "adog and an animal may accept both labels one such category would require an object's for her pet if an adult explains to her, "A dog having more than one set of correlated attri- is a kind of animal" (Callanan, 1989; Mark- butes. As a result, a single object tends not to man, Horton, & McLanahan, 1980; Mervis, belong to more than one richly structured cat- 1987; Waxman & Shipley, 1987). Young chil- egory. In order for categories to be informa- dren also seem to be sensitive to a variety of tive, then, they will tend to be mutually ex- rather subtle cues that mutual exclusivity clusive. If children are inclined to look for does not hold in certain situations. Merriman mutually exclusive categories to map novel (1986) found that 4- and 6-year-olds accepted words on, they also will tend to construct the two names for the same object if the same most useful kinds of category. object properties had been highlighted when each name was introduced. Not only is the mutual exclusivity as- Markman and Wachtel found that some sumption reasonable, it is also potentially (1988) 4-year-olds very powerful. As Merriman and Bowman suspended the mutual exclusivity assumption (1989) pointed out, it could affect word learn- when it conflicted with the taxonomic con- Merriman ing in four ways. First, it could affect chil- straint. and Bowman (1989) and dren's decisions about the referent of a new Anglin (1977) found that even if preschoolers had a name for word. The dog and lemur example is an illus- specific something, they would avoid a tration of this effect. Second, it could compel applying general name to it if it was an member of the children to narrow the category they have only atypical cate- constructed for a familiar name whenever gory denoted by the more general name. For they hear a new name used for a member of instance, if they were told that a novel car was that category. The result could be either cor- a "bave," they would avoid calling it a "car" if it was an rection of an overextension (e.g., after hearing only atypical car. to a the child goat applied goat, stops apply- This article will examine two kinds of ing to it) or creation of an underextension dog knowledge that may help word learners sus- (e.,g., after hearing chihuahua to a applied pend the mutual exclusivity assumption to chihuahua, the child to stops applying dog it). learn multiple names for objects. The first is Merriman (1986) observed this effect in 4- the knowledge that words can pick out cate- and 6-year-olds in a word-learning experi- gories from different levels of a hierarchy. ment (see also Barrett, 1978; Leopold, 1949). The second is the knowledge that an object Third, mutual exclusivity could also lead chil- can have different names in different lan- dren to reject a novel label for something they guages. can name already (e.g., a child who knows car denies that a car can also be called a vehicle). Hierarchical organization of categories Such behavior has been observed in toddlers named in languages.-Most, if not all, object

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions 1476 Child Development categories can be organized into hierarchies. if the names pick out categories from different Within a hierarchy, more specific categories levels of a hierarchy. Studies 2 and 3 to be (e.g., dog) are included in more general ones reported here further examine whether pre- (e.g., animal). Such categories are clearly not school children will violate mutual exclusiv- mutually exclusive. By contrast, categories ity across levels of categorization but will within the same level of specificity are mutu- honor mutual exclusivity within each level. ally exclusive (e.g., dog, cat, horse, tiger). If names in different lan- we name things at a particular level in a Different guages.-Bilingual children generally begin hierarchy, we will be correct in assuming that to refer to objects with two different names, words denote mutually exclusive categories. one in each language, after they have ac- In fact, we do tend to name things at what is quired about 150 words (Clark, 1987; Taesch- known as "the basic level of categorization" ner, 1983). There is some evidence that bilin- (Rosch, Mervis, Gray, Johnson, & Boyes- gual children may do so even from their first Braem, 1976). In neutral or unmarked situa- words on. For instance, Pye (1986) reported tions, we usually refer to an object with a that one bilingual child seemed to have al- label such as dog or chair. We tend not to use lowed cross-language equivalents from age a more general label such as mammal, 14 months on. By age 3 or 4 years, bilingual animal, or or a more furniture, artifact, children can readily produce and under- specific label such as terrier or recliner stand many equivalents across languages Both adults and children tend to name (McLaughlin, 1984). These observations sug- objects with basic-level category labels (e.g., gest that bilingual preschoolers do not honor Anglin, 1977; Brown, 1958; Rosch et al., mutual exclusivity across languages. How- 1976; Wisniewski & Murphy, 1989), and ever, there are some experimental data that within the basic level, categories are mutually seem to suggest the contrary (Glusman, 1988). exclusive. Therefore, when one sees a dog In one study, five Spanish-English bilingual and a lemur and hears "Look at the lemur," children were first taught a novel category one may think it is a good bet that the novel name in English (e.g., mido) on a novel toy word picks out a basic category that does not animal (e.g., a lemur with sewn-on horns). overlap with dog. Study 1 examines whether, Then a different experimenter showed the like preschoolers, adults also honor mutual children several toy animals (two lemurs and exclusivity when interpreting a novel noun, two seals, with novel features added to them) even though they know that mutual exclusiv- and asked the children in Spanish to find ity is not an infallible assumption. something that could be named by a second novel word. For a child be Studies 2 and 3 focus on whether chil- example, might asked "Is there a here?" in dren will two labels for the same ob- twice, lepid Span- accept ish. Four of these five children if believe that the labels denote cate- bilingual ject they avoided the of the cate- from different levels of a choosing exemplars gories hierarchy. labeled in another Most have more than one cate- gory previously language preschoolers the two chose the label for certain For (i.e., lemurs). Instead, they gory things. instance, the Al- know that their is an animal as as-yet-unlabeled toys (i.e., seals). they may pet the size was it well as a that their train is a as though sample small, sug- dog; toy toy that children avoid as- well as a train. That to learn that gested bilingual might is, they begin two names to the same can be at levels. signing category objects categorized multiple even when the names came from dif- If children have reasons to believe that some- object, ferent languages. one is referring to an object at more than one level of categorization, will they accept two Glusman (1988) has also replicated this names for the same object? There is some evi- finding with a larger sample and a somewhat dence that even 2- and 3-year-olds can learn a different procedure. Eight of the nine bilin- new subordinate label, such as terrier and gual children in that study honored mutual mutt, for an object that they already have a exclusivity across languages. Unfortunately, basic label for, such as dog (Mervis, 1987; while the sample size was larger in that study, Taylor & Gelman, 1989; Waxman & Shipley, only one exemplar instead of two was pre- 1987). Two- and 3-year-olds can learn su- sented for each animal category. One could perordinate labels such as toy and food for argue that some of the children might have things for which they already know the basic- interpreted the novel labels as proper names level labels (Callanan, 1989; Callanan & such as Fido and Spotty, and that this study Markman, 1982; Waxman & Gelman, 1986). may simply have shown that children were In other words, preschool children sometimes reluctant to give two proper names to the are willing to accept two names for an object same toy animal. Glusman's findings are

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difficult to interpret also because the experi- edge that a thing can have different labels in menter who ran the Spanish part of the proce- different languages to suspend the mutual ex- dure was bilingual in English and Spanish, clusivity assumption appropriately when they and the children had heard her speak in both are sure that the labels come from different languages prior to the experiment. Perhaps languages. Study 6 looks at whether even these bilingual children did honor mutual ex- monolingual children will do so when the clusivity within a language, and they were not novel names clearly come from different lan- sure whether the novel word introduced by guages. Together, these six studies examine the bilingual experimenter came from the whether children and adults limit the use of same language as the first novel word. It is mutual exclusivity appropriately to learn mul- possible that they thought both terms were tiple names for an object when they believe English words and hence should name mutu- that the names pick out categories from differ- ally exclusive categories. It remains to be ent levels of a hierarchy or that the names seen, then, whether bilingual children will come from different languages. readily accept two labels for the same object when they are sure that the labels come from different languages. Study 1 As children Given that Glusman pronounced the acquire multiple category names for more and more will novel words with accents appropriate to the things, they mutual because context languages, it might seem unlikely that give up exclusivity they realize that it is a Or will the children could not tell which language faulty assumption? hold on to it as a default because the novel labels belong to, especially when 5- they option month-old infants seem able to discriminate people tend to refer to things at the basic level of within that English and Spanish on the basis of pho- categorization and, level, are indeed exclusive? It nological cues (Bahrick & Pickens, 1988). categories mutually is that children will continue to However, when characteristics of language possible honor mutual because it is a use- mixing are considered, it seems plausible that exclusivity not when phonological cues alone might not be ful, though infallible, assumption a first about a new word mean- sufficient to mark which language a novel making guess This had two it at- word comes from. When bilingual speakers ing. study goals. First, to the of mix language, the "foreign" element is often tempted replicate finding previous studies that children honor mutual assimilated phonologically into the context preschool when a novel noun. language (Gibbons, 1987; Gumperz & Her- exclusivity interpreting it examined whether adults also nindez-Chavez, 1971). For instance, an En- Second, honor mutual in word glish word embedded in a Spanish utterance exclusivity learning. is often with a accent. pronounced Spanish Method Thus, if the bilingual children in Glusman's studies were not sure whether a novel term Subjects.-Twenty children from two centers in Rhode Island and was an English word or a Spanish word, hear- day-care (12 boys and 26 students at Brown Univer- ing it pronounced with a Spanish accent in eight girls) men and 10 in the context of a Spanish utterance might not sity (16 women) participated have been sufficient to assure the children this study. The children ranged in age from 3- 6 to 5-11 = that the novel label was a Spanish word. (mean 4-5). There is anecdotal evidence that a suggesting Stimulus materials.-Stuffed animals child can acquire two languages faster if some toy were modified to yield two stimulus sets. One people speak to the child in one language and set consisted of four mammals (two lemurs others in the other language and no one and two seals); the other set, four reptiles (two speaks both languages to the child (Pav- alligators and two dinosaurs). Unusual fea- lovitch, 1920; Ronjat, 1913; Taeschner, 1983). tures such as the children in Glusman's horns, floppy ears, and feathered Perhaps bilingual tails were sewn onto would have two labels these animals so that (1988) study accepted even from different for the same if adults should not have ready labels for languages object them. members the two lemur- each experimenter had consistently spoken Category (e.g., like animals) were modified from identical only one language in front of the children. toys but had different added features. The Such "one person, one language" mapping novel labels used in this were might have made it clear to the children that category study two-syllable nonsense words. The stimulus the labels came from different languages. words used were: archo, chorda, gavi, glire, Studies 4 and 5 examine whether bilin- lepid, loric, mido, nycti, odob, pinni, syri, and gual adults and children can use their knowl- theri.

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Procedure.-Children were tested indi- exclusivity, there would be no need to avoid vidually in a quiet room in their day-care cen- choosing the previously labeled toys. Experi- ter; adults, in a quiet comer of a library or a menter 2 went on to point at the toy used cafeteria on campus. Each subject saw two earlier for introducing the first novel label and experimenters. Experimenter 1 first taught a asked, "Can this be a theri? Why? [or Why subject a novel label on a novel object. Exper- not?]" She then said that she had to go and imenter 2 then asked the subject to find refer- the other experimenter would come back. Fi- ents for a second novel label. If the subject nally, Experimenter 1 returned to test the honored mutual exclusivity when interpret- subject's memory for the first novel word. She ing novel nouns, the subject should avoid ap- displayed the four toys and asked, "Can you plying both novel labels to the same object. hand me a mido? Can you hand me another Two experimenters were used here because mido?" The stimulus sets and nonsense we wanted to compare the findings with words were randomly assigned to subjects. monolingual subjects in this study to those Each subject saw only one stimulus set, with bilingual subjects in Study 4, which namely, either the mammals or the reptiles. would use a procedure similar to that of Glus- Each toy was used roughly equally often for man's (1988) and hence would have two ex- introducing the first novel label. perimenters as well. The procedure of the present study will be illustrated with the Results and Discussion novel terms mido and theri, the stimulus set Most of the adults and children seemed consisting of two seals and two lemurs, and to honor mutual exclusivity when interpreting the first novel label being taught as applicable novel nouns. That is, they avoided assigning to one of the lemurs. two category names (e.g., mido and theri) to the same object (e.g., a lemur). The results Introduction of a novel label: Experi- will be organized into two parts: (1) the acqui- menter 1 taught the subject the novel name, sition of the first novel label, (2) the interpre- mido, on a novel toy animal, the lemur with tation of the second novel label. sewn-on pink hornms.An adult would hear, "This is a mido." A child would hear the The acquisition of the first novel label.- novel term seven times: "This is a mido. Can Recall that the subjects were asked to identify you say mido? Do you like this mido? Can referents for the novel label (e.g., mido) both you touch the mido?" and so on. The subject immediately after the introduction of the was then shown the lemur again, along with label and at the end of the procedure. Eigh- the other three toys in the stimulus set (an- teen of the 20 children and 21 of the 26 adults other lemur and two seals). Experimenter 1 chose both members of the target category then asked, "Can you show me a mido?" (e.g., the two lemurs) and not the other toys Once the subject handed her one toy, she (e.g., the two seals) on both occasions. The asked, "Can you show me another mido?" Ex- other two children and five adults consis- perimenter 1 then said that she had to be tently chose only the toy that was used for away for a little while, and that another exper- introducing the novel label (e.g., the lemur imenter wished to talk to the subject in the with sewn-on pink horns) but not the other meantime. If the subject was a child, Experi- toy in the same basic-level category (e.g., the menter 1 would also say that when she re- lemur with sewn-on purple horns). It is un- turned, she and the child would play a game clear whether these seven subjects inter- with the midos, and so it was important that preted the novel label as a proper name like the child remember what the midos looked Fido or as a name for the category "lemur like. with pink horns." If they interpreted the term as a proper name, any reluctance to accept a of a second novel label: Interpretation second name for the original toy (e.g., the 2 the and Experimenter greeted subject put pink-horned lemur) could reflect reluctance out the same four (two lemurs and two toys to give two proper names to the same toy She then seals). asked, "Can you show me a animal. Since the focus of this study was on Once the theri?" subject handed her a toy, the acquisition of object category terms rather she "Can show me asked, you another theri?" than proper names, these seven subjects' re- If the assumed that words subject picked out sponses were excluded from further analyses. mutually exclusive categories, the subject However, it is important to note that exclud- should avoid two names to the same giving ing these subjects' responses did not change For when asked to object. instance, find a the major results of this study. theri, the subject should avoid choosing the two lemurs because they had been labeled as Interpretation of the second novel midos. If the subject did not honor mutual label.-When Experimenter 2 asked the sub-

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions Au and Glusman 1479 jects to find referents for a second novel word, preting novel nouns. It further showed that most subjects avoided choosing the toy ani- both children and adults assume that words mals to which the first novel label had been pick out mutually exclusive categories if there assigned. For instance, if the children as- is no evidence to the contrary. This is rather sumed that the lemurs were called midos, surprising because adults undoubtedly know when twice asked, "Is there a theri here?" many words that name overlapping categories they chose the two seals and not the lemurs. (e.g., dog, animal, pet). Nonetheless, they Seventeen out of 18, or 94%, of the children seem to honor mutual exclusivity when inter- did so (p < .0005), as did all of the 21 adults (p preting novel nouns. Perhaps like children, < .0001; unless specified otherwise, all statis- they do so because they notice that when peo- tical tests reported in this article were two- ple introduce novel labels for objects, such tailed sign tests). That is, all but one subject labels tend to denote mutually exclusive cate- seemed to honor mutual exclusivity. This gories. This intuition would be quite consis- finding is consistent with Merriman and Bow- tent with the fact that people tend to name man's (1989) view that this assumption is a things at the basic level of categorization, and default option. That is, when there is no evi- within that level in a hierarchy, terms do de- dence contradicting mutual exclusivity, ev- note mutually exclusive categories. However, eryone should select the default option. In- despite its usefulness in word learning, deed, in the absence of any contradicting mutual exclusivity is not an entirely reliable information, 94% of the children and 100% of assumption about word meanings. It is there- the adults in this study did so. fore critical for children to learn when not to make this assumption. The subjects were then asked explicitly whether a previously labeled toy could also be a referent for the second novel label. Sup- Study 2 a had learned to label the lemurs pose subject There is some evidence that as midos and avoided the lemurs from quite choosing on children can learn to an when asked to find the theris. The early label object subject at more than one level of a As was then shown a lemur and "Can this hierarchy. asked, noted can learn to label be a theri?" Thirteen out of or of the earlier, 2-year-olds 18, 72%, at both the basic children and 13 out of or of the objects level, for example, 21, 62%, with the word and adults "No." children and dog, subordinate level, for responded Eight with the word nine adults their answers example, collie; 3-year-olds are justified by saying able to learn such that their stimulus was else superordinate labels as toy something animal and That some- "It can't be a theri because it's a food. is, preschoolers (e.g., mido"). times will mutual in The adults who "Yes" ex- suspend exclusivity or- eight responded der to learn to label an at different that mido could be a kind of theri, object plained levels of What remains unclear that mido and theri could be or categorization. synonyms, is whether children will that names were and could violate mutual ex- arbitrary people across levels but to name to an The five clusivity honor it within agree give any object. each level of a This children "Yes" "Be- hierarchy. study examines responding simply said, whether children will cause it could be!" about two- accept two names for Importantly, the same when thirds of the children and adults de- object they have reason to be- explicitly lieve that the nied that the second label could to a names come from different apply levels of referent for the first label. Since neither ex- a hierarchy and, at the same time, will avoid giving an two names within perimenter had applied theri to any object, its object one level of the hierarchy. meaning was open to various interpretations such as "pink-horned lemur," "spotty-tail Method seal," "mammal," "toy," "object," and so forth Subjects.-Twenty children attending in addition to the apparently favored interpre- two day-care centers in Rhode Island partici- tation "seal." That is, while these subjects pated in this study. There were seven boys could have applied their second novel word and 13 girls, and they ranged in age from 3-9 (e.g., theri) to a category that overlapped with to 5-9 (mean = 4-9). the category labeled by their first novel word for the labels (e.g., mido), they opted applying Stimulus materials.-The toy animals to two mutually exclusive categories. and the nonsense words of Study 1 were used In short, this study replicated the finding here. Four additional nonanimal toys, of previous studies that preschoolers avoid namely, two blocks and two balls, were also giving two category names to an object and used in a comprehension test for the term thereby honor mutual exclusivity when inter- animal.

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Procedure.-The procedure was identi- jects (e.g., the seals). Unlike the first novel cal to that used with children in Study 1 ex- label, the second label, theri, had not been cept for two modifications. First, a compre- taught on any object at all. As far as the chil- hension test of the term animal was added at dren were concerned, it was open to different the beginning of the procedure. Experi- interpretations because no one had told them menter 1 began by showing a child an array of what it meant or what it could refer to. If the four toy animals (e.g., two lemurs and two superordinate-level term animal had made seals) and four nonanimal toys (i.e., two children reluctant to apply another label to a blocks and two balls). She then asked, "Is novel animal, the children could have hon- there an animal here?" After the child had ored mutual exclusivity across levels by refus- handed her one toy from the array, she asked ing to pick any animal when asked, "Can you the question again. This process repeated un- show me a theri?" Or, at least they could have til the question was asked five times. If the protested that they did not know what the child understood the term animal, the child novel label meant. Children's willingness to should pick only the four animals and then apply the second novel label to some of the say there was no animal left. Following this toy animals, then, suggests that perhaps they test, the experimenter taught a new word interpreted the novel label as a basic-level such as mido as before. As in Study 1, only term, and so mutual exclusivity did not hold four toy animals-either four mammals or between the novel term theri and the four reptiles-were presented when the chil- superordinate-level term animal because dren were asked to find referents for their two these terms came from different levels of a novel words. The second modification was hierarchy. that 2 asked an additional Experimenter ques- that children tend tion before she left the child. She at Second, assuming to pointed novel terms as basic-level the used for the first novel interpret labels, toy introducing this that children label and "Can this be a finding suggests honor (e.g., mido) asked, mutual mido and also an animal?" exclusivity when they believe two terms (e.g., mido and theri) come from the Results and Discussion same level in a hierarchy. There was further Of the 20 children, 17 correctly chose all support for this hypothesis. When Experi- four animal toys and none of the nonanimal menter 2 pointed to the toy used for introduc- toys when asked to identify referents for ing the first novel label (e.g., a pink-homed animal. The other three children either lemur previously labeled as mido) and asked, picked randomly or chose the four animal and "Can this be a theri? Why? [or Why not?]," all then one of the nonanimal toys; their re- 16 children responded "No." Ten of them ex- sponses were excluded from further analyses. plained that the toy animal was something Of the 17 remaining children, 16 applied the else (e.g., "Because it's a mido!"). In other first novel label (e.g., mido) to both exemplars words, these children denied that both novel of the target category (e.g., the two lemurs) labels could apply to the same toy. Since no and not those of the other category (e.g., the one had made clear to the children what theri two seals), both immediately after the in- meant, they could have interpreted the word troduction of the label and at the end of the as "pink-horned lemur," "four-legged ani- procedure. One child limited the label to only mal," "furry animal," "toy," and so forth. As the toy used for introducing the label. This a result, it could have been appropriate to call child's responses were excluded from further the mido a "theri" as well. Children's denials analyses because the child might have inter- that theri as well as mido could apply to the preted the novel label as a proper name rather stimulus toy suggest that the children favored than an object category name. Thus, 16 chil- interpreting the novel labels as denoting two dren's responses were retained in the anal- mutually exclusive categories. The explicit yses. probe questions focusing on the first novel label further the that When twice "Can show me a supported hypothesis asked, you child would honor mutual within theri [or whatever the second label was]?" all exclusivity a level and suspend it across levels of a hierar- of the 16 children avoided choosing the ani- chy. While all 16 children said that a mido mals to which the first label had been applied cannot be a 14 of them (p < .0001). That is, they chose only the as- theri, subsequently when "Can this be a yet-unlabeled toys (e.g., the two seals). This responded "Yes" asked, mido and also an animal?" result is important for two reasons. First, it (p < .005). reveals that the children were not at all reluc- A possible explanation is that the chil- tant to accept two labels, namely, animal and dren were sensitive to the fact that when peo- a novel term such as theri, for the same ob- ple introduce novel labels for novel objects,

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions Au and Glusman 1481 they tend to use basic-level category labels, by the difference in the wording of the ques- and that those labels do name mutually exclu- tions. The wordings for the within-level and sive categories. As a result, these children across-level questions were made as similar might assume that novel labels such as mido as possible in Study 3. A second problem was and theri pick out mutually exclusive basic- that the within-level question always pre- level categories. Furthermore, perhaps they ceded the across-level question in Study 2. were also sensitive to the fact that animal is The different responses to the two questions more inclusive than basic-level terms such as could be simply an order effect. The order of dog and cat, which are what people tend to these two questions was randomized and use when naming things. In other words, the counterbalanced across children in Study 3. A children might have believed that the novel third problem was that, in Study 2, the com- labels (e.g., mido, theri) and animal came prehension test for the upper-level label from different levels of a hierarchy, with the animal was given at the beginning of the pro- categories denoted by the novel labels in- cedure, and only those children who passed cluded in the category "animal." the test were kept in the study. Because those who remained in the study had com- These findings, then, suggest that even publicly mitted themselves to the label children are quite willing to accept two labels applying animal to the toy animals to be used in the for the same object (e.g., animal and mido; or comprehension tests of the novel their animal and if they think that the labels labels, theri) agreeing that a mido could also be an animal pick out categories at different levels of a might not be very In the next hierarchy. For instance, while they have a surprising. study, the comprehension test for the superordinate label animal for a novel object upper- level label was put off till the end of the such as a lemur and seal, they are willing to pro- cedure, and performance on the test was not learn a basic label for the category "lemur." used as a criterion to exclude from Moreover, they will also readily apply an en- subjects the study. tirely novel label to the basic category "seal." By contrast, they are reluctant to accept two labels for the same object if they think that the Study 3 labels out at the same level of pick categories Preschool children generally have plenty a such as the basic level. The hierarchy next of basic-level object-category labels but have examines whether this of results study pattern far fewer subordinate-level labels. While they would hold at the basic level and the subordi- may have little doubt that basic-level labels nate level of Because the categorization. hy- pick out mutually exclusive categories given of interest here is pothesis whether children their extensive experience with such labels, it will honor mutual within exclusivity any one is unclear whether they also hold such a be- level of and will it across hierarchy suspend lief about subordinate-level labels. This study levels, it is important to see whether mutual examined whether children would honor will be maintained within exclusivity a level mutual exclusivity within the subordinate other than the basic level. Thus far, experi- level and suspend it across the basic and the mental support for mutual exclusivity concen- subordinate levels. If this turns out to be the trates at the basic level mostly of categoriza- case, one can go beyond the conclusion of tion Studies 1 and (the present 2; Dockrell & Study 2 to a more general one, that children Golinkoff et Campbell, 1986; al., 1985; honor mutual exclusivity not just within the Markman & Hutchinson, 1986; Wachtel, basic level but also within any one level of a 1988; Merriman & Bowman, 1989). The next hierarchy. study examines whether the same pattern of results holds at the subordinate level of cate- Method gorization. Subjects.-Twenty-two children attend- ing two day-care centers in Rhode Island par- Before moving on to the next study, how- ticipated in this study. There were ever, several methodological problems with eight boys and 14 girls, and they ranged in age from 3-11 Study 2 have to be considered. First, the to 5-5 (mean = 4-7). within-level questions (e.g., "Can this be a theri?") and the across-level questions (e.g., Stimulus materials.-Four stuffed toy "Can this be a mido and also an animal?") had animals (a mutt, a beagle, a camel, and a different wording. In Study 2, children flamingo) were used in the comprehension tended to respond "No" to the within-level test for the basic-level label dog. Two toy question and "Yes" to the across-level ques- mutts and two toy beagles-including those tion. While these results are consistent with used in the dog comprehension test-were our hypothesis, they could also be explained used for testing the novel labels. Nonsense

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions 1482 Child Development words such as mido, theri, lepid, and gavi whether the toy used for introducing the first served as novel labels. label could be called by the second novel label as well. For instance, Experimenter 2 Procedure.-The was identi- procedure might point at a beagle and ask, "Can this be a cal to that of Study 2 with these exceptions. mido and also a theri?" Twelve out of 17, or in 2 each child saw of First, Study exemplars 71%, of the children said "No." By contrast, two basic-level either categories, namely, they had little trouble accepting that it could lemur and seal or dinosaur and In alligator. be both a mido and a dog. When Experi- this children saw of two sub- study, exemplars menter 2 pointed at the toy used for introduc- ordinate-level of categories dogs, namely, ing the first novel label and asked, "Can this mutt and children in 2 beagle. Second, Study be a mido [or whatever the novel label was] were asked five "Is there an animal times, and also a dog?" 13 out of 17, or 76%, of the here?" when shown an of four animals array children in this study said "Yes" (p < .05). two lemurs and two or two di- (either seals, Individual children's response patterns were nosaurs and two alligators), two blocks, and also examined. If a child honored mutual ex- two balls. This test for the comprehension up- clusivity within a level but not across levels, label was at the of per-level given beginning the child should respond "No" to the within- the In this the procedure. study, comprehen- level question and "Yes" to the across-level sion for the label was at upper-level dog given question. Eleven of the 17 children gave this the end of the children were procedure. Also, pattern of responses (chance = .25, by a bino- shown four animals a only toy (a beagle, mutt, mial test, p < .001). a camel, and flamingo) and were asked three times, "Is there a dog here?" Third, the word- There was no order effect for these two ings of the within-level and across-level ques- questions. Children were randomly assigned tions were made more comparable than those to one of the two possible orders, 'with 11 chil- in Study 2. If, for example, the within-level dren in each group. The two groups did not question was, "Can this be a mido and also a differ reliably in how well they learned the theri?" the across-level question would be, first novel label (73% vs. 82%, by Fisher's Ex- "Can this be a mido and also a dog?" Fourth, act Test, p > .4), in their tendency of choosing unlike in Study 2, the order of the two ques- the toys as yet unlabeled at the subordinate tions was counterbalanced across children in level as referents for the second novel label this study. Half the children heard the within- (88% vs. 100%, p > .4), in their responses to level questions before the across-level ques- the within-level question (75% vs. 67%, p > tion; the other half heard the questions in the .4) or the across-level question (63% vs. 89%, opposite order. Children were randomly as- p > .2), or in their performance on the dog signed to one of these two groups; the groups comprehension test (88% vs. 89%, p > .4). were balanced for = 4 roughly age (means Most of the children responded appropri- 6 months and 4 8 and sex years years months) ately to the dog comprehension test. Fifteen composition. of the 17 children chose only the beagle and Results and Discussion mutt and refused to pick a third toy animal when "Is there a here?" three Of the 22 children, 17 applied their first asked, dog times. One other child chose the mutt novel label (e.g., mido) to the exemplars of only and refused to of the ani- the target category (e.g., beagle) and not the pick any remaining mals still another child exemplars of the other category (e.g., mutt), (beagle, camel, bird); refused to of the four animals. both immediately after the introduction of the pick any toy that 16 of the 17 children had novel label and near the end of the proce- Recall applied one novel label to the mutts and another to dure. The other five children either picked the mutual ex- only the toy used for introducing the novel beagles, thereby honoring within the subordinate level when word or picked one exemplar from each sub- clusivity their second novel label. All but type, and their responses were excluded from interpreting of these 16 children mutual further analyses. one suspended exclusivity for the second novel label across Of the remaining 17 children, 16 avoided levels. Suppose a child had applied her first choosing the previously labeled toys (e.g., the novel label mido to the two beagles and her two beagles labeled as midos) when asked second label theri to the two mutts. Now twice, "Can you show me a theri [or whatever when shown a mutt, a beagle, a camel, and a the second novel label was]?" (p < .0005). bird, the child would pick the mutt and the That is, they chose the toys as yet unlabeled beagle and nothing else when asked, "Is at the subordinate level (e.g., the two mutts). there a dog here?" three times. Note that the The children were then asked explicitly second novel label was entirely novel to the

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions Au and Glusman 1483 children; no one had told them what it meant same level of a hierarchy. Studies 1 and 2 or could refer to. In interpreting an entirely suggest that when children are presented novel label, then, most of children in this with objects from different novel basic-level study seemed quite ready to suspend mutual categories and are asked to interpret some exclusivity across the basic level and the sub- novel labels, they tend to interpret the labels ordinate level, while at the same time they as mutually exclusive basic-level labels. would honor it within the subordinate level. Study 3 suggests that children also honor mutual within the subordinate These results are consistent with exclusivity previ- level of that this ous studies that showed children can categorization, suggesting young is not restricted to the learn a subordinate-level label such as mutt phenomenon basic level. Studies 2 and 3 also that when have a basic-level label suggest chil- they already dren are to mutual such as for the quite willing suspend ex- dog object (Mervis, 1987; Tay- when have reason to think lor & Waxman & clusivity they that Gelman, 1989; Shipley, the terms come from different levels of a 1987). The present study further suggests that children neither honor mutual in hierarchy. In these studies, children had at exclusivity least one label for each animal all nor do violate familiar toy situations, they always animal in in mutual when have (e.g., Study 2; dog Study 3). exclusivity. Instead, they were to reason to believe that are to Nonetheless, they quite willing inter- people referring an novel word as the label for an at different levels of a pret entirely a object hierarchy, subset of the animals. These will two names for the same ob- toy findings sug- they accept that children are to In this children heard an adult re- gest willing suspend ject. study, mutual when the terms seem to a novel label such as mido to a exclusivity peatedly apply come from different levels of a such as a Most of them hierarchy. In dog beagle. suspended these three studies the the mutual to allow short, support hy- exclusivity assumption that children honor mutual both mido and the familiar basic-level term pothesis exclusiv- ity within each level of a hierarchy but not dog as labels for the beagle. They did so per- across different levels of a hierarchy. haps because they were sure that dog was an appropriate label for the beagle, and at the However, these results also afford other same time, the adult made it clear that quite One alternative view is that mido was an it. One interpretations. appropriate label for way these results have little to do with children's for the children to the old and new integrate about word In these word was to mido as a assumptions meanings. meanings interpret children were with exem- label for a of when studies, presented subtype dog. Indeed, of two rather distinct shown two and two mutts and asked plars categories (e.g., beagles lemurs and and the first to find referents for most children seals), experimenter mido, a label for one of the the and not the mutts. provided categories (e.g., picked beagles Quite mido for When the second the contrast between these two lemur). experi- plausibly, menter came with a label subordinate-level was salient along (e.g., theri), categories the child think that if one of these cate- to the children to might enough encourage interpret had a the other one mido as a label for a kind of And when gories name, might also dog. have a name. In other the re- were asked to a second novel words, present they interpret sults could be in terms of term that it explained children's (e.g., theri), they probably thought skills to form with too was a label for a kind of In most cognitive categories, along dog. fact, an that of the children seemed to the sec- assumption categories normally have interpret names. This view offers another reminder ond novel term as a label for the yet as-yet- of the intricate relation between unnamed subordinate-level concepts and category (i.e., word and that between mutt). It seems, then, that when the context is meanings conceptual and semantic development (Carey, 1983; supportive, even preschool children can read- No further research is subordinate-level labels for ob- Clark, 1983). doubt, ily acquire needed to sort out whether the for which basic-level present jects they already have reflect labels. More honor mutual ex- findings children's mutual exclusivity important, they about word or chil- within the subordinate level but not assumption meanings clusivity One across the subordinate and basic levels of dren's categorization skills. possible ap- is to what when categorization. In order to do so, children proach compare happens novel labels need to have some about hier- are used-as in the present stud- understanding ies-and when archical organization of object categories. nonlinguistic arbitrary tags (e.g., colored dots) are used in the procedure Together, the first three studies suggest (see Gelman & Markman, 1986). Another ap- that children honor mutual exclusivity by de- proach may be to use more extended sets of fault when the terms seem to come from the stimuli. Previous research suggests that con-

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions 1484 Child Development text can affect rather dramatically how chil- of them were well aware that their tentative dren categorize objects (e.g., Gelman, Spelke, guesses that the two labels picked out mutu- & Meck, 1983). If the present findings have to ally exclusive categories could be wrong. As a do with assumptions about word meanings result, when asked explicitly whether both rather than merely categorization skills, they labels could be applied to the same object, should hold across a variety of stimulus sets. some children and adults acknowledged such With future studies such as the ones proposed a possibility. In other words, the discrepancy here, it may be possible to assess whether the between the two tasks can be reconciled present findings are specific to word within the theoretical framework of mutual meanings. exclusivity. Still another view is that perhaps the Further work is clearly needed to evalu- present findings reflected children's prag- ate these competing accounts of the present matic strategies for dealing with the experi- findings. Nonetheless, these three studies do mental situation. The argument goes like this. offer support for the hypothesis that children In these studies, the first experimenter taught honor mutual exclusivity within each level of a child a new category name (e.g., mido) and a hierarchy but not across levels of a hierar- made it very clear that it was important that chy. Children's knowledge of the hierarchical the child remember this word. Then the sec- organization of object categories seems to ond experimenter came along and asked the help children determine when to and when child twice, "Can you show me a theri?" It is not to honor mutual exclusivity in word learn- possible that the child took the second experi- ing. menter's question as a test of whether the child remembered the first novel name. For Study 4 instance, the child might think, "She wants to see if I remember mido. She's testing me to When bilingual children acquire two lex- see if I mis-remember it as theri. If I did, I icons simultaneously, does knowing the label would pick the midos. But I do remember for a category in one language help or hurt the what midos are, so I won't pick the midos!" In acquisition of a corresponding label in the other words, the children's choice might have other language? One view is that it should not to do with their hypothesis about the experi- hurt, or may even help. It argues that once menters' intentions rather than their assump- children have tagged a label in one language tions about word meanings. onto a conceptual category, they should not have much difficulty in tagging a second label There seems to be some for this support to it because they have done the hard work of view. When the second experimenter pointed constructing the to-be-named conceptual cat- at a referent for the first novel word and asked egory. It may even help because having if it could be labeled the second novel by named a category in one language, children fewer children maintained mutual ex- word, may actively seek out its name in another lan- Some of them conceded that the ob- clusivity. guage (Fantini, 1985; Imedadze, 1967; could take both novel labels. ject conceivably Leopold, 1947). A different view is that it may The results with adults were similar. These hurt because of children's reluctance to give that the initial avoidance of findings suggest two names to the same category due to their two names to the same could applying object mutual exclusivity assumption (Glusman, have been in due to the of the part pragmatics 1988; Taeschner, 1983). Thus far, there is lim- context. While this view seems experimental ited empirical support for each view, and it there is another to account reasonable, way remains unclear whether having learned a for these results. Merriman and Bowman label for a category in one language would that mutual (1989) proposed exclusivity may help or hurt the acquisition of a label for it in be a default in the of old option integration another (see also McLaughlin, 1984; and new word Children and adults language meanings. Taeschner, 1983). Study 4 addresses this issue may rely on this assumption to make initial, by examining whether bilingual children and new word tentative guesses about meanings. adults avoid giving a second label to a cate- But they are willing to suspend it when con- gory even if it belongs to a different language fronted with discomfirming evidence, and from the first label. they are likely to be aware that such guesses could very well be wrong even before any Glusman's (1988) work suggested that disconfirming evidence comes in. In the pres- bilingual children resisted giving two names ent studies, then, the subjects may have re- to the same object even when one name was lied on mutual exclusivity to find referents for presented in Spanish and the other in En- their second novel label. Nonetheless, some glish. But her findings were inconclusive be-

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions Au and Glusman 1485

cause one study used a very small sample, were introduced to an English label and then and the other study used only one exemplar a Spanish label by the same experimenter, per category. Moreover, the children had who was bilingual in these two languages. heard the experimenter who introduced the When the experimenter switched from En- Spanish label speak both Spanish and En- glish to Spanish, she emphasized the switch glish prior to the experiment. This might have by saying to the bilingual adults, "Let's speak made the children unsure of whether the in Spanish now." label introduced this was by experimenter Results and Discussion or English. The present study tried to Spanish Because can have different names minimize such confusion by making things potential in different sure that the two experimenters spoke only languages, bilingual speakers should not honor mutual across one in front of the children. In short, exclusivity language this knowl- this examines whether bilingual chil- languages. Indeed, metalinguistic study seems to children as well as adults dren as well as adults know enough cross- edge help limit the use of mutual when in- that they are quite will- exclusivity language equivalents novel nouns. In this all of to two names for the same category terpreting study, ing accept the 18 adults the label to as as they can be sure that the names applied English long both of the and not come from different languages. exemplars target category those of the other category. When asked to Method find referents for a novel Spanish label, seven Subjects.-Twenty Spanish-English bilin- adults in this study chose the exemplars of the gual children from two day-care centers in category to which the novel Enlgish label had Rhode Island (seven boys and 13 girls) and 18 been applied. The other 11 adults chose the Spanish-English bilingual adults at Brown exemplars of another category. The adults' University (nine men and nine women) par- choices in this study did not differ reliably ticipated in this study. The children ranged in from random guessing (p > .4). That is, these age from 3-7 to 6-5 (mean = 5-1). They spoke adults did not reliably avoid applying two Spanish at home and English at their day-care names to the same objects when the names center. While they varied in how fluent they came from different languages. This finding is were in these languages, all of them could in marked contrast with the finding that adults have at least simple conversations in both lan- in Study 1 avoided giving two names to the guages. The adults spoke both languages same object when both names were pre- fluently. sented as English words. When the experi- menter pointed at the toy used earlier for in- Stimulus materials.-The stimulus sets- troducing the English label (e.g., a lemur for the mammals and the reptiles-and the non- mido) and asked in Spanish, "Can this be a sense words of Study 1 were used here. Two theri?" only four out of 18, or 22%, of the novel terms were introduced to each subject, adults in this study responded "No." By con- one in English and the other in Spanish. The trast, in Study 1, where both labels came from words were pronounced with the phon- the same language, 13 out of 21, or 62%, of the ology appropriate to each language. For in- adults responded "No" to an analogous ques- stance, mido, theri, lepid, and gavi were pro- tion (p < .05, by Fisher's Exact Test). To- nounced in English as [miIdo], [0.ri], gether, these findings suggest that bilingual [efpld], [givi], and in Spanish as (m•do], adults do not honor mutual exclusivity across [ttri], [ei6pid], and [gB3i]. These pronuncia- languages. tions were the same as those used in Glus- man's (1988) studies. Because the age range for the children in this study was rather large, the children were Procedure.-The was identi- procedure divided into two groups in the exploratory cal to that of 1 with the Study following data analyses. There were 10 3-4-year-olds modifications. In both novel labels Study 1, (3-7 to 4-10, mean = 4-4) and 10 5-6-year- were introduced to the children adults and as olds (5-1 to 6-5, mean = 5-10). The sex com- words two ex- English by English-speaking position was roughly the same in these two In this the children were perimenters. study, age groups. As it turned out, the results were taught a novel English label (e.g., mido) on a identical in the two groups. Therefore, re- novel toy (e.g., a lemur with sewn-on horns) sponses from these 20 children were analyzed by Experimenter 1. They were then asked in as a group. Spanish by Experimenter 2 to find referents for a novel Spanish label (e.g., theri). Each Of the 20 children, two children failed to experimenter spoke in only one language in learn the English label for their target cate- front of the children. The adults in this study gory and were excluded from the study. The

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions 1486 Child Development remaining 18 children applied their novel but it remains unclear whether they would English label to the exemplars of their target honor it within a language. It may be that category and not to the exemplars of the other bilingual adults' knowledge of so many cross- category, both immediately after the introduc- language equivalents can compel them to tion of the English label and at the end of the abandon mutual exclusivity altogether- procedure. After the children had learned an within a language as well as across languages. English label for a novel category, they were To examine this possibility, two novel words asked in Spanish to find referents for another from the same language are introduced to novel label from an array of four toy animals. bilingual adults by a single experimenter in Twelve of the 18 remaining children chose this study to see if they honor mutual ex- the exemplars of the category previously clusivity within a language. This study also labeled in English (e.g., the two lemurs); six examines whether the number of experiment- children chose the exemplars of the unnamed ers in the procedure makes a difference. category (e.g., the two seals). This result did Since the monolingual adults in Study 1 saw not differ reliably from random guessing (p > two experimenters-one for each novel .2). Like the bilingual adults, then, these word-and the bilingual adults in Study 4 bilingual children did not reliably avoid giv- saw only one experimenter, the different re- ing two novel names to the same object when sults in these studies could have been due to the names came from different languages. the difference in the number of experiment- ers. In this study, monolingual adults hear a When an at the experimenter pointed toy single experimenter introduce two novel used for the label and introducing English words. If the number of experimenters makes asked in "Can this be a Spanish, theri?" only no difference, the results should be similar to four out of or of the children re- 18, 22%, those of Study 1, namely, that monolingual "No." This was in marked contrast to sponded adults honor mutual exclusivity within a lan- the result that 13 out of or of 18, 72%, the guage. children responded "No" to an analogous question in Study 1 where both novel labels Method were introduced in English (p < .005, by Subjects.-Fifteen Spanish-English bilin- Fisher's Exact Test). These findings are con- gual adults (seven men and eight women) sistent with Waxman and Gelman's (1986) and 20 monolingual English-speaking finding that monolingual preschoolers are adults (12 men and eight women) at Brown willing to learn Japanese labels for categories University participated in this study. The for which they already have English labels bilingual adults spoke both languages flu- (e.g., clothing, animal, food). Monolingual ently. children's to willingness suspend mutual ex- Stimulus materials and procedure.-The across will be further ex- clusivity languages stimulus materials and procedure were iden- plored in 6. Study tical to those for adults in Study 4 except that Together, these findings suggest that all adults in this study were tested in only one bilingual children as well as bilingual adults language, that is, one experimenter intro- readily accept two names for an object when duced two novel labels in only one language the names clearly come from different lan- to each subject. The monolinguals were guages. There is one caveat. In Study 1, the tested in English. The bilinguals were ran- adults were monolingual and they saw two domly assigned to either an English or a experimenters. In this study, the adults were Spanish procedure, with about half of them in each bilingual and they saw only one experi- procedure. menter. While the results of these two studies Results and Discussion are consistent with the hypothesis that adults Both the monolingual and bilingual will honor mutual exclusivity within a lan- adults honored mutual exclusivity within a but guage will suspend it across languages, language in their initial hypotheses about they could also be explained by the confound- their second novel label. That is, if a subject ing factors-the number of languages the assumed that the first label, mido, referred to adults spoke and the number of experiment- the lemurs, when asked twice, "Can you ers they saw. Study 5 is designed to rule out show me a theri?" the subject would choose these two alternative explanations. the seals but not the lemurs. All of the 20 monolingual and all 15 bilingual adults did Study 5 this (p < .0001 in both cases). The bilingual adults in Study 4 sus- When the experimenter pointed at the pended mutual exclusivity across languages, toy used for introducing the first novel label

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions Au and Glusman 1487 and asked, "Can this be a theri [or whatever glish-speaking children were more prone to the second label was]?" 70% of the monolin- be confused by the story than the bilingual gual adults and 67% of the bilingual adults Serbian-English children because they were said "No." These findings are similar to those less familiar with language switching and for- of Study 1. Together, they suggest that adults eign languages in general. The present study honor mutual exclusivity within a language examined whether monolingual children when there is no evidence contradicting it. could suspend mutual exclusivity across lan- This conclusion holds regardless of whether guages when they had no doubt that the the adults spoke one or two languages, labels came from different languages. whether the novel labels were introduced by one experimenter or two, and whether the Method language was English or Spanish. The bilin- Subjects.-Twenty-one monolingual En- guals' responses in Studies 4 and 5 also glish-speaking children attending four day- strongly suggest that bilingual adults honor care centers in Rhode Island participated in mutual exclusivity within a language but not this study. There were 15 girls and six boys, across languages. The next study looks at and they ranged in age from 3-4 to 5-7 (mean whether even monolingual children can take 4-7). advantage of the knowledge that a thing can Stimulus materials and have different names in different procedure.-The languages to stimulus materials were identical to those of limit the use of mutual exclusivity appropri- Study 1. The procedure used with children in ately. Study 1 was used here with the following 6 modifications. After Experimenter 1 had in- Study troduced a novel English label (e.g., mido) for In this study, monolingual English- a novel category (e.g., lemur), Experimenter 2 speaking children were taught a novel En- said to the child, "Do you speak Spanish? Do glish label for an object. They were then you want to learn a word in Spanish? Okay, tested to see whether they would accept a now I'm going to teach you a word in Span- Spanish label for the same object. If monolin- ish. Theri is a Spanish word. Can you say gual children can use the metalinguistic theri? Well, theri is the Spanish word for a knowledge that an object can have different kind of animal which is here." Experimenter names in different languages to suspend 2 then displayed the four toys in the stimulus mutual exclusivity across languages, they set (e.g., two lemurs and two seals) and asked, should not avoid giving an English label and "Can you guess which one Spanish-speaking a Spanish label to the same object. This abil- children would call a theri? Is there another ity could have important implications for sec- one that Spanish-speaking children would ond-language education. For instance, if chil- call a theri?" If children honored mutual ex- dren are explicitly told whether a novel word clusivity across languages, they should avoid comes from their native language or their sec- choosing the toy animals to which the novel ond language, they may learn cross-language English label had been applied. Otherwise, equivalents more readily by suspending they needed not avoid giving two names- mutual exclusivity across languages. one in English and one in Spanish-to the same object. Experimenter 2 then at There is some evidence that pointed suggestive the toy used earlier for the En- children be less to introducing monolingual might likely glish label and asked, "Can this be a theri in suspend mutual across exclusivity languages Spanish?" Throughout the procedure, she than bilingual children. Kutlesic (1988) taught pronounced the "Spanish" label with a Span- Serbian-English bilingual and English-speak- ish accent. ing monolingual 6-year-olds a novel English label on an object. Then she asked the chil- Results and Discussion dren to find referents for either a novel En- Although these children spoke only En- glish label or a novel French label. She found glish, they all seemed to know that Spanish, that while both the monolingual and bilingual like English, is a language. Some of them children tended to honor mutual exclusivity might have found out about this through tele- within a language, the bilinguals were more vision programs such as "Sesame Street." willing to suspend it across languages than Also, some of these children had Spanish- the monolinguals. But in this study, the infor- English bilingual friends at their day-care mation that the second label was a French center. Perhaps they learned that Spanish is a word was embedded in a rather lengthy language from their friends, parents, or the story-well over 150 words, with part of it day-care staff. When Experimenter 2 asked told in French. Perhaps the monolingual En- whether they spoke Spanish, all of them ap-

This content downloaded from 171.67.216.22 on Fri, 27 Sep 2013 01:58:24 AM All use subject to JSTOR Terms and Conditions 1488 Child Development propriately responded "No." When asked uniqueness principle (Pinker, 1984). As Stud- whether they would like to learn a Spanish ies 1 and 5 suggested, the mutual exclusivity word, they all either nodded or said "Yes." assumption seems to be useful enough that monolingual and bilingual adults as well as Of the 21 children, 18 applied the novel monolingual children make it when interpret- English label (e.g., mido) to the exemplars of ing novel nouns within a language. Other the target category (e.g., two lemurs) and not studies have shown that bilingual children those of the other category (e.g., two seals), also seem to honor mutual exclusivity within both immediately afterthe introductionof the a language (Glusman, 1988; Kutlesic, 1988). label and at the end of the procedure. The other three children failed to do so and their But despite its usefulness, mutual ex- responses were excluded from furtheranaly- clusivity is not an entirely reliable assump- ses. tion about word meanings. One way to deal with this problem is to treat mutual exclusiv- When Experimenter2 asked the children as a default in new to find the referents for a label ity option integrating Spanish (e.g., names with the old ones (Merriman& Bow- in an of four animals two theri) array (e.g., man, 1989). That is, word learners can still lemurs and two seals), half the children chose take of this useful in the animals to which a novel label advantage assumption English making first guesses about new word mean- had been applied, and half chose the as-yet- In the absence of evi- unlabeled This ings. any contradicting animals. 50-50 split suggested dence, then, word learners should honor this that the children and did guessed randomly assumption. This account would explain why not honor mutual exclusivity across lan- adults and children did so in Studies 1 and 5 guages. Indeed, when Experimenter 2 as well as in several studies of at the used earlier for previous pointed toy introducing mutual exclusivity. This "default option" ac- the English label and asked, "Can this be a count can also children and in 16 out of or of the explain why theri Spanish?" 18, 89%, adults seem quite willing to suspend mutual children said "Yes"(p < .005). These findings in some situations. We have that even children are exclusivity pro- suggest monolingual posed that two kinds of knowledge can help willing to accept two novel labels for an ob- children limit the use of this if the context makes it clear that the assumption ap- ject very propriately.One has to do with the hierarchi- labels come from different languages. Studies cal of denoted sin- 4 and that the organization categories by 6, then, suggest metalinguistic gle words, and the other has to do with knowledge that an object can have different names for an across lan- names in different monolin- multiple object languages helps guages. gual as well as bilingual children suspend mutual exclusivity across languages. Studies 2 and 3.revealed that by age 4, children can use what they know about the General Discussion hierarchical organizationof object categories to limit their use of mutual tend exclusivity appro- When people refer to objects, they priately. They seem to know that use such categories to basic-level labels as dog, cat, are mutually exclusive within one level within the any chair, and table. Since categories but not across levels in a hierarchy. When basic level are most of the mutually exclusive, they interpret novel object terms, they seem novel object names that children come across reluctant to apply two names to the same ob- do It is denote mutually exclusive categories. ject within any one level but are willing to do to as Markman Wachtel easy see why, and so across levels in a hierarchy. (1988) suggested, children are tempted to as- sume that words pick out mutually exclusive Study 4 suggested that like bilingual categories. There may also be other reasons adults, bilingual preschoolers can use their why children would make this assumption. knowledge that an object can have different For instance, mutual exclusivity may be one names in different languages to limit the use instance ofchildren's primitive attemptsto or- of mutual exclusivity. That is, they will read- ganize and systematize their linguistic and ily accept two novel labels for the same object conceptual knowledge (Clark, 1987; Mark- if the labels clearly come from different lan- man, 1989; Markman& Wachtel, 1988; Merri- guages. Study 6 further showed that even man & Bowman, 1989). That is, this assump- monolingual children can take advantage of tion may be related to other principles this metalinguistic knowledge to limit their children seem to honor in systematizing their use of mutual exclusivity appropriately, as linguistic knowledge, such as the one-to-one long as the context makes it very clear that the mapping principle (Slobin, 1973) and the labels come from differentlanguages (see also

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Waxman & Gelman, 1986). Importantly, they Carey, S. (1983). Constraints on the meanings of can do so without being able to speak more naturalkind terms. In T. Seiler & W. Wannen- than one language. These findings suggest macher (Eds.), Concept development and the that the metalinguistic knowledge, rather development of word meaning (pp. 126-143). than the ability to speak two or more lan- Berlin: Springer-Verlag. guages, enables children to suspend mutual Clark,E V. (1973) What'sin a word? On the child's exclusivity across languages. acquisition of semantics in his first language. In T. E. Moore (Ed.), Cognitive development these findings suggest that Together, and the acquisition of language (pp. 65-110). even preschool children can use knowledge New York:Academic Press. about and to limit categorization language Clark,E. V. (1983). Meaningsand concepts. In J. H. use of mutual their exclusivity appropriately. Flavell & E. M. Markman(Eds.), P. H. Mussen As children become more about sophisticated (Series Ed.), Handbook child psychology: can fine tune their use of this of languages, they Vol. 3. Cognitive development (pp. 787-840). even further. When they en- assumption New York:Wiley. counter more to mutual exclusiv- exceptions Clark, E. V. (1987). The principle of contrast:A do not have to decide whether they ity, they constrainton language acquisition. In B. Mac- should abandon the assumption entirely or Whinney (Ed.), Mechanisms of language ac- hold on to it the counterevidence. In- despite quisition (pp. 1-33). Hillsdale, NJ: Erlbaum. their will be to understand stead, challenge Dockrell, J., & Campbell,R. (1986).Lexical acquisi- the and out when to and exceptions figure tion strategiesin the preschoolchild. In S. Kuc- when not to honor mutual exclusivity when & M. Barrett (Eds.), The development of novel labels. zaj interpreting category word meaning (pp. 121-154). Berlin: Springer- Verlag. a References Fantini, A. E. (1985). Language acquisition of bilingual child: A sociolinguistic perspective Anglin,J. M. (1977).Word, object, and conceptual (to age ten). San Diego, CA: College-Hill. development. New York:Norton. Gelman, R., Spelke, E. S., & Meck, E. (1983).What Au, T. K. (1985).Children's word-learning strate- preschoolers know about animate and inani- gies. Papers and Reports on Child Language mate objects. In D. Rogers & J. A. Sloboda Development, 24, 22-29. (Eds.), The acquisition of symbolic skills (pp. Au, T. K. (1990). Children's use of informationin 297-326). New York:Plenum. word learning.Journal of Child Language, 17. Gelman, S. A., & Markman,E. M. (1986). Catego- Bahrick, L. E., & Pickens, J. N. (1988). Classi- ries and induction in young children. Cogni- fication of bimodal English and Spanish lan- tion, 23, 183-209. guage passages by infants.Infant Behaviorand Gelman, S. A., Wilcox, S. A., & Clark,E. V. (1989). Development, 11, 277-296. Conceptual and lexical hierarchies in young Baldwin, D. A. (1989). Priorities in children's ex- children. Cognitive Development, 4, 309-326. pectations about object label reference: Form Gibbons, J. (1987). Code-mixingand code choice:A over color. Child Development, 60, 1291-1306. Hong Kong case study. Clevedon, England: Barrett, M. D. (1978). Lexical development and MultilingualMatters. overextension in child language. Journal of Glusman,M. (1988).One namefor one thing: Bilin- Child Language, 5, 205-219. guals' and monolinguals' use of mutual ex- Bauer, P. J., & Mandler,J. M. (1989). Taxonomies clusivity. Unpublished thesis, Brown Univer- and triads: Conceptual organizationin one- to sity. two-year-olds.Cognitive Psychology, 21, 156- Golinkoff, R. M., Hirsh-Pasek,K., Lavallee, A., & 184. Baduini, C. (October,1985). What's in a word? Brown, R. (1957). Linguistic determinism and the The young child's predisposition to use lexical partof speech. Journal of Abnormaland Social contrast. Paper presented at the Boston Uni- Psychology, 55, 1-5. versity Conference on Child Language, Bos- Brown, R. (1958). How shall a thing be called? Psy- ton. chological Review, 65, 14-21. Goodman, N. (1955). Fact, fiction, and forecast. Callanan,M. A. (1989). Development of object cat- Cambridge,MA: HarvardUniversity Press. egories and inclusion relations: Preschoolers' Gumperz, J. J., & Hemrnndez-Chavez,E. (1971). hypotheses about word meanings. Develop- Bilingualism,bidialectalism, and classroomin- mental Psychology, 25, 207-216. teraction. In C. B. Cazden, V. P. John, & D. Callanan,M. A., & Markman,E. M. (1982), Princi- Hymes (Eds.), Functions of language in the ples of organizationin young children'snatural classroom (pp. 84-108). New York:Teachers language hierarchies. Child Development, 53, College Press. 1093-1101. Hutchinson, J. E. (1986). Children's sensitivity to

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