When knowing only one word for “car” leads to weak application of mutual exclusivity

Cognition 196 (2020) 104087

Contents lists available at ScienceDirect

Cognition journal homepage: www.elsevier.com/locate/cognit

When knowing only one word for “car” leads to weak application of mutual exclusivity

T

Elena Nicoladisa,*, Angélique Laurentb a b

University of Alberta, Canada Université de Sherbrooke, Canada

A R T I C LE I N FO

A B S T R A C T

Keywords: Mutual exclusivity Synonyms Mental lexicon Lexicon structure hypothesis

From a very young age, monolingual children assume their language has no synonyms, or use the principle of mutual exclusivity (only one label per object). In contrast, bilingual children often accept more novel synonyms than monolinguals. One possible explanation for this difference is the lexicon structure hypothesis: having synonyms (across languages) in the lexicon reduces adherence to mutual exclusivity. The purpose of this study is to test the lexicon structure hypothesis by comparing three- to five-year-old children who speak either Canadian French or English. Canadian French allows more synonyms than English. French-speaking children should therefore accept more novel synonyms than English-speaking children. The children did a disambiguation task, choosing whether a familiar or an unfamiliar object was the referent of a novel word (e.g., moli). Surprisingly, the French-speaking children accepted significantly fewer novel synonyms than English-speaking children. However, they accepted the most synonyms for objects that had synonyms in French but they did not know both synonyms. These results support a modified version of the lexicon structure hypothesis, one that accounts for children’s weak access to synonyms.

1. Introduction Children learn lots of new words fairly quickly, mastering thousands of words by middle childhood (Anglin, 1993; see reviews in Biemiller, 2003; Bloom, 2002). One skill that allows children to learn so many words so quickly is fast-mapping, the ability to deduce the meaning of a novel word upon hearing the word used in context. Fast-mapping can be observed in children at least as young as 18 months (Kalashnikova, Escudero, & Kidd, 2018). In theory, there are an infinite number of possible meanings of a novel word (Quine, 1964). In order to correctly infer the meaning of a novel word, young children may therefore rely on some constraints, such as the principle of mutual exclusivity (Markman, 1990, 1992). The principle of mutual exclusivity means that a single object can have only one name (Markman, 1990, Merriman & Bowman, 1989). If children follow the principle of mutual exclusivity, they will prefer unfamiliar objects, objects for which they do not know a label, as the referents of novel words. Indeed, when asked to indicate the referent of a novel word (like dax) in a disambiguation task, monolingual children tend to pick unfamiliar objects (like a whisk) over familiar objects (like a cat; Frank & Poulin-Dubois, 2002; Graham, Poulin-Dubois, & Baker, 1998; Grassmann, Schulze, & Tomasello, 2015; Markman, 1990; Markman & Wachtel, 1988; Markman, Wasow, &

⁎

Hansen, 2003; Merriman & Bowman, 1989). Bilingual children, in contrast, sometimes pick out more familiar objects than monolinguals on this same sort of disambiguation task (Byers-Heinlein & Werker, 2013; Davidson & Tell, 2005; Davidson, Jergovic, Imami, & Theodos, 1997; Healy & Skarabela, 2008; Kandhadai, Hall, & Werker, 2017; Rowe, Jacobson, & Saylor, 2015). By picking a lot of familiar objects (e.g., a tree) as the referents of a novel word (e.g., dax), bilingual children are violating the principle of mutual exclusivity, thereby allowing words to have synonyms (see also McMurray, Horst, & Samuelson, 2012, for a word learning model that shows similar results). Not all studies have shown differences between bilinguals and monolinguals (Frank & Poulin-Dubois, 2002; Kalashnikova, Mattock, & Monaghan, 2014; Merriman & Kutlesic, 1993; or at least when memory for the novel word was measured over a short delay, see Kalashnikova et al., 2018). Nevertheless, researchers have offered a number of possible explanations for bilingual children’s tendency to rely on mutual exclusivity less than monolinguals. These explanations include greater flexibility in thinking among bilinguals (Davidson et al., 1997) and greater use of social and/or pragmatic cues than mutual exclusivity among bilinguals to infer the meaning of words (Buac, Tauzin-Larché, Weisberg, & Kaushanskaya, 2019; Hung, Patrycia, & Yow, 2015; Jaswal & Hansen, 2006; Verhagen, Grassmann,

Corresponding author. E-mail address: [email protected] (E. Nicoladis).

https://doi.org/10.1016/j.cognition.2019.104087 Received 7 February 2019; Received in revised form 30 September 2019; Accepted 1 October 2019 0010-0277/ © 2019 Elsevier B.V. All rights reserved.

Cognition 196 (2020) 104087

E. Nicoladis and A. Laurent

speakers use the word bicycle in French (with French phonology), even though there are already two existing words to refer to bicycles in French: vélo and bicyclette. The word bicycle may be borrowed from English. If the lexicon structure hypothesis is correct, then CanadianFrench-speaking children should show more violations of mutual exclusivity than English-speaking children because they know more synonyms. The French-speaking children’s willingness to accept novel synonyms could change with age, either decreasing or increasing. In favor of decreasing acceptance with age, Byers-Heinlein and Werker (2009) argued that toddlers who speak more than one language might be delayed relative to monolinguals in their ability to apply a one-word-perreferent principle within a language. If so, then as French-speaking children get older, they may accept fewer novel synonyms. Alternatively, it is possible that with increasing age, French-speaking children are more likely to accept novel synonyms. Davidson and Tell (2005) found that 5- to 6- year-old bilingual children used less mutual exclusivity than same-aged monolingual children, while there were no differences between language groups among 3- to 4-year-old children (see also Kalashnikova et al., 2015). Some studies have shown that even monolingual children’s willingness to accept novel synonyms changes with age (Frank & PoulinDubois, 2002; Kalashnikova et al., 2014; Merriman & Kutlesic, 1993). Frank and Poulin-Dubois (2002) showed, for example, that two-yearolds allowed more mutual exclusivity violations than three-year-olds. These age-related changes could be related to vocabulary growth. Kalashnikova, Mattock, and Monaghan (2016) found that the larger the size of the vocabulary, the more likely the child was able to use mutual exclusivity (as did Graham et al., 1998; cf. Byers-Heinlein & Werker, 2009). Further evidence for the role of vocabulary comes from Grassmann et al. (2015). They observed that children are particularly likely to choose an unfamiliar referent of a non-word if they could produce a name for the familiar object. We have designed this study to take into account both children’s age and vocabulary size as possible markers of developmental change in willingness to accept novel synonyms.

& Küntay, 2017). The purpose of the present study was to test one other possible explanation for bilinguals’ weaker application of mutual exclusivity: the lexicon structure hypothesis (Byers-Heinlein & Werker, 2013, 2009; Davidson et al., 1997). According to this hypothesis, bilinguals are willing to accept novel synonyms because their mental lexicon includes synonyms (e.g., dog-perro). The knowledge of many words to refer to one concept leads to children’s willingness to interpret novel words as synonyms for existing words. For bilinguals, the synonyms are across languages, but the lexicon structure hypothesis posits that what leads to the reduction of adherence to mutual exclusivity is that one concept maps to many words. The lexicon structure hypothesis should therefore extend to monolinguals who have a lot of synonyms in their mental lexicon. One challenge in testing the lexicon structure hypothesis with bilinguals is that bilinguals differ from monolinguals on a variety of word-learning strategies and cue uses that could affect their use of mutual exclusivity. Previous studies have shown that bilinguals differ from monolinguals in their word learning strategies/cues and expectations about what words might mean (Byers‐Heinlein, 2017; Groba, De Houwer, Mehnert, Rossi, & Obrig, 2018; Kandhadai et al., 2017) as well as what phonological forms could even constitute words (Graf Estes & Hay, 2015). In the present study, we tested the lexicon structure hypothesis by comparing two groups of monolingual children: one group whose language included many synonyms (Canadian French speakers) and one whose language did not (Canadian English speakers). Some languages, like English and continental French, represent a standard language culture (Milroy, 2001), meaning that there is a great deal of uniformity in what things are called and a strong belief in the correctness of particular linguistic constructions. These languages have many near-synonyms, words that have similar but not identical meanings and differ in degree of denotation, connotation, or use (such as big and huge or child and infant). However, they have only a few synonyms, words that have the same meaning (e.g., for the first author, at least, couch and sofa have the same meaning; Cruse, 2000; Edmonds & Hirst, 2002). In contrast, Canadian French has many synonyms (Roberts & Doucet, 2011; Yan & Nicoladis, 2009), even in child-directed speech (such as chaussure/soulier ‘shoe’, auto/voiture ‘car’). For example, in picture-naming tasks, both Canadian-French-speaking children (Yan & Nicoladis, 2009) and adults (Roberts & Doucet, 2011; Sirois, Kremin, & Cohen, 2006) used several different acceptable words to name pictures. Yan and Nicoladis (2009) gave the example of a pencil sharpener that was sometimes called taille-crayon literally ‘carve-pencil’ and sometimes aiguisoir ‘sharpener’ (p. 327). Both are acceptable labels in Canadian French. In contrast, the English-speaking children in that same study usually named pictures with only one clear target word (Yan & Nicoladis, 2009). Further evidence for the existence of synonyms in child-directed speech comes from the Canadian French version of the MacArthur Communicative Development Inventory (Boudreault, Cabirol, Poulin-Dubois, Sutton, & Trudeau, 2007; Trudeau & Sutton, 2011). This vocabulary inventory lists 13 pairs of synonyms among the common nouns (e.g., sacoche/sac à main ‘purse’). No synonyms appear in the American English version among the common nouns (Fenson et al., 2006). On the Canadian French inventory, parents are asked to indicate only if their children know at least one label for the referent for the 13 synonyms, not whether both labels are known. Some of the synonyms in use in Canadian French are due to regionalisms (e.g., maïs ‘corn’ is used worldwide while blé d’Inde ‘corn’ is a regionalism). Another source of variability in Canadian French is contact with English (Berry, 1984). Many first language speakers of French also speak English. In 2016, Statistics Canada reported that the two provinces with French as at least one official language are home to a high percentage of French-English bilinguals: 43% of the population in Quebec and 33% in New Brunswick (Statistics Canada, 2017). When languages are in contact, words can be borrowed from the other language (Sankoff, 2002). For example, we have heard Canadian-French

1.1. This study The purpose of this study was to test the lexicon structure hypothesis (Byers-Heinlein & Werker, 2013, 2009; Davidson et al., 1997) with children who speak Canadian French and children who speak Canadian English. According to this hypothesis, when children’s mental lexicon includes synonyms, they are less likely to use mutual exclusivity. Given that Canadian French-speaking children are likely to know more synonyms than English-speaking children, we predicted that Frenchspeaking children would demonstrate greater acceptance of novel synonyms than English-speaking children. The lexicon structure hypothesis could also predict age-related changes in the use of mutual exclusivity, either a delay (Byers-Heinlein & Werker, 2009) or a relaxation with increasing age (Davidson & Tell, 2005; Kalashnikova et al., 2015). In the present study, we included children between 3 and 5 years of age, an age range similar to that in Davidson and Tell (2005). We also included standardized measures of children’s receptive vocabulary, to test for the possibility that vocabulary size contributes to children’s use of mutual exclusivity. A few bilingual children participated in this study, allowing us to test for the effects of bilingualism. The lexicon structure hypothesis predicts that bilinguals should accept more novel synonyms than monolinguals (e.g., Davidson & Tell, 2005). 2. Method 2.1. Participants A total of 98 children between the ages of three years (36 months) 2

Cognition 196 (2020) 104087

E. Nicoladis and A. Laurent

and five years (64 months) of age were included in the final analyses of this study. Children were recruited through daycares and preschools. Parents received an information sheet describing the purpose and the procedure of the study and a consent form that has been approved by the ethics board of the University of Alberta. Two groups of monolingual children were constituted and paired by age. The final sample of the French-speaking group consisted of 49 children (28 girls) between the ages of three and five years, living in Sherbrooke, Québec. Five children in this final sample were fluently bilingual (three also spoke English, one Serbo-Croatian, and one Vietnamese), according to parental report. They did not differ by more than a standard deviation from the average of the monolinguals on any of the measures in our study, including vocabulary scores. Five other children were tested but not included in the final sample: one child scored lower than three standard deviations on the French vocabulary test, one child chose only pictures on the right side in the disambiguation task, and three did not have a close age match among the English-speaking children. The final sample of the English-speaking group consisted of 49 children (17 girls) between the ages of three and five years, living in Edmonton, Alberta. These were the children who most closely matched the French-speaking children on age (all within two months of age) out of a sample of 51. Nine children out of the final sample were bilingual (three also spoke Chinese, two Hungarian, and one each: Malayalam, Nepali, Spanish, and Urdu). All the bilinguals scored within a standard deviation and a half of the average on the English vocabulary test and within a standard deviation on all other tasks in this study. Two children were tested but not included in the final sample, as they did not have a close age match among the French-speaking children. In the present study, we analyzed age as a continuous variable in months. The French-speaking children averaged 49.2 months of age (SD = 7.3; range 36–64) and the English-speaking children 48.7 (SD = 7.7; range 36-64). There was no significant difference on age between the two language groups, t (96) = .32, p = .75, d = .067. As we recruited both French- and English-speaking children in daycares close to universities that are known to cater to universityeducated parents, we were surprised to find that the French-speaking children had higher standard vocabulary scores (M = 115.8, SD = 19.5) than the English-speaking children (M = 103.6, SD = 17.1), t (96) = 3.28, p = .002, d = .665. These are normed scores (see below for further description of the vocabulary tests) so there is no a priori reason to think that there would be differences between the language groups. There were more bilingual children among the English-speaking children than among the French-speaking children, but even removing the bilingual children of each group from the analysis revealed the same pattern of results. We know of no studies directly comparing the standard scores in English and French so it is theoretically possible that the standard scores are not directly comparable. Regardless, we analyzed the results of the disambiguation task controlling for vocabulary since vocabulary has been linked with the use of mutual exclusivity in previous studies (e.g., Graham et al., 1998).

Table 1 Background characteristics of participants.

Average age Age range #Girls/Boys Vocabulary

French

English

49.2 (7.3) 36-64 28/21 115.8 (19.5)

48.7 (7.7) 36-64 17/32 103.6 (17.1)

Age is reported in months.

Peabody (or EVIP, Forme A; Dunn, Thériault-Whalen, & Dunn, 1993). In English, we used the Peabody Picture Vocabulary Test-III (PPVT), Version A (Dunn & Dunn, 1997). The raw scores for the French and English versions are not on the same scale; we therefore used the norm scores for easier comparisons across languages.

2.4. Disambiguation task The disambiguation task consisted of 20 items, each consisting of a pair of pictures: a familiar object and an unfamiliar object (see Fig. 1 for example). The unfamiliar objects were unnameable for most adults (Horst & Hout, 2016). Familiar objects had labels that appeared in child-adult interactions in English on the CHIld Language Data Exchange System (CHILDES; MacWhinney, 2000), in both French and English for slightly older children (Yan & Nicoladis, 2009), or according to our experience within the relevant communities. To choose the familiar objects, we first identified ten objects that had synonyms in Canadian French (aiguisoir/taille-crayon ‘pencil sharpener’, auto/voiture ‘car’, cercle/rond ‘circle’, cocotte/pomme de pin ‘pine cone’, dentifrice/ pâte à dents ‘toothpaste’, efface/gomme ‘eraser’, essuie-tout/papier ‘paper towel’, maringouin/moustique ‘mosquito’, patate/pomme de terre ‘potato’, pierre/roche ‘rock’). For each of the remaining ten objects with a synonym in French, we chose a semantically-related object with no common synonym in French (respective to the order of objects with synonyms: ciseaux ‘scissors’, bateau ‘boat’, carré ‘square’, pomme ‘apple’, brosse à dents ‘toothbrush’, pinceau ‘paintbrush’, éponge ‘sponge’, abeille ‘bee’, carotte ‘carrot’, arbre ‘tree’). To see if these words are likely to be familiar to the youngest children, we looked at frequency of these words in child-adult interactions and age of acquisition measures (see Appendix A). As can be seen in this Appendix, these indices are much sparser for Canadian French words than for English words. Where the indices exist, most of the words included in this study are often acquired before the age of three years. We have some independent support for our classification of French words as having synonyms or not. In our conversations with adult native speakers of Canadian French, all but two pairs of synonyms were usually described as having the same meaning. One exception was maringouin/moustique ‘mosquito’. Some adults told us that maringouins differ in size from moustiques (some said bigger and some said smaller). However, they were quick to add that most people use these two words interchangeably. Thus, we think it is likely that child-directed speech would not distinguish between the two meanings. The other exception was pierre/roche ‘rock’, with pierre allowing the interpretation of ‘gem’ while roche does not. Here again, we expected that this distinction was too subtle to affect preschool children’s performance on the disambiguation task. The consultation with native speakers of Canadian French was done on an ad hoc basis so other Canadian French speakers might have other intuitions. However, another piece of supporting evidence for our classification comes from a study on adult picturenaming norms that included 11 out of our 20 items (Brodeur et al., 2012). Brodeur et al. (2012) found that six of the items we had classified as having synonyms in Canadian French had modal name agreement among adults between 21 and 73%: aiguisoir (73%), cocotte (50%), dentifrice (25%), efface (53%), papier (à main) (21%), and patate (70%). In contrast, five of the items we had classified as having no

2.2. Materials and procedure The children were tested in a quiet corner of their daycares or preschools by a native speaker of French (for the French-speaking children) or English (for the English-speaking children). The experimenter first administered the vocabulary test following the examiner’s manual for the respective version of the test. She then administered the disambiguation task and finally the comprehension task. 2.3. Vocabulary tests To assess the children’s vocabulary, we used receptive vocabulary tests that have been standardized in both English and Canadian French (see Table 1). In French, we used the Échelle de vocabulaire en images 3

Cognition 196 (2020) 104087

E. Nicoladis and A. Laurent

Fig. 1. Example of Items on Disambiguation Task.

first 20 items. The order of these last 10 items was randomized once and presented to all children in the same order. To administer the comprehension task, the experimenter continued fluidly from the disambiguation task by asking children to point to the picture that corresponded to each word for the familiar objects.

synonyms in Canadian French had modal name agreement between 89 and 100%: ciseaux (97%), brosse à dents (100%), pinceau (90%), éponge (89%), and carotte (100%). The pictures chosen to depict the familiar objects were as stereotypical as possible (we found the bee in Fig. 1, for example, to be a rather typical bee). The 20 unfamiliar objects were randomly paired with the 20 familiar objects once (see Appendix B for pairing). For half the items, the unfamiliar object was on the left and for half on the right. The same 20 items were used to test all children. We constructed 20 different non-words in French and English, following the phonotactics of each language (see Appendix C). The nonwords were randomly assigned to items for every child. To administer the disambiguation test, the experimenter told the children that they would see some pictures and wanted them to point to the picture of the object corresponding to the word just said. To make sure the children understood the directions, the experimenter showed the children a picture with an elephant and a banana and asked them to point to the banana. The experimenter then proceeded to the 20 test items, asking the children to point to the picture corresponding to a non-word. The order of the 20 test items was random for each child. The experimenter recorded on paper whether children pointed to the familiar or the unfamiliar object.

2.6. Data processing and analysis For the comprehension task, we present the percentage correct for both all 30 items and only the first 20 items. Recall that, for the Englishspeaking children, the last 10 items were duplicates of items that they had heard previously. For the disambiguation task, the dependent variable was the percentage of unfamiliar objects chosen for each child. Our initial analyses showed that age and vocabulary did not interact with language group, so we entered both as independent variables in a linear regression, predicting the percentage of unfamiliar objects chosen. Bilingualism/ monolingualism and language group were coded as dummy variables for this analysis. 3. Results 3.1. Comprehension task

2.5. Comprehension test

On the complete 30-item comprehension task, the French-speaking children scored, on average, 80.4% (SD = 16.7%) on the comprehension task while the English-speaking children averaged 83.6% (SD = 13.1%) correct. There was no significant difference by language group, t (96) = 1.06, p = .29, d = .212. Note that the 30-item comprehension task contained 10 repeated items for the English-speaking children (while the last 10 items were synonyms for the Frenchspeaking children). We also compared the children in the two language groups on their accuracy on the first 20 items on the comprehension task. The French-speaking children averaged 81.4% (SD = 13.0%) and the English-speaking children 85.0% (SD = 12.8%). There was no significant difference by language group, t (96) = 1.36, p = .18, d = .279. Any differences between French- and English-speaking children on the disambiguation task cannot be attributed to differences in familiarity with words for the familiar objects. For the 20 words on the comprehension task that were synonyms, the French-speaking children gave the correct answer for both synonyms for an average of 59.8% (SD = 25.2%) of the items. The percentage of items for which both synonyms were known was highly correlated with both age, r (47) = .594, p < .001, and with vocabulary scores, r (47) = .577, p < .001. All but one French-speaking child knew at least one pair of synonyms.

In order to verify that the children knew labels for the familiar items and that the French-speaking children knew both synonyms, we administered a 30-item comprehension test to all children. Each item was composed of four possible pictures: 1) the target familiar object (e.g., “bee” in Fig. 2), 2) its paired unfamiliar object (like in Fig. 1), 3) the corresponding familiar semantically-related object (e.g., “mosquito” in Fig. 2), and 4) the unfamiliar object that had been paired with #3. See Appendix D for the grouping. The first 20 items of the comprehension test were the same as in the disambiguation task. The order of these 20 items was randomized once and presented to all children in the same order. This item was used to test knowledge of both “bee” and “mosquito” For the last 10 items of the comprehension test, children were presented with duplicate items for the words in French that have synonyms. In these last 10 items in the French version, the children were tested on the 10 synonyms that they had not heard in the first 20 items. Half the French-speaking children heard one set of 10 synonyms among the first 20 items (i.e., moustique, gomme, pierre, dentifrice, pomme de pin, voiture, essuie-tout, cercle, pomme de terre, and taille-crayon) and the other 10 synonyms among the last 10 items (i.e., maringouin, efface, roche, pâte à dents, cocotte, auto, papier, rond, patate, and aiguisoir). The other half of the French-speaking children did the reverse. There were no differences between children on their performance on the comprehension test based on the order in which they had heard the synonyms (ps > .54). In the last 10 items in the English version, children were tested again on items (mosquito, eraser, rock, toothpaste, pine cone, car, paper towel, circle, potato, and pencil sharpener) they had heard in the

3.2. Disambiguation task We performed a linear regression predicting the percentage of unfamiliar objects, with age, vocabulary, bilingualism, and language group as predictor variables. Age and vocabulary scores were included 4

Cognition 196 (2020) 104087

E. Nicoladis and A. Laurent

Fig. 2. Example of comprehension item.

as continuous variables. Bilingualism was entered as a dummy variable (1 = bilingual, 0 = monolingual). Language group was also entered as a dummy variable (1 = French, 0 = English). The overall results were significant, F (4, 97) = 9.86, p < .001, R2 = .298. Table 2 summarizes the results of the predictor variables. As expected, age and vocabulary were significant predictors in the predicted direction (i.e., younger children and children with lower vocabulary scores chose fewer unfamiliar objects). There were two surprising results. First, bilingualism was not significant, with the average for the bilingual children (M = 77.3%, SD = 10.5%) differing little from the monolingual children (M = 78.4%, SD = 15.8%). We will return to this finding in the Discussion. Second, while the effect of Language Group was significant, it went in the opposite direction to predictions. The French-speaking children chose more unfamiliar objects than the English-speaking children. The French-speaking children chose, on average, 82.5% (SD = 11.2%) unfamiliar objects on the disambiguation task while English-speaking children chose 74.0% (SD = 17.3%). In other words, the French-speaking children were more constrained by mutual exclusivity than English-speaking children. We next turn to an analysis of the role of synonyms on the French-speaking children’s performance on the disambiguation task.

more unfamiliar objects for the ten items that had synonyms in French than for the ten items that did not. The French-speaking children chose significantly more unfamiliar objects for items that did not have synonyms (M = 87.4%, SD = 12.2%) than for items that did have synonyms (M = 78.0%, SD = 16.8%) on a paired t-test, t (48) = 3.41, p = .001, d = .488. In other words, the French-speaking children allowed more novel synonyms for objects that already have synonyms in French. We next analyzed the French-speaking children’s performance on the disambiguation task depending on whether they demonstrated that they knew synonyms for the ten items for which a synonym existed in French in the comprehension task. For each child, we calculated the percentage of unfamiliar objects for the items for which s/he gave the correct answer on the comprehension task for both synonyms and the percentage of unfamiliar object for the items for which s/he demonstrated comprehension of only one or none of the synonym pairs. These results were analyzed with a one-way repeated measures ANOVA, comparing the percentage of unfamiliar items for: 1) items for which the child knew both synonyms, 2) items for which the child did not know both synonyms, and 3) items for which there are no synonyms in French (see Fig. 3). A repeated-measures ANOVA on these three categories revealed a significant effect, F (2, 94) = 11.25, p < .001, η2p = .193. The pairwise comparisons shed some light on the source of this effect. Children were less likely to choose unfamiliar objects for items for which they did not know synonyms than both for items for which they did know both synonyms (mean difference = 13.8%, p = .001) and for items for which there are no synonyms in French, (mean difference = 15.9%, p = .001). There was no significant difference between items for which the children knew both synonyms and for which there are no synonyms in French (p = .49). In sum, the French-speaking children were particularly willing to accept synonyms for objects that have a synonym in French but for which they did not demonstrate knowledge of both synonyms on the comprehension task. In the discussion, we will argue that these results are due to weak links to synonyms.

3.3. Disambiguation task: the role of synonyms for French-speaking children

4. Discussion

To test whether knowledge of synonyms affected the Frenchspeaking children’s responses, we first analyzed whether children chose

The purpose of this study was to test the lexicon structure hypothesis. According to this hypothesis, bilingual children are more willing to

Table 2 Summary of regression analysis predicting percent unfamiliar objects on disambiguation task. Independent Variables

β

p

Age Vocabulary Bilingualism Language Group

.29 .31 -.06 .18

.003 .003 .54 .049

Notes: Bilingualism dummy coded so that 0 = monolingual and 1 = bilingual; Language Group dummy coded so that 0 = English and 1 = French.

5

Cognition 196 (2020) 104087

E. Nicoladis and A. Laurent

Fig. 3. Average percentage unfamiliar objects chosen by French-speaking children based on availability of synonyms. Error bars show standard error of the mean.

have shown (Graham et al., 1998; Kalashnikova et al., 2016). These results could be interpreted as consistent with weak-links-to-words leading to choosing more novel synonyms (Grassmann et al., 2015). Grassmann et al. (2015) argued for the effects of weak knowledge of any label at all on mutual exclusivity. The authors found that monolingual children were more likely to use mutual exclusivity when they could produce (rather than simply understand) a word for the familiar object in a disambiguation task. They argued that weak lexical access to a label led to weaker application of mutual exclusivity. Our results provide some evidence for that argument and further suggest that there is a similar explanation for children’s knowledge of only one synonym (cf. McMurray et al., 2012). If this explanation is correct, it is possible that even the English monolingual children might particularly avoid novel synonyms for words that have near-synonyms. Recall that we argued that English has few synonyms but many near-synonyms (like small and little). If English monolingual children have weak links to one near-synonym, they may, too, be particularly willing to accept a novel synonym for that referent. Our explanation also leads to predictions about larger groups of bilingual children: they should use mutual exclusivity less often than monolinguals only when they have weak lexical access to the label of a familiar object in one language. For example, if a Spanish-English bilingual could access both dog and perro easily, s/he should use mutual exclusivity to constrain the meaning of a novel word as not referring to a dog. But, if s/he knew the word cat well but had only heard gato occasionally, s/he might accept a novel word as possibly referring to a cat. Bilingual children may often be precisely in the latter situation. Bilinguals often know one language better than the other (Gathercole, 2016). As a result, bilingual children can sometimes know words in some semantic domains quite well in one language and not well at all in the other. For example, De Houwer (1990) reported on a Dutch-English bilingual child who learned color words in English in a school context before learning similar words in Dutch. Our explanation could explain why some studies have found that bilinguals differ from monolinguals on the use of mutual exclusivity (Byers-Heinlein & Werker, 2013; Davidson & Tell, 2005; Davidson et al., 1997; Healy & Skarabela, 2008; Kandhadai et al., 2017; Rowe et al., 2015) and others have not (Frank & Poulin-Dubois, 2002; Kalashnikova et al., 2014; Merriman & Kutlesic, 1993; the present study). Our results suggest that the use of mutual exclusivity is highly dependent on individual children’s strong lexical access to both synonyms. Studies showing differences of bilinguals and monolinguals may have included many individuals with weak lexical access to at least one cross-language synonym. In contrast, studies finding no differences may have included many individuals with strong lexical access to translation

suspend mutual exclusivity because their lexicon contains many multiple-word-to-single-object mappings (Byers-Heinlein & Werker, 2013, 2009; Davidson et al., 1997). We tested this hypothesis in two groups of children: speakers of Canadian French and speakers of Canadian English. There are many synonyms in Canadian French. If the existence of synonyms in the mental lexicon leads to children’s suspension of mutual exclusivity, we predicted that French-speaking children would choose fewer unfamiliar objects on a disambiguation task than Englishspeaking children. In other words, they would allow more novel synonyms. This is not what we found. We found the reverse to this prediction. The French-speaking children chose significantly more unfamiliar objects than English-speaking children. In other words, the French-speaking children were even more strongly biased than Englishspeaking children toward rejecting new synonyms. Moreover, when the French-speaking children knew two words to refer to the same object, they were just as strongly biased by mutual exclusivity as when they knew only one word (see Fig. 3). Further evidence against the lexicon structure hypothesis comes from the lack of an effect of bilingualism on the disambiguation task. While only a few bilingual children participated in this study, their performance did not differ from that of the monolingual children. Taken together, these results contradict a strong version of the lexicon structure hypothesis, that having synonyms in one’s mental lexicon leads to greater acceptance of novel synonyms (Byers-Heinlein & Werker, 2013). We did, however, find some support for a modified version of the lexicon structure hypothesis, one that incorporates lexical access (see McMurray et al., 2012, for a theoretical stance on lexical knowledge that could support this interpretation). Namely, children may suspend mutual exclusivity when they know that an object has more than one label but their access to that other label is weak. Evidence for this argument comes from the fact that the French-speaking children chose the most familiar objects when those objects had synonyms in Canadian French but they did not know both synonyms. A concrete example might help illustrate our argument. Imagine a child knew the word dentifrice for ‘toothpaste’ and had also heard the word pâte à dents but not often enough to reliably associate the latter word with toothpaste. Upon being asked to locate the “tipeau” (one of our non-words in this study), the child may think that “tipeau” could be that other word for toothpaste that s/he had heard before. This child might then point to toothpaste as the referent for “tipeau”. As many previous studies have shown, we found that as children got older, they accepted fewer novel synonyms (Byers-Heinlein & Werker, 2009; Frank & Poulin-Dubois, 2002; Kalashnikova et al., 2014; Merriman & Kutlesic, 1993). We also found that as children’s vocabulary increased, they accepted fewer novel synonyms, as other studies 6

Cognition 196 (2020) 104087

E. Nicoladis and A. Laurent

per the lexicon structure hypothesis). We have argued that children’s weak lexical access to one synonym may instead lead to reduced use of mutual exclusivity.

equivalents. Future research can systematically test that explanation, while correcting for some of the limitations of the present study, such as our lack of direct measures of the children’s socio-economic status. Our results also have implications for methodological approaches to assessing children’s lexical access in future studies. In the present study, we inferred the French-speaking children’s weak lexical access to a synonym through the fact that 1) a synonym exists in French and 2) they failed to give the correct response for a synonym on a comprehension task. Future studies could include more sensitive measures of weak lexical access, such as implicit recognition tasks or ERP measures. In conclusion, we have shown that simply having synonyms in one’s mental lexicon does not lead to a reduced use of mutual exclusivity (as

Acknowledgements We would like to thank all the children who participated in this study and the research assistants, Joanie Giroux, Gillian Kastendieck, Kimberly Ning, Jamie Nisbet, Sherani Sivakumar, Julie Vaillancourt, Shivani Vaza, Julia Wood, and Catherine Zoleta, for helping collecting data. This study was funded by the Natural Sciences and Engineering Research Council of Canada to the first author.

Appendix A. Frequency and Age of Acquisition (AoA) for Familiar Objects

Word

Frequency†

MCDI: AoA††

Adult AoA†††

Apple Bee Boat Car Carrot Circle Eraser Mosquito Paintbrush Paper towel Pencil sharpener Pine cone Potato Rock Scissors Sponge Square Toothbrush Toothpaste Tree Abeille Aiguisoir Arbre Auto Bateau Brosse à dents Carotte Carré Cercle Ciseaux Cocotte Dentifrice Efface Éponge Gomme Essuie-tout Maringouin Moustique Papier (à main) Patate Pâte à dents Pierre Pinceau Pomme Pomme de pin Pomme de terre Roche Taille-crayon Voiture

1,275 397 935 5,420 233 563 23 15 12 10 7 2 365 477 182 43 238 41 25 1,053 2 0 2 56 135 0 0 1 0 3 0 0 0 0 0 0 6 0 0 71 0 0 8 16 0 0 11 0 11

18 22 21 18 24 n/a n/a n/a n/a 23 n/a n/a 25 22 25 n/a n/a 22 n/a 20 23 n/a 23 17 18 21 21 n/a n/a 25 n/a n/a n/a n/a n/a n/a n/a n/a 21 21 n/a At 30 months, 40% could produce n/a 19 n/a n/a 23 n/a n/a

4.2 5.0 3.8 3.4 2.7 3.7 5.0 6.1 6.2 n/a 5.3 4.6 4.8 3.2 4.5 5.0 4.1 4.3 3.3 3.6 n/a n/a n/a 1.9 2.3 n/a 2.0 n/a n/a 2.5 n/a n/a n/a n/a n/a n/a n/a n/a n/a 1.9 n/a n/a 2.7 1.7 n/a n/a n/a n/a n/a

†For English, out of the 3,443,311 words in English in child-adult interactions on CHILDES available through childfreq.sumsar.net/result. For French, out 122,133 words in the Canadian French transcripts of the York database (Plunkett, 2003) on CHILDES (MacWhinney, 2000). ††First age (in months) when 50% of the children produced the word on the MacArthur Communicative Developmental Inventories, Words and Sentences, as summarized by Wordbank (wordbank.stanford.edu); the Canadian French data were contributed by Boudreault et al. (2007) and Trudeau and Sutton (2011). †††Subjective age of acquisition in years as estimated retrospectively by adults. In English, these come from Kuperman et al. (2012). In French, 7

Cognition 196 (2020) 104087

E. Nicoladis and A. Laurent

these come from Sirois (2007). Appendix B. Familiar and unfamiliar objects paired for disambiguation task

Familiar

Unfamiliar†

Apple Bee Boat Car Carrot Circle Eraser Mosquito Paintbrush Paper towel Pencil sharpener Pine cone Potato Rock Scissors Sponge Square Toothbrush Toothpaste Tree

2033 2025 2034 2018 2037 2021 2014 2013 2026 2019 2023 2017 2022 2015 2039 2035 2036 2029 2016 2027

††The numbers refer to images available in Horst and Hout (2016). Appendix C. Non-words in French and English French: Arteau, balatte, coudelle, frouppe, golard, jéfa, lebour, moli, nalane, piche, quiffe, ripon, rotent, tipeau, satte, sonie, tripon, toma, voppe, zios. English: Blem, blicket, coodle, fiffen, goke, jefa, leam, mense, nare, plail, rel, shede, sprock, tand, toma, tulver, virdex, wiot, yosp, zios. Appendix D. Items on a single slide for comprehension task

Familiar

Unfamiliar†

Apple, Pine cone Car, Boat Circle, Square Eraser, Paintbrush Mosquito, Bee Paper towel, Sponge Pencil sharpener, Scissors Potato, Carrot Rock, Tree Toothbrush, Toothpaste

2033, 2018, 2021, 2014, 2013, 2019, 2023, 2022, 2015, 2029,

2017 2034 2036 2026 2025 2035 2039 2037 2027 2016

†The numbers refer to images available in Horst and Hout (2016). Appendix D. Supplementary data Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.cognition.2019.104087.

E., et al. (2012). The bank of standardized stimuli (BOSS): Comparison between French and English norms. Behavior Research Methods, 44, 961–970. Buac, M., Tauzin-Larché, A., Weisberg, E., & Kaushanskaya, M. (2019). Effect of speaker certainty on novel word learning in monolingual and bilingual children. Bilingualism: Language and Cognition, 22, 883–895. Byers‐Heinlein, K. (2017). Bilingualism affects 9‐month‐old infants’ expectations about how words refer to kinds. Developmental Science, 20, e12486. Byers-Heinlein, K., & Werker, J. F. (2013). Lexicon structure and the disambiguation of novel words: Evidence from bilingual infants. Cognition, 128, 407–416. Byers-Heinlein, K., & Werker, J. F. (2009). Monolingual, bilingual, trilingual: Infants’ language experience influences the development of a word-learning heuristic. Developmental Science, 12, 815–823. Cruse, D. A. (2000). Meaning in language: An introduction to semantics and pragmatics. Oxford: Oxford University Press. Davidson, D., Jergovic, D., Imami, Z., & Theodos, V. (1997). Monolingual and bilingual

References Anglin, J. M. (1993). Vocabulary development: A morphological analysis. Monographs of the Society for Research in Child Development, 58 Serial #238. Berry, J. W. (1984). Multicultural policy in Canada: A social psychological analysis. Canadian Journal of Behavioural Science/Revue canadienne des sciences du comportement, 16, 353–370. Biemiller, A. (2003). Vocabulary: Needed if more children are to read well. Reading Psychology, 24, 323–335. Bloom, P. (2002). How children learn the meanings of words. Cambridge, MA: MIT Press. Boudreault, M. C., Cabirol, E. A., Poulin-Dubois, D., Sutton, A., & Trudeau, N. (2007). MacArthur Communicative Development Inventories: Validity and preliminary normative data. La Revue Canadienne d’Orthophonie et d’Audiologie, 31, 27–37. Brodeur, M. B., Kehayia, E., Dion-Lessard, G., Chauret, M., Montreuil, T., Dionne-Dostie,

8

Cognition 196 (2020) 104087

E. Nicoladis and A. Laurent

Kandhadai, P., Hall, D. G., & Werker, J. F. (2017). Second label learning in bilingual and monolingual infants. Developmental Science, 20, e12429. Kuperman, V., Stadthagen-Gonzalez, H., & Brysbaert, M. (2012). Age-of-acquisition ratings for 30,000 English words. Behavior Research Methods, 44, 978–990. MacWhinney, B. (2000). The CHILDES project: Tools for analyzing talk (third edition). Mahwah, NJ: Lawrence Erlbaum Associates. Markman, E. M. (1992). Constraints on word learning: Speculations about their nature, origin and domain specificity. In M. R. Gunnar, & M. Maratos (Vol. Eds.), Modularity and constraints in language and cognition, Minnesota symposium on child psychology: vol. 20, (pp. 59–101). Hillside, NJ: Lawrence Erlbaum. Markman, E. M. (1990). Constraints children place on word meanings. Cognitive Science, 14, 57–77. Markman, E. M., & Wachtel, G. F. (1988). Children’s use of mutual exclusivity to constrain the meanings of words. Cognitive Psychology, 20, 121–157. Markman, E. M., Wasow, J. L., & Hansen, M. B. (2003). Use of the mutual exclusivity assumption by young word learners. Cognitive Psychology, 47, 241–275. McMurray, B., Horst, J. S., & Samuelson, L. K. (2012). Word learning emerges from the interaction of online referent selection and slow associative learning. Psychological Review, 119, 831–877. Merriman, W. E., & Bowman, L. L. (1989). The mutual exclusivity bias in children’s word learning. Monographs of the Society for Research in Child Development, 54(3/4) serial no. 220. Merriman, W. E., & Kutlesic, V. (1993). Bilingual and Monolingual children’s use of two lexical acquisition heuristics. Applied Psycholinguistics, 14, 229–249. Milroy, J. (2001). Language ideologies and the consequences of standardization. Journal of Sociolinguistics, 5, 530–555. Plunkett, B. (2003). Null subjects and the setting of subject agreement parameters in child French. In A.-T. Pérez-Leroux, & Y. Roberge (Eds.). Romance linguistics: Theory and acquisition (pp. 351–366). Amsterdam: John Benjamins. Quine, W. V. (1964). Word and object. Oxford: MIT Press. Roberts, P. M., & Doucet, N. (2011). Performance of french-speaking Quebec adults on the Boston naming test. Canadian Journal of Speech-Language Pathology & Audiology, 35, 254–267. Rowe, L., Jacobson, R., & Saylor, M. M. (2015). Differences in how monolingual and bilingual children learn second labels for familiar objects. Journal of Child Language, 42, 1219–1236. Sankoff, G. (2002). Linguistic outcomes of language contact. In J. K. Chambers, P. Trudgill, & N. Schilling-Estes (Eds.). The handbook of language change and variation (pp. 638–668). Malden, MA, USA: Blackwell Publishing. Sirois, M. (2007). L’influence de l’âge d’acquisition du mot dans la dénomination et la catégorisation sémantiqueUnpublished master’s thesis. Université du Québec à Montréal. Sirois, M., Kremin, H., & Cohen, H. (2006). Picture-naming norms for Canadian French: Name agreement, familiarity, visual complexity, and age of acquisition. Behavior Research Methods, 38, 300–306. Statistics Canada (2017, August 31). English–French bilingualism reaches new heights. Retrieved from: https://www12.statcan.gc.ca/census-recensement/2016/as-sa/98200-x/2016009/98-200-x2016009-eng.cfm. Trudeau, N., & Sutton, A. (2011). Expressive vocabulary and early grammar of 16-to 30month-old children acquiring Quebec French. First Language, 31, 480–507. Verhagen, J., Grassmann, S., & Küntay, A. C. (2017). Monolingual and bilingual children’s resolution of referential conflicts: Effects of bilingualism and relative language proficiency. Cognitive Development, 41, 10–18. Yan, S., & Nicoladis, E. (2009). Finding le mot juste: Differences between bilingual and monolingual children’s lexical access in comprehension and production. Bilingualism: Language and Cognition, 12, 323–335.

children’s use of the mutual exclusivity constraint. Journal of Child Language, 24, 3–24. Davidson, D., & Tell, D. (2005). Monolingual and bilingual children’s use of mutual exclusivity in the naming of whole objects. Journal of Experimental Child Psychology, 92, 25–42. De Houwer, A. (1990). The acquisition of two languages from birth: A case study. Cambridge: Cambridge University Press. Dunn, L. M., & Dunn, L. M. (1997). Peabody picture vocabulary test-III. Circle Pines, MN: American Guidance Service. Dunn, L. M., Thériault-Whalen, C. M., & Dunn, L. M. (1993). Échelle de vocabulaire en images Peabody: EVIP. Toronto: Psycan. Edmonds, P., & Hirst, G. (2002). Near-synonymy and lexical choice. Computational Linguistics, 28, 105–144. Fenson, L., Marchman, V., Thal, D., Dale, P., Reznick, S., & Bates, E. (2006). The MacArthur communicative development inventories: User’s guide and technical manual (2nd ed.). Baltimore, MD: Brookes. Frank, I., & Poulin-Dubois, D. (2002). Young monolingual and bilingual children’s responses to violation of the Mutual Exclusivity Principle. International Journal of Bilingualism, 6, 125–146. Gathercole, V. C. M. (2016). Factors moderating proficiency in bilingual speakers. In E. Nicoladis, & S. Montarnari (Eds.). Bilingualism across the lifespan (pp. 123–140). Washington, DC: De Gruyter Mouton. Graham, S. A., Poulin-Dubois, D., & Baker, R. K. (1998). Infants’ disambiguation of novel object words. First Language, 18, 149–164. Graf Estes, K., & Hay, J. F. (2015). Flexibility in bilingual infants’ word learning. Child Development, 86, 1371–1385. Grassmann, S., Schulze, C., & Tomasello, M. (2015). Children’s level of word knowledge predicts their exclusion of familiar objects as referents of novel words. Frontiers in Psychology, 6, 1200. https://doi.org/10.3389/fpsyg.2015.01200. Groba, A., De Houwer, A., Mehnert, J., Rossi, S., & Obrig, H. (2018). Bilingual and monolingual children process pragmatic cues differently when learning novel adjectives. Bilingualism: Language and Cognition, 21, 384–402. Healy, E., & Skarabela, B. (2008). Are children willing to accept two labels for a single object? A comparative study of mutual exclusivity in monolingual and bilingual children. In T. Marinis, A. Papangeli, & V. Stojanovik (Eds.). Proceedings of the 2007 Child Language Seminar (pp. 48–56). Horst, J. S., & Hout, M. C. (2016). The Novel Object and Unusual Name (NOUN) Database: A collection of novel images for use in experimental research. Behavior Research Methods, 48, 1393–1409. Hung, W. Y., Patrycia, F., & Yow, W. Q. (2015). Bilingual children weigh speaker’s referential cues and word-learning heuristics differently in different language contexts when interpreting a speaker’s intent. Frontiers in Psychology, 6, 796. Jaswal, V. K., & Hansen, M. B. (2006). Learning words: Children disregard some pragmatic information that conflicts with mutual exclusivity. Developmental Science, 9, 158–165. https://doi.org/10.1111/j.1467-7687.2006.00475.x. Kalashnikova, M., Escudero, P., & Kidd, E. (2018). The development of fast‐mapping and novel word retention strategies in monolingual and bilingual infants. Developmental Science, 21, e12674. Kalashnikova, M., Mattock, K., & Monaghan, P. (2016). Mutual exclusivity develops as a consequence of abstract rather than particular vocabulary knowledge. First Language, 36, 451–464. https://doi.org/10.1177/0142723716648850. Kalashnikova, M., Mattock, K., & Monaghan, P. (2014). The effects of linguistic experience on the flexible use of mutual exclusivity in word learning. Bilingualism: Language and Cognition, 18, 626–638. Kalashnikova, M., Mattock, K., & Monaghan, P. (2015). The effects of linguistic experience on the flexible use of mutual exclusivity in word learning. Bilingualism: Language and Cognition, 18(4), 626–638.

9