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1 THEORY OF MIND, EXECUTIVE FUNCTIONING AND LANGUAGE IN MONOLINGUAL AND BILINGUAL PRESCHOOL CHILDREN By VANESSA DIAZ A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQU IREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2011
2 2011 Vanessa Diaz
3 To all bilinguals out there (includi ng those in my family, of course) trying to make sense of our fragmented experiences
4 ACKNOWLEDGMENTS I would l ike to thank the open minded parents, the enthusiastic children, the for their collaboration on this project. I would also like to thank my willing (and unwilling) frien ds and family who listened and learned to care about theory of mind, the Jacquelin Goldman Graduate Student Research Award for financial support, and my advisory committee for the opportunity to work under their supervision
5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 6 ABSTRACT ................................ ................................ ................................ ..................... 7 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ ...... 8 Executive Functioning ................................ ................................ ............................... 9 Language ................................ ................................ ................................ ................ 11 Bilingualism ................................ ................................ ................................ ............. 14 Bilingualism and Executive Function ................................ ................................ 15 Bilingualism and Language ................................ ................................ .............. 17 Bilingualism and Theory of Mind ................................ ................................ ...... 18 Hypotheses ................................ ................................ ................................ ............. 20 2 METHOD ................................ ................................ ................................ ................ 22 Participants ................................ ................................ ................................ ............. 22 Measures ................................ ................................ ................................ ................ 22 Theory of Mind ................................ ................................ ................................ 23 Executive Functioning ................................ ................................ ...................... 25 Language ................................ ................................ ................................ ......... 26 Procedure ................................ ................................ ................................ ............... 28 3 RESULTS ................................ ................................ ................................ ............... 31 4 DISCUSSION ................................ ................................ ................................ ......... 37 Bilingual Monolingual Differences ................................ ................................ ........... 37 Theory of Mind Relationships ................................ ................................ ................. 40 Limitations and Future Directions ................................ ................................ ........... 42 Conclusion ................................ ................................ ................................ .............. 42 LIST OF REFERENCES ................................ ................................ ............................... 44 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 47
6 LIST OF TABLES Table page 2 1 Bili ....... 3 0 3 1 Means, standard deviations, estimated means and standard errors for b ilinguals ................................ ................................ ................................ ............ 35 3 2 Means, standard deviations, estimated means and standard errors for m onolinguals ................................ ................................ ................................ ...... 35 3 3 orrelations and partial c orrelations between t heory of m in d, e xecutive f unctioning and l a nguage for the total s ample ................................ .. 35 3 4 heory o f m ind e xecutive f unctoning and language for b ilinguals ................................ ............. 36 3 5 heory o f m ind e xecutive f unctioning and language for m onolinguals ................................ ....... 36 3 6 Summary of hierarchical r egressio n analysis for variables predicting t heory o f m ind ................................ ................................ ................................ .................... 36
7 Abstract of T hesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science THEORY OF MIND, EXECUTIVE FUNCTIONING AND LANGUAGE IN MONOLINGUAL AND BILINGUAL PRESCHOOL CHILDREN By Vanessa Diaz M ay 2011 Chair: M. Jeffrey Farrar Major: Psychology Several cognitive factors have been documented to impact theory of mind (ToM) development, particularly false be liefs in preschool children, such as general language ability, syntactic comprehension, and executive functioning (EF). Most of these studies have examined these relations in monolingual children. However, bilingual children have been documented to perfor m better on EF tasks, but poorer on language tasks, which raises important issues regarding their ToM development Two questions were of interest in the current study: Are there differences in bilingual monolingual preschoolers on ToM, language, and EF? ; and (2) What is the role of language and EF in predicting ToM performance in these monolingual and bilingual groups? These questions were examined by comparing 32 Spanish English bilinguals and 33 English monolinguals between the ages of 3 and 5 years of age. Even though monolinguals outperformed bilinguals on language measures, after controlling for language, bilinguals outperformed monolinguals on ToM. There were no differences between the groups on EF measures. Finally, after controlling for age, langu age ability was correlated to ToM performance in the monolingual group; no such relationship was present in the bilingual group.
8 CHAPTER 1 INTRODUCTION How do children learn to think about the social world, one filled with agents, desires and necessary a nd sometimes uncomfortable compromise? These abilities are referred to as social cognition. In social cognition children need to take into account contextual circumstances, self awareness, and the infinite universe of mental worlds. Acknowledging mental wo rlds, or the realization that minds exist, that the child herself has a mind and that others have minds, has been called theory of mind (ToM) development. ToM is usually measured in preschool children by looking at their ability to conceptualize the conten ts of the minds of others as different from their own, specifically understanding o f the knowledge of others could be interpreted as a reflection of reality and not necessarily as an understanding of mental states (Wellman, Cross, & Watson, 2001). For this reason, ToM understanding is measured by using situations in which the child knows the truth, while somebody else holds a mistaken belief; this is referred to as the false belief task (Wimmer & Perner, 1983). An example of a false belief task is the now widely known Sally Anne task, which deals with a false belief about the location of an object. In it, Sally has a basket and Anne has a box. Sally places a marble in her basket and goes away. Anne then moves the marble to her box. When Sally returns, the children are asked where will Sally look for the marble? In order to pass this task, children need to ignore their own correct knowledge, and appropriately assess what
9 1978, research on ToM has proliferated, providing us with a developmental description of the acquisition of ToM abilities. According to this description, children begin to pass the standard ToM false belief task around 4 years of age as reported for exampl e in a meta analysis by Wellman et al. (2001). ToM research has also focused on determining which cognitive factors predict ToM acquisition. From this research, different studies have found associations between ToM and executive functioning (EF) (Carlson & Moses, 2001), ToM and general language ability ( Milligan, Astington & Ain (Dack), 2007), and ToM and a particular type of syntactic structure called complementation syntax consisting of sentences with embedded clauses (de Villiers & Pyers, 2002). Most o f these studies have examined children learning English. However, recently, the development of ToM has begun to be explored in children who are bilingual. Of primary interest in the current study is the relative contribution of language and EF to ToM under standing in monolingual and bilingual preschoolers. Also of interest are differences in these cognitive abilities in monolingual and bilingual children. Executive Functioning EF is probably best described in terms of what it does, rather than what it is, a s there is still considerable disagreement among researchers in terms of its true nature. ( Zelazo Mller, Frye, & Marcovitch, 2003). In spite of this conceptual disagreement, several functions have been readily associated with EF such as inhibitory contro l, cognitive flexibility, planning, categorization, working memory, and following directions among others (Zelazo et al., 2003). Zelazo and colleagues have conceptualized EF performance more explicitly in terms of the cognitive flexibility required to hol d dual representations and to switch between different rules and demands. Of the processes
10 associated with EF, inhibitory control is thought to be primarily involved in ToM tasks. sponses, execute desired ones and decide among relevant information (Carlson & Moses, 2001). An example of a task demanding inhibitory control is the classic Stroop task (Stroop, 1935); in it, one is asked to name the color a word is written in, as oppose d to reading the word which is a different color name. For example, the word blue is written in red and one is inhibit their own correct knowledge (for example that the marble is now in the box in the case of the Sally Ann task), correctly assessing the false beliefs of others, and saying what others would think as opposed to what they themselves think (saying that Sally would think contr ol. Carlson and Moses (2001) for example, found that inhibitory control and ToM were strongly correlated even after controlling for factors such as age and language ability. In their study, inhibitory control tasks were either conflict tasks (requiring the children to inhibit a preponderant response in favor of a conflicting novel one) or delay tasks (requiring the children to delay a preponderant response). The conflict tasks were more strongly correlated with ToM than the delay tasks, thus adding support to the idea that inhibitory control helps children sort out between conflicting beliefs, and inhibit the impulse to respond the ToM questions from their own knowledge. In addition, Wellman et al. (2001) reported in their meta analysis that false beliefs we re easier for children
11 when the hidden object would disappear (e.g., a chocolate would get eaten) rather than be displaced. With no current preponderant location of the object to inhibit, the task became easier by reducing the inhibitory control demands. T his low inhibitory control task, however, still requires dual representation of the ultimate fate of the object. Such dual representation and switching demands continue to be necessary for ToM tasks even when inhibitory control demands are low as perhaps a nother form of EF required for ToM performance. To summarize, there is considerable theoretical as well as empirical information supporting the role of EF as a major contributor to ToM performance in children. In addition, another aspect of EF that will b e considered in this project is short term memory. false belief reasoning, research shows that even though working memory is correlated with false belief performance, it does not med iate more important relationships such as that of language and ToM (Slade & Ruffman, 2005). Language As discussed earlier, a large portion of ToM research has focused on the role of language. Many aspects of language are linked to ToM performance, and ther e are different proposals as to which language component is most important. At the most basic level there is the language comprehension and production demands implicated in interpreting and answering the ToM tasks, which are predominantly verbal. More imp ortantly, is the theoretical argument that language provides the cognitive structures and tools needed to represent and reason about a false belief. Jenkins and Astington (1996), for example, investigated the cognitive abilities that were related to ToM pe rformance after controlling for age. They found that language ability and verbal
12 memory for sentences significantly predicted false belief understanding in 3 5 year olds. In addition, they identified a potential language competency threshold that children needed to attain before understanding false beliefs. This was identified to be the language level of a child 4 years and 1 month old or older, using the Test of Early Language Development (Hresko, Reid, & Hammill, 1981). Schick, deVilliers, deVilliers, and Hoffemeister (2007) also conceptualized language as providing important evidence deaf children of hearing parents, but with no developmental disabilities. This ToM defici ency was not seen in deaf children of deaf parents who had signed to and with their children since birth. In terms of which particular aspect of language are most related to ToM, there are important proposals that have linked ToM performance with semanti c knowledge; thoughts and other mental actions such as remembering (de Rosnay & Hughes, 2006). Understanding and correctly using these terms seems to denote an awarenes s of mental activity. General grammar and semantic knowledge have also been associated with ToM performance in preschool children. Slade and Ruffman (2005) studied the role of general grammar and semantic abilities, and found that while a composite of gene ral grammar and semantics predicted ToM performance 6 months later, no particular aspect of these composites significantly predicted ToM. Some researchers however, argue that language provides the structures necessary to hold a ToM by way of specific compl ex grammatical structures that might require false belief related logic and often involve mental state talk (de Villiers, 2005 ) This kind of sentence structure is called
13 complementation syntax in which a sentence contains an embedded structure or a compl really is i representation in that though the reality is one, and only agrees with one part of the sentence; both parts of the sentence can be true. The ability to understand this kind of sentence by correctly identifying what is really happening in this scenario has been put forth as a predictor of ToM performance. In a longitudinal study by de Villiers and Pyers (2002), participants of different age cohorts, reliably passed complementation compreh ension tasks before ToM tasks, thus prompting the authors to theorize that perhaps being able to understand this kind of grammar allows children to differentiate between reality and the content of another n previous research to be more highly correlated with ToM capacities than other forms of language. In a recent metananalysis by Milligan et al. (2007), they reported the largest effect size for complement understanding in predicting ToM In their analysis, however, only a small number or studies investigated the relationship between ToM and complementation comprehension. Moreover, the effect has not been reliably replicated (Cheung, Hsuan Chih, Creed, Ng, Wang and Mo, 2004). Cheung and colleagues found t hat the correlation between ToM and complementation language became insignificant after controlling for general language ability. In sum, the particular aspects of language
14 necessary for false belief are still being debated, in particular the exact contrib ution that complementation comprehension makes independently of general language ability. This relation of both language and EF to false belief understanding has primarily been demonstrated in monolingual children. Surprisingly, however, the relative role of both factors has rarely been investigated. Studies of EF and false belief, typically control for verbal ability (as measured by vocabulary) and show that EF still contributes (e.g., Carlson & Moses, 2001). Only a few studies have specifically examined the relative role of language and EF. Most of these direct comparisons have been done using samples of deaf children in which they find that language is more important for ToM related reasoning than EF (e.g. de Villiers, 2005). In addition, while most rese archers assume that language makes a larger contribution to ToM, Hughes and Ensor (2007), found that EF was a stronger predictor of ToM than verbal ability. A shortcoming of this study however, is the fact that the authors did not examine grammatical abil ities, which are often a stronger predictor of ToM than vocabulary measures (Milligan et al., 2007) Bilingualism In recent years, ToM and EF researchers have begun to investigate the development of these abilities in bilingual children, or those who are fluent in two languages. This population presents an interesting case in that the unique language experience of bilinguals offers natural variations in EF, ToM and language demands that might inform each of these research fields. For example, since very ea rly in development bilinguals are faced with an arguably larger need than monolinguals to assess the knowledge base, and therefore mind content, of every interlocutor they encounter. This requirement will potentially make them more experienced with ToM rel ated reasoning than monolingual children. In addition, after identifying the language
15 of the person, bilingual children need to plan, inhibit the other language, and switch to the appropriate one to produce the proper language output from potentially equal ly preponderant linguistic responses. This process will arguably lead bilinguals to also be more experienced with EF, particularly inhibitory control related demands. It is not hard to see then, that bilingual children due to their increased experience w ith two languages might potentially outperform monolingual children of a similar age in ToM and EF tasks While there is a known bilingual disadvantage on language tests compared to monolinguals (e.g., Bialystok & Viswanathan, 2009), there is evidence that there is an advantage for bilinguals in both ToM and EF as reviewed below. Given that both EF and language are known predictors of ToM in monolingual children, we are interested in the mpared to monolingual children. Bilingualism and E xecutive F unction There is an accumulating body of literature supporting an observed advantage of bilingual children over monolingual children on EF related tasks. Bialystok and Viswanathan (2009) investigated which comp onents of EF are responsible for the bilingualism advantage in bilingual children in two cultures. They compared 8 year old Canadian monolingual children to Canadian bilingual children who spoke English and one of a variety of other languages, and Indian b ilingual children who also spoke English and another of two different languages. Results indicated that monolinguals outperformed the bilinguals on English language tests and there were no differences between the two bilingual groups and the monolingual gr oup on short term memory and working memory tasks. In spite of this, when given EF tasks testing response suppression, inhibitory control and switching, bilingual children outperformed
16 monolinguals on tasks requiring inhibitory control and switching. Howev er, there were no bilingual monolingual differences on response suppression tasks. In this study, the researchers found bilingual monolingual differences on EF tasks involving inhibitory control and switching, in spite of vast cultural differences between the bilingual groups. Similar findings were reported in another study discussed by Bialystok (2010) where Martin Rhee and Bialystok (2008) found significant bilingual monolingual ren outperformed monolinguals only when the task required the children to ignore a misleading cue such as in the Simon Says task, and not when they only had to refrain from executing a salient response. Similarly, Carlson and Meltzoff (2008) tested Spanish English bilinguals, English monolinguals and English speakers enrolled in a second language immersion kindergarten on a variety of EF tasks. After controlling for marked differences in socio economic status, Spanish English bilinguals performed better on EF tasks than English monolinguals and the language immersion group. Importantly, the advantage for bilinguals was only present for EF tasks that required cognitive flexibility such as sorting cards according to different rules (conflict tasks), as opposed to impulse control tasks such as delayed gratification (delay tasks). In contrast to these findings, Bialystok (2010) reported a series of studies where six year old bilinguals and monolinguals performed two EF tasks: the global local and the trail making task. In the global local task, participants were asked to identify a letter constituted of smaller letters (either the same letter or a different one) or to identify the smaller letters. In the trail making task, participants were asked to first draw a t rail connecting the numbers 1 to 25 on a page. In the next task, they were asked to connect
17 both numbers and letters (1, A, 2, B, etc). In this study, Bialistok found that bilinguals outperformed monolinguals in both the congruent and incongruent trials of the global local task, as well as in both the trial tasks connecting both letter and numbers and numbers only. This study provided evidence of a bilingualism advantage even in EF tasks that do not require inhibition. This EF advantage for bilinguals has a lso been reported in infants. Kovcs and Mehler (2008) found that 7 month old bilingual infants displayed greater EF in the form infants using eye tracking devices. In these studies, both bilinguals and monolinguals learned to predict the location of a coming stimulus using either speech or visual cues. The bilingual infants, however, displayed greater cognitive flexibility by rapidly learning to switch when the stimu lus started coming from another location. Since 7 month old bilingual infants are not yet required to suppress one language while producing another, the authors theorized that just the processing and representation of two different languages requires more cognitive flexibility from the infants in order to effectively acquire both these languages. Bilingualism and Language Regarding the other cognitive factor shown to impact ToM performance, language ability has been a contentious topic in which to compare b ilinguals and monolinguals. Early in development bilingual children are faced with two competing language groups creating phonetic semantic and grammatical conflicts that need to be resolved. The child is faced with the need to acknowledge that the same ob ject can have two phonetically distinct labels, in order to acquire semantic knowledge. These conflict demands are not experienced nearly as often by monolinguals. It is not surprising then,
18 that often bilingual children score lower on language ability tes ts compared to monolinguals (e.g. Bialystok & Viswanathan, 2009, Carlson & Meltzoff, 2008,); one might argue that this is a result of the fact that their separate performance in each of the individual languages does not really describe all their language k nowledge. A possible solution to this dilemma, creating a composite of their knowledge in both languages, would not be comparable to single language tests for monolinguals. The topic of comprehension for complementation syntax is one that has not been inv estigated in bilingual populations. It will be interesting to investigate this question with a bilingual monolingual comparisons because rather than consisting of a strictly language dimension such as semantics, comprehension for complements seems to inclu de broader language knowledge and perhaps reasoning related to ToM (Milligan et al. 2007) Exploring this question empirically with these populations will allow us to examine the relationship between ToM and general language, with comprehension for complem ents for bilinguals and monolinguals. It is important to note that complementation syntax works the same in Spanish as in English, where the conjugation que acts as the transition that. Bilingualism and T heory o f M ind In summary, bilingual children have been shown t o have an advantage over monolingual in EF tasks and a disadvantage on language ability. Further, both EF and language have been shown to be related to ToM performance in monolingual children. There is very limited research comparing bilinguals and monoli nguals on ToM development. There has been some evidence that bilinguals attain ToM related reasoning before monolinguals. Goetz (2003) compared the performance of Chinese English bilinguals on ToM measures to both English and Chinese monolinguals. Goetz
19 fo und that bilinguals outperformed both groups of monolinguals on false belief tasks, spite of coming from two vastly different language and cultural backgrounds. Goetz attri buted the increased performance of bilinguals on ToM to greater EF, such as increased linguistic inhibitory control over conflicting representations; greater metalinguistic understanding, such as increased awareness of the arbitrariness of language (which, she argues, increase representational capabilities); and a greater sensitivity to sociolinguistic interactions with interlocutors. However, EF was not measured in these groups. In a similar fashion, Kovcs (2009) found that 3 year old Hungarian Romanian bilinguals passed ToM tasks more often than Romanian monolinguals. In this study, performance on a modified ToM task that included a language switching situation. In this task, children were presented with a bilingual and a monolingual puppet, with one language in common, as the puppets go buy ice cream. There, the puppets encounter an ice cream seller who only speaks the language that the monolingual does not, and a sandw ich seller who speaks the common language. The ice cream seller then announces in the non common language that he ran out of ice cream, but that the monolingual puppet go buy ice c language knowledge alone could account for their increased performance on ToM, then they should perform better on the bilingual modified task than in the standard task. Since bilinguals performed equally on the standard and the modified task, Kovcs
20 theorized that the improved performance of bilinguals compared to monolinguals was a result of increased cognitive abilities related to EF. Though both Goetz and Kovcs explained the bilingual advantage on ToM tas ks to increased EF abilities, none actually measured EF performance of bilinguals in their articles. In summary, a large body of research attests to the fact that different aspects of s has been posited as an influential factor enhancing both ToM and EF performance. However, in these studies of ToM in bilingual children, neither the relative role of EF or language has been directly examined in their ToM task performance. The present st udy will investigate whether there are performance differences between Spanish English bilinguals and English monolinguals on ToM tasks as has been found in other language groups. Of particular interest is whether language and EF play different roles in To M development for bilinguals and monolinguals. This latter question will help illuminate the relationship between ToM, EF, and language. Hypotheses 1) Of interest in the present study is whether Spanish English bilinguals would differ from English monoling uals on ToM, EF and language measures. To my knowledge, this is the first research study comparing both ToM and EF for this language pair. Based on previous literature, we predicted an advantage for Spanish English bilinguals on ToM and EF performance com pared to English monolinguals, who would in turn outperform bilinguals on language tests. 2) The second question involves whether EF and language ability are related differently to ToM for Spanish English bilinguals compared to English monolinguals. First regarding the relationship of EF to ToM, given the prediction that bilinguals and monolinguals would perform differently on
21 EF, it was expected that EF would be more related to ToM performance for bilingual than for monolingual children. Second, regardin g the role of language ability, as a preliminary hypothesis, it was predicted that overall language ability comprised of both vocabulary and grammar, would be more related to ToM performance for English monolinguals, as their language ability was expected to be higher than that of bilinguals. performance on ToM reasoning.
22 CHAPTER 2 METHOD Participants Thirty two Spanish English bilingual and thirty three English monolingual chi ldren 36.5 to 74.4 months of age (bilingual M = 50.51, SD =6.93, monolingual M = 50.82, SD = 8.14), were recruited from Florida preschools. Bilingual children were identified by their parents as being fluent in both Spanish and English, and regularly inter acting with speakers of both these languages. The majority of the bilingual children (62%) had been exposed to both languages since birth, and all had been exposed to their non dominant language for at least one year. In addition, parents reported that in 61% of preschool the child attends both were spoken, and 46% of parents read to their children in both languages. Additionally, 58% of mothers to bilingual children speak to th em in Finally, 19% of both mothers and fathers actually indicated that their native language in Table 2 1 In relation to socioeconomic status, there was a significant difference between these groups on maternal level of education with monolingual mothers having significantly higher educational achievement at t(62) = 3.85, p < .001. There were no significant diff erences between the groups on age and gender distribution, or significant gender differences on any of the measures below. Measures All children were administered the following tests.
23 Theory of Mind Unexpected content task (Perner, Leekman, & Wimmer,1987 ). A closed crayon er receiving and answer ide the box. What does each of the two belief questions for a total of two possible points if he or she also pass ed the memory control questions. Unexpected location task (Wimmer & Perner, 1983). E introduced Ernie, a box, Now he is going outside to play. He Elmo is taking the Elmo where the toy car was, and a total of two points if she also passed the memory control question as to where the object is right now and where it was placed originally. Object disappearance, low inhibitory control demands (as described in Wellman et al.). Maxi. Maxi is putting his chocolate inside the box. Now he is going outs ide to play. Here
24 received a pass or fail for the last question, and another point for the mom tells Maxi that she ate the chocolate, before she told him that, would he have questions as to where the object is right now and where was it p laced originally. Appearance Reality, object identity task. E introduced a sponge that looks like k to your eyes right now? What is it really? Is it really a sponge or is it really a rock? When you first saw this, before you squeezed it, what did you think it was a rock or a sponge? Elmo has never touched this before. What does Elmo think this is a sp received a pass or fail for the last three questions, if she also passed the question Appearance Reality: Fish Task Object property E introduced a white fish ur eyes right now, what color The child received a pass or fail for the las t two questions for a total of two point. A theory of mind ( ToM ) on all these measures for a total of eleven points.
25 Executive Functioning Day/night Stroop like task (Gerstadt, Hong & Diamond, 1994). The child was first asked to identify a card depicting a sun and one depicting a moon and stars. If Understanding was confirmed by giving the child one practice trial with each card. The instructions and practice trials were repeated until the child passed the practic e trial. The child was then given 16 trials in a fixed random order for a total of 16 trials in which she was asked to name each card according to the rule. The final score was the sum of times the child named the card correctly on all 16 trials. Dimension al change card sort task (Frye, Zelazo, & Palfai, 1995). E introduced two c ontainers, one labeled with a red rabbit another with a blue boat. E gave the child the following instructions: the shape game, in the shape game the rabbits go with the rabbits and the boats go with the boats E then demonstrated the instructions with a blue rabbit and a red boat and asked the child to sort a blue rabbit a r ed boat a b lue boat a r ed rabbit and a b lue rabbit E then instructed the child to ow we are going to change to the color game, in the color game the blues go with the blues and the reds go with the reds and began a new trial by asking the child to sort a r ed boat a r ed rabbit a blue rabbit, a b lue boat a r ed boat and a b lue rabbit based on the correct sorting of the red boat (twice) and blue rabbit (twice) in the second set.
26 Bear/dragon Simon says like task (Reed, Pien & Rothbart, 1984) E first asked talks to us, we will do what he tells us to do, and this is naughty Dragon, so when he ran practice trials with each puppet until the child effectively followed at least one bear command, and resisted at least one dragon co mmand. When the task began, five bear trials and five dragon trials of different actions were given in alternating order. The child received one point for ignoring each of the dragon commands, and one point for following each of the bear commands for a tot al of 10 points. An executive function ( EF ) composite score was created by transforming each task score into a z score due to the differing number of questions per task. A composite was created by adding the z scores. Short term memory Digit span (as reported in Bialystok, 20 10) E read single digit lists at a rate of one per second starting with two digits. The child was asked to repeat the numbers in the same order. One digit was added after each second trial until the child was unable to reproduce both trials at a particula r level. The final score consisted of the last number of digits in which the child was able to reproduce at least one sequence. Language Language tests were provided in English to English monolinguals, and to Spanish English bilinguals in their dominant la nguage. Clinical Evaluation of Language Fundamentals (CELF).
27 Sentence Structure, and Word Structure, in English or Spanish as appropriate. For Expressive voca bulary, children were shown a series of pictures and were asked to name each one. The trial was discontinued after 7 consecutive zero scores. In the sentence structure trial, the child was read a series of sentences and was asked to point to the picture th at represents the sentence out of 4 related drawings. The trial was discontinued after 5 consecutive zero scores. For the word structure trial, the child was asked to use the progressive ing, prepositions, pronouns, plurals, etc. The trial was discontinu ed after 8 consecutive zero scores. Total CELF scores and subtests scores were obtained. Receptive One Word Picture Vocabulary Test (ROWPVT). vocabulary was measured using the English or Spanish English bilingual versions of the ROWPV T as appropriate. For this test, children were presented with a series of 4 drawings. The experimenter instructed the child to point to the picture that matched the word that the experimenter said. The trial was discontinued after 6 incorrect responses out of 8 consecutive items. Expressive One Word Picture Vocabulary Test (EOWPVT). expressive vocabulary was measured using the English or Spanish English bilingual versions of the EOWPVT. This test was administered in English for the English monol inguals, and in the language identified as non parents. Children were presented with a series of drawings, and were asked to name what was on the picture. The trial was discontinued after 6 incorrect responses out of 8 consecutive items.
28 Complementation (de Villiers & Pyers, 2002). Comprehension for complementation was measured in the following manner: E read to the child 12 sentences with embedded complements, accompanied with illustrative pictures. E then asked a compr Procedure Parents were asked for informed consent in English for the English monolingual parents, and in either Spanish or English, according to their preference, for the parents of the bilingual children. With the informed consent parents were asked to fill out a demographic questionnaire as well as a language questionnaire that asked about the conducted in quiet corners at the children like interaction. These sessions were less than two weeks apart. All measures were given in English to English monolinguals, and to bilinguals in in the parent questionnaire, with the exception of one expressive vocabulary test, the EOWPVT. This test was given to bilingual children in their non dominant language at the end of the second session. The tasks were given to bilinguals in their dominant language in order dominance of their second language. The author, who is a native Spanish speaker doctoral student fluent in English, did the translation of all testing and consent materia ls, as well as conducted all the testing sessions. The testing sessions began with a language test involving
29 pointing to make the child familiar with the experimenter before he/she was asked to speak. Testing then proceeded with ToM and EF tasks in alterna ting order. The tasks were given to all children in a fixed sequence.
30 Table 2 1. % English only % Spanish only % Both Languages Child Speaks 100 Child's Preferred Language 81 .3 12.5 6.3 Home 19.4 19.4 61.3 Spoken at Preschool 77.4 3.2 19.4 Language of Peers 77.4 22.6 Mother's Native Language 16.1 64.5 19.4 Father's Native Language 12.9 67.7 19.4 Other's Native Language 7.1 92.9 Language Mother Talks to Child 19.4 2 2.6 58.1 Language Father Talks to Child 25.8 25.8 48.4 Language Siblings Talk to a Child 69.2 7.7 23.1 Language Other Talks to Child 71.4 28.6 Reading Language at Home 45.5 9.1 45.5
31 CHAPTER 3 RESULTS Means and standard deviations of all the measur es are presented in Table 3 1 and Table 3 2. The first question of interest is whether monolingual and bilingual children differed on theory of mind ( ToM ) executive func tion ( EF ) and language abilities. Comparisons of monolingual and bilingual children were conducted on all the measures usin g t tests. As hypothesized, analyses indicated that there were significant differences between bilinguals and monolinguals on language ability as indicated by the CELF at ( t (62) = 5.11, p < .001), the ROWPVT at ( t ( 62 ) = 4.93 p < .001) and complementation comprehension at ( t ( 63 ) = 2.08 p < .0 5). Monolinguals outperformed bilinguals on each of these language measures. In contrast to the hypothesis, there were no differences between monolingual and bilingual children on the EF measures. Specifically, there were no differences on the standardized composite, or the individual components (Day/Night, Bear/Dragon, and dimensional change card sort), all t p Similarly, there were no differences on the short term memory measure at t (63) = 1.21, p > .05. Finally, comparison of bilingual and monolingual children on the ToM composite indicated no differences between the groups. When looking at the individual components however, there were differences between the groups on the Appearance/Reality compone nt at t (63) = 2.096, p= .040, with monolinguals outperforming bilinguals. To further explore whether there are differences between the monolingual and bilingual children on EF and ToM, a series of ANCOVAs were conducted controlling for overall language abi lity as assessed by the CELF and ROWPVT. Regarding EF, the standardized task composite revealed that there was a marginal main effect of
32 bilingualism status on EF that approached significance at F (1, 64) = 3.70, p = .059. Although this result was non sign ificant, the estimated means controlling for language ability were in the direction of bilinguals outperforming monolinguals (see Table 3 1 and Table 3 2). There were no significant main effects of bilingualism status on the EF subcomponents after controll ing for language ability. For the ToM composite, the ANCOVA indicated that there was a significant main effect for bilingualism status on ToM task performance at F (1, 64) = 4.02, p < .05, with bilinguals significantly outperforming monolinguals. Estimated means are displayed on Table 3 1 and Table 3 2. These results indicate that after controlling for the marked differences on language ability between these groups, bilinguals display a significant advantage over monolinguals on ToM related reasoning. Fina lly, to further examine whether bilingualism was related to performance on the EF, language, and ToM measures we examined subgroups of the bilingual children based on competency in their non dominant language by doing a median split on the EOWPT expressive vocabulary score. We did not find within bilinguals differences on any of our measured variables. Additionally, we conducted similar analyses comparing cradle (n=20) versus non cradle bilinguals (n=10) (those who had been exposed to their L2 after 1 year) but did not find any differences within these groups on EF, language and ToM measures. The second question of interest was how language and EF were related to ToM in the monolingual and bilingual groups. To examine these relations, correlations and parti al correlations controlling for age were initially conducted for the total sample, and separately for each of the language groups. The results of these analyses can be found
33 in Table 3 3, Table 3 4, and Table 3 5 For the total sample, correlations indicat e that as expected ToM correlated significantly with all of our language measures, (the CELF, ROWPVT and complementation comprehension), as well as the EF composite and short term memory. Examining at the individual language groups, for monolinguals ToM co rrelated with the EF composite as well as with the Bear/Dragon task in particular. ToM also correlated with the three language measures (CELF, ROWPVT, and complementation), and with the short term memory task. In contrast, however, for bilinguals the corre lation between ToM and EF was marginal ( p =.059), while for this group ToM correlated with another one of the EF tasks, namely, the dimensional change card sort task. In addition, ToM also correlated with the three language measures, similar to the monoling ual children, but as mentioned above, not with the EF composite as a whole. Since age correlated significantly with ToM in both language groups, partial correlations were conducted controlling for age. For the total sample, ToM correlated with the CELF, c omplementation comprehension, and marginally with short term memory ( p =.059), but no longer with EF or the ROWPVT. Similarly, for the monolingual sample only, after controlling for age ToM correlated with short term memory, complementation, and the CELF. A different pattern was found, however, for the bilingual preschoolers. Specifically, ToM, after controlling for age, did not correlate with either EF or language for the bilingual group as predicted. These relations were also examined by conducting a mult iple hierarchical regression analysis with the ToM composite as the dependent variable. To the first block of predictors we added language status (bilingual versus monolingual) and age in
34 months. To the second block we added complementation, EF, general la nguage (CELF), and receptive vocabulary. The beta weights associated with age and the CELF were the only significant ones at b = .44, t (58) = 3.73, p < .001, and b = .55, t (58) = 3.48, p = .001 respectively. The beta weights for language status, EF, and th e other language predictors were non significant (see Table 3 6 ). These latest findings lead support to the hypothesis that general language is more important for ToM performance than particular syntactic abilities such as comprehensions for complements.
35 Table 3 1 Means, Standard Deviations, Estimated Means and Standard E rrors for B ilinguals ToM EF CELF ROWPVT Complements (n=32) M 6.22 .25 46.00 44.71 7.69 SD (2.42) (2.15) (14.43) (13.55) (3.74) Estimated M a 7.29 .49 SE (.41) (.34) Note. Standard deviations and standard errors in parentheses. a Estimated means and standard errors obtained from ANCOVA controlling for language ability. Table 3 2 Means, Standard Deviations, Estimated Means and Standard E rrors for M onolinguals ToM EF CELF ROWPVT Complements (n = 33) M 7.09 .24 62.45 59.18 9.55 SD (2.70) (1.72) (10.96) (9.75) (3.47) Estimated M a 6.04 .47 SE (.40) (.32) Note. Standard deviations and standard errors in parentheses. a Estimated means and standard er rors obtained from ANCOVA controlling for language ability. Table 3 3 Language Measures for the Total Sample ToM EF CELF ROWPVT (n=65) ToM EF .37**(.18) CELF .61**(.43** ) .52**(.45**) ROWPVT .49**(.24) .43**(.27^) .76**(.69**) Complementation .45**(.35*) .50** (.44**) .56**(.51**) .58**(.56**) Note. Partial correlations between parentheses. ^ p< .10; p <.05; ** p <.01
36 Table 3 4 Language Measures for Bilinguals ToM EF CELF ROWPVT (n=32) ToM EF .34 ^(.08) CELF .58**(.28) .52**( .47*) ROWPVT .38*( .08) .44*( .14) .73**( .35) Complemen tation .41*(.21) .46**( .22) .56**( .27) .60**(.48*) Note. Partial correlations between parentheses. ^ p< .10; p <.05; ** p <.01 Table 3 5 ToM, EF, and Language Measures for Monolinguals ToM EF CELF R OWPVT (n=33) ToM EF .39*(.30) CELF .70**(.43*) .60**( .47**) ROWPVT .61**(.34^) .42*( .32) .62**( .63**) Complementation .44*( .42*) .53**(.45*) .47**(.59**) .47**( .49*) Note. Partial correlations between parentheses. ^ p< .10; p <.05; p <.01 Table 3 6 Summary of Hierarchical Regression Analysis for Variables Predicting ToM Variable B SE B Step 1 (n= 65) Language status .81 .52 .16 Age .20 .03 .59** Step 2 Language status .41 .62 .08 Age .15 .04 .44** CELF .09 .03 .55** Complementation .13 .08 .19 EF .14 .15 .10 ROWPVT .0 3 .03 .17 p <.05; ** p <.01
37 CHAPTER 4 DISCUSSION There were two main objectives to this study. First we wanted to examine performance differences between bilinguals and monolinguals on theory of mind ( ToM ) executive function ( EF ) and language measures. Although bilinguals tend to underperf orm on language measures when compared to monolinguals (e.g., Bialystok & Viswanathan, 2009), they often outperform on EF measures (Bialystok & Viswanathan, 2009; Bialystok, 2010; Carlson & Meltzoff, 2008; Kovcs & Mehler, 2008; Martin Rhee & Bialystok, 20 08), as well as on ToM measures (Goetz, 2003; Kovcs; 2009). Since this latest finding has only been reported in a handful of studies, we set out to expand prior findings, and examine other language pairs such as Spanish and English on ToM task performance The second objective of this study was to examine the ways in which EF and language; known predictors of ToM, might be related differently for ToM in bilinguals and monolinguals. Given the reported bilingual advantage on EF, it was hypothesized that EF monolinguals. Bilingual Monolingual Differences Using a Spanish English bilingual sample and an English monolingual sample, we found that as expected monolinguals significantly outperformed bilin guals on language ability using general language (CELF), receptive vocabulary, and complementation comprehension tasks. Importantly, after controlling for this significant language imbalance between the groups, bilinguals outperformed monolinguals on ToM r elated reasoning tasks. This indicates that growing up in a bilingual environment has the potential to enhance ToM related reasoning in ways that are not adequately explained
38 by better language abilities since bilinguals actually underperform in language t ests, or by enhanced executive function as will be discussed below. Interestingly, we found no significant performance differences between bilinguals and monolinguals on the EF composite. We had predicted based on previous findings that bilinguals would outperform monolinguals in EF, but this was not the case. This failure to find bilingual monolingual differences in EF is very intriguing in light of the previous research that attests to this difference (see Bialystok & Viswanathan, 2009; Bialystok, 2010; Carlson & Meltzoff, 2008; Kovcs & Mehler, 2008; Martin Rhee & Bialystok, 2008). Even though we failed to replicate the findings that bilinguals significantly outperform monolinguals on EF, our results were in that direction. One reason for this failure to replicate previous findings could be sample size. Since our results were in the direction of bilinguals outperforming monolinguals after controlling for language ability, we hypothesize that with a larger sample size we would have more statistical power to detect this significance. Another possibility for this lack of replication collected. Ostensibly, bilingual children raised in Miami, Florida, might not inhabit a Spanis h English bilingual environment where the use of these languages would be compartmentalized (say one at home, one at preschool), but rather one in which a large proportion of the population these bilingual children interact with is also bilingual. For exam languages are spoken, as well as in 19% of their preschools. Additionally, 58% of mothers to bilingual children speak to them in both languages, as do 48% of fathers.
39 Finally, 19% of both mothers and fathers actually indicated that their native language perhaps t inhibit one language for the other as often as other bilingual groups might be. This was corrobo rated during data collection when we observed that the bilingual children were being spoken to almost simultaneously in both Spanish and English or in a combination of the two. Arguably, this kind of bilingual environment might diminish the EF demands thes e children experience by not being really required to switch and inhibit one language for the other, but rather, as far as production is concerned, in a lot of situations any individual or combined linguistic output from the child would be acceptable. The end result of this could be that with a less demanding bilingual environment regarding EF demands, these bilingual children might resemble monolingual children more than other bilingual children with more compartmentalized linguistic experiences. Importan tly, our inability to find a bilingual monolingual difference in EF in addition to a bilingual advantage on ToM, points to the need to question the claim made by ToM bilingualism researchers (i.e. Goetz, 2003; Kovcs, 2009) that enhanced EF is perhaps the outperformed monolinguals in ToM, they did not do so on EF. As an example, Goetz (2003) compared Chinese English bilinguals in the United States to both English and Chinese monolinguals on ToM tasks and found that the bilinguals outperformed both monolingual groups. Relatedly, Kovcs (2009) found that Romanian Hungarian
40 bilinguals outperformed Romanian monolinguals in ToM. In their discussions, both these researchers argued t hat perhaps bilinguals outperformed monolinguals on ToM due to their enhanced EF even though EF was not measured in these studies. As stated above, this claim was not supported by our data. Instead, our findings point to necessary future research where oth linguistic awareness. Metalinguistic awareness refers to an understanding of the arbitrariness of language. Prior research o n this topic found that meta linguistic awareness is related to ToM reasoning (Doherty, 2000), and that bilinguals tend to outperform monolinguals on these metalinguistic awareness tasks (Ben Zeev, 1977), thus making metalinguistic awareness a good candida precocious understanding of language as a representational system rather than as a direct portrayal of reality might be related to their understanding that mental states are also representational in nature. T heory o f M ind Relationships For our second objective we looked at how EF and language might be related differently to ToM for each of the language groups. Our analysis of correlations before controlling age revealed that while EF was correlated with ToM in b oth the monolingual and the general samples, in the bilingual group this relationship did not reach significance. These relationships between EF and ToM were not significant after controlling for age, which suggest that for both bilinguals and monolinguals language ability might be more important for ToM performance than EF for it was still correlated with ToM in the partial correlations. Similar findings were obtained through regression analyses, where general language and age had the only significant beta weights when
41 EF, complementation, receptive vocabulary and language status were also added as independent predictors. A possible exception for this obviation of EF after controlling for age was that for both the total and monolingual samples short term me mory was still correlated with ToM after controlling for age. This was not the case for the bilinguals either before or after controlling for age, indicating that in fact bilinguals are relying on other cognitive abilities when engaged in ToM reasoning. Th ese results in the very intriguing finding that in fact after controlling for age, none of the relations with ToM in the bilingual group remained significant, which again suggests that other unmeasured mance. One possible candidate is metalinguistic awareness In our correlational and regression analyses we also looked at which particular aspects of language were more related to ToM, and found that overall general language ability comprised of both expres sive vocabulary and grammar, was more related to ToM than receptive vocabulary or complementation comprehension. This pattern was maintained for the total sample and the individual language groups before controlling for age in the partial correlations. Aft er controlling for age, however, the correlations between ToM and language were only significant for the monolingual group. These findings contradict previous reported findings arguing for the primacy of complementation comprehension over general language (de Villiers and Pyers, 2002; de Villiers, 2005; Milligan et al. 2007 ). Instead, at least for monolinguals, our findings agree with those reported by Slade and Ruffman (2005) where a combination of general grammar and semantic abilities was the best predi ctor of ToM reasoning.
42 Limitations and Future Directions There were some limitations to this study. For example, our sample size was perhaps too small for regressions analyses. Similarly as discussed above, bilingual monolingual differences in EF controlli ng for language ability were marginally significant in the direction of bilinguals outperforming monolinguals as has been shown previously in the literature. A bigger sample could have given us more power to detect this difference. Finally, another limitat ion is the lack of a Spanish monolingual group for comparison. Although we have no particular reason to suspects that ToM development might be different in Spanish from English, the possibility of differential predictability of certain linguistic factors o ver others is an intriguing one. For future directions, this study provides strong evidence for the need to measure other factors that might be associated with ToM in bilinguals since we failed to find any significant correlations after controlling for ag e. One possibility for this is metalinguistic awareness which is strongly associated with ToM (Doherty, 2000) as well as has been shown to be acquired earlier by bilinguals (Ben Zeev, 1977). Additionally, it is important to measure the factors represented in the current study as well as those unmeasured ones suspected to have an effect, in a longitudinal matter that will allow us to look at direction of effects, as well as potential differences in developmental trajectories regarding bilingualism. Conclusio n In conclusion, in this study we looked at bilingual monolingual differences in ToM, EF and Language, and how both EF and language might be related differently to ToM in bilinguals and monolinguals. Regarding the first objective, we found that as expected monolinguals outperformed bilinguals in all of our L1 measurements. Once we
43 controlled for this difference in language ability, bilinguals outperformed monolinguals in ToM. Contrary to expectations, however, bilinguals did not outperform monolinguals EF, nor was EF related to ToM performance in bilinguals. These findings cast doubt on the in ToM. Regarding the relationship between ToM and language ability, we found th at general language ability was more highly correlated with ToM than comprehension for complements in the monolingual sample only, for after controlling for age, none of the language measures were correlated with ToM in the bilingual sample. Based on this absence of relatedness with ToM in the bilingual sample, other abilities such as metalinguistic awareness are considered for future research that might effectively predict ToM performance in this group.
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47 BIOGRAPHICAL SKETCH Vanessa Diaz is a doctoral student in the Department of Psychology at the University of sychology from Florida International University in Miami, where she a lso obtained a minor in French language and c ul ture, graduating Phi Beta Kappa. Coming from a multicultural background, Vanessa is deeply interested in figuring out how we begin to adapt and thrive in inter subjectivity, especially throu gh different languages.