Child Development, July/August 2015, Volume 86, Number 4, Pages 1159–1174

Meta-Analysis of Theory of Mind and Peer Popularity in the Preschool and Early School Years Virginia Slaughter, Kana Imuta, Candida C. Peterson, and Julie D. Henry University of Queensland

It has been argued that children who possess an advanced theory of mind (ToM) are viewed positively by their peers, but the empirical findings are mixed. This meta-analysis of 20 studies including 2,096 children (aged from 2 years, 8 months to 10 years) revealed a significant overall association (r = .19) indicating that children with higher ToM scores were also more popular in their peer group. The effect did not vary with age. The effect was weaker for boys (r = .12) compared to girls (r = .30). ToM was more strongly associated with popularity (r = .23) than with rejection (r = .13). These findings confirm that ToM development has significant implications for children’s peer relationships.

When children acquire a theory of mind (ToM), they become capable of predicting and explaining what is in their own and other people’s minds and understanding how mental states influence behavior. This is reflected in a striking developmental change, between ages 3 and 5 years, in understanding of false belief (Gopnik & Slaughter, 1991). Most 3-year-olds fail first-order false-belief tasks requiring inferences about how a protagonist who holds a false belief will behave, whereas most 6-year-olds pass (Wellman, Cross, & Watson, 2001). Beyond the preschool period, ToM becomes increasingly sophisticated. Second-order false-belief understanding, which is the ability to reason about one protagonist’s false belief about another’s true or false belief, develops in most children by ages 9 or 10 (Perner & Wimmer, 1985). Over the period from ages 6 to 10, there are also changes in understanding of complex social situations involving people’s thoughts, intentions, and feelings, for instance, recognizing when someone makes a faux pas in conversation (Baron-Cohen, O’Riordan, Stone, Jones, & Plaisted, 1999). Given these developments in ToM understanding from preschool through middle childhood, it seems highly plausible that these cognitive gains should encourage even more effective forms of social interaction (Hughes, 2011), which in turn should influence how children We sincerely thank the scholars who took time from their busy schedules to respond to our requests for information to include in this meta-analysis. We also thank Hilal Sen Harma and three anonymous reviewers for comments on earlier versions. Correspondence concerning this article should be addressed to Virginia Slaughter, School of Psychology, University of Queensland, Brisbane, Qld, Australia 4072. Electronic mail may be sent to [email protected].

interact with and are perceived by those around them. Thus, theoretically, children’s ToM development should significantly influence their everyday social experiences. In line with this hypothesis, researchers have evaluated correlations between individual differences in children’s ToM understanding as measured in the laboratory, and their social competence with adults and/or peers. This body of work examines, for instance, links between children’s ToM and communicative competence (Davis-Unger & Carlson, 2008; Fernandez, 2013; Slaughter, Peterson, & Moore, 2013), prosocial behavior (Cassidy, Werner, Rourke, Zubernis, & Balaraman, 2003), and aggression (Olson, LopezDuran, Lunkenheimer, Chang, & Sameroff, 2011; Renouf et al., 2010). An emerging picture is that, at any given age, those children whose ToM understanding is more advanced also tend to engage in relatively sophisticated social and communicative behaviors. However, the links are not always consistent nor are they typically very strong (see review by Hughes & Leekam, 2004). Another way to test the real-world significance of children’s ToM development is to consider whether individual differences in children’s ToM understanding are related to the quality of their peer relationships. In the current meta-analysis, we aggregate findings from over 20 years of research, to address this question.

© 2015 The Authors Child Development © 2015 Society for Research in Child Development, Inc. All rights reserved. 0009-3920/2015/8604-0012 DOI: 10.1111/cdev.12372

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There are several ways to operationalize children’s peer relationships (Gifford-Smith & Brownell, 2003). A prominent approach in the literature on children’s ToM has been to measure the extent to which children are accepted and liked by other children. This dimension of children’s peer relationships has been referenced with various labels including “peer acceptance,” “sociometric status,” “likability,” “peer rejection,” and, most commonly, “popularity” (Cillessen & Marks, 2011). In recent years, a theoretical and empirical distinction has emerged between sociometric popularity and perceived popularity (Cillessen & Rose, 2005). Sociometric popularity refers to how much a child is liked or disliked by peers. The technique for assessing sociometric popularity is peer nomination, whereby all children within the peer group identify the other children whom they like most (LM) and least (LL; Coie & Dodge, 1983). Perceived popularity refers to the extent to which peers or other observers consider a child to have high status within the peer group. This is assessed via peer or teacher reports about which children are “popular” or, on the other side of the coin, which children are “rejected.” Sociometric and perceived popularity are distinct constructs, although there is also a good deal of overlap. Correlations between sociometric and perceived popularity range from around .45 up to .63 in samples of school-aged children (Babad, 2001; LaFontana & Cillessen, 1999; Parkhurst & Hopmeyer, 1998). The correlation decreases as children get older (Babad, 2001). Furthermore, the behavior profiles of sociometrically popular and perceived popular children diverge somewhat, with the former tending to have strong interpersonal and communication skills, to be prosocial and cooperative, and to be low on aggression (for a review, see Rubin, Bukowski, & Parker, 2006). Perceived popular children also tend to be communicative and prosocial, but at the same time, they often engage in relational aggression (Cillessen & Mayeux, 2004; Cillessen & Rose, 2005), which they may use strategically to manipulate others in order to gain or maintain their position in the social group (Hawley, 2003). While associated with different assessment techniques and potentially different behavioral patterns of peer interaction (Parkhurst & Hopmeyer, 1998), both perceived and sociometric popularity could arguably be correlated with advanced ToM understanding. Alternatively, their correlations with ToM understanding could be different. There seems to be empirical support for both of these possibilities.

For instance, if sociometrically popular children are highly sensitive to others’ feelings and perspectives, in line with their good communication skills and prosociality (e.g., Cillessen & Rose, 2005), then their ToM understanding may be related to how well they are liked by their peers. By contrast, children who are high on perceived popularity might achieve their social status without being as sensitive to others’ perspectives. This would be consistent with research showing that adults with high social status or power demonstrate lower ToM abilities than their lower status peers (Galinsky, Magee, Inesi, & Gruenfeld, 2006; Rutherford, 2004). However, it might instead be that children who are high on perceived popularity gain status through skillful, reputation-enhancing interactions with peers, which would predict that this group should also show sophisticated ToM understanding. In the current meta-analysis, we explore these alternative hypotheses by separately analyzing associations between children’s ToM and sociometric versus perceived popularity. Where appropriate, and consistent with the published literature, we use the term “peer popularity” to simultaneously reference sociometric and perceived popularity. As reported below, sociometric popularity was far more commonly assessed in this literature, in keeping with the surge in sociometric research in the 80s and 90s (Babad, 2001; Cillessen & Marks, 2011) that corresponded with a period of intense study of children’s ToM development. Children’s ToM and Peer Popularity: Mixed Findings Many authors assume that children’s performance on ToM tests does correlate with peer popularity (Hughes & Cutting, 1999). However, those who have gathered data to test for a link often acknowledge that the findings are mixed (Banerjee, Watling, & Caputi, 2011; Braza et al., 2009; Caputi, Lecce, Pagnin, & Banerjee, 2012). For instance, some studies report robust associations between children’s ToM and peer popularity (Banerjee et al., 2011; Cassidy et al., 2003; Peterson & Siegal, 2002), but others have reported no concurrent correlation, both with (Flynn & Whiten, 2012; Watson, Nixon, Wilson, & Capage, 1999) and without accounting for additional variables such as chronological age and/or verbal ability (Diesendruck & Ben-Eliyahu, 2006; Slaughter, Dennis, & Pritchard, 2002). This literature is therefore ideal for metaanalysis, in which it is possible to aggregate diverse individual study results to identify the overall mean effect.

ToM and Peer Popularity

A potential contributor to the inconsistent results is that this literature has typically not distinguished between sociometric and perceived popularity. Another potential contributor may be variation in the ages of children sampled across different studies. Indeed, there are reports that ToM is associated with peer popularity exclusively among older children (Angelopoulos, 1999; Banerjee et al., 2011; Slaughter et al., 2002), or only when longitudinal associations are considered (e.g., early ToM and later peer popularity; Caputi et al., 2012). Developmental theory might suggest that the association between children’s ToM and peer popularity is moderated by age. During the preschool years, children’s social lives and emotional wellbeing are primarily influenced by their interactions with parents and siblings and these are significantly correlated with individual differences in ToM understanding (e.g., McAlister & Peterson, 2013; Perner, Ruffman, & Leekam, 1994). But with entry into in primary school, peer interactions become more frequent, complex, and independent from adult supervision (Rubin et al., 2006). This has led to the suggestion that children’s ToM understanding may become more strongly associated with aspects of peer relationships after age 6, as they gain wider interpersonal experience and their social focus moves from family to peers (Caputi et al., 2012; Slaughter et al., 2002). If this is the case, then we would expect the ToM–peer popularity association to be stronger among schoolaged children as opposed to preschoolers. We addressed this question by separately analyzing results for preschoolers (age 5 years and younger) and school-aged children (6 years and up). We chose this cutoff because many studies contributing to the meta-analysis included children only up to age 5, in keeping with much of the ToM literature that has traditionally focused on the 3- to 5-yearold preschool period when significant developmental changes occur in children’s ToM (Wellman et al., 2001). The decision to split studies into 2- to 5- and 6- to 10-year-old age groups was largely a practical one that allowed us to maximize the number of study-level effects that contributed to the analyses by age group. The literature on ToM and peer popularity includes several studies that report significant gender differences, but these findings are also mixed. Some indicate correlations between ToM task scores and peer popularity only among girls (Badenes, Clemente Estevan, & Garcıa Bacete, 2000; Banerjee, Rieffe, Terwogt, Gerlein, & Voutsina, 2006; Braza et al., 2009). The argument is that girls are generally

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more “interpersonally oriented” than boys, and as such, their peer relationships tend to be more intimate and involve more complex communication (Banerjee et al., 2006). If this is the case, then girls’ peer popularity may be more closely tied to their ToM understanding than that of boys. However, some studies have reported no gender differences (Banerjee et al., 2011), and one study reported a significant association between ToM and peer popularity only among boys (Dockett & Degotardi, 1997). We therefore performed separate analyses for girls and boys, to clarify the existing findings. Overview and Research Questions Here for the first time, we adopted a meta-analytic approach to clarify the extent to which children’s peer popularity is related to their developing ToM in the preschool and primary school period. We defined ToM as children’s ability to infer a protagonist’s internal mental state based on his or her physical situation and/or to articulate an understanding of how internal mental states may influence people’s behavior. Thus, the ToM assessments that went into the meta-analysis include standard first- and/or second-order false-belief tasks. We also included perspective-taking tasks, broadly defined as any test that required children to recognize that different people’s perception of, or beliefs about, the same reality may differ. We did not include emotion understanding or empathy in our definition of ToM. Although emotions are internal states that can influence behavior, the development of emotion understanding follows a distinct trajectory from that of ToM (Cutting & Dunn, 1999; de Rosnay, Pons, Harris, & Morrell, 2004; O’Brien et al., 2011). Furthermore, children’s emotion understanding in relation to both peer popularity (de Rosnay, Harris, & Pons, 2008) and social competence more broadly (Trentacosta & Fine, 2010) has been reviewed elsewhere. We focused on concurrent associations between children’s ToM and peer popularity, since only a handful of published studies have taken a longitudinal approach (Banerjee et al., 2011; Caputi et al., 2012; Fink, Begeer, Hunt, & de Rosnay, 2014). In each of these, the researchers reported correlations between ToM and peer popularity at one or more age points. We included their data on concurrent correlations only, acknowledging that this approach precludes assessment of alternative developmental models. In evaluating associations between children’s ToM and their concurrent peer popularity, it is

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necessary to distinguish two related but nonmutually exclusive effects. On the assumption that a more advanced ToM understanding enables a wider variety of effective social interactions, children’s ToM could be positively linked to their being liked and having high status in their peer group. That is, a relatively advanced ToM may be associated with greater peer popularity. It is also conceivable that children’s ToM could be linked to their being disliked by peers; that is, those children whose ToM understanding is relatively slow to develop might be actively disliked by their peer group. Many of the researchers who have assessed peer popularity using Coie and Dodge’s (1983) sociometric technique have evaluated these effects separately, reporting independent correlations between children’s ToM and their positive and negative peer nominations. This also has led to mixed results; for instance, Banerjee and Watling (2005) found that older children’s ToM understanding was significantly correlated with their positive nominations, but not with negative nominations, whereas Flynn and Whiten (2012) reported a significant association between children’s ToM and negative but not positive peer nominations. Other researchers have focused exclusively on either the positive model (Watson et al., 1999) or the negative one (Hoglund, Lalonde, & Leadbeater, 2008). As outlined in Appendix S1, many of the studies to date have included a mix of positive and negative indicators of peer popularity; therefore, we conducted separate analyses to evaluate whether children’s ToM associates more strongly with positive versus negative peer regard. We address five questions via meta-analysis: (a) Is there an overall association between children’s ToM, as measured with standard tasks, and their concurrent peer popularity? Consistent with theory, we expected that overall there would be a positive association indicating that children who outperform their peers on standard tests of ToM understanding will be relatively popular in their peer group. We also asked: (b) Does ToM correlate differentially with sociometric popularity (e.g., likability) versus perceived popularity (e.g., high status)? (c) Is the association between ToM and peer popularity similar for preschool-aged and older children? (d) Is the ToM–peer popularity association similar for boys and girls? And finally: (e) Does children’s ToM associate more strongly with positive peer regard (e.g., being nominated or rated as well liked or popular) or with negative regard (e.g., being nominated or rated as disliked or rejected)?

Method Literature Search A systematic search of the existing research literature on the relation between ToM and peer popularity was completed in October 2013. Identification of studies eligible for inclusion was achieved by searching the Web of Science (Thomson Reuters), Psych INFO (American Psychological Association), Scopus (SciVerse), and Google-Scholar (Google) databases. The key words searched were: “popularity,” “sociometric,” “peer acceptance,” “peer likability,” “peer rejection,” “peer status,” “peer evaluation,” “peer nomination,” “peer relations,” in combination with, “ToM,” “mindreading,” “mentalizing,” “false belief,” “mental representations,” “mind understanding,” and “mental states.” Backward citation searches were also undertaken. Inclusion Criteria Studies that were included in the meta-analysis met the following criteria: 1. They were published in English or Japanese (because these were the languages in which members of our team were fluent). 2. They had a research design that included healthy preschool or school-aged children. We set an upper age limit of 10 years, which maximized the number of available studies while avoiding preadolescent and adolescent samples. Healthy was defined as the absence of psychiatric or neurological illness or severe sensory impairment (e.g., profound deafness). 3. They included a behavioral measure of ToM with a primary focus on mental state attribution. As discussed earlier, tasks that involved assessment of empathy, emotional reactivity, or emotion understanding were not included. In line with the literature, most of the studies in our meta-analysis used a battery of ToM tasks and almost all included at least one standard test of false-belief understanding. We also included data from hidden emotion, affective perspective-taking, and faux pas tasks because all of these require children to distinguish between two different mental perspectives. 4. The studies had to include a measure of peer popularity assessed concurrently with children’s ToM. We included measures of both sociometric and perceived popularity, and treated them separately in the meta-analysis. Sociometric popularity was measured via peer

ToM and Peer Popularity

nominations of likability (e.g., “Name the three classmates that you like most and the three classmates that you like least”), which were reported as “LM” and “LL” nominations, as weighted social preference (SP) and/or social impact (SI) scores, or as mutually exclusive classifications of children as popular, average, controversial, rejected or neglected, based on their SP and SI scores (see Coie & Dodge, 1983, for details). Sociometric popularity was also sometimes assessed with Likert-scale peer likability ratings (e.g., “How much do you enjoy playing with _____?”). Perceived popularity was assessed with peer or teacher ratings or rankings (e.g., “How popular is _____?” or “To what extent is _____ rejected by his/her peers?”). We did not include studies that assessed self-reported number of friends or mutual friendships because these have been shown to be distinct from popularity (Bukowski, Hoza, & Newcomb, 1994). We also excluded studies that assessed relations between children’s ToM and social competence defined behaviorally (e.g., observations of prosocial behavior, teacher ratings of social skills, etc.) unless they also provided data on peer popularity. 5. Included studies had to report precise statistics convertible to effect sizes. Studies that reported correlations between the two key dependent measures were only considered eligible where raw correlations were reported (i.e., partial correlations did not contribute). For studies that did not present all necessary statistics, authors were contacted directly to request the relevant data (these were: Angelopoulos, 1999; Badenes et al., 2000; Banerjee et al., 2006; Caputi et al., 2012; Diesendruck & Ben-Eliyahu, 2006; Dockett & Degotardi, 1997; Fink et al., 2014; Flynn & Whiten, 2012; Peterson & Siegal, 2002; Slaughter et al., 2002). Of these, only Badenes et al. (2000) and Peterson and Siegal (2002) were not included, either because the authors did not respond or because they were unable to locate the original raw data set. Gender-separate correlations for female participants from Dockett and Degotardi’s (1997) study were also not included because the published paper did not include the necessary data. Lastly, effect sizes were derived from means and standard deviations provided by the corresponding author of Banerjee et al.’s (2006) study. This was because the study involved preselected groups of children (classified as popular and

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rejected based on peer nomination), and thus the data did not include continuous scores that could be correlated with children’s ToM scores. The initial search revealed 44 studies. Twenty of those met all of the inclusion criteria listed above. Of those eliminated, 16 were discounted because their peer popularity assessment did not fit the definition of sociometric or perceived popularity (e.g., they measured social competence, self-reported number of friends, bullying, etc.), 3 were eliminated because they did not meet the criterion for ToM assessment (e.g., they assessed emotion understanding), 2 were in a language that our team did not read (in both cases, Chinese), 2 included children older than age 10, and 2 were unable to supply appropriate data (as mentioned above). Sample Characteristics The 2,096 children who participated in the 20 studies that were included in our meta-analysis were from 10 different countries: Australia, Canada, England, Israel, Italy, Japan, New Zealand, Scotland, Spain, and the United States. The majority of children were recruited from day care centers, kindergarten, preschool, and primary schools in the cities in which data were collected. In all but 6 studies (Braza et al., 2009; Caputi et al., 2012; Caravita et al., 2010; Diesendruck & Ben-Eliyahu, 2006; Mizokawa & Koyasu, 2011; Morino, 2005), the children’s primary language was English. In the remaining 6 studies, children’s primary languages were Arabic/Hebrew, Italian, Japanese, and Spanish. In all but 3 studies (Diesendruck & BenEliyahu, 2006; Mizokawa & Koyasu, 2011; Morino, 2005), the majority of children were Caucasian. The children in Diesendruck and Ben-Eliyahu (2006) represented a variety of Jewish family backgrounds (e.g., from European, North African, or Middle Eastern descent), and all children in Mizokawa and Koyasu (2011) and Morino (2005) were Japanese. Although children across the 20 studies were from a mixture of working-, middle-, and upper-class families, they were predominantly middle-class. Statistical Analysis Meta-analysis is a rigorous, quantitative alternative to the traditional review process, as it involves statistical integration of results. The basis of this methodology is the effect size, a standardized statistic that quantifies the magnitude of an effect. We use r in the current meta-analysis, based on its

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*Diesendruck, G., & Ben-Eliyahu, A. (2006). The relationships among social cognition, peer acceptance, and social behavior in Israeli kindergarteners. International Journal of Behavioral Development, 30, 137–147. doi:10.1177/0165025406063628 *Dockett, S., & Degotardi, S. (1997). Some implications of popularity at age four. Journal of Australian Research in Early Childhood Education, 1, 21–31. Easterbrook, P. J., Berlin, J. A., Gopalan, R., & Matthews, D. R. (1991). Publication bias in clinical research. Lancet, 337, 867–872. doi:10.1016/0140-6736 (91)90201-Y Fernandez, C. (2013). Mindful storytellers: Emerging pragmatics and theory of mind development. First Language, 33, 20–46. doi:10.1177/0142723711422633 *Fink, E., Begeer, S., Hunt, C., & de Rosnay, M. (2014). The role of theory of mind in establishing, maintaining, and modifying peer acceptance. Child Development, 85, 2389–2403. doi:10.1111/cdev.12302 *Flynn, E., & Whiten, A. (2012). Experimental “microcultures” in young children: Identifying biographic, cognitive, and social predictors of information transmission. Child Development, 83, 911–925. doi:10.1111/J.14678624.2012.01747.X Galinsky, A. D., Magee, J. C., Inesi, M. E., & Gruenfeld, D. H. (2006). Power and perspectives not taken. Psychological Science, 17, 1068–1074. doi:10.1111/j.14679280.2006.01824.x Gifford-Smith, M., & Brownell, C. (2003). Childhood peer relationships: Social acceptance, friendships, and peer networks. Journal of School Psychology, 41, 235–284. doi:10.1016/S0022-4405(03)00048-7 Gopnik, A., & Slaughter, V. (1991). Young children’s understanding of changes in their mental states. Child Development, 62, 98–110. doi:10.1111/J.14678624.1991.Tb01517.X Hawley, P. H. (2003). Prosocial and coercive configurations of resource control in early adolescence: A case for the well-adapted Machiavellian. Merrill-Palmer Quarterly, 49, 279–309. doi:10.1353/Mpq.2003.0013 Hedges, L., & Olkin, I. (1985). Statistical methods for metaanalysis. New York, NY: Academic Press. Henry, J. D., & Crawford, J. R. (2004). A meta-analytic review of verbal fluency performance following focal cortical lesions. Neuropsychology, 18, 284–295. doi:10.1037/0894-4105.18.2.284 *Hoglund, W. L. G., Lalonde, C. E., & Leadbeater, B. J. (2008). Social-cognitive competence, peer rejection and neglect, and behavioral and emotional problems in middle childhood. Social Development, 17, 528–553. doi:10.1111/J.1467-9507.2007.00449.X Hughes, C. (2011). Social understanding and social lives: From toddlerhood through to the transition to school. Hove, UK: Psychology Press. Hughes, C., & Cutting, A. L. (1999). Nature, nurture, and individual differences in early understanding of mind. Psychological Science, 10, 429–432. doi:10.1111/14679280.00181

Hughes, C., & Leekam, S. (2004). What are the links between theory of mind and social relations? Review, reflections and new directions for studies of typical and atypical development. Social Development, 13, 590–619. doi:10.1111/j.1467-9507.2004.00285.x Kloo, D., & Perner, J. (2008). Training theory of mind and executive control: A tool for improving school achievement? Mind Brain and Education, 2, 122–127. doi:10.1111/J.1751-228x.2008.00042.X Ladd, G. W. (2006). Peer rejection, aggressive or withdrawn behavior, and psychological maladjustment from ages 5 to 12: An examination of four predictive models. Child Development, 77, 822–846. doi:10.1111/ j.1467-8624.2006.00905.x Ladd, G. W., & Troop-Gordon, W. (2003). The role of chronic peer difficulties in the development of children’s psychological adjustment problems. Child Development, 74, 1344–1367. doi:10.1111/1467-8624.00611 LaFontana, K. M., & Cillessen, A. H. N. (1999). Children’s interpersonal perceptions as a function of sociometric and peer-perceived popularity. Journal of Genetic Psychology, 160, 225–242. doi:10.1080/00221329909595394 Lockl, K., & Schneider, W. (2007). Knowledge about the mind: Links between theory of mind and later metamemory. Child Development, 78, 148–167. doi:10.1111/ J.1467-8624.2007.00990.X Margolin, S. (2001). Interventions for nonaggressive peerrejected children and adolescents: A review of the literature. Children and Schools, 23, 143–159. doi:10.1093/cs/ 23.3.143 McAlister, A., & Peterson, C. C. (2013). Siblings, theory of mind and executive functioning in children aged 3 to 6 years: New longitudinal evidenceChild Development, 84, 1442–1458. doi:10.1111/cdev.12043 *McNab, C. (2001). Peer acceptance and theory of mind. Unpublished master’s thesis, University of Canterbury, Christchurch, New Zealand. Milligan, K., Astington, J. W., & Dack, L. A. (2007). Language and theory of mind: Meta-analysis of the relation between language ability and false-belief understanding. Child Development, 78, 622–646. doi:10.1111/j.14678624.2007.01018.x *Mizokawa, A., & Koyasu, M. (2011). Understanding false beliefs, hidden emotions, and social interactions among five- and six-year-olds. Japanese Journal of Developmental Psychology, 22, 168–178. doi:10.2117/ Psysoc.2007.291 Moller, L. C., Hymel, S., & Rubin, K. H. (1992). Sex typing in play and popularity in middle childhood. Sex Roles, 26, 331–353. doi:10.1007/Bf00289916 *Morino, M. (2005). Preschoolers’ theory of mind, understanding of emotions and interactions with peers. Japanese Journal of Developmental Psychology, 16, 36–45. Newcomb, A. F., Bukowski, W. M., & Pattee, L. (1993). Children’s peer relations: A meta-analytic review of popular, rejected, neglected, controversial, and average sociometric status. Psychological Bulletin, 113, 99–128.

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Table 1 Mean Effects for the Association Between ToM and Peer Popularity for All Participants, and Separately as a Function of Measurement Type, Age Group, Gender, and Valence 95% CI Contrast

Mr

Lower

All studies Separately by measure Sociometric popularity Perceived popularity Separately by age group Age 5 and under Age 6 and up Separately by gender Males Males minus outlier Females Separately by valence Positive peer regard Negative peer regard

.19*

Upper

SE

PVAF

K

N

Q

.15

.24

.02

3.6

20

2,096

18.6

.19* .23*

.15 .12

.24 .34

.02 .06

3.6 5.3

16 5

1,688 492

13.7 6.7

.18* .18*

.09 .12

.26 .24

.04 .03

3.2 3.2

9 10

668 1,126

10.9 9.4

.18* .12 .30*

.01 .01 .20

.34 .25 .40

.09 .07 .05

3.2 1.4 9.0

8 7 7

340 329 307

17.9* 8.6 5.4

.23* .13*

.12 .06

.33 .20

.05 .03

5.3 1.7

10 9

1,068 1,000

25.8* 9.2

Note. A positive effect size indicates that more advanced ToM is associated with greater popularity; a negative effect size indicates the reverse. ToM = theory of mind; Mr = mean r; PVAF = percentage of variance shared between the two dependent measures (i.e., ToM and peer popularity); K = number of studies; N = to the number of participants that contributed to the effect; Q = degree of variability in the effects contributing to each Mr. *p < .05.

2,096 children. For each study, the year of publication and the number, age, and gender of the participants (where reported) were recorded. Appendix S1 presents a study-by-study breakdown of effect sizes for the association between the measure of ToM and peer popularity measures. Note that some of these effect sizes were taken directly from the published papers whereas others were derived. The first stage in analysis of these data involved calculating an overall mean-weighted effect size (with a single effect size permitted to contribute for each independent data set, and these effects in turn weighted for sample size). A positive effect indicates that, as hypothesized, relatively advanced ToM was associated with peer popularity (e.g., being well liked or perceived as popular); a negative effect indicates the reverse. As can be seen in Table 1, the overall mean effect size was significant, but small in magnitude (r = .19). Thus, collapsed across all studies, children’s performance on standard ToM tests is concurrently associated with peer popularity, but this association is a relatively weak one. Analyses by Measure: Sociometric Versus Perceived Popularity The first subanalysis focused on measurement type. For this, we separately calculated mean effect

sizes for correlations between ToM and sociometric popularity and between ToM and perceived popularity. These results are also presented in Table 1. Sixteen studies contributed to the mean effect size for sociometric popularity, and just five contributed to perceived popularity (some publications included both types of measures, which is why the total K here is greater than the overall study K). The mean effect sizes for both popularity measures are significant and similar in magnitude (rs = .19 and .23, respectively), indicating that the positive association between ToM and peer popularity is similar whether it is measured via sociometry or in terms of perceived popularity. Because of the similar mean effect sizes identified for sociometric and perceived popularity, we felt that it was justifiable and parsimonious to collapse across these measurement types for the remaining subanalyses. Analyses by Age Group: Preschoolers Versus Older Children The next subanalysis focused on age group, and specifically preschool-aged cohorts between 2 and 5 years of age versus cohorts aged 6–10. Nine studies contributed to the former, and 10 contributed to the latter effect. As evident in Table 1, the mean effect sizes for both age groups are identical (both rs = .18) and both are statistically significant. This

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indicates that the positive association between ToM and peer popularity is the same for preschoolers and school-aged children. Analyses by Gender We then focused on identifying whether the magnitude of this effect varied as a function of gender. Consequently, the analyses were rerun, but this time, only with those studies that reported effect sizes separately for males and females (8 and 7 respectively). It can be seen in Table 1 that although effect sizes for both groups were significant, the magnitude of the effect for females was substantially larger than that for males (rs = .30 vs. .18, respectively). Specifically, the percentage of variance shared between ToM and peer popularity was nearly 3 times as large for females (9.0%) as for males (3.2%). It is worth noting too, that for all but two of the mean effect sizes identified, the homogeneity statistic Q was not significant. This indicates that for each of these mean effect sizes, there was little variability in the contributing study-level effects. The two exceptions were the mean effect size for positive peer regard, discussed next, and the mean effect size for males. Closer inspection of the mean effect sizes for males revealed that one study contributed an effect to this mean that was a statistical outlier (Dockett & Degotardi, 1997), where the effect size for a small sample of boys (n = 11) was .68, more than 3 SD greater than the Mr. Recalculation of the aggregate mean with this outlier excluded yielded nonsignificant, smaller association between ToM and peer popularity for males (r = .12), but also a homogeneity statistic that was no longer significant. This indicates that, as for the other mean effect sizes, when this one statistical outlier is excluded, there is no significant hetereogeneity in the study-level effects contributing to the mean effect for males. Analyses by Valence: Positive Versus Negative Peer Regard Finally, we focused on assessing whether the association between ToM and peer popularity varied according to valence. Consequently, these analyses were rerun for the subset of studies that reported independent effect sizes for positive versus negative peer popularity metrics, either alone or separately. Positive metrics included summed LM nominations and popularity/likability scores or ratings. Negative metrics included summed LL nomi-

nations or ratings that specifically assessed peer rejection. Ten studies provided positive measures and nine provided negative measures. Weighted measures, for instance, SP scores that combine LM and LL scores, were not included in this analysis. As shown in Table 1, both positively (r = .23) and negatively (r = .13) valenced mean effects are statistically significant. There does appear to be a substantially larger effect size for the former, with the percentage of variance shared between ToM and positive peer regard (5.3%) more than twice as large as the percentage of variance shared between ToM and negative peer regard (1.7%). That said, however, there is significant heterogeneity in the individual study level effects contributing to the former, but not the latter, mean effect size. This heterogeneity does not reflect the presence of outliers (no individual study level effect size was > 2 SD beyond the aggregate mean). Rather, there is simply a greater spread of study-level effects for positively valenced peer popularity. Testing for Publication Bias A number of validity threats have been identified that may lead to imprecise conclusions in both nonquantitative and meta-analytic reviews. Particularly problematic is “the file drawer problem” (Rosenthal, 1979), which refers to the fact that significant results are more likely to be published than nonsignificant results (Easterbrook, Berlin, Gopalan, & Matthews, 1991; Sterling, 1959). To assess whether this bias posed a threat to the results of the present study, funnel-plot diagrams were constructed. In these diagrams, sample size is plotted against the corresponding study-level effect. If statistically nonsignificant results have been discriminated against, there should be a relative absence of studies with small sample sizes that report weak effects. This was done for all nine mean effect sizes (see Figure 1; it should be noted that where the x-ordinate meets the y-ordinate indicates the mean effect size for each variable of interest). Although mean effects based on a relatively small number of studies can be regarded as less robust to the potential problem of publication bias than those based on a larger number of studies, it can be seen that only for the mean effect size for males is there evidence of this confound operating in the funnel plots constructed (with a particularly large effect size evident for a very small sample). As noted above, the mean effect size for males was recalculated with this studylevel effect omitted.

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Figure 1. Funnel-plot diagrams illustrating: (A) Mr values for all 20 studies included in the present meta-analysis and the total N for each study; (B) Mr values for the 16 studies that reported separate data for sociometric popularity measures and the N for the respective studies; (C) Mr values for the 5 studies that reported separate data for perceived popularity measures and the N for the respective studies; (D) Mr values for the 9 studies that reported data for children at or below 5 years of age and the N for the respective studies; (E) Mr values for the 10 studies that reported data for children above 5 years of age and the N for the respective studies; (F) Mr values for the 8 studies that reported gender-separate data for males and the N for the respective studies; (G) Mr values for the 7 studies that reported gender-separate data for females and the N for the respective studies; (H) Mr values for the 10 studies that reported data for positively valenced peer popularity and the N for the respective studies; (I) Mr values for the 9 studies that reported data for negatively valenced peer popularity and the N for the respective studies.

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Discussion This is the first meta-analysis to evaluate the extent to which children’s ToM understanding relates to their everyday social lives and the results provide important and timely clarification of previously mixed findings. Pooling data across 20 distinct data sets revealed a statistically significant mean effect indicating that children’s ToM understanding is positively linked to their concurrent peer popularity. This finding is consistent with the idea that children who are competent at understanding others’ mental states engage in effective social behaviors, leading to their being well liked and highly regarded by their peers, while those whose ToM is relatively poor are less socially capable and as a result are not well liked or regarded as popular by their peers. However, the magnitude of this overall effect is small, with children’s ToM understanding accounting for just 3.6% of the variance in peer popularity. This explains why the literature previously presented a confusing picture; because the effect is small, it can only be resolved where sample size is sufficient. It is precisely for this type of effect that meta-analysis is particularly important. The nonsignificant Q statistic showed that there was no substantive variability in effect sizes across the data sets. Thus, the overall association between children’s ToM and peer popularity is consistent, with much of the prior variance reported in the literature an artifact of sampling error. The small overall effect size is understandable in light of the research on determinants of children’s peer popularity that indicates that, in addition to ToM understanding, there are numerous physical, personality, cognitive, and behavioral factors that are associated with children’s sociometric and perceived popularity (for reviews, see Coie, Dodge, & Kupersmidt, 1990; Newcomb, Bukowski, & Pattee, 1993; Rubin et al., 2006). Some of these factors, such as communicative competence, cooperativeness, prosociality, and low levels of overtly aggressive behavior may themselves be at least partially linked to children’s ToM (Cassidy et al., 2003; de Rosnay, Fink, Begeer, Slaughter, & Peterson, 2014; Renouf et al., 2010; Slaughter et al., 2002), whereas other factors such as attractiveness, athletic ability, IQ, and academic achievement, would be independent of ToM understanding. Furthermore, the small magnitude of the ToM–peer popularity association could reflect the fact that even if children possess a good understanding of others’ mental states, allowing them to perform well on standard tests of ToM, they may not always use this understanding to

guide their everyday interactions with peers (Hughes, 2011). Turning to the results of our subanalyses, we found that children’s ToM was related to both sociometric and perceived popularity, and that these effects were comparable. Thus, children with relatively advanced ToM are both well liked by their peers and recognized by peers and teachers as having high status within the peer group. This is interesting given the somewhat divergent behavioral profiles of sociometric and perceived popular children. The underlying ToM understandings are similar, but they seem to produce different types of behavior that lead to children being well liked versus perceived as popular within the peer group. Among the sociometrically popular children, ToM understanding may contribute to interpersonal sensitivity and responsiveness, good communication skills, and prosociality (Rubin et al., 2006), which are associated with this dimension of peer popularity. Perceived popular children’s ToM, in addition to underpinning prosocial behaviors, may also enable sophisticated forms of relational aggression, which is often typical of children who enjoy high levels of perceived popularity (Cillessen & Mayeux, 2004; Cillessen & Rose, 2005). These findings reinforce the notion that ToM understanding is a “neutral social tool” that children (and adults) use flexibly to achieve social goals (Repacholi, Slaughter, Pritchard, & Gibbs, 2003, p. 72). It is worth noting that these findings are partially at odds with the adult literature, which suggests a negative association between high social status and ToM understanding (Galinsky et al., 2006; Rutherford, 2004). Further research will be required to reconcile this developmental difference, but one possible explanation is that the adult studies used short-term manipulations of social status, which may have temporarily altered the adults’ ToM task performance, whereas perceived popularity in childhood is acquired over an extended period and therefore may associate differently with ToM. The second sub analysis indicated that the association between ToM and peer popularity was equivalent for preschool-aged (2–5 years) and school-aged (6–10 years) children. This is an important finding that also brings clarity to this literature. The pattern of results for the younger age group suggests that the fundamental changes in ToM that occur during the preschool period, including acquisition of false-belief understanding (Wellman et al., 2001), are indeed relevant to children’s social lives. The ToM–peer popularity association was also

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evident among older school-aged children. This latter association has more than one interpretation. One possibility is that mastery of more advanced ToM concepts, for instance, recognizing what one peer thinks another peer is thinking, is itself linked to children’s peer popularity as they enter and progress through the increasingly complex social world of primary school. Alternatively, it is possible that the ToM–peer popularity association among older children is a longitudinal extension of the earlier correlation, such that preschoolers with relatively good ToM understanding continue to have good social-cognitive skills and they also maintain their earlier-achieved positive peer regard. This latter model is consistent with research showing that both ToM understanding (Caputi et al., 2012; Lockl & Schneider, 2007) and sociometric popularity and rejection (Brendgen, Vitaro, Bukowski, Doyle, & Markiewicz, 2001) tend to be longitudinally stable. Of course, concurrent and longitudinal effects may operate simultaneously. Additional studies are now warranted to test these developmental hypotheses. The third subanalysis revealed that the association between ToM and peer popularity was stronger among girls compared to boys. This suggests that determinants of peer popularity may differ somewhat for boys and girls. This is an important finding, since the majority of studies to date on correlates of peer popularity in childhood have generalized across gender, or else focused exclusively on either boys or girls (Rubin et al., 2006). Although more research is required to understand why ToM is more strongly linked to peer popularity among girls compared to boys, this finding could reflect gender differences in how preschoolers and schoolaged children tend to relate to each other. Compared to boys, girls’ peer relationships from preschool to early adolescence are generally characterized by higher levels of intimacy, conflict resolution, and empathic understanding (Rose & Asher, 1999; Rose & Rudolph, 2006). Thus, many of girls’ day-to-day peer interactions are likely to rely on ToM understanding, and possessing a relatively advanced ToM may enable girls to function particularly effectively in these contexts (Banerjee et al., 2006). By contrast, boys’ day-to-day interactions in preschool and primary school are characterized by more physical and rule-based play (Moller, Hymel, & Rubin, 1992), and less negotiation and cooperation than those of girls (Rose & Rudolph, 2006). Thus, boys may rely less on ToM in their everyday peer interactions, leading to a weaker ToM–peer popularity association for boys compared to girls in this age range.

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A final subanalysis indicated that children’s ToM understanding was significantly associated both with positive and with negative measures of peer popularity. This indicates that preschool and school-aged children who have a good understanding of others’ mental states are at the same time liked or seen as popular among their peers, and those with a relatively poor ToM are concurrently disliked or rejected. The effect was stronger for positive peer regard; children’s ToM accounted for 5.3% of the variance in positive peer nominations and ratings (e.g., likability, popularity) but only 1.7% of the variance in negative nominations and ratings (e.g dislike and rejection). This pattern fits with the idea that ToM is more important for acting effectively in social situations than for failing to do so. For instance, significant correlates of children’s peer popularity are sensitivity, prosociality, and effective communication (Gifford-Smith & Brownell, 2003; Rubin et al., 2006). A good understanding of others’ mental perspectives is likely to underpin all of these. On the other hand, peer rejection is associated with externalizing problem behaviors, such as aggression and classroom disobedience (Bierman, 2004; Ladd & Troop-Gordon, 2003) and it might be argued that these behaviors have multiple antecedents besides a poor underlying ToM. However, some caution should be exercised here because there was significant heterogeneity (reflected in a significant Q statistic) in the study-level effects that were pooled to calculate the mean effect size for positive peer regard. This indicates that the correlation between children’s ToM and positive indicators of peer popularity varied considerably from study to study. This discussion is necessarily speculative, because all of these effects are derived from an aggregation of correlations. We cannot draw any conclusions from the meta-analysis about what might be the causal pathway from ToM to peer popularity. The predominant theoretical model in this literature holds that children who possess a strong ToM are sensitive to others’ perspectives and nuances in social situations, and this leads them to act in ways that promote their likability and status within the peer group (Hughes & Cutting, 1999; Rubin, Coplan, Chen, Buskirk, & Wojslawowicz, 2005). Equally possible, an alternative causal model holds that children achieve peer popularity by virtue of attributes or behaviors that are not necessarily related to their ToM understanding, but the experience of being well liked and/ or enjoying high status within their peer group gives them opportunities to advance their ToM

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understanding. We cannot address these different models with meta-analysis, but having established that there is a concurrent link between children’s ToM understanding and their peer popularity, additional research—longitudinal studies in particular— is now warranted to further investigate the potentially complex causal relations behind the effect. A notable strength of this meta-analysis is that the contributing studies came from several different countries across North America, Europe, the Middle East, and Australasia. This gives us confidence that the effects are not specific to any particular set of cultural or socialization practices, such as prevalence of preschool participation, age of initial formal schooling, or content of early education. That said, research has established that cultural norms dictate how social behaviors are judged within children’s peer groups (Rubin et al., 2005). Thus, the specific behaviors that are enabled by children’s ToM and contribute to their peer popularity may vary across cultures. A limitation of this study is that we could not assess the effect of additional variables, over and above age and gender, on the ToM–peer popularity relation. For instance general IQ, which is an independent predictor of preschool children’s sociometric popularity (Rubin & Daniels-Beirness, 1983), or specific cognitive variables such as inhibitory control or verbal ability, which are well-established correlates of ToM (e.g., Carlson, Moses, & Claxton, 2004; Milligan, Astington, & Dack, 2007), may systematically influence the association between children’s ToM and their peer popularity. We could not assess these variables because the studies that contributed to the meta-analysis differed in their inclusion of control variables, so there was limited power to isolate any of these for subanalysis. The control variable included most frequently was language ability, but because the majority of studies did not report language-controlled associations in a way that would allow extraction of the relevant effect size, we did not perform a subanalysis addressing the impact of language. However, the reported results are informative: Two studies reported that nonsignificant ToM–peer popularity correlations remained nonsignificant when language ability was taken into account (Slaughter et al., 2002; Watson et al., 1999), and six reported significant associations between ToM and peer popularity even with language ability controlled (Banerjee et al., 2006, 2011; Caputi et al., 2012; Cassidy et al., 2003; Fink et al., 2014; Mizokawa & Koyasu, 2011). Although additional analyses directly assessing the role of language and other cognitive control

variables would be desirable in future, these results suggests that the small ToM–peer popularity correlation revealed by this meta-analysis is likely to remain, even when the effect of language ability is controlled. In conclusion, this meta-analysis has revealed that 2- to 10-year-old children’s ToM understanding, as assessed with standard tasks, is significantly associated with their concurrent popularity within their peer group. This is the first such analysis to confirm that children’s ToM understanding impacts upon their everyday social lives with peers. The findings support the proposal that a good understanding of mental states and how these are related to behavior, enables children to engage with their peers in ways that lead to their being well liked and perceived as popular. The effect is small, and it remains to be fully determined what are the causal pathways from children’s ToM understanding to peer popularity. Despite these caveats, the significant association between children’s ToM and popularity has implications for maximizing children’s well-being and adjustment in their peer group. Peer rejection in preschool and primary school is associated with poor outcomes both in the short and longer terms (Bierman, 2004; Choukas-Bradley & Prinstein, 2014; Ladd, 2006; Rubin et al., 2006; Sturaro, van Lier, Cuijpers, & Koot, 2011), leading researchers and practitioners to consider a variety of interventions (Bierman, 2004; Margolin, 2001). Given that some aspects of ToM understanding can be trained in early childhood (Appleton & Reddy, 1996; Kloo & Perner, 2008; Slaughter & Gopnik, 1996), as well as later in life (Santiesteban et al., 2012), this meta-analysis suggests that there could be value in such training, especially for girls, as a means to positively influence young children’s social lives with their peers.

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Supporting Information Additional supporting information may be found in the online version of this article at the publisher’s website: Appendix S1. Details of Studies Included in Meta-Analysis