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Social Aggression in Children and Adolescents: AMeta-Analytic ReviewCathy LongaUniversity of Miami, cathylonga@gmail.com

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UNIVERSITY OF MIAMI

SOCIAL AGGRESSION IN CHILDREN AND ADOLESCENTS: A META-ANALYTIC REVIEW

By

Cathy Longa

A DISSERTATION

Submitted to the Faculty of the University of Miami

in partial fulfillment of the requirements for the degree of Doctor of Philosophy

Coral Gables, Florida

August 2011

2011 Cathy Longa

All Rights Reserved

UNIVERSITY OF MIAMI

A dissertation submitted in partial fulfillment of the requirements for the degree of

Doctor of Philosophy

SOCIAL AGGRESSION IN CHILDREN AND ADOLESCENTS: A META-ANALYTIC REVIEW

Cathy Longa Approved: Debbiesiu Lee, Ph.D. Assistant Professor of Educational and Psychological Studies

Terri A. Scandura, Ph.D. Dean of the Graduate School

Soyeon Ahn, Ph.D. Assistant Professor of Educational and Psychological Studies

Ora Prilleltensky, Ed.D. Clinical Assistant Professor of Educational and Psychological Studies

Annette La Greca, Ph.D. Professor of Psychology and Pediatrics

LONGA, CATHY (Ph.D., Counseling Psychology) Social Aggression in Children and Adolescents: (August 2011) A Meta-Analytic Review Abstract of a dissertation at the University of Miami. Dissertation supervised by Professors Debbiesiu Lee and Soyeon Ahn. No. of pages in text. (112)

Social aggression has been widely studied; however, findings have been inconsistent

leading to confusion within the current literature. Previous research has linked social

aggression to negative outcomes; including poor peer relations, internalizing symptoms,

and low levels of empathy; as well as positive attributes, including prosocial behaviors,

high social status, and social intelligence. This meta-analysis examined the relationship

between social aggression and various correlates, both positive and negative, as well as

how age and gender moderate these relationships. With 896 correlations derived from

108 studies (of a total of 107 published articles), the results using the random-effects

model for computing overall effect sizes indicated that social aggression is related with

maladaptive correlates, such as externalization ( r = 0.46), internalization ( r = 0.16),

negative individual traits ( r = 0.32), as well as negative peer relations ( r = 0.28).

However, findings also suggest that social aggression is associated with popularity ( r =

0.22) and social skillfulness ( r = 0.16). Implications, limitations, and future directions

are discussed.

iii

TABLE OF CONTENTS LIST OF FIGURES .............................................................................................................v LIST OF TABLES ............................................................................................................. vi CHAPTER 1. INTRODUCTION ........................................................................................1 CHAPTER 2. LITERATURE REVIEW .............................................................................4

Theoretical Models ......................................................................................................... 6

Early childhood. .......................................................................................................... 8 Middle Childhood. ...................................................................................................... 9 Adolescence. ............................................................................................................. 12

Previous Meta-Analyses on Social Aggression ............................................................ 14 Current Study ................................................................................................................ 17 Meta-Analysis ............................................................................................................... 18

CHAPTER 3. METHODS .................................................................................................20

Search Procedure .......................................................................................................... 20 Coding of Studies .......................................................................................................... 23 Power ............................................................................................................................ 25 Effect Size ..................................................................................................................... 26 Analysis......................................................................................................................... 27

CHAPTER 4. RESULTS ...................................................................................................29

Characteristics of Studies .............................................................................................. 29 Publication Bias ............................................................................................................ 30 Overall Model ............................................................................................................... 30

Gender differences. ................................................................................................... 32

iv

Age differences. ........................................................................................................ 32 Relationship Between Individual Characteristics and Social Aggression .................... 36

Gender differences. ................................................................................................... 39 Age differences. ........................................................................................................ 42

Relationship Between Peer Relations and Social Aggression ...................................... 46

Gender differences. ................................................................................................... 46 Age differences. ........................................................................................................ 49

CHAPTER 5. DISCUSSION .............................................................................................53

Future Interventions ...................................................................................................... 65 Future Research ............................................................................................................ 69 Limitations .................................................................................................................... 71 Conclusion .................................................................................................................... 72

REFERENCES ..................................................................................................................74 APPENDIX ........................................................................................................................93

v

LIST OF FIGURES

Figure 1. Study selection chart...........................................................................................21 Figure 2. Funnel plot of effect sizes against study sizes ....................................................31 Figure 3. Overall model .....................................................................................................33

vi

LIST OF TABLES

Table 1. Overall Model of Relationships with Social Aggression .................................... 31 Table 2. Differences by Gender in Overall Model. .......................................................... 34 Table 3. Differences by Age in Overall Model. ................................................................ 35 Table 4. Relationship between Individual characteristics and Social Aggression. ........... 37 Table 5. Differences by Gender in the Relationship between Social Aggression and Individual Characteristics. ................................................................................................ 40 Table 6. Differences by Age in the Relationship between Social Aggression and Individual Characteristics ................................................................................................ 43 Table 7. Relationship between Peer Relations and Social Aggression. ............................ 47 Table 8. Differences by Gender in the Relationship between Social Aggression and Peer Relations. .......................................................................................................................... 48 Table 9. Differences by Age in the Relationship between Social Aggression and Peer Relations. .......................................................................................................................... 50

1

CHAPTER 1

INTRODUCTION

It is no question that children can be extremely cruel to one another, as aggression

is a widely studied construct within the psychological literature. Aggressive behaviors

can take a variety of forms: physical aggression, verbal insults, relationship manipulation,

and nonverbal expressions of disdain. Much of the previous research on aggression has

focused on physical aggression (Underwood, Galen, & Paquette, 2001). Recently, there

has been an explosion of interest in forms of aggression that emphasize nonphysical

strategies: indirect aggression (Bjorkqvist, Lagerspetz, & Kaukiainen, 1992), relational

aggression (Crick & Grotpeter, 1995), and social aggression (Galen & Underwood,

1997).

Much has been made in the media and popular psychology books (e.g., Dellasega

& Nixon, 2003; Simmons, 2002; Wiseman, 2002) concerning the negative consequences

of social aggression, particularly as it relates to girls. It has been suggested that socially

aggressive behaviors are maladaptive, hurtful, and related to negative outcomes in both

the victim and the aggressor (e.g., Bjorkqvist, Osterman, & Lagerspetz, 1994; Crick,

Casas, & Mosher, 1997; Heilbron &Prinstein, 2008). There have even been efforts to

determine if socially aggressive behaviors belong within the Diagnostic and Statistical

Manual [DSM] (Keenan, Coyne, & Lahey, 2008).

Although the introduction of these constructs has generated a very useful body of

research (Underwood, Galen, & Paquette, 2001), within this literature many

disagreements, discrepancies, and questions remain. Included among these incongruities

is whether social aggression represents a form of maladjustment arising from deficiencies

2

and leading to negative outcomes, or a form of socially skillful, though perhaps not

desirable, behaviors leading to positive social attributes. One way to explain these

differences in the literature is to consider a developmental perspective, where aggression

is proposed to change with development. As children mature, their social skills, cognitive

abilities, and emotional development also change. Therefore, it is reasonable to expect

that the nature, correlates, and consequences of social aggression may also change with

age. Thus, it is fair to expect differing associations between social aggression and various

outcomes based on developmental stage.

Two previous meta-analyses (Archer, 2004; Card, Stucky, Sawalani, & Little,

2008) have been conducted to explore and better understand social aggression. Archers

(2004) meta-analytic review of gender differences indicated more evidence of social

aggression in girls among children; however the gender differences were not as consistent

as would have been expected from previous individual studies. Archers (2004) study is

limited in that he utilized a more narrow definition of social aggression, searching only

for indirect aggression, therefore including only 41 studies of this construct. In

addition, he used a fixed-effects model for his analysis, which may have affected the

generalization of findings.

Card et al.s (2008) meta-analysis found that girls use more social aggression than

boys, but that this result was trivial in magnitude. In addition, Card et al. found that

social aggression was more strongly associated with internalizing problems (i.e.,

depression and anxiety) than physical aggression, with no gender moderation of these

relationship found. Card et al.s (2008) study is limited by several issues, such as

excluding many studies that solely focused on social aggression, failing to examine age

3

as a potential moderator, and not examining social adjustment or potentially positive

outcomes associated with social aggression.

Although both studies provide useful information concerning social aggression,

the studies have limitations and questions remain. Given these discrepancies in the

literatures, it seems that a comprehensive review and analysis of the literature is

warranted. By including more studies, examining age as a moderator, and examining a

wider range of correlates, a better understanding of social aggression can be yielded.

Thus, this study aimed at clarifying and providing a better understanding of the correlates

(both positive and negative) of social aggression, while examining the role age and

gender play in these relationships.

4

CHAPTER 2

LITERATURE REVIEW

Researchers have struggled for decades to describe and measure aggressive

behavior (see Coie & Dodge, 1998, for a review). Despite the numerous articles devoted

to this topic, there are significant challenges for understanding aggression. One

significant difficulty is the vast number of subtypes suggested by investigators. For

example, Underwood, Galen, and Paquette (2001) argue that aggression is difficult to

define operationally because neither the intentions of an aggressor nor the perceptions of

harm by a victim can be directly observed. What is considered aggressive behavior relies

greatly on social judgments, of both the aggressor and the perceiver (Underwood, Galen,

& Paquette, 2001).

In general, definitions of aggression involve the intent to inflict harm on others

(Archer & Coyne, 2005). Harre and Lamb (1983) noted that researchers have proposed

over 200 different definitions of aggressive behavior, but that most of these definitions

share two common features: (1) the behavior is intended to harm, and (2) the behavior is

perceived as hurtful by the victim. Direct acts of verbal and physical aggression in

situations of interpersonal conflict readily fit such a definition. However, research has

demonstrated that children engage in a variety of aggressive behavior. Hence, although

the injury necessary for a behavior to be labeled aggression has been most often

interpreted by researchers to mean bodily harm, these terms could also apply to damage

to ones self-esteem or social standing (Galen & Underwood, 1997).

In considering the various types of aggression it is important to note that all forms

of aggression can be considered social strategies that have evolved to represent different

5

means to harm others (Archer & Coyne, 2005). In arguing the significance of

nonphysical forms of aggression, Olweus (1996) stated that negative actions can be

carried out by physical contact, by words, or in other ways, such as making faces and

nasty gestures or by intentional exclusion from a group (p. 16). While physical

aggression involves overt actions such as threatening physical injury, nonphysical forms

of aggression are behaviors intended to cause social or interpersonal harm through overt

or covert ways, such as gossiping, excluding from social interactions, and spreading

rumors (Archer & Coyne, 2005; Heilbron & Prinstein, 2008).

Nonphysical forms of aggression have been given three different names in the

literature: indirect aggression (Lagerspetz, Bjorkqvist, & Peltonen, 1988), relational

aggression (Crick & Grotpeter, 1995), and social aggression (Cairns, Cairns,

Neckerman, Feguson, & Gariepy, 1989). Indirect aggression refers to behaviors such as

gossiping or exclusion that harms others without direct confrontation of the victim

(Lagerspetz et al., 1988). Relational aggression involves harming others by manipulating

peer relationships (Crick, 1995). Finally, social aggression refers to behaviors aimed at

damaging the victims self-esteem or social status. Social aggression includes actions

such as negative facial expressions, verbal rejection, rumors, or social exclusion (Galen

& Underwood, 1997).

Researchers using these three labels disagree over which term is the most

practical for describing these nonphysical forms of aggression. Further, these is some

dispute regarding how similar indirect, relational, and social aggression really are, as well

as which term best depicts the behaviors (Bjorkqvist, 2001; Underwood, et al., 2001).

Although there may be subtle differences, the constructs converge around the common

6

theme of behaviors that attack a victims actual or perceived social relations with others,

often (though not always) in ways that avoid direct confrontation (Card, et al., 2008). For

the purposes of this paper, the term social aggression will be utilized to refer to the

behaviors in question.

Along with the general constructs of aggression, bullying can be characterized as

a subset of aggressive behaviors. As with aggressive behaviors, bullying intentionally

causes harm to the recipient (Aluede, Adeleke, Omoike, & Afen-Akpaida, 2008). This

harm can be both physical and psychological and has an influence on the victims

physical, emotional, social, and educational well-being (Smith, 2004). Rigby (2002)

points out that it seems like splitting hairs to distinguish between aggression and

bullying (p. 30).

Recent research on bullying has differentiated between the various types of

bullying. Like aggression, bullying can manifest in several ways, including physical

bullying, verbal bullying, and social bullying (e.g., disrupting the social relationships

between victims and peers; Berger, 2007). Given that bullying is a subset of the broader

category of aggression, and that researchers have acknowledged that both bullying and

aggression can be classified as indirect or social, it seems odd that researchers continue to

study these constructs as completely separate phenomena. Therefore, this study included

both social aggression and nonphysical forms of bullying to obtain a better understanding

of the similar behaviors that frequently occur within the child and adolescent population.

Theoretical Models

To varying extents, theoretical models are beginning to be constructed to explain

social aggression. In general, these theories can be divided into two groups: those who

7

argue that social aggression is maladaptive and engaged in by children who have a deficit

in their social or cognitive competence (e.g., Crick & Dodge, 1994; Michiels, Gietens,

Onghena, Kuppens, 2008; Prinstein & Cillessen, 2003), and those who argue that social

aggression is used by socially skilled and manipulative individuals (e.g., Hawley, 2007;

Garandeau & Cillessen, 2006). The first group links aggression with negative outcomes,

including poor peer relations, internalizing symptoms, and low levels of empathy. The

latter group links aggression with positive attributes, including prosocial behaviors, high

social status, and social intelligence. Interestingly, there is evidence to support both

theories.

One way to explain why some theorists view social aggression as maladaptive and

other theorists see it as beneficial may be that this behavior has different effects at

different developmental stages. A developmental model of social aggression can assist in

our understanding of developmental processes over time by highlighting the importance

of individual and environmental interactions (Pepler & Craig, 2005; Rutter, 1990). From

a developmental perspective, the nature and form of aggression is assumed to change

with development. These changes emerge as a result of maturation within the child

together with changing social interactions and expectations (Pepler & Craig, 2005). Thus,

it is reasonable to expect differing associations between social aggression and various

outcomes based on developmental stage.

Although the conceptualization of aggression as a form of psychopathology

predominantly dominates the empirical literature, there are notable exceptions to this

emphasis (e.g., Hawley et al., 2007). For some children and adolescents, socially

aggressive behavior is positively related to dominance, social impact, perceived

8

popularity, and higher levels of social power (Heilbron & Prinstein, 2008). A review of

the literature on social aggression reveals conflicting findings at different developmental

stages (i.e., early childhood, middle childhood, adolescence).

Early childhood. Although researchers have only recently begun to investigate

the occurrence of social aggression in early childhood, some researchers suggest that

preschool children as young as age 3 engage in these behaviors (e.g., Crick, Casas,

Mosher, 1997; Juliano, Werner, Cassidy, 2006; McNeilly-Choque, Hart, Robinson,

Nelson, Olsen, 1996). Crick and colleagues (1999) suggest that the manifestations of

social aggression at these ages are simple and obvious (e.g., directly telling a peer they

will not play with them unless certain conditions are met) and enacted as a response to an

immediate problem. Thus, young children are beginning to learn social skills and as such

social aggression at this developmental stage may take the form of overt, straightforward

forms (Underwood, 2003).

Although the study of social aggression in early childhood remains a relatively

new area of research, several studies have examined the link between social aggression

and measures of problematic adjustment, positive attributes, social skills, and language

ability with mixed findings. For example, social aggression has been associated with

impulsive, oppositional, anxious, or depressive behaviors (Juliano, et al., 2006), as well

as high levels of deception (Ostrov, 2006) and poor expressive language skills (Estrem,

2005). However, other studies have found social aggression related with a variety of

markers of positive adjustment in young children, including verbal skills (Bonica, et al.,

2003) and receptive language ability (Hawley, 2003), moral maturity (in girls; Hawley,

2003) and the ability to express guilt (Hawley, 2003).

9

With regard to social relationships, research has indicated that social aggression is

associated with current and future peer rejection (Crick, et al., 1997; Crick, Ostrov, &

Werner, 2006; Ostrov & Crick, 2007), peer exclusion (Ostrov & Keating, 2004), lower

prosocial behavior (Crick, et al., 1997; Ostrov & Keating, 2004), and lower levels of peer

acceptance (McNeilly-Choque et al., 1996). In contrast, other studies have suggested that

social aggression is linked with average to above average social skills (Carpenter &

Nangle, 2003), social competence (Vaugh, Vollenweider, & Bost, 2003), increased

friendship intimacy (Burr, et al., 2005), higher numbers of stable and mutual friendships

over the course of the school year (Burr, et al., 2005), higher peer acceptance (Crick, et

al., 1997), and higher sociability (Nelson, Robinson, & Hart, 2005).

Middle Childhood. The socially aggressive acts employed by grade-schoolers

likely reflect the social and cognitive advances of the middle-childhood period (Crick et

al., 1999). Although important at any age, needs for acceptance by peers and for mutually

satisfying friendships become increasingly relevant during the grade-school years and are

typically met through relationships with same-gender peers (Bukowski & Hoza, 1989;

Crick et al., 1999; Maccoby, 1990). Bjrkqvist and colleagues (1992) posits that because

physical aggression becomes socially unacceptable as children mature, social aggressive

strategies replace overt aggression. Furthermore, these researchers propose that as

children mature cognitively, they reduce their use of physical forms of aggression and

increase their use of social forms of aggression (Bjrkqvist, et al., 1992). It seems likely

that the increase in the importance of social issues (i.e., socially accepted behaviors), in

addition to the language and cognitive skills acquired during middle childhood (e.g.,

increases in memory and vocabulary, the ability to view ones own thoughts, feelings and

10

behaviors from another persons perspective), contributes to childrens ability to use the

peer group as an effective means for hurting others (Crick et al., 1999).

Accordingly, the socially aggressive behaviors expected at this developmental

stage are suggested to involve relatively covert actions, with less confrontation and a

focus on the interactions with other peer group members (Crick et al., 1999). These

covert forms of social aggression require a certain degree of cognitive complexity for

both the aggressor (i.e., to recognize that the action will be an effective strategy) and the

victim (i.e., to recognize that others are being mean to them on behalf of the aggressor;

Crick et al., 1999). The ability to understand anothers perspective and information in the

broader social network makes the nonconfrontational aggressive strategy more feasible at

this period of development (Xie, Cairns, & Cairns, 2005). Thus, as social competence

increases, children learn additional ways of harming others, including ways that do not

place him or her at the direct risk of retaliation (Bjrkqvist, et al., 1992). However, other

researchers argue that it is the lack of social-emotional competencies that contribute to

the development of aggressive behaviors (Benson, 2006).

Social-emotional learning is described as the process of acquiring competencies to

regulate emotions, understand the perspectives of others, establish and maintain positive

relationships with others, and manage challenging interpersonal situations (Durlak et al.,

2011; Elias et al., 2007). It is posited that these abilities provide a basis for positive

social actions, less behavioral problems, and better emotional regulation (Greenberg et

al., 2003). Theorists suggest that by achieving social-emotional competence, children

and adolescents learn to internalize values and beliefs that promote caring and concern

11

for others, as well as taking responsibility for ones choices and behaviors (Bear &

Watkins, 2006).

Developmental researchers suggest that failure to acquire social-emotional

competencies is associated with a variety of personal and social difficulties (e.g.,

Eisenberg, 2006; Guerra & Bradshaw, 2008). Research has suggested that many students

do not develop these social-emotional abilities as they mature which, in turn, has a poor

effect on behavior. For example, in one study, social competencies such as empathy and

conflict resolution skills were only noted in about 30% of a national sample of middle-

and high-school students (Benson, 2006). Similar to research among children in early

childhood, studies examining social aggression among children in middle childhood have

also examined the association between social aggression and measures of internalizing

and externalizing difficulties. Numerous studies have linked social aggression with

internalizing and externalizing symptoms (Crick, 1997), specifically higher levels of

anxiety (Marsee, Weems, & Taylor, 2008), depressive symptoms (Crick & Grotpeter,

1995; Henington, et al., 1998; Murray-Close & Crick, 2007; Zimmer-Gembeck, Hunter,

& Pronk, 2007), general aggression (Crick, Ostrov, & Werner, 2006), delinquency (in

boys; Crick, Ostrov, & Werner, 2006), impulsivity (Musher-Eizenman, et al., 2004),

attention-deficit hyperactivity disorder (Zalecki & Hinshaw, 2004), as well as lower

emotional regulation (Bowie, 2010). However, there has been a lack of attention paid to

the measurement of possible indices of positive adaption (Heilbron & Prinstein, 2008).

In terms of social relationships, research has also found discrepant findings within

the middle childhood population. For example, studies have indicated that social

aggression is associated with increased peer rejection (Crick, 1996; Crick & Grotpeter,

12

1995; Rys & Bear, 1997; Tomada & Schneider, 1997), lower social acceptance (Crick,

1996; Henington, et al., 1998; Lancelotta & Vaughn, 1989), lower social preference

(Johnson & Foster, 2005; Murray-Close & Crick, 2006; Werner & Crick, 2004; Zimmer-

Gembeck, et al., 2007), and fewer mutual friendships (Johnson & Foster, 2005). In

contrast, other studies have suggested that social aggression is positively associated with

social intelligence (Kaukiainen, et al., 1999), peer-perceived popularity (Andreou, 2006;

Lease, Kennedy, & Axelrod, 2002), and higher rates of friendship exclusivity, self-

disclosure by friends, and social intimacy (Grotpeter & Crick, 1996).

Adolescence. The developmental period of adolescence contains several

challenges including puberty, entering new schools, beginning to separate from parents,

developing an individual identity, and, for many, developing romantic relationships

(Underwood, 2003). Social methods of aggression may be favored by adolescents

because they are considered socially acceptable and less easy to identify by on-lookers

as bullying or aggression. Furthermore, the increased importance of social status and

romantic relationships may have an effect on interpersonal relations of adolescents (Xie,

Cairns, & Cairns, 2005). Competition for friends, a romantic partner, and social visibility

or status may generate interpersonal conflicts that evoke the use of social aggression

(Xie, Cairns, & Cairns, 2005). According to Underwood (2003), younger adolescents

social aggression might be used to protect the boundaries of social groups and for

confirming high peer status. For older adolescents, social aggressive strategies,

particularly gossip, may be used less for self-protection and more in the service of self-

understanding, identity development, and moral negotiation (Underwood, 2003). During

adolescence, social means of aggression are expected to coexist with direct verbal means,

13

with the individual using the strategy that is most suitable in the particular situation

(Bjorkqvist, et al., 1992).

Research among adolescent samples have resulted in much the same types of

findings as those for middle childhood. Several studies have documented both

externalizing and internalizing difficulties among socially aggressive adolescents. For

example, research has revealed positive associations with externalizing behavior

(Prinstein, Boergers, & Vernberg, 2001), anger to provocation (Marsee & Frick, 2007),

callous-unemotional traits (Marsee & Frick, 2007), lower empathy (Kaukiainen, et al.,

1999), social anxiety (Loukas, Paulos, & Robinson, 2005), and negative self-

representation (Moretti, Holland, & McKay, 2001). Conversely, several studies have

demonstrated links between social aggression and positive adjustment among adolescents

(Heilbron & Prinstein, 2008). For example, studies have shown that socially aggressive

individuals have higher levels of social intelligence (Kaukiainen, et al., 1999), ability to

influence peers (Xie, et al., 2002), and ratings of Olympian traits (i.e., athletic,

attractive; Xie, et al., 2002).

Investigations into the social relationships of socially aggressive adolescents have

yielded mixed findings. Some studies have suggested that social aggression is positively

associated with higher peer acceptance (Cillessen & Borch, 2006; Salmivalli,

Kaukiainen, & Lagerspetz, 2000), social preference (Prinstein & Cillessen, 2003), peer-

perceived popularity (e.g., Cillessen & Borch, 2006; Cillessen & Mayeux, 2004;

Leadbeater, Boone, Sangster, & Mathieson, 2006; Vaillancourt & Hymel, 2006), social

network centrality (Xie, et al., 2002), and social impact (Zimmer-Gembeck, et al., 2005),

as well as lower levels of peer rejection (Salmivalli, et al., 2000). Conversely, other

14

studies have indicated that socially aggressive adolescents have higher levels of peer

rejection (Vaillancourt & Hymel, 2006) and lower levels of social preference (Cillessen

& Mayeux, 2004; Lafontana & Cillessen, 2002; Rys & Bear, 1997; Zimmer-Gembeck, et

al., 2005).

Previous Meta-Analyses on Social Aggression

Social aggression has been explored in two previous meta-analyses (Archer,

2004; Card, et al., 2008). Archers (2004) meta-analytic review of gender differences in

various forms of aggression included 41 published and unpublished studies that examined

social forms of aggression. These researchers found more evidence of social aggression

in the female direction among children. However, the sex differences were not as large or

consistent as would have been expected from previous individual studies of children

(Archer, 2004).

Archer (2004) found that the method of measurement for social aggression (i.e.,

self-report, peer report, teacher report, and observation) was an important moderator to

explain variations in study findings. Specifically, when social aggression was measured

using observations, the largest gender difference on social aggression was found,

indicating that females showed more social aggression (d = -.74); however, this result

was based on only four studies. Data from peer-ratings suggested that females engage in

more social aggression (d = -.19), and gender differences increases with age (d = -.00 for

under age 11; d = -.13 for ages 12-13; d = -.35 for ages 14-17). Similarly, teacher-reports

also revealed social aggression in the female direction (d = -.13). In contrast, although

small, self-reports suggested that males engage in greater levels of social aggression (d =

15

.03). This effect also increased with age (d = .03 for ages 6-13; d = .12 for ages 14-17;

Archer, 2004).

While Archers (2004) study provides a basis for understanding gender

differences in aggression, the analysis has several limitations. Archer only used the term

indirect aggression in its search for relevant articles, therefore including only 41 studies

of this construct, Further, inclusion required the sample to contain both males and

females. In addition, Archer used a fixed-effects model for his analysis, which may have

affected the generalization of findings.

In 2008, Card et al. conducted a meta-analysis of 107 published and unpublished

studies examining the correlation between gender and type of aggression (i.e., physical

and social), the relationship between physical and social aggression, and the association

between type of aggression and psychosocial adjustment. In terms of gender differences,

Card et al.s (2008) results found that girls use more social aggression than boys, but that

this result, although statistically significant (r = -.03), was trivial in magnitude and

therefore negligible (p. 1194). Similar to Archer (2004), Card and colleagues found

method of measurement (i.e., self-report, peer report, teacher report, parent report, and

observation) moderation effects when looking at the relationship between gender and

social aggression. However, in contrast to Archer, Card et al.s meta-analysis indicated

that the magnitude of such effects was trivial regardless of the reporter. In particular,

Card et al.s findings found statistically significant gender differences for social

aggression in the female direction based on parent (r = -.08) and teacher (r = -.07), but

not researcher-observation (r = -.05) or peer nominations (r = -.02). Statistically

16

significant gender differences in the male direction were found based on self-report (r =

.03).

Card et al.s (2008) meta-analysis also found physical and social aggression to be

strongly correlated (r = .76), yet separable demonstrating the presence of two related, yet

different constructs. In addition, Card et al. explored the relationship between form of

aggression and psychosocial adjustment. Their findings indicate that physical and social

aggression are uniquely related to various aspects of maladjustment. Specifically,

physical aggression was more strongly related to emotional dysregulation and conduct

problems, while social aggression was more strongly associated with internalizing

problems (i.e., depression and anxiety). No gender moderation of these relationships was

found.

Card et al.s (2008) study provides a useful step in the understanding of social

aggression, however is also limited by several issues. First, their criteria for study

inclusion into the meta-analysis (e.g., only studies including both social and physical

aggression) excluded many studies whose focus was solely on social aggression. Second,

these authors did not examine age as a potential moderator for the relationships in

question. Third, the psychosocial adjustment factors studied by Card et al. represent a

limited representation of the possible correlates associated with social aggression. By

focusing solely on maladjustment in the form of internalizing and externalizing

behaviors, Card et al. did not examine social adjustment or the potential positive

outcomes associated with social aggression, thereby limiting the results and subsequent

understanding of this phenomenon.

17

Thus, although both meta-analyses (Archer, 2004; Card et al., 2008) have

provided useful information, the studies have limitations and the results raise further

questions. By including more studies using a broader definition of social aggression,

including age as a moderator, and examining all potential correlates (both positive and

negative), a better understanding of social aggression can be yielded. This understanding

can, in turn, affect the generalizability of study findings.

Current Study

From the review above it is clear that there are many inconclusive findings in the

research concerning social aggression. Within the literature, social aggression has been

viewed as either maladaptive or adaptive, each with empirical evidence to support the

claim. Some researchers have suggested that social aggression is related to negative

outcomes such as peer rejection, psychological distress, and behavioral difficulties.

Conversely, other researchers have argued that although socially aggressive behaviors are

not desirable, they are associated with positive outcomes, such as peer acceptance, social

skills, and prosocial behavior. Although a previous meta-analyses explored the

relationship of social aggression and some areas of psychosocial adjustment, it contained

notable limitations.

Furthermore, given the effort to explore and combat social aggression among

girls, it is important to determine the role of gender in the association between social

aggression and different outcomes. Although prior meta-analyses have explored this area,

results are unclear and would benefit from further clarification. In addition, because of

the discrepancy in the results of various studies, it is important to determine if these

inconsistencies are due to another factor, such as age. A resolution of conflicting

18

evidence is necessary to further advance the field of social aggression and to apply these

findings to future and current interventions. The more able we are to identify how social

aggression relates to other facts, such as peer relations, social skills, and psychological

distress, the more able we are to create interventions that specifically target these types of

behaviors. Thus, the purpose of this current study is to, (1) examine the relationship

between social aggression and both positive and negative correlations, (2) explore

whether the relation among these variables are moderated by gender, and (3) explore

whether the relation between these variables are moderated by age.

Meta-Analysis

One way to address mixed findings to a research question is to conduct a meta-

analysis (Rosenthal & DiMatteo, 2001). Meta-analysis allows for the combining the

results from multiple, as well as discover moderators and mediators that can examine

mixed findings (Rosenthal & DiMatteo, 2001). This allows for researchers to generate

results that are more generalizable than can be presented in any one study. As Rosenthal

and DiMatteo (2001) note,

Meta-analysis is more than a statistical technique; it is a methodology for

systematically examining a body of research, carefully formulating hypotheses,

conducting an exhaustive search and establishing inclusion/exclusion criteria for

articles, recording and statistically synthesizing and combining data and effect

sizes from these studies, searching for moderator and mediator variables to

explain effects of interest, and reporting results. (p. 62)

19

Thus, a meta-analysis was used to better understand the phenomenon of social

aggression and its connection to various correlates by other important moderators, such

as gender and age, which might explain inconsistent findings.

20

CHAPTER 3

METHODS

Search Procedure

A comprehensive search for empirical research focusing on social aggression,

broadly defined, was used. Studies to be included in the meta-analysis were selected

using the following search procedures. A broad search was conducted in several relevant

online databases, including: PsycINFO, ERIC (Educational Resources Information

Center), Social Science Citation Index, and Family & Society Studies Worldwide in April

2010. Because of the disagreement among researchers on terms used to describe social

aggression, a wide search with several search terms was carried out to ensure a thorough

collection of relevant articles. Specific keywords included: social aggress* or indirect

aggress* or relational aggress* or covert aggress* or nonphysical aggress* or

bullying. The broad keyword bullying was also used because bullying behaviors were

often not indicated within the keywords of articles. Although related constructs, terms

specific to physical aggression and peer victimization were not included in the search in

order to focus on the specific behaviors of social aggression and the factors associated

with aggressors.

This initial search process resulted in the identification of over 20,000 articles

with potential for inclusion in the meta-analytic database (see Figure 1). These articles

were further narrowed by several criteria within each search database: (1) written in

English, (2) examined a sample of children and/or adolescents, aged 2-17, excluding

college students, (3) be an empirical study, and (4) be within a peer-reviewed journal. In

databases where the age of participants was not provided as a search criteria, additional

21

22

search terms were added, specifically: child or childhood or children or

adolescent or adolescence or youth. All citations were subsequently placed into

EndNote X3 (a computer citation software program) and analyzed for duplicate

references. This initial search process resulted in the identification of over 4,600 articles

with potential for inclusion in the meta-analytic database.

As shown in Figure 1, abstracts of all collected citations were reviewed to

eliminate articles that clearly did not meet the goals of the present meta-analysis.

Abstracts were excluded if they did not examine social aggression (N = 2488); examined

the general concept of bullying, rather than assessing a particular form of social

bullying (N = 1510)); did not meet the initial criteria (as outlined above, N = 203); did not

provide sufficient information for computing effect size (N = 76); or were primarily

composed of children with mental retardation or pervasive developmental disorders (N =

19) in which social development would presumably be impaired. The remaining 365

studies were included in the initial database. Of those, studies that were relevant to

individual characteristics or peer relations were extracted, yielding a total of 107 studies

included in the present meta-analysis.

A reliability check of included and excluded articles was conducted. A graduate

student in psychology reviewed a random sample of 10% of the initially identified

articles. Studies were randomly chosen by selecting every 10th study in the database (i.e.,

within the database of identified articles, study #1, #10, #20, and so on were selected).

The graduate student independently categorized the chosen studies as included or

excluded. Interrater reliability was assessed by computing the percent of total agreement

between the author and graduate student. The agreement rate for this study was 98%.

23

Coding of Studies

Studies which were deemed to be relevant to the present investigation were

collected and coded. Coding involves evaluating each study and collecting the pertinent

information into a coding form. If an article contained multiple samples, each sample was

treated as an independent study sample. Similarly, if an article contained multiple studies,

each study was coded separately. Data from each study was coded on forms created in

Microsoft Access and then automatically transferred to a database created in Microsoft

Excel . This automatic exporting of data minimized opportunity of human error on data

entry.

To ensure reliability of the coding process, another individual was recruited to

code the articles in the database. This individual is a fellow graduate student in

Psychology and was trained on the specific categories that were assessed in the current

research. The authors coding form was compared item-by-item to the research assistants

form for each study. Calculation of the reliability estimate was done via agreement rate

within each study. The inter-rater agreement for this subset of studies was 97%. All

discrepancies found during the reliability check were on items not included in these

analyses (i.e., names of measures, and source of funding).

Each article was coded on five general characteristics:

1) Study characteristics: general article information, such as authors, publication

year, journal, and whether the study was part of a funded project.

2) Sample information: number of participants; location of sample; age; education

level (i.e., preschool, elementary, etc.); gender information; ethnicity.

24

3) Social aggression: information regarding what term was used by authors (e.g.,

indirect aggression, relational aggression); information regarding measures;

sources of data (e.g., peer-rating, self-report, teacher-report).

4) Correlates: information regarding the outcomes of each study was identical to that

of measures of social aggression; whether correlate was considered positive (e.g.,

social skills, popularity) or negative (e.g., peer-rejection, psychological distress).

5) Summary statistics: information relating to each of the measures and results,

including correlations and sample size for computing the associated variances.

Each variable was sorted into categories (i.e., individual characteristics, peer

relations) created to address the research questions. Within each category, the correlates

were divided based on their coding as either positive or negative and further separated

into subcategories with the goal of maximizing similarities.

The subcategories for individual characteristics included: externalization,

internalization, positive individual traits, and negative individual traits. Within each

subcategory, several groupings of correlates were created (Please see Appendix for

examples of measures for each subcategory). For externalization, they included: conduct

problems, deception, defiance, delinquency, externalizing behavior, hyperactivity,

impulsivity, inattention, sexual activity, and substance use. Correlates for internalization

were grouped into: anxiety, depression, emotional dysregulation, internalizing symptoms,

and withdrawal. For positive individual traits, groups included: self-efficacy, social

skills, sociability, self-esteem, empathy, cooperative, leadership, language ability, peer-

valued traits (e.g., athleticism, attractiveness, humor, etc.), and positive personality

features (i.e., agreeableness, openness, conscientiousness). Negative individual traits

25

were grouped into: anger, dominance, undesirable traits (e.g., bossy, mean, jealousy,

etc.), callous-unemotional traits, narcissism, emotional, and borderline personality

features.

The subcategories for peer relations included positive and negative groupings. For

positive peer relations, groupings of correlates included: peer-acceptance, social support,

social intimacy, peer-liking, popularity, positive social friendships, and prosocial

behavior. Negative peer relations were grouped into: peer-conflict, peer-dislike, peer-

rejection, and peer-victimization. This process of grouping variables was conducted by

the author and research assistant independently. Complete agreement (100%) was

reached for the placement of correlates into categories and subcategories. In addition, the

categories and placement of variables in the respective categories were reviewed by a

professor in Counseling Psychology as an added verification for content validity. Any

discrepancies were discussed until there was complete agreement.

Power

Prospective power analyses are useful to make sure that the power of statistical

tests is sufficient for the effect size to be of practical significance in any given situation

(Hedges & Pigott, 2001). Before a meta-analysis is conducted, a power analysis can

provide the chance of obtaining a statistically significant result provided certain criteria:

expected magnitude of the overall effect size, estimated number of studies included in the

review, and the average sample size within the studies (Hedges & Pigott, 2001).

Given that, at the onset of the analysis process, the factors were undetermined

(i.e., number of studies, typical sample size), the lower acceptable numbers for each

factor were used to determine the range of power. With a small effect size of 0.10, 25

26

studies, and a minimum average sample size of 50, the power obtained for finding a

statistically significant overall result is 0.94. Given these factors, analysis of moderators

with as few as five studies would result in a range of power from 0.82 for large between-

group heterogeneity to 0.99 for small between-group heterogeneity. These results indicate

that, even when using the lowest acceptable criteria, the chance of obtaining a statistically

significant result was above 0.80. Thus, the power analysis of the current study adds an

additional confidence yielding statistical inferences with an acceptable power.

Effect Size

The results of each study were standardized into a common metric, known as an

effect size. Effect sizes express the magnitude and direction of the relationship between

two variables (Cooper, Hedges, & Valentine, 2009). The majority of the studies in this

meta-analysis reported correlational coefficients regarding social aggression and the

associated outcomes. Pearsons correlation coefficient (r) is a measure of linear

association, and thus it provides an indication of the degree of the relationship between

two variables. Consequently, Pearsons product moment correlation (r) is the primary

effect size used for the meta-analysis. However, because correlation coefficients are not

normally distributed they were transformed to Fishers z (Borenstein, 2009). Each of the

estimates (e.g., mean, 95% confidence interval) computed based on Fishers z was then

converted back to the r metric using the formula provided by Borenstein (2009). This

conversion allowed the estimates to be interpreted as correlation coefficients. Rosenthal

and DiMatteo (2001) noted several advantages of using the Pearson r in meta-analyses;

including the fact that r is more simply interpreted in terms of practical importance.

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Analysis

As described previously, meta-analyses allows for estimating the overall

relationship using a number of studies examining the same phenomenon (Cooper, 2009)

and further examining the sources of mixed findings, using moderators (Rosenthal &

DiMatteo, 2001). Three methods of meta-analysis are often used in contemporary studies

(Field, 2001): The methods devised by Hedges and Olkin (1985); by Rosenthal and

Rubin (see Rosenthal, 1991), and by Hunter and Schmidt (2004). The current study

employed the methods put forward by Hedges and Olkin (1985) and described by

Cooper, Hedges, and Valentine (2009). According to these authors, first one must

establish which model (i.e., fixed-effect, random-effect, or mixed-effect) is most

appropriate for the data. Essentially, in fixed-effects models (also called the

homogenous case) the effect size is assumed to be from the same underlying

population for all studies included in the meta-analysis (Field, 2001). In contrast,

random-effects models (also called the heterogeneous case) assume that effect sizes

vary from study to study such that the population effect size is likely to be different than

any other study in the meta-analysis (Field, 2001).

To determine which model was more appropriate for the data in the current study,

an overall homogeneity test of effect sizes using the heterogeneity statistics (also known

as Q statistics) was performed using the method described in Konstantopoulos and

Hedges (2009). The heterogeneity Q statistic approximately follows a chi-square

distribution with its associated degree of freedom (k), where k indicates the number of

effect sizes (Konstantopoulos & Hedges, 2009). If the Q statistic was statistically

significant, indicating that the fixed-effects model was not supporting that the effect sizes

28

were from the same population, a random-effects model for computing the overall effect

sizes or mixed-effects model with predictors for comparing effect sizes by predictors was

applied. If the Q statistic was not significant, the mean effect size was computed under

the fixed-effect model, in which the effect sizes were weighted by the inverse of their

associated variance.

As discussed in the literature review of this paper, there are several discrepancies

in the relationship between social aggression and various correlates. Moderator analyses

can help clarify these discrepancies. For this meta-analysis, moderators were chosen in

advance based on theory and included: gender and age group (e.g., preschool,

elementary, etc.). Mean correlation by each categorical moderator were compared under

the mixed-effects categorical model.

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CHAPTER 4

RESULTS

Characteristics of Studies

Upon completion of the primary study coding process, it was determined that 108

studies would contribute data for the current meta-analytic database. These 108 studies,

derived from 107 published articles, produced 896 correlation coefficients (r). One article

provided statistical findings from two studies, and thus these findings were treated as two

independent study samples. The majority of studies (s = 76; 70.4%) were from the

United States. International studies were from Asia (s = 6; 5.6%), Australia (s = 2;

1.9%), Europe (s = 11; 10.2%), and North America (s = 12; 11.1%, excluding the United

States). One study used samples from multiple locations (i.e., Russell, Hart, Robinson, &

Olsen, 2003 used samples from the United States and Australia). Articles were published

between 1996 and 2010, with the majority of articles (s = 101; 93.5%) published within

the last ten years. Of the seven articles published in the previous decade, two were

published each year from 1996 to 1998, with one article published in 1999.

The total number of participants across all studies was 52,173. Sample sizes

ranged from 37 to 7,290 (M=487.60, SD = 843.86). The age of participants ranged from

2 to 17 years old, with an average age of 10.2 years (SD = 3.8). The majority of studies (s

= 48; 44.4%) focused on the 10 to 13 year old or middle-school range, with other studies

(s = 60; 55.6%) evenly representing the other age groups (e.g., ages 2-5: s = 22, 20.4%;

ages 6-9: s = 21, 19.4%; ages 14-17: s = 15; 13.9%). Two studies (i.e., Dukes, 2009;

Graves 2007) did not provide participants age information. There were 26,865 (51.5%)

female and 22,285 male participants. Six studies did not provide gender information (i.e.,

30

Albrecht, Galambos, & Jansson, 2007; Cillessen, Jiang, West, & Laszkowski, 2005; Ellis

& Zarbatany, 2007; Mayeux & Cillessen, 2008; Ostrov et al., 2009; Yu & Gamble,

2008). Seven studies (i.e., Linder & Gentile, 2009; Loeber et al., 2009; Marsee & Frick,

2007; Mikami, Lee, Hinshaw, & Mullin, 2008; Ohan & Johnston, 2007; Putallaz et al.,

2007; Zalecki & Hinshaw, 2004) used all-female samples, while no studies used all-male

samples.

Publication Bias

One way to assess publication bias is to examine a funnel plot. A funnel plot is a

graphic representation of the relationship between effect sizes and its associated sample

sizes. If there is no publication bias, the plot of effect sizes against sample sizes appears

to be funnel-shaped. In the current study, a scatter plot of 2,078 correlation coefficients

against sample sizes appeared asymmetrical and did not resemble a funnel shape (see

Figure 2), suggesting possible publication bias. In addition to the visual inspection of the

funnel plot, a statistical test commonly used to detect publication bias was conducted.

Eggers regression test for funnel plot asymmetry (Sutton, 2009) was found to be

statistically significant for correlation coefficients (t (2076) = 18.84, p < .01), thus

indicating the presence of potential publication bias. Such results were due to the

inclusion of studies published in peer-reviewed journals, which would limit the

generalizability of findings in the current meta-analysis.

Overall Model

The aim of this meta-analysis was to examine the relationship between social

aggression and various correlates. After coding all of the articles, correlates were grouped

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32

into two general categories: individual characteristics and peer relations (as seen in

Figure 3). Under the random-effects model, each category was found to be significantly

correlated with social aggression: individual characteristics (r = 0.25, p < .01), peer relations (r = 0.10, p < .01; see Table 1). Post-hoc comaprisons using Bonferonni adjustments indicated that individual characteristics had a statistically higher mean

correlation with social aggression than peer relations (z = 6.71, p < .01). Several

moderators were examined to determine their role in each relationship and are discussed

below.

Gender differences. Table 2 shows results from the moderator analysis using

gender. The relationship between individual characteristics and social aggression

significantly differed by gender; however, not for peer relations. Under the mixed-effects

model, the relationship between individual characteristics and social aggression, was

significant for female-only, male-only, and mixed-gender groups. Similarly, the

relationship between peer relations and social aggression was significant and positive for

female-only, male-only, and mixed-gender groups. Post-hoc comparisons using

Bonferonni adjustments indicated that the relation of social aggression to individual

characteristics was statistically higher for female-only than for male-only (z = 2.40, p <

.01).

Age differences. Table 3 shows results from the moderator analysis by age.

Mixed-effects models showed that the overall relationship between social aggression and

individual characteristics and peer relations differed by age. The relationship between

social aggression and individual characteristics was significant and positive for

preschool-, elementary-, middle-school-, and high-school-aged samples. Simiarly, the

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34

35

36

relationship between peer relations and social aggression was significant and positive for

preschool-, middle-school-, and high-school-aged groups; however, not significant for

elementary-aged samples. Post-hoc comparisons using Bonferonni adjustments indicated

a statistically higher difference in the relation of social aggression to individual

characteristics for high-school than for middle-school-aged samples (z = 2.83, p < .01).

Post-hoc comparisons also indicated a statistically higher difference in the relation of

social aggression to peer relations for preschoolers as compared to elementary- (z = 3.77,

p < .01) and high-school-aged samples (z = 2.60, p < .01); as well as for middle-school in

comaprison to elementary-school children (z = 2.50, p < .01).

Relationship Between Individual Characteristics and Social Aggression

A more specific goal of the present study was to determine whether positive or

negative correlates were related to social aggression. For each general category,

correlates were separated into those respective groups and analyzed independently.

Again, gender and age moderators were examined to determine their roles in each

relationship.

The general category of individual characteristics was divided into four

subcategories (i.e., externalization, internalization, positive individual traits, negative

individual traits) and then estimated separately for its relationship with social aggression.

Overall, the four types of individual characteristics showed significant and positive

relationships with social aggression (see Table 4). Post-hoc comparisons using

Bonferonni adjustments indicated statistically different relationships between social

aggression and externalization as compared to internalization (z = 3.88, p < .01) and

positive individual traits (z = 5.89, p < .01). Additionally, post-hoc comparisons showed

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38

statistically different relationships between social aggression and negative individual

traits as compared to internalization (z = 3.33, p < .01) and positive individual traits (z =

5.42, p < .01). Finally, post-hoc comparisons indicated statistically different relationships

between social aggression and internalization as compared to positive individual traits (z

= 3.05, p < .01).

Correlates categorized into the externalization of individual characteristics were

each estimated separately for their relationship with social aggression. All but one of the

subcategories (i.e., sexual activity) were significantly and positively associated with

social aggression. Post-hoc comparisons using Bonferonni adjustments indicated

statistically lower relationships between social relations and conduct problems as

compared to defiance (z = 2.98, p < .01) and inattention (z = 3.00, p < .01). In addition,

post-hoc comparisons showed statistically lower relationships between social relations

and substance use as compared to defiance (z = 3.64, p < .01), inattention (z = 5.59, p <

.01), delinquency (z = 2.63, p < .01), externalization (z = 1.20, p < .01), and hyperactivity

(z = 2.19, p < .01).

Variables grouped into the internalization of individual characteristics were also

estimated separately for their association with social aggression. The overall correlation

indicated positive and significant relationships between emotional dysregulation and

social aggression, as well as between internalizing symptoms and social aggression. Post-

hoc using Bonferonni adjustments indicated statistically different relationships between

social aggression and internalizing symptoms as compared to emotional dysregulation (z

= 3.05, p < .01).

39

Correlates classified into the positive individual traits were estimated separately

for their relationship with social aggression. The overall correlation indicated positive

and significant relationships for social skills, sociability, leadership, language ability, and

peer-valued traits with social aggression. Several correlates indicated negative

relationships with social aggression, such as self-efficacy, empathy, cooperative, and

positive personality traits, however these correlations were not statistically significant.

Variables grouped into the undesirable individual traits were also estimated

separately for their association with social agression. The overall correlation indicated

positive and significant relationships for anger, dominance, callous-unemotional traits,

narcissism, and borderline personality traits. Post-hoc comparisons using Bonferonni

adjustments indicated statistically lower relation between social aggression and

borderline traits as compared to anger (z = 3.40, p < .01), dominance (z = 5.55, p < .01),

callous-unemotional traits (z = 2.69, p < .01), and narcissism (z = 3.80, p < .01).

Gender differences. Table 5 shows results from the moderator analyses by

gender. Mixed-effects models showed that the relationship between social aggression and

externalization, internalization, positive individual traits, and negative individual traits

significantly differed by gender. The relationship between externalization and social

aggression was significant and positive for female-only and mixed-gender groups;

however, not significant for male-only groups. The association between internalization

and social aggression was significant for female-only, male-only, and mixed-gender

groups. Conversely, the correlation between positive individual traits and social

aggression was significant for mixed-gender groups; however, not significant for female-

only or male-only groups. Finally, the relationship between negative individual traits and

40

41

social aggression was significant for female-only, male-only, and mixed-gender groups.

Post-hoc comparisons using Bonferonni adjustments indicated that the relations of social

aggression to externalization was statistically higher for female-only than for mixed-

gender (z = 2.57, p < .01).

Of the effect sizes related to externalization, three were able to be analyzed for

gender differences: defiance, externalizing behavior, and hyperactivity. Defiance was

positively and significantly related to social aggression for female-only groups and

mixed-gender groups. Female-only groups showed a significant relationship between

externalizing behavior and social aggression, while male-only groups did not. The

association between hyperactivity and social aggression was significant for female-only,

male-only, and mixed-gender groups. Post-hoc comparisons on the relation of defiance to

social aggression indicated statistically higher relationships for female-only than for

mixed-gender groups (z = 2.72, p < .01). Similarly, post-hoc comparisons on the

association between hyperactivity and social aggression indicated statistically different

relationships for female-only than for male-only (z = 5.53, p < .01) and mixed-gender

groups (z = 4.02, p < .01).

All of the effect sizes related to internalization were able to be analyzed for

gender differences. The association between depression and social aggression was

significant for mixed-gender groups; however, not significant for female-only or male-

only groups. Emotional dysregulation was positively and significantly related to social

aggression for female-only groups and mixed-gender groups. Similarly, internalizing

symptoms was significantly associated to social aggression in female-only, male-only,

42

and mixed gender groups. Neither anxiety nor withdrawal showed significant

associations for female-only or mixed-gender groups.

Of the effect sizes related to positive individual traits, two were able to be

analyzed for gender differences: language ability and sociability. Language ability was

positively and significantly associated with social aggression for female-only and mixed-

gender groups; however, was negatively and significantly related male-only groups.

Sociability was not significantly related to social aggression for either female-only or

mixed gender groups. Post-hoc comparisons on the association between language ability

and social aggression indicated statistically different relationships for female-only as

compared to male-only groups (z = 3.39, p < .01).

Three effect sizes related to negative individual traits were able to be analyzed for

gender differences: dominance, negative traits, and callous-unemotional traits. Both

dominance and callous-unemotional traits were positively and significantly associated

with social aggression for female-only and mixed-gender groups. Negative traits, such as

being mean or jealous were significantly associated with social aggression for

mixed-gender groups; however, not significant for female-only groups. Post-hoc

comparisons indicated that the relation of social aggression to callous-unemotional traits

was statistically higher for female-only than for mixed-gender groups (z = 5.89, p < .01).

Age differences. Table 6 shows results from the moderator analyses by age.

Mixed-effects models showed that the relationship between social aggression and

externalization, internalization, positive individual traits, and negative individual traits

significantly differed by age of sample. The relationship between externalization and

social aggression was significant for preschool-, elementary-, middle-school-, and high-

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44

school-aged groups. The association between internalization and social aggression was

significant for middle-school- and high-school-aged children; however, this relationship

was not significant for preschoolers or elementary-school children. Conversely, the

relationship between positive individual traits and social aggression was significant for

preschool- and elementary-school-aged samples; however, not significant for middle-

school or high-school groups. Finally, the relationship between negative individual traits

and social aggression was significant for preschool-, elementary-, middle-school-, and

high-school-aged groups. Post-hoc comparisons using Bonferonni adjustments indicated

that the relationships of social aggression to externalization was statistically higher for

elementary-school than for high-school-aged children (z = 2.74, p < .01).

Several correlations related to externalization were able to be analyzed for age

differences. Delinquency was significantly related to social aggression for elementary-,

middle-school-, and high-school-aged children. Conduct problems was significantly

associated with social aggression for preschool-, middle-school-, and high-school-aged

groups; however, was not significant for elementary-school children. Both deception and

impulsivity were significantly correlated with social aggression for preschoolers and

middle-school-aged children. Although both externalizing behaviors and inattention were

significantly related to social aggression for middle-school children, only inattention was

also significant for elementary-school children. Finally, substance use was significantly

associated with social aggression for high-school groups, but not for middle-school

groups. Post-hoc comparisons on the association of conduct problems and social

aggression indicated a statistically higher relation for preschoolers as compared to

middle-school-aged children (z = 2.56, p < .01).

45

Two correlates related to internalization were able to be analyzed for age

differences. Internalizing symptoms was significantly related with social aggression for

both elementary- and middle-school-aged samples. Depression was significantly

associated with social aggression for high-school gorups; however, this relationship was

not significant for preschoolers or elementary-school aged children. Post-hoc

comparisons on the relation of social aggression to internalizing symptoms indicated

statistically higher relation for middle-school- than for elementary-school children (z =

2.06, p < .01).

Two effect sizes related to positive individual traits were able to be analyzed for

age differences. Language ability was positively and significantly related to social

aggression for preschoolers, but negatively and significantly associated for middle-

school-aged children. Social skills was not significantly related to social aggression for

preschool- or middle-school-aged children.

Four effect sizes related to negative individual traits were able to be analyzed for

age differences. Dominance was significantly associated with social aggression for

preschoolers and high-school children. Both anger and narcissism were significantly

associated with social aggression for middle-school- and high-school-aged children.

Callous-unemotional traits were significantly correlated with social aggression for

elementary-, middle-school-, and high-school-aged groups. Post-hoc comparisons on the

association between social aggression and callous-unemotional traits indicated

statistically lower relation for middle-school children than for elementary- (z = 3.71, p <

.01) and high-school-aged groups (z = 4.02, p < .01).

46

Relationship Between Peer Relations and Social Aggression

Peer relations was divided into positive and negative subcategories and estimated

separately for its association with social aggression (see Table 7). While both positive

and negative peer relations were both positively associated with social aggression, only

negative peer relations was significantly related. Correlates categorized into positive peer

relations were each estimated separately for their association with social aggression. The

overall correlation coefficients indicated positive and significant relationships for

intimacy and popularity, as well as negative and significant relationships for peer-liking

and positive social relations. Prosocial behavior, social acceptance, and social support did

not show statistically significant relationships with social aggression. Post-hoc

comparisons using Bonferonni adjustments indicated statistically different associations

between social aggression and popularity as compared to peer-dislike (z = 3.88, p < .01)

and negative friendships (z = 6.01, p < .01). Correlates grouped into negative peer

relations were also estimated separately for their association with social aggression. All

of the subcategories (i.e., social conflict, peer dislike, peer rejection, peer victimization)

were positively and significantly associated with social aggression. Post-hoc comparisons

using Bonferonni adjustments indicated statistically higher relationships between social

aggression and peer-victimization as compared to peer-rejection (z = 2.50, p < .01).

Gender differences. Table 8 shows results from moderator analyses by gender.

Mixed-effects models showed that the relationship between social aggression and both

positive and negative peer relations significantly differed by gender. The relationship

between positive peer relations and social aggression was significant for mixed-gender

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48

49

groups; however, was not significant for female-only or male-only groups. Conversely,

the association between negative peer relations and social aggression was significant and

positive for female-only, male-only, and mixed-gender groups. Post-hoc comparisons

using Boneronni adjustments indicated that the relationships of social aggression to

negative peer relations was statistically higher for female-only than for mixed-gender

groups (z = 2.65, p < .01).

Of the effect sizes related to positive peer relations, all but one (i.e., intimacy)

were able to be analyzed for gender differences. Popularity was significantly associated

with social aggression for female-only, male-only, and mixed-gender groups. Peer-liking

was significantly related to social aggression in mixed-gender groups, however not for

female-only or male-only groups. Positive friendships was significantly associated with

social aggression for female-only groups; however, was not significantly related for

male-only or mixed-gender groups. Finally, neither social acceptance, social support, or

prosocial behavior was significantly associated with social aggression for female-only,

male-only, or mixed-gender groups.

All of the effect sizes related to negative peer relations were able to be analyzed

for gender differences. Both social conflict and victimization were significantly related to

social aggression for female-only, male-only, and mixed-gender groups. Peer-dislike and

peer-rejection were significantly correlated with social aggression for female-only and

male-only groups, however not for mixed-gender groups.

Age differences. Table 9 shows results from the moderator analyses by age.

Mixed-effects models showed that the relationship between social aggression and both

positive and negative peer relations significantly differed by age of sample. The

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relationship between positive peer relations and social aggression was significant and

positive for middle-school- and high-school-aged groups, as well as significant and

negative for elementary-school children. However, this association was not significant for

preschoolers. The association between negative peer relations and social aggression was

significant for preschool-, elementary-, and middle-school-aged children, however not

significant for high-school groups. Several effect sizes related to positive peer relations

were able to be analyzed for age differences. Popularity was significantly related with

social aggression for middle-school and high-school groups. Social acceptance and peer-

liking were significantly associated with social aggression for elementary- and high-

school-aged children, however not for preschoolers or middle-school children. Positive

friendships was significantly related to social aggression for preschool and elementary-

school groups, but not for middle-school- or high-school-aged children. Social support

was significantly correlated with social aggression for high-school groups, but not for

elementary-school aged children. Finally, prosocial behavior was not significantly

associated with social aggression for any age group. Post-hoc comparisons using

Bonferonni adjustments on the relation of social aggression and popularity indicated a

statistically higher relation for high-school than for middle-school-aged children (z =

3.61, p < .01).

All of the effect sizes related to negative peer relations were able to be analyzed

for age differences. Peer-dislike was significantly associated with social aggression for

elementary- and high-school-aged children. Both peer-rejection and peer-victimization

were significantly related with social aggression for all age groups. Finally, social

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conflict was significantly correlated with social aggression for elementary and middle-

school groups, but not for high-school-aged children.

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CHAPTER 5

DISCUSSION

This meta-analysis was inspired by the hypothesis that social aggression can be

associated with both positive and negative psychosocial correlates. To explore this

premise, correlates were separated into positive and negative groups and their association

with social aggression was analyzed. In addition, age and gender were considered as

moderators to this relationship. Below, the findings of this meta-analysis are reported;

theoretical and practical implications are discussed; shortcomings are identified; and

directions for future research are suggested.

As described in the literature review of this paper, there is evidence that social

aggression is associated with both positive and negative correlates. In order to examine

this discrepancy, correlates of each category were grouped into positive (i.e., positive

individual traits, positive peer relations) and negative characteristics (i.e., externalization,

internalization, negative individual traits, and negative peer relations). In general, results

suggest that social aggression is more greatly associated with negative correlates.

However, evidence of significant relationships for some positive socially-oriented

variables with social aggression was also identified.

Research linking social aggression to indices of maladjustment has made an

impressive contribution to the scientific literature. Experiences of social aggression in

children and adolescents have been implicated in concurrent social and emotional

difficulties for both boys and girls by previous studies (e.g., Crick et al., 2002a; Crick &

Bigbee, 1998; Prinstein et al., 2001). Similar findings were noted in the current meta-

analysis. Within the category of individual characteristics, positive significant

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relationships with social aggression were found for externalization, internalization, and

negative individual traits. Although significant, the association between positive

individual traits and social aggression was trivial in magnitude. Further, analyses

indicated that positive individual traits had a statistically lower relationship with social

aggression than externalization, internalization, and negative individual traits. That is, for

the correlates grouped into individual characteristics, those that were deemed negative

were more greatly associated with social aggression than those that were considered

positive.

In terms of maladjustment, findings indicate significant relationships between

social aggression and both externalizing and internalizing difficulties. Current results

reveal positive and significant associations with social aggression for several aspects of

externalization, including: deception, defiance, delinquency, externalizing behaviors,

hyperactivity, impulsivity, inattention, conduct problems, and substance use. These

unsurprising results are akin to previous research findings. For example, social

aggression has bee