Standing up to bullying: A social ecological review of peer defending in offline and online contexts

Abstract Bullying is a relationship problem that most often occurs in the presence of peers. Peers who witness bullying play a critical role in intervening. Peer intervention, or defending, is a complex behavior. Defending a victimized peer can occur offline and online, with many similarities between the two contexts. This paper, guided by the Social Ecological Model, systematically reviewed the correlates associated with defending at different levels including: individual, peer, family, and school. Inclusion criteria retrieved a final sample of 130 original, peer-reviewed research articles on offline defending, and 25 articles for online defending. Consistent results across both contexts reveal that individuals who defend tend to be girls, have high empathy and low moral disengagement, are popular and well-liked by their peers, and perceive supportive relationships with their parents, teachers, and schools. More research is needed to understand interactions that may occur between levels of the model, as defending is a complex behavior that cannot be characterized by isolated correlates.

[1]  Jodie A. Baird,et al.  Tell the Teacher or Tell the Bully Off: Children's Strategy Production for Bystanders to Bullying. , 2012 .

[2]  C. Salmivalli,et al.  Reducing Bullying and Victimization: Student- and Classroom-Level Mechanisms of Change , 2015, Journal of abnormal child psychology.

[3]  Christina Salmivalli,et al.  Unique and Interactive Effects of Empathy and Social Status on Involvement in Bullying , 2009 .

[4]  D. Pepler,et al.  Does defending come with a cost? Examining the psychosocial correlates of defending behaviour among bystanders of bullying in a Canadian sample. , 2017, Child abuse & neglect.

[5]  Amanda B. Nickerson,et al.  Bullying participant roles and gender as predictors of bystander intervention , 2017, Aggressive behavior.

[6]  Lisa J. Patterson,et al.  Adolescent Bystander Behavior in the School and Online Environments and the Implications for Interventions Targeting Cyberbullying , 2017 .

[7]  Isabel Correia,et al.  School Bullying : Belief in a Personal Just World of Bullies, Victims, and Defenders , 2008 .

[8]  M. Overpeck,et al.  A cross-national profile of bullying and victimization among adolescents in 40 countries , 2009, International Journal of Public Health.

[9]  René Veenstra,et al.  Bullying in classrooms: participant roles from a social network perspective. , 2012, Aggressive behavior.

[10]  A. Cillessen,et al.  Participant roles of bullying in adolescence: Status characteristics, social behavior, and assignment criteria. , 2016, Aggressive behavior.

[11]  K. Rudolph,et al.  A review of sex differences in peer relationship processes: potential trade-offs for the emotional and behavioral development of girls and boys. , 2006, Psychological bulletin.

[12]  F. Goossens,et al.  New Participant Role Scales: comparison between various criteria for assigning roles and indications for their validity , 2006 .

[13]  S. Caravita,et al.  Main and moderated effects of moral cognition and status on bullying and defending. , 2012, Aggressive behavior.

[14]  J. Hubbard,et al.  Children's physiological and emotional reactions to witnessing bullying predict bystander intervention. , 2013, Child development.

[15]  Amanda B. Nickerson,et al.  Empathetic responsiveness, group norms, and prosocial affiliations in bullying roles. , 2014, School psychology quarterly : the official journal of the Division of School Psychology, American Psychological Association.

[16]  C. Salmivalli Bullying and the peer group: A review , 2010 .

[17]  Philip Smith,et al.  Psychological correlates of peer victimisation in preschool: Social cognitive skills, executive function and attachment profiles , 2005 .

[18]  Wen-chi Wu,et al.  Defending behaviors, bullying roles, and their associations with mental health in junior high school students: a population-based study , 2016, BMC Public Health.

[19]  Lenka Kollerová,et al.  Good and evil at school: Bullying and moral evaluation in early adolescence , 2014 .

[20]  Insoo Oh,et al.  Investigation of the bystander effect in school bullying: Comparison of experiential, psychological and situational factors , 2017 .

[21]  C. Dalbert,et al.  Belief in a just world and well-being of bullies, victims and defenders: a study with Portuguese and Indian students , 2009, Anxiety, stress, and coping.

[22]  Sara Erreygers,et al.  Helping behavior among adolescent bystanders of cyberbullying: The role of impulsivity , 2016 .

[23]  Marie-Louise Obermann Moral Disengagement Among Bystanders to School Bullying , 2011 .

[24]  Chien Chou,et al.  An analysis of multiple factors of cyberbullying among junior high school students in Taiwan , 2010, Comput. Hum. Behav..

[25]  G. Altoé,et al.  Determinants of adolescents' active defending and passive bystanding behavior in bullying. , 2008, Journal of adolescence.

[26]  P. Frick,et al.  The incremental utility of callous-unemotional traits and conduct problems in predicting aggression and bullying in a community sample of boys and girls. , 2013, Psychological assessment.

[27]  Shelley Hymel,et al.  Bystander Responses to School Bullying: A Cross-Sectional Investigation of Grade and Sex Differences , 2010 .

[28]  H. Vandebosch,et al.  Who bullies whom online: A social network analysis of cyberbullying in a school context , 2014 .

[29]  Rebecca P. Ang,et al.  Bystanders' Reactions to Bullying: A Cross‐cultural Analysis of Personal Correlates Among Italian and Singaporean Students , 2012 .

[30]  Noel A. Card,et al.  Defenders of Victims of Peer Aggression: Interdependence Theory and an Exploration of Individual, Interpersonal, and Contextual Effects on the Defender Participant Role , 2015 .

[31]  Christina Salmivalli,et al.  Stability and change of behavior in connection with bullying in schools: A two‐year follow‐up , 1998 .

[32]  Gianluca Gini,et al.  Friendship selection and influence in bullying and defending: effects of moral disengagement. , 2014, Developmental psychology.

[33]  Ying-Yao Cheng,et al.  Choosing to be a defender or an outsider in a school bullying incident: Determining factors and the defending process , 2016 .

[34]  Nicholas Brody,et al.  Bystander Intervention in Cyberbullying , 2016 .

[35]  E. Andreou,et al.  The relationship of academic and social cognition to behaviour in bullying situations among Greek primary school children , 2004 .

[36]  D. Pepler,et al.  Peer involvement in bullying: insights and challenges for intervention. , 1999, Journal of adolescence.

[37]  Sigal Eden,et al.  Bystanders’ Behavior in Cyberbullying Episodes , 2017, Journal of interpersonal violence.

[38]  F. Goossens,et al.  Differential Personality Correlates of Early Adolescents’ Bullying-Related Outsider and Defender Behavior , 2015 .

[39]  L. Lei,et al.  Childhood maltreatment and Chinese adolescents' bullying and defending: The mediating role of moral disengagement. , 2017, Child abuse & neglect.

[40]  F. Goossens,et al.  Factors Influencing Interventions on Behalf of Victims of Bullying , 2016 .

[41]  Anna Ševčíková,et al.  Bystanders’ Supportive and Passive Responses to Cyberaggression , 2018 .

[42]  P. Nail,et al.  Defensive Egotism and Bullying: Gender Differences Yield Qualified Support for the Compensation Model of Aggression , 2016 .

[43]  U. Bronfenbrenner Contexts of child rearing: Problems and prospects. , 1979 .

[44]  Moral motivation in defending classmates victimized by bullying , 2015 .

[45]  Donna Cross,et al.  Adolescent bystanders' perspectives of aggression in the online versus school environments. , 2016, Journal of adolescence.

[46]  C. Salmivalli,et al.  Connections between attitudes, group norms, and behaviour in bullying situations , 2004 .

[47]  C. Salmivalli,et al.  The Role of Teachers in Bullying: The Relation between Antibullying Attitudes, Efficacy, and Efforts to Reduce Bullying. , 2014 .

[48]  K. Bussey,et al.  Predictors of student defenders of peer aggression victims: Empathy and social cognitive factors , 2011 .

[49]  K. Varjas,et al.  School personnel social support and nonsupport for bystanders of bullying: Exploring student perspectives. , 2017, Journal of school psychology.

[50]  J. Mitchell Vaterlaus,et al.  College student cyberbullying on social networking sites: Conceptualization, prevalence, and perceived bystander responsibility , 2016, Comput. Hum. Behav..

[51]  M. Hauser,et al.  Bullies have enhanced moral competence to judge relative to victims, but lack moral compassion , 2011 .

[52]  Heidi Vandebosch,et al.  Personal characteristics and contextual factors that determine "helping," "joining in," and "doing nothing" when witnessing cyberbullying. , 2014, Aggressive behavior.

[53]  Ariel M. Aloe,et al.  The Relation of Empathy and Defending in Bullying: A Meta-Analytic Investigation , 2015 .

[54]  Robert Thornberg,et al.  Bullying and defending behavior: The role of explicit and implicit moral cognition. , 2016, Journal of school psychology.

[55]  M. Camodeca,et al.  Aggression, social cognitions, anger and sadness in bullies and victims. , 2005, Journal of child psychology and psychiatry, and allied disciplines.

[56]  Robert W. Faris,et al.  Toxic Ties , 2016 .

[57]  Robert Thornberg,et al.  Bystander behavior in bullying situations: basic moral sensitivity, moral disengagement and defender self-efficacy. , 2013, Journal of adolescence.

[58]  Friendship Networks and Bullying in Schools , 1996 .

[59]  A. Hofman,et al.  Detecting bullying in early elementary school with a computerized peer-nomination instrument. , 2014, Psychological assessment.

[60]  Elisa Poskiparta,et al.  Bystanders Matter: Associations Between Reinforcing, Defending, and the Frequency of Bullying Behavior in Classrooms , 2011, Journal of clinical child and adolescent psychology : the official journal for the Society of Clinical Child and Adolescent Psychology, American Psychological Association, Division 53.

[61]  C. Salmivalli,et al.  Early Adolescents’ Participation in Bullying: Is ToM Involved? , 2010 .

[62]  Gianluca Gini,et al.  Why Do Bystanders of Bullying Help or Not? A Multidimensional Model , 2013 .

[63]  C. Salmivalli Intelligent, Attractive, Well-Behaving, Unhappy: The Structure of Adolescents' Self-Concept and Its Relations to Their Social Behavior. , 1998 .

[64]  Lenka Dedkova,et al.  Brief report: The bystander effect in cyberbullying incidents. , 2015, Journal of adolescence.

[65]  W. Bukowski,et al.  A Longitudinal Study of the Associations Between Moral Disengagement and Active Defending Versus Passive Bystanding During Bullying Situations , 2015 .

[66]  A. Cillessen,et al.  Predicting Adolescents' Bullying Participation from Developmental Trajectories of Social Status and Behavior. , 2018, Child development.

[67]  Donna Cross,et al.  Adolescent perceptions of bystanders’ responses to cyberbullying , 2017, New Media Soc..

[68]  H. Machácková,et al.  Bystanders' responses to offline bullying and cyberbullying: The role of empathy and normative beliefs about aggression. , 2016, Scandinavian journal of psychology.

[69]  Amanda B. Nickerson,et al.  Attachment and empathy as predictors of roles as defenders or outsiders in bullying interactions. , 2008, Journal of school psychology.

[70]  P. Frick,et al.  Gender differences in the assessment, stability, and correlates to bullying roles in middle school children. , 2011, Behavioral sciences & the law.

[71]  A. Vieno,et al.  The role of individual correlates and class norms in defending and passive bystanding behavior in bullying: a multilevel analysis. , 2012, Child development.

[72]  Noel A. Card,et al.  Effects of Defending: The Longitudinal Relations Among Peer‐perceived Defending of Victimized Peers, Victimization, and Liking , 2015 .

[73]  C. Salmivalli,et al.  Bullying as a group process: Participant roles and their relations to social status within the group , 1998 .

[74]  A. Cillessen,et al.  Adolescents' explicit and implicit evaluations of hypothetical and actual peers with different bullying participant roles. , 2017, Journal of experimental child psychology.

[75]  C. Salmivalli,et al.  Victims and their defenders: A dyadic approach , 2011 .

[76]  F. Goossens,et al.  Associations between Dutch and Indian adolescents’ bullying role behavior and peer-group status , 2017 .

[77]  A. Costabile,et al.  A Cross-National Comparison of Aggressors, Victims and Defenders in Preschools in England, Spain and Italy , 2011, The Spanish journal of psychology.

[78]  Marilyn A. Campbell,et al.  On standby? A comparison of online and offline witnesses to bullying and their bystander behaviour , 2015 .

[79]  Gianluca Gini,et al.  Active Defending and Passive Bystanding Behavior in Bullying: The Role of Personal Characteristics and Perceived Peer Pressure , 2010, Journal of abnormal child psychology.

[80]  C. Salmivalli,et al.  Classroom norms of bullying alter the degree to which children defend in response to their affective empathy and power. , 2015, Developmental psychology.

[81]  D. Espelage,et al.  Teacher and staff perceptions of school environment as predictors of student aggression, victimization, and willingness to intervene in bullying situations. , 2014, School psychology quarterly : the official journal of the Division of School Psychology, American Psychological Association.

[82]  D. Laible,et al.  The Influences of Parent and Peer Attachment on Bullying , 2017, Journal of Child and Family Studies.

[83]  Wan-Ying Lin,et al.  How do victims react to cyberbullying on social networking sites? The influence of previous cyberbullying victimization experiences , 2015, Comput. Hum. Behav..

[84]  Elisa Poskiparta,et al.  Vulnerable Children in Varying Classroom Contexts: Bystanders' Behaviors Moderate the Effects of Risk Factors on Victimization , 2010 .

[85]  T. Snijders,et al.  Victims, bullies, and their defenders: A longitudinal study of the coevolution of positive and negative networks , 2014, Development and Psychopathology.

[86]  L. Hides,et al.  Associations between the group processes of bullying and adolescent substance use. , 2016, Addictive behaviors.

[87]  K. Varjas,et al.  Students’ views of factors affecting their bystander behaviors in response to school bullying: a cross-collaborative conceptual qualitative analysis , 2018 .

[88]  C. Salmivalli,et al.  What Does It Take to Stand Up for the Victim of Bullying?: The Interplay Between Personal and Social Factors , 2010 .

[89]  V. Poteat,et al.  Who intervenes against homophobic behavior? Attributes that distinguish active bystanders. , 2016, Journal of school psychology.

[90]  Joel M. Hektner,et al.  Links from Teacher Beliefs to Peer Victimization and Bystander Intervention , 2012 .

[91]  Isabel Correia,et al.  Moral Disengagement, Normative Beliefs of Peer Group, and Attitudes Regarding Roles in Bullying , 2009 .

[92]  Brad J. Bushman,et al.  Unresponsive or un-noticed?: Cyberbystander intervention in an experimental cyberbullying context , 2015, Comput. Hum. Behav..

[93]  Amanda B. Nickerson,et al.  Perceptions of School Climate as a Function of Bullying Involvement , 2014 .

[94]  M. K. Demaray,et al.  Bullying Participant Behaviors Questionnaire (BPBQ): Establishing a Reliable and Valid Measure , 2016 .

[95]  I. Rivers,et al.  The use of homophobic language across bullying roles during adolescence , 2010 .

[96]  T. Pigott,et al.  A Meta-Analysis of School-Based Bullying Prevention Programs' Effects on Bystander Intervention Behavior , 2012 .

[97]  C. Steglich,et al.  The support group approach in the Dutch KiVa anti-bullying programme: effects on victimisation, defending and well-being at school , 2016 .

[98]  M. Bartini,et al.  Social context of bullying: Do misperceptions of group norms influence children's responses to witnessed episodes? , 2013 .

[99]  A. Kohm Childhood bullying and social dilemmas. , 2015, Aggressive behavior.

[100]  M. Camodeca,et al.  Empathy in adolescence: Relations with emotion awareness and social roles. , 2016, The British journal of developmental psychology.

[101]  F. Goossens,et al.  Children's intervention strategies in situations of victimization by bullying: social cognitions of outsiders versus defenders. , 2013, Journal of school psychology.

[102]  D. Pepler,et al.  Individual Motivations and Characteristics Associated With Bystander Intervention During Bullying Episodes Among Children and Youth , 2012 .

[103]  Gianluca Gini,et al.  Friend similarity in attitudes toward bullying and sense of responsibility to intervene , 2013 .

[104]  S. Jimerson,et al.  An Examination of Differences in Moral Disengagement and Empathy Among Bullying Participant Groups , 2017, Journal of Relationships Research.

[105]  M. Zimmer‐Gembeck,et al.  Popularity: Does it magnify associations between popularity prioritization and the bullying and defending behavior of early adolescent boys and girls? , 2017 .

[106]  Su-mi Choi,et al.  Influence of psychological and social factors on bystanders’ roles in school bullying among Korean-American students in the United States , 2013 .

[107]  Izabela Zych,et al.  Empathy and Callous–Unemotional Traits in Different Bullying Roles: A Systematic Review and Meta-Analysis , 2019, Trauma, violence & abuse.

[108]  D. Espelage,et al.  Early adolescents' willingness to intervene: what roles do attributions, affect, coping, and self-reported victimization play? , 2014, Journal of school psychology.

[109]  C. Belacchi,et al.  Prosocial/hostile roles and emotion comprehension in preschoolers. , 2010, Aggressive behavior.

[110]  D. Espelage,et al.  Willingness to Intervene in Bullying Episodes Among Middle School Students , 2012 .

[111]  Paula Costa Ferreira,et al.  Student bystander behavior and cultural issues in cyberbullying: When actions speak louder than words , 2016, Comput. Hum. Behav..

[112]  H. Machácková,et al.  Bystanders' Support of Cyberbullied Schoolmates , 2013 .

[113]  Karolien Poels,et al.  Mobilizing Bystanders of Cyberbullying: an Exploratory Study into Behavioural Determinants of Defending the Victim , 2012, Annual Review of Cybertherapy and Telemedicine.

[114]  Heather A. Turner,et al.  Victim Reports of Bystander Reactions to In-Person and Online Peer Harassment: A National Survey of Adolescents , 2015, Journal of youth and adolescence.

[115]  Maria Hughes,et al.  A two-method investigation of early adolescents' responses upon witnessing peer victimization in school. , 2012, Journal of adolescence.

[116]  Bruce Johnson,et al.  A Qualitative Exploration of Cyber-Bystanders and Moral Engagement , 2014 .

[117]  C. Salmivalli,et al.  Peer networks and bullying in schools , 1997 .

[118]  J. Hubbard,et al.  Relations Between Actual Group Norms, Perceived Peer Behavior, and Bystander Children's Intervention to Bullying , 2017, Journal of clinical child and adolescent psychology : the official journal for the Society of Clinical Child and Adolescent Psychology, American Psychological Association, Division 53.

[119]  Christina Salmivalli,et al.  Standing Up for the Victim, Siding with the Bully or Standing by? Bystander Responses in Bullying Situations , 2012 .

[120]  H. Tiemeier,et al.  Behind bullying and defending: same-sex and other-sex relations and their associations with acceptance and rejection. , 2013, Aggressive behavior.

[121]  Karolien Poels,et al.  Deciding whether to look after them, to like it, or leave it: A multidimensional analysis of predictors of positive and negative bystander behavior in cyberbullying among adolescents , 2016, Comput. Hum. Behav..

[122]  Karolien Poels,et al.  Determinants of Self-Reported Bystander Behavior in Cyberbullying Incidents Amongst Adolescents , 2014, Cyberpsychology Behav. Soc. Netw..

[123]  Robert Thornberg,et al.  School bullying and the mechanisms of moral disengagement. , 2014, Aggressive behavior.

[124]  Tomas Jungert,et al.  Early adolescents' motivations to defend victims in school bullying and their perceptions of student-teacher relationships: A self-determination theory approach. , 2016, Journal of adolescence.

[125]  C. Salmivalli,et al.  Student-, classroom-, and school-level risk factors for victimization. , 2013, Journal of school psychology.

[126]  Jaclyn E. Tennant,et al.  Social, Emotional, and Cognitive Factors Associated With Bullying , 2017 .

[127]  M. Camodeca,et al.  Children's opinions on effective strategies to cope with bullying: the importance of bullying role and perspective , 2005 .

[128]  M. Camodeca,et al.  Bullying in preschool: The associations between participant roles, social competence, and social preference. , 2015, Aggressive behavior.

[129]  Peter Y. Chen,et al.  Roles of fatalism and parental support in the relationship between bullying victimization and bystander behaviors , 2015 .

[130]  Amanda B. Nickerson,et al.  Bystander Intervention in Bullying: Role of Social Skills and Gender , 2019 .

[131]  Elizabeth R. Peterson,et al.  Bystander Intervention, Bullying, and Victimization: A Multilevel Analysis of New Zealand High Schools , 2015 .

[132]  Karolien Poels,et al.  ‘Can I afford to help?’ How affordances of communication modalities guide bystanders' helping intentions towards harassment on social network sites , 2015, Behav. Inf. Technol..

[133]  Michael von Grundherr,et al.  School Bullying and Moral Reasoning Competence , 2017 .

[134]  Robert Thornberg,et al.  Unique and Interactive Effects of Moral Emotions and Moral Disengagement on Bullying and Defending among School Children , 2015, The Elementary School Journal.

[135]  Kay Bussey,et al.  The effect of victims' responses to overt bullying on same-sex peer bystander reactions. , 2015, Journal of school psychology.

[136]  P. Nail,et al.  Defensive egotism and self-esteem: A cross-cultural examination of the dynamics of bullying in middle school , 2017 .

[137]  M. Camodeca,et al.  Bullying, empathic concern, and internalization of rules among preschool children , 2016 .

[138]  Thomas N. Friemel,et al.  Selection and influence effects in defending a victim of bullying: The moderating effects of school context , 2013 .

[139]  Sarah N. Woods,et al.  “FearNot!”: a computer-based anti-bullying-programme designed to foster peer intervention , 2011 .

[140]  F. Goossens,et al.  Bullying-related behaviour in a mainstream high school versus a high school for autism: Self-report and peer-report , 2016, Autism : the international journal of research and practice.

[141]  B. Schneider,et al.  Bullying and the Big Five , 2003 .

[142]  Robert Thornberg,et al.  Getting angry matters: Going beyond perspective taking and empathic concern to understand bystanders' behavior in bullying. , 2017, Journal of adolescence.

[143]  C. Salmivalli,et al.  Defending victims: What does it take to intervene in bullying and how is it rewarded by peers? , 2017, Journal of school psychology.

[144]  D. Faulkner,et al.  The Relationship between Bullying Roles and Children's Everyday Dyadic Interactions , 2011 .

[145]  E. Casey,et al.  The Situational-Cognitive Model of Adolescent Bystander Behavior: Modeling Bystander Decision-Making in the Context of Bullying and Teen Dating Violence , 2017, Psychology of violence.

[146]  Kimberley R. Allison,et al.  Individual and collective moral influences on intervention in cyberbullying , 2017, Comput. Hum. Behav..

[147]  Ken Rigby,et al.  Expressed Readiness of Australian Schoolchildren to Act as Bystanders in Support of Children who are Being Bullied , 2006 .

[148]  S. Coyne,et al.  Pow! Boom! Kablam! Effects of Viewing Superhero Programs on Aggressive, Prosocial, and Defending Behaviors in Preschool Children , 2017, Journal of abnormal child psychology.

[149]  E. Ahmed ‘Stop it, that's enough’: Bystander intervention and its relationship to school connectedness and shame management , 2008 .

[150]  J. Pryor,et al.  Peer Bystanders to Bullying: Who Wants to Play with the Victim? , 2014, Journal of abnormal child psychology.

[151]  D. Pepler,et al.  Naturalistic Observations of Peer Interventions in Bullying , 2001 .

[152]  Magdalena Obermaier,et al.  Bystanding or standing by? How the number of bystanders affects the intention to intervene in cyberbullying , 2016, New Media Soc..

[153]  Karolien Poels,et al.  Cyberbullying on social network sites. An experimental study into bystanders' behavioural intentions to help the victim or reinforce the bully , 2014, Comput. Hum. Behav..

[154]  A. Williamson,et al.  Adaptation of the Participant Role Scale (PRS) in a Spanish Youth Sample , 2014, Journal of interpersonal violence.

[155]  M. Vermande,et al.  Defending victimized peers: Opposing the bully, supporting the victim, or both? , 2016, Aggressive behavior.

[156]  Aaron Smith,et al.  Teens, Kindness and Cruelty on Social Network Sites , 2011 .

[157]  C. Salmivalli,et al.  Self-Evaluated Self-Esteem, Peer-Evaluated Self-Esteem, and Defensive Egotism as Predictors of Adolescents’ Participation in Bullying Situations , 1999 .

[158]  Lyndsay N. Jenkins,et al.  Social Capital and Bystander Behavior in Bullying: Internalizing Problems as a Barrier to Prosocial Intervention , 2017, Journal of youth and adolescence.

[159]  G. Gini Social cognition and moral cognition in bullying: What's wrong? , 2006 .

[160]  Peter K. Smith,et al.  Bullying as a group process: An adaptation of the participant role approach , 1999 .

[161]  B. Latané,et al.  Bystander intervention in emergencies: diffusion of responsibility. , 1968, Journal of personality and social psychology.

[162]  K. Bussey,et al.  The Role of Individual and Collective Moral Disengagement in Peer Aggression and Bystanding: A Multilevel Analysis , 2015, Journal of abnormal child psychology.

[163]  Gianmarco Altoè,et al.  Does empathy predict adolescents' bullying and defending behavior? , 2007, Aggressive behavior.

[164]  C. Salmivalli,et al.  Interactive effects of guilt and moral disengagement on bullying, defending and outsider behavior , 2016 .

[165]  D. Espelage,et al.  Classroom relationship qualities and social-cognitive correlates of defending and passive bystanding in school bullying in Sweden: A multilevel analysis. , 2017, Journal of school psychology.

[166]  Regan A. R. Gurung,et al.  A Facebook analysis of helping behavior in online bullying. , 2013 .