Bullying is an extremely damaging type of violence that is present in schools all over the world, but there are still many gaps in knowledge regarding different variables that might influence the phenomenon. Two promising research lines focus on empathy and callous–unemotional traits but findings from individual studies seem to be contradictory. This article reports the results of a systematic review and a meta-analysis on empathy and callous–unemotional traits in relation to school bullying based on 53 empirical reports that met the inclusion criteria. Bullying perpetration is negatively associated with cognitive (odds ratio [ OR] = 0.60) and affective ( OR = 0.51) empathy. Perpetration is also positively associated with callous–unemotional traits ( OR = 2.55). Bully-victims scored low in empathy ( OR = 0.57). There is a nonsignificant association between victimization and empathy ( OR = 0.96), while the relationship between callous–unemotional traits and victimization is significant but small ( OR = 1.66). Defenders scored high on cognitive ( OR = 2.09) and affective ( OR = 2.62) empathy. These findings should be taken into account in explaining and preventing bullying.

Research on cyberbullying started at the beginning of the 21st century and the number of studies on the topic is increasing very rapidly. Nevertheless, the criteria used to define the phenomenon and evaluation strategies are still under debate. Therefore, it is still difficult to compare the findings among the studies or to describe their prevalence in different geographic areas or time points. Thus, the current systematic review has been conducted with the objective of describing the studies on the phenomenon in Spain taking into account its different definitions and evaluation strategies in relation to its prevalence. After conducting systematic searches and applying the inclusion criteria, 29 articles reporting the results of 21 different studies were included. It was found that the number of studies on the topic in Spain is growing and that most of the definitions include the criteria of repetition, intention, and power imbalance. It was also found that timeframes and cut-off points varied greatly among the studies. All the studies used self-reports with one-item or multi-item instruments. The prevalence also varied depending on the evaluation strategies and when assessed with multi-item instruments it was about twice as high as when assessed with one-item instruments. It is suggested that specific instruments should be chosen depending on the research questions posed in each investigation and that it could be useful to unify the criteria for further advancement of the field