The research team set out to test a specific theoretical proposition. Schools, they argue, provide daily interaction opportunities in which aggressive behavior is gradually discouraged through peer feedback, adult supervision, and the social consequences of visible conflict. Remove that environment, and aggression might either decay from lack of practice or intensify as frustration builds. The closure of schools for an entire academic trimester offered a natural experiment: what happens to aggression when the primary arena for peer conflict disappears?

To answer that question, the researchers used a short-longitudinal design, measuring aggression at two time points separated by the closure. Participants, of whom 49.1 percent were female, completed self-report instruments assessing both the forms and the functions of aggression, as well as a measure of the forms of aggression alone. This distinction matters in aggression research. Forms describe how aggression is expressed, whether physically, verbally, relationally, or through damage to reputation, while functions describe why it is deployed, for example proactively to gain an advantage or reactively in response to provocation. Separating the two allows researchers to see not just whether aggression changed, but whether its underlying character shifted.

The statistical approach was correspondingly careful. The team fitted mixed-effects regression models using established R packages, including lme4 and glmmTMB, and subjected the results to residual diagnostics with the DHARMa framework. Because the study involved multiple comparisons across aggression subtypes and sexes, the authors controlled the false discovery rate using the Benjamini-Hochberg procedure, a standard safeguard against spurious findings. Effect sizes were evaluated through variance components appropriate to generalized linear mixed models. This methodological rigor is worth noting because studies of pandemic-era behavior often relied on cross-sectional snapshots; here, the same adolescents were compared with themselves across time, which strengthens causal interpretation, even if no study of this kind can fully isolate the closure as the sole cause of change.

The headline result is one of stability. For most measured forms and functions of aggression, scores before the closure did not differ significantly from scores after it. In other words, adolescents did not become more aggressive overall when schools closed, nor did they become noticeably less aggressive. That null result is itself informative. It suggests that the developmental trajectory of aggressive behavior in this age group is robust enough to withstand a major disruption to the social environment, at least over the timescale of a single trimester.

But the stability was not uniform. The one clear exception was reputational aggression, a form of aggression aimed at damaging another person’s social standing through gossip, rumor-spreading, and public humiliation. Reputational aggression increased over the closure period, but only among girls. Boys’ reputational aggression remained steady. This sex-specific finding is one of the most intriguing elements of the study, because reputational aggression depends heavily on social networks and communication channels rather than physical proximity. The researchers’ interpretation is that digital technology may have substituted for in-person contact, giving adolescents, and particularly girls, new avenues for the kind of status-focused conflict that reputational aggression represents.

The broader sex differences in the data align with a long tradition of aggression research. Boys reported being overall more aggressive than girls across most measures, a pattern documented repeatedly in developmental studies across many countries. The exceptions were relational aggression, which involves excluding or manipulating social relationships, and reputational aggression, where the boys’ advantage disappeared. These two forms of aggression are often described as more covert or indirect, and previous work has suggested they are deployed at comparable rates by both sexes, sometimes with girls showing equal or greater use. The new findings fit that picture and extend it by showing that the sex gap in these covert forms persisted through a period of radically altered social conditions.

What does the stability of aggression actually mean? The authors propose a balance hypothesis. On one side of the ledger, the loss of in-person contact removed many opportunities for physical and verbal confrontation in corridors, classrooms, and playgrounds, which should have pushed aggression down. On the other side, adolescents compensated by moving their social lives online, where aggression can take digital forms: hostile messages, exclusion from group chats, and the public circulation of damaging content. If the decrease in face-to-face aggression was roughly offset by an increase in technology-mediated aggression, the total would appear stable even though its composition changed. The rise in girls’ reputational aggression is consistent with this account, since reputation management and social comparison are especially salient in online environments popular with adolescent girls.

The study sits within a larger body of pandemic-era research on adolescent development. Systematic reviews have documented widespread effects of social isolation and loneliness on youth mental health, and neurodevelopmental work emphasizes that adolescence is a sensitive period for social learning, when peer interaction shapes everything from emotion regulation to identity. Depriving adolescents of peer contact for months was never going to be developmentally neutral. Yet the effects on specific behaviors have proved harder to predict. Some studies reported increases in stress-related aggression during lockdowns, while others found that removing adolescents from high-conflict school environments temporarily reduced bullying. The new findings suggest that aggression is not simply suppressed or unleashed by school attendance; it adapts to whatever social ecology is available.

For educators and clinicians, the practical implications are sobering. If aggression migrates rather than disappears when schools close, then anti-bullying and violence-prevention programs, which are typically delivered in classrooms and rely on bystander training and teacher supervision, may need digital counterparts that operate where adolescents actually socialize. The finding that girls’ reputational aggression rose during the closure points to a specific target for such interventions: online rumor, gossip, and status attacks that adults may not witness. The authors also caution that their sample was modest in size and drawn from a single cultural context, and that self-report measures depend on adolescents’ willingness to disclose aggressive behavior. Data from the study are available from the corresponding author upon reasonable request, and the work was funded by the Portuguese social inclusion organization EPIS with additional support from the Portuguese Foundation for Science and Technology. As schools worldwide periodically close for public health reasons, the lesson of this study is that adolescent aggression is not a fixture of the schoolyard alone. It is a flexible behavior that follows its opportunities, and understanding it requires watching not just where adolescents are, but where they go when their usual world closes.

Subject of Research: Changes in the forms and functions of adolescent aggressive behavior before and after school closure

Article Title: Aggressive behavior in adolescence: comparisons from before to after school closure

Article References: Vagos, P., Carvalhais, L., Pinto, D., & Cabral, J. (2026). Aggressive behavior in adolescence: comparisons from before to after school closure. Current Psychology, 45(20), Article 1598. https://doi.org/10.1007/s12144-026-10154-0

Image Credits: AI Generated

DOI: 10.1007/s12144-026-10154-0

Keywords: aggression, adolescence, school closure, reputational aggression, relational aggression, sex differences, cyberbullying, digital technology, longitudinal study, peer conflict, COVID-19, developmental psychology