Programs to prevent peer sexual violence that encourage positive bystander intervention are proliferating. Yet, little is known about how these prosocial behaviors unfold over time across middle to later adolescence. The current study examined helpful bystander actions over three years among students in grades 7–10 (mean age 13.7, range 12–18) at baseline (N = 2539, 53.2% girls). Surveys assessed bystander behavior, social norms, and use of alcohol. Multilevel logistic regression examined patterns of change over time, as well as how changes in attitudes and binge drinking predicted changes in taking bystander action to prevent peer violence. Positive bystander behaviors overall decreased over time, consistent with previous work on bullying. Higher positive social norms and lower denial of sexual violence as a problem were associated with more positive helping behaviors across different waves of data. These findings suggest that the effectiveness of bystander intervention training for peer sexual violence prevention may be enhanced by developing strategies to work against the observed developmental decline in helping, perhaps by social marketing campaigns that can bolster positive social norms.

鼓励积极的旁观者干预的预防同伴性暴力的计划正在激增。然而，关于这些亲社会行为如何随着时间的推移在青春期中后期展开，我们知之甚少。目前的研究在基线（N = 2539，53.2% 的女孩）。调查评估了旁观者的行为、社会规范和酒精的使用。多级逻辑回归检查了随时间变化的模式，以及态度和酗酒的变化如何预测采取旁观者行动以防止同伴暴力的变化。积极的旁观者行为总体上随着时间的推移而减少，这与之前关于欺凌的研究一致。较高的积极社会规范和较低的对性暴力问题的否认与不同数据波中更积极的帮助行为有关。这些研究结果表明，通过制定策略来对抗观察到的帮助方面的发展下降，也许可以通过可以加强积极社会规范的社会营销活动来提高旁观者干预培训对同伴性暴力预防的有效性。