The Campbell Collaboration online library
Full text keyword search[?]
"search" : Search for an exact word or phrase
-search : Exclude a word. Add a dash (-) before a word to exclude all results that include that word.
OR : Search for either word. If you want to search for pages that may have just one of several words, include OR (capitalised) between the words. For example, "labor" OR "labour" will show results containing pages with "labor" and "labour". Without the OR, your results will show only pages that match all terms.
intitle: Search for a word or phrase. Unlike the Title search field below the Keyword search field, you can combine terms. For example: intitle:female OR intitle:women will show results containing pages with "female" and "women" in the title.
intext: Search only in the description text field of the page. This field usually contains the abstract or summary of the publication.
Campbell systematic reviews
Browse by Coordinating Group
- Crime and Justice
- International Development
- Knowledge Translation and Implementation
- Social Welfare
See all reviews
Planned publications (titles and protocols)
Browse by Coordinating Group
- Business and Management
- Crime and Justice
- International Development
- Knowledge Translation and Implementation
- Social Welfare
See all planned publications
Effects of bystander programs on the prevention of sexual assault among adolescents and college students
- Authors: Heather Hensman Kettrey, Robert A. Marx, Emily E. Tanner-Smith
- Published date: 2019-01-04
- Coordinating group(s): Crime and Justice
- Type of document: Title, Protocol, Review, Plain language summary
- Volume: 15
- PLS Title: Bystander programs increase bystander intervention but no effect on perpetrating sexual assault
- PLS Logo:
- PLS Description: Sexual assault is a significant problem among adolescents and college students across the world. One promising strategy for preventing these assaults is the implementation of bystander sexual assault prevention programs, which encourage young people to intervene when witnessing incidents or warning signs of sexual assault. This review examines the effects bystander programs have on knowledge and attitudes concerning sexual assault and bystander behavior, bystander intervention when witnessing sexual assault or its warning signs, and participants’ rates of perpetration of sexual assault.
- Title: Effects of bystander programs on the prevention of sexual assault among adolescents and college students
About this systematic review
Sexual assault is a significant problem among adolescents and college students across the world. One promising strategy for preventing these assaults is the implementation of bystander sexual assault prevention programs, which encourage young people to intervene when witnessing incidents or warning signs of sexual assault. This review examines the effects bystander programs have on knowledge and attitudes concerning sexual assault and bystander behavior, bystander intervention when witnessing sexual assault or its warning signs, and participants’ rates of perpetration of sexual assault.
What are the main results?
Bystander programs have an effect on knowledge and attitudes for some outcomes. The most pronounced beneficial effects are on rape myth acceptance and bystander efficacy outcomes. There are also delayed effects (i.e., one to four months after the intervention) on taking responsibility for intervening/acting, knowing strategies for intervening, and intentions to intervene outcomes. There is little or no evidence of effects on gender attitudes, victim empathy, date rape attitudes, and on noticing sexual assault outcomes. Bystander programs have a beneficial effect on bystander intervention. There is no evidence that bystander programs have an effect on participants’ rates of sexual assault perpetration.
Sexual assault among adolescents and college students
Sexual assault is a significant problem among adolescents and college students in the United States and globally. Findings from the Campus Sexual Assault study estimated that 15.9% of college women had experienced attempted or completed sexual assault (i.e., unwanted sexual contact that could include sexual touching, oral sex, intercourse, anal sex, or penetration with a finger or object) prior to entering college and 19% had experienced attempted or completed sexual assault since entering college (Krebs, Lindquist, Warner, Fisher, & Martin, 2009). Similar rates have been reported in Australia (Australian Human Rights Commission, 2017), Chile (Lehrer, Lehrer, & Koss, 2013), China (Su, Hao, Huang, Xiao, & Tao, 2011), Finland (Bjorklund, Hakkanen-Nyholm, Huttunen, & Kunttu, 2010), Poland (Tomaszewska & Krahe, 2015), Rwanda (Van Decraen, Michielsen, Herbots, Rossem, & Temmerman, 2012), Spain (Vazquez, Torres, Otero, 2012) and in a global survey of countries in Africa, Asia, and the Americas (Pengpid & Peltzer, 2016).
The bystander approach
One promising strategy for preventing sexual assault among adolescents and young adults is the implementation of bystander programs, which encourage young people to intervene when witnessing incidents or warning signs of sexual assault. Bystander programs seek to sensitize young people to warning signs of sexual assault, create attitudinal changes that foster bystander responsibility for intervening (e.g., creating empathy for victims), and build requisite skills and knowledge of tactics for taking action (Banyard, 2011; Banyard, Plante, & Moynihan, 2004; Burn, 2009; McMahon & Banyard, 2012). Many of these programs are implemented with large groups of adolescents or college students in the format of a single training/education session (e.g., as part of college orientation). However, some programs use broader implementation strategies, such as advertising campaigns that post signs across college campuses to encourage students to act when witnessing signs of violence.
By treating young people as potential allies in preventing sexual assault, bystander programs have the capacity to be less threatening than traditional sexual assault prevention programs, which tend to address young people as either potential perpetrators or victims of sexual violence (Burn, 2009; Messner, 2015; [Jackson] Katz, 1995). Instead of placing emphasis on how young people may modify their individual behavior to either respect the sexual boundaries of others or reduce their personal risk for being sexually assaulted, bystander programs aim to foster prerequisite knowledge and skills for intervening on behalf of potential victims. Thus, by treating young people as part of the solution to sexual assault, rather than part of the problem, bystander programs may limit the risk of defensiveness or backlash among participants (e.g., decreased empathy for victims, increased rape myth acceptance) (Banyard et al., 2004; Katz, 1995).
The overall objective of this systematic review and meta-analysis was to examine what effects bystander programs have on preventing sexual assault among adolescents and college students. More specifically, this review addressed three objectives.
- The first objective was to assess the overall effects (including adverse effects), and the variability of the effects, of bystander programs on adolescents’ and college students’ attitudes and behaviors regarding sexual assault.
- The second objective was to explore the comparative effectiveness of bystander programs for different profiles of participants (e.g., mean age of the sample, education level of the sample, proportion of males/females in the sample, proportion of fraternity/sorority members in the sample, proportion of athletic team members in the sample).
- The third objective was to explore the comparative effectiveness of different bystander programs in terms of gendered content and approach (e.g., conceptualizing sexual assault as a gendered or gender-neutral problem, mixed- or single-sex group implementation).
Candidate studies were identified through searches of electronic databases, relevant academic journals, and gray literature sources. Gray literature searches included contacting leading authors and experts on bystander programs to identify any current/ongoing research that might be eligible for the review, screening bibliographies of eligible studies and relevant reviews to identify additional candidate studies, and conducting forward citation searches (searches for reports citing eligible studies) using the website Google Scholar.
To be included in the review studies had to meet eligibility criteria in the following domains: Types of study, Types of participants, Types of interventions, Types of outcome measures, Duration of follow-up, and Types of settings.
Types of studies
To be eligible for inclusion in the review, studies must have used an experimental or controlled quasi-experimental research design to compare an intervention group (i.e., students assigned to a bystander program) with a comparison group (i.e., students not assigned to a bystander program).
Types of participants
The review focused on studies that examined outcomes of bystander programs that target sexual assault and were implemented with adolescents and/or college students in educational settings. Eligible participants included adolescents enrolled in grades 7 through 12 and college students enrolled in any type of undergraduate postsecondary educational institution. The mean age of samples could be no less than age 12 and no greater than age 25.
Types of interventions
Eligible intervention programs were those that approached participants as allies in preventing and/or alleviating sexual assault among adolescents and/or college students. Some part of the program had to focus on ways that cultivate willingness for a person to respond to others who are at risk for sexual assault. All delivery formats were eligible for inclusion (e.g., in-person training sessions, video programs, web-based training, advertising/poster campaigns). There were no intervention duration criteria for inclusion.
Eligible comparison groups must have received no intervention services targeting bystander attitudes/behavior or sexual assault.
Types of outcome measures
We included studies that measured the effects of bystander programs on at least one of the following primary outcome domains:
- General attitudes toward sexual assault and victims (e.g., victim empathy, rape myth acceptance).
- Prerequisite skills and knowledge for bystander intervention as defined by Burn (2009) (e.g., noticing sexual assault or its warning signs, identifying a situation as appropriate for intervention, taking responsibility for acting/intervening, knowing strategies for helping/intervening).
- Self-efficacy with regard to bystander intervention (e.g., respondents’ confidence in their ability to intervene).
- Intentions to intervene when witnessing instances or warning signs of sexual assault.
- Actual intervention behavior when witnessing instances or warning signs of sexual assault.
- Perpetration of sexual assault (i.e., participants’ rates of perpetration).
Duration of follow-up
Studies reporting follow-ups of any duration were eligible for inclusion. When studies reported outcomes at more than one follow-up wave, each wave was coded and identified by its reported duration. Follow-ups of similar durations were analyzed together.
Types of settings
The review focused on studies that examined outcomes of bystander programs that target sexual assault and were implemented with adolescents and/or college students in educational settings. Eligible educational settings included secondary schools (i.e., grades 7-12) and colleges or universities. There were no geographic limitations on inclusion criteria. Research conducted in any country was eligible.
Data collection and analysis
Selection of studies
Once candidate studies were identified, two reviewers independently screened each study title and abstract for eligibility; disagreements between reviewers were resolved by discussion and consensus. Potentially eligible studies were then retrieved in full text, and these full texts were reviewed for eligibility, again using two independent reviewers.
Data extraction and management
Two reviewers independently double-coded all included studies, using a piloted codebook. Coding disagreements were resolved via discussion and consensus. The primary categories for coding were as follows: participant demographics and characteristics (e.g., age, gender, education level, race/ethnicity, athletic team membership, fraternity/sorority membership); intervention setting (e.g., state, country, secondary or post-secondary institution, mixed- or single-sex group); study characteristics (e.g., attrition, duration of follow-up, study design, participant dose, sample N); outcome construct (e.g., type, description of measure); and outcome results (e.g., timing at measurement, baseline and follow-up means and standard deviations or proportions).
Measures of treatment effect
During the coding process, relevant summary statistics (e.g., means and standard deviations, proportions, observed sample sizes) were extracted from research reports to calculate effect sizes. Effect sizes were reported as standardized mean differences (SMD), adjusted for small sample size (Hedges’ g). Positive effect size values (i.e., greater than 0) indicate a beneficial outcome for the bystander intervention group.
Intervention effects for each outcome construct were synthesized via meta-analyses using random-effects inverse variance weights. All statistical analyses were conducted with the metafor package in R. Synthesis results are displayed using forest plots. Mean effect sizes are reported with their 95% confidence intervals.
Objective 1: Effects on Knowledge, Attitudes, and Behavior
Knowledge/Attitudes. Effects for knowledge and attitude outcomes varied widely across constructs. The most pronounced beneficial effect in this domain was on rape myth acceptance. The effect for this outcome was immediate and sustained across all reported follow-up waves (i.e., from immediate post-test to six- to seven-months post-intervention). Intervention effects on bystander efficacy were also fairly pronounced, with an effect observed at both immediate post-test and one- to four-months post-intervention. A significant effect was not observed for this outcome six months post-intervention; however, this should be interpreted with caution, as only one study reported bystander efficacy effects at this follow-up period.
Effects on other knowledge and attitude outcomes were either delayed or unobserved. Intervention effects on taking responsibility for intervening or acting, knowing strategies for intervening, and intentions to intervene were non-significant at immediate post-test, but significant and beneficial by one- to four-months post-intervention. We found limited or no evidence of significant intervention effects on gender attitudes, victim empathy, date rape attitudes, and noticing sexual assault.
Behavior. The results indicated that bystander programs have a beneficial effect on bystander intervention behavior. However, this effect, which was observed at one-to four-months post-intervention, was not statistically significant at six months post-intervention. Bystander programs did not have a significant effect on sexual assault perpetration.
Objective 2: Effects for Different Participant Profiles
We had planned to conduct moderator analyses to assess a wide range of participant characteristics as potential effect size moderators. However, our review only yielded a sufficient number of studies (n > 10) to conduct moderator analyses for the bystander intervention outcome domain. The results indicated that mean age, education level, and proportion of males/female were not statistically significant predictors of the magnitude of intervention effects.
Objective 3: Effects Based on Gendered Content/Implementation
We conducted moderator analyses to assess any differential effects of bystander programs on measured outcomes based on (1) the gender of perpetrators and victims in specific bystander programs and (2) whether programs were implemented in mixed- or single-sex settings. Our review only produced a sufficient number of studies (n > 10) to conduct such moderator analyses for the bystander intervention outcome domain. We found that neither of these measures was a significant predictor of the effectiveness of bystander programs on bystander intervention.
Implications for practice and policy
The overwhelming majority of eligible studies assessing the effects of bystander programs were conducted in the United States. This is not necessarily surprising considering that the United States has implemented public policy that encourages the implementation of such programs on college campuses. The United States 2013 Campus Sexual Violence Elimination (SaVE) Act requires post-secondary educational institutions participating in Title IX financial aid programs to provide incoming college students with primary prevention and awareness programs addressing sexual violence. The Campus SaVE Act mandates that these programs include a component on bystander intervention. Currently, there is no comparable legislation regarding sexual assault among adolescents (e.g., mandating bystander programs in secondary schools).
Findings from this review indicate that bystander programs have beneficial effects on bystander intervention behavior. This review therefore provides important evidence of the effectiveness of mandated programs on college campuses. Additionally, results from the moderator analyses indicated that the effects on bystander intervention are similar for adolescents and college students, which suggests that early implementation of bystander programs (i.e., in secondary schools with adolescents) may be warranted.
Importantly, although we found that bystander programs had a significant effect on bystander intervention behavior, there was no evidence that these programs had an effect on participants’ sexual assault perpetration. Although most bystander sexual assault prevention programs aim to shift attitudes in the hopes of preventing sexual assault perpetration, this review provided no evidence that these programs decrease participants’ perpetration rates. This suggests that bystander programs may be appropriate for targeting bystander behavior but may not be appropriate for targeting the behavior of potential perpetrators. Additionally, effects of bystander programs on bystander intervention diminished six-months post-intervention. Thus, booster sessions may be needed to yield any sustained intervention effects.
Implications for research
Findings from this review suggest there is a fairly strong body of research assessing the effects of bystander programs on attitudes and behaviors. However, there are important questions worth further exploration.
First, according to one prominent logic model, bystander programs promote bystander intervention by fostering prerequisite knowledge and attitudes (Burn, 2009). Our meta-analysis provides inconsistent evidence of the effects of bystander programs on knowledge and attitudes, but promising evidence of short-term effects on bystander intervention behavior. These results cast uncertainty on the proposed relationship between knowledge/attitudes and bystander behavior. However, our methods do not permit any formal evaluation of this relationship. The field’s understanding of the causal mechanisms of program effects on bystander behavior would benefit from further analysis (e.g., path analysis mapping relationships between specific knowledge/attitude effects and bystander intervention).
Second, bystander programs exhibit a great deal of content variability, most notably in framing sexual assault as a gendered or gender-neutral problem. That is, bystander programs tend to adopt one of two main approaches to addressing sexual assault: (1) they present sexual assault as a gendered problem (overwhelmingly affecting women) or (2) they present sexual assault as a gender-neutral problem (affecting women and men alike). Differential effects of these two types of programs remain largely unexamined. Our analysis indicated that (1) the sex of victims/perpetrators presented in interventions (i.e., portrayed in programs as gender neutral or male perpetrator and female victim) and (2) whether programs were implemented in mixed- or single-sex settings were not significant predictors of program effects on bystander intervention. However, these findings are limited to a single outcome and they should be considered preliminary, as they are based on a small sample (n = 11). The field’s understanding of the differential effects of gendered versus gender neutral programs would benefit from the design and implementation of high-quality primary studies that make direct comparisons between these two types of programs (e.g., RCTs comparing the effects of two active treatment arms that differ in their gendered approach).
Finally, as previously noted, all but two eligible studies were conducted in the United States. Thus, high-quality studies conducted outside of the United States are needed to provide a global perspective on the efficacy of bystander programs.