Key Findings Rethinking Serial Perpetration © National Sexual Violence Resource Center 2015. All rights reserved. This document was supported by Cooperative Agreement #5UF2CE002359-02 from the Centers for Disease Control and Prevention (CDC). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the CDC. The content of this publication may be reprinted with the following acknowledgement: This material was reprinted, with permission, from the National Sexual Violence Resource Center’s publication titled “Key Findings: Rethinking Serial Perpetration.” This guide is available by visiting www.nsvrc.org. Key Findings Rethinking Serial Perpetration For several years, the serial perpetration hypothesis has been the dominant narrative of rape perpetration. The hypothesis has three primary components: (1) a small number of men perpetrate the vast majority of rapes, (2) these men perpetrate rape consistently over time, and (3) most rapists have numerous victims. Recent research challenges the first two elements of the hypothesis. The third element remains unclear due to measurement limitations.(1) The serial perpetration hypothesis is most strongly based on a cross-sectional study using a sample of 120 self-identified rapists (age 18 to 71) pooled from four studies conducted over seven years from a single university (Lisak & Miller, 2002). The authors found that among male students who reported perpetrating attempted or completed rape, 63% report multiple rape acts (an average of 5.8 rapes per serial rapist). Although this study is most often cited, at least one other study, using similar methods also found a high rate of self-reported repeat offending (McWhorter et al., 2009). The hypothesis suggests that these serial perpetrators are severely pathological men who instrumentally groom their victims prior to the assault, use alcohol to incapacitate their victims, and often perpetrate other acts of interpersonal violence as well; the hypothesis was personified in a widely shown video of an actor portraying the serial perpetrator “Frank” (e.g., Schontzler, 2013). More recently, it was reflected in the movie The Hunting Ground, which depicted the issue of college rape. The field quickly embraced this conceptualization of an offender and the serial perpetration hypothesis has become the dominant narrative of perpetration in the field, and has often served as the explanation of perpetration that underlies prevention efforts. 1 Most self-report measures that assess sexual violence, including the Sexual Experiences Survey, use behaviorally-based items to measure a range of sexually violent acts. |Each question describes a specific sex act (e.g., vaginal sex) achieved through a specific tactic (e.g., physical force). It is likely that many men committed multiple acts that meet definitions for rape within the context of one assault (e.g., using multiple tactics, such as alcohol and physical force; or multiple forms of rape, such as oral and vaginal). Therefore, if a man endorses multiple items that indicate acts of rape on the Sexual Experiences Survey, it is not possible to know if those multiple acts of rape occurred within the context of one or multiple assaults. Therefore, unless specifically accounted for in the methods, studies that use the SES may either overestimate the total number of rapes and victims if each rape act is counted as a separate rape and studies that dichotomize the responses for a particular time frame (rape vs no rape in past year) may underestimate the total number of rapes and victims. Although it is clear that a subset of perpetrators do commit multiple acts of rape over time, recent research suggests that most perpetrators do not chronically offend over time. Instead, perpetrators are much more heterogeneous in terms of their risk factors, methods of coercion, and pattern of offending over time. Despite some inconsistencies with other research on sexual violence (e.g., approximately half of all rapes do not involve alcohol—Abbey, Zawacki, Buck, Clinton, & McAuslan, 2004; many perpetrators are opportunistic rather than premeditated—Prentky & Knight, 1991), the serial perpetration hypothesis played an important role in the field of rape prevention by raising awareness about the seriousness of undetected or non-adjudicated rapists. Characterizing rape as a crime perpetrated by a few men may have made the problem seem more easily managed by simply identifying and prosecuting the guilty few. Indeed, the potential return on investment from intervening in the majority of rapes by detecting and adjudicating only a few men is attractive to many institutions. In addition, the hypothesis has led to the perception that we must focus on a bystander to intervene in high risk situations because perpetrators are so pathological that their behavior cannot be changed by prevention strategies. However, research has accumulated; and, although some perpetrators do offend repeatedly over time, the majority of perpetrators do not chronically perpetrate. In this article we describe the patterns of rape perpetration supported by research, critique the hypothesis based on this research, discuss the unintended consequences of perpetuating the hypothesis, and provide an alternative, research-based conceptualization of perpetration and opportunities for prevention. The serial perpetration hypothesis implies that three developmental trajectories of rape perpetration exist [using percentages from Lisak and Miller (2002) for illustration]: a trajectory of non-offenders (94%), which is comprised of the majority of men in society who never rape; a trajectory of one-time rapists (2%); and, a trajectory of high rate rapists (4%), which is comprised of men who maintain a high rate of offending that is consistent across time. The implication of these three trajectories is that a large proportion or majority of the offenses are committed by that small high-rate offender group. The conceptualization of a small group of high- rate offenders was widely accepted because, until recently, research on rape rarely used methods that could model trajectories of offending over time. In the absence of such research, studies that assessed offending and offender characteristics at a single point in time were selectively used to support the idea of serial perpetration. Recent research using analytic techniques that look at patterns of behavior over time sheds new light on how rape perpetration manifests across time.(2) This research now refutes two of the three elements of the serial perpetration hypothesis— that only a few men perpetrate rape and that these men offend consistently across time. Using latent class growth analysis to specifically test the serial perpetration hypothesis, Swartout, Koss, White, Thompson, Abbey, and Bellis (2015) investigated the extent to which the majority of rapists consistently perpetrate across the pre-college and college years using trajectory analyses of data from two large longitudinal studies (n = 847 and n = 795) of college men’s rape.(3) Rape perpetration was assessed using the Sexual Experiences Survey (Koss, Gidycz, & Wisniewski, 1987; Koss et al., 2007), which has strong correspondence with face-to-face interview questions and has been recognized in federal and scientific reviews as an effective strategy for obtaining accurate reports of sexual violence (Krebs, 2014). To most accurately test the serial perpetration hypothesis, this study included only completed rape perpetration as defined by the FBI (“penetration, no matter how slight, of the vagina or anus with any body part or object, or oral penetration by a sex organ of another person, without the consent of the victim” [FBI, 2012]). To understand the likelihood of consistent perpetration across the college years, the researchers coded whether or not a man reported committing rape at each assessment.(4) The researchers found very similar results across both samples, so for brevity we will review findings from the second sample. Approximately 13.3% of men perpetrated a completed rape in their lifetime, with 5.1% reporting rape perpetration before college, 11.6% during college, and 3.5% both before and during college. Of the men who committed college rape, 72.8% only reported perpetration during one year and 27.2% reported perpetration during two or more years. Although the study did not capture how many rapes may have been perpetrated during each college year given the measurement limitations noted above, the sample descriptive statistics begin to paint a different picture than the serial perpetrator hypothesis, such that over twice as many men as in Lisak and Miller (2002) report perpetrating rape (6% vs. 13.3%), but the majority of them do so at only one time point. Most men (92.6%) , including 689 (86.7%)5 men who did not report rape at any time-point and 56 (7.0%)6 who reported rape at only one time point, were classified in a trajectory with a generally low likelihood of perpetrating rape across the pre-college and college years (Figure 1; teal line). Although 56 men in this trajectory reported committing rape, none did so at more than one assessment. This led the researchers to consider these men as having a low or time-limited likelihood of committing rape. Two dynamic trajectories were also identified: one with decreasing rape likelihood and another with increasing likelihood. The decreasing trajectory (dark blue line) accounted for 5.3% of the second sample; men in this trajectory were much more likely to perpetrate pre-college rape than men in the other groups, but their rape likelihood significantly decreased after they began college (Figure 1). The increasing trajectory (light blue line) accounted for 2.1% of the sample; men in this group were unlikely to perpetrate pre-college rape, but their rape likelihood significantly increased once they began college and remained high throughout the college years. (Image of a gold clock on a wooden stand.) 2 The originally published paper (posted August 2015) reflected the original JAMA article published online July 13, 2015 and this version has been updated to reflect the updated version of the JAMA article published October 19, 2015. 3 The researchers used the two largest longitudinal data sets of college men’s sexual violence (also the two data sets respectively used in the studies described above). The data set previously used by Swartout and colleagues (2015) was used to build the trajectory model (Sample 1, Derivation Model, on Page 4), and the data set previously used by Thompson and colleagues (2013) (Sample 2, Validation Model, on Page 4) was used to confirm the trajectory model. 4 A within-assessment test of the serial rapist assumption was not possible due to the inability to separate offenses that occurred during either single or multiple incidents measured at the same assessment. 5 Based on the sum of estimated probabilities of membership in each trajectory. 6 Based on most-likely trajectory membership; will differ slightly from percentages based on sum of probabilities. (Two figures show trajectories via the Derivation Model and the Validation Model.) These findings were mirrored by those from the first sample. Notably, no trajectory was identified for individuals who consistently perpetrated at a high rate over time. Other recent research also does not support the serial perpetration hypothesis. For example, Abbey, Wegner, Pierce, and Jacques-Tiura, (2012) also identified trajectories of sexual violence perpetration in a community sample of young men. From self- reports of sexually violent behavior (using a modified version of the Sexual Experiences Survey; Abbey, Parkhill, BeShears, Clinton-Sherrod, & Zawacki, 2006) collected at baseline and a one year follow-up, Abbey et al. (2012) manually identified three groups of perpetrators: repeat offenders, offenders who reported offending at baseline but not at follow-up, and offenders who offended at follow-up but not at baseline. Using advanced analytic techniques, the authors found that some of these groups had stronger associations with certain risk factors than did other groups. For example, repeat offenders had higher rates of childhood victimization than the other groups, men who stopped offending had fewer sexual partners at follow- up than repeat offenders, and men who started offending at follow-up were more likely to report intoxication in sexual situations than were non- perpetrators. Taken together, recent research on sexual violence perpetration across time using community and collegiate samples supports the existence of heterogeneity among sexually violent men, commonly marked by onset of sexually violent offending and patterns across time. Implications for Prevention As described above, Swartout and colleagues (2015) found that approximately 13% of college men had perpetrated a completed rape in their lifetime, with 5% reporting rape perpetration before college and over 11% during college. These findings caution against a uniform approach to rape response and prevention across development. For reasons we do not yet fully understand, many of the men who engage in perpetration during adolescence will greatly reduce this behavior in young adulthood/college; however, there are other groups of men at low risk for rape perpetration entering young adulthood/college who will perpetrate at higher rates after matriculation. In specific regard to campus rape, a majority of college men who perpetrate do so during limited time frames. Although some men perpetrate rape across multiple college years, these men are not at high risk entering college and account for a small percentage of campus perpetrators. As 72.8% of perpetrators reported perpetration during only one year a sole focus on chronic perpetrators would result in missing three of four men who have raped while in college. Moreover, focusing only on rape perpetrators obscures a large body of evidence which indicates that other forms of sexual violence are perpetrated—by the same and different men—at much higher rates. In addition to rape, sexual violence includes being made to penetrate someone else, sexual coercion (e.g., non-physically forced unwanted penetration), unwanted sexual contact (e.g., groping), and non-contact unwanted sexual experiences (e.g., verbal sexual harassment; Basile et al., 2014). Rates of sexual coercion perpetration, involving the use of verbal manipulation and pressure to obtain unwanted sex, have been reported by 22% to 69% of males across several studies, with most estimates near 30% and fairly consistent findings for college and community men (DeGue & DiLillo, 2004). In fact, Zinzow and Thompson (2015) found high rates of repeated perpetration when the full range of sexually violent behaviors — unwanted sexual contact to completed rape — were analyzed together, meaning that many men (68% of offenders) consistently use coercive sexual tactics over time, but only 12-22% of repeat offenders perpetrated rape at each time point, meaning that repeat offenders perpetrated other forms of sexual violence over time and periodically perpetrated rape. Of note, these findings are based upon the same data set Swartout and colleagues (2015) used to fit their validation model, providing further evidence that behavior other than rape constituted much of the repeated sexual violence. (PHOTO: A large group of people on a public sidewalk walks in many different directions.) Sexual harassment perpetration, including unwanted sexual touching, are studied less often and rates vary substantially in the literature. A recent national study found that 18% of boys and 14% of girls in middle or high school reported perpetrating sexual harassment in the 2010-11 school year (Hill & Kearl, 2011). Sexual violence is not strictly a problem of rape, but includes a wide spectrum of problematic sexual behaviors that facilitate, co-occur with, create an environment conducive to rape, and are harmful in and of themselves. Prevention approaches that focus in on a small subset of the most dangerous and high-risk rapists will ultimately miss the majority of sexual violence perpetration that occurs in our communities and may address only a subset of risk factors that are most relevant to the larger population of at-risk men. The public health approach to sexual violence prevention is focused on primary prevention, or preventing violence before it occurs, and emphasizes reducing rates of violence at the population level. This approach points to strategies focused on reducing the number of potential perpetrators and addressing the social norms and systems that facilitate and support sexual violence as critical to ensuring impact on violence rates in the population. The public health model is framed around four interactive steps that guide prevention research and practice: (1) defining and monitoring the problem through surveillance, (2) identifying risk and protective factors, (3) developing and evaluating prevention strategies, and (4) ensuring widespread adoption of effective approaches. Only when the development of prevention strategies accurately reflects the best available science regarding the nature and etiology of sexual violence would we expect those strategies to be effective in reducing rates of perpetration and victimization when implemented in communities. Although primary prevention implications of the serial perpetration hypothesis have been suggested to prevent it before it begins, such as early identification of males at risk for serial rape perpetration (Lisak & Miller, 2002); oftentimes the implication is that secondary, rather than primary, prevention is needed to detect and prosecute serial perpetrators (See http://tinyurl.com/comprehensive-prevention-pc for discussion). In other words, the prevailing argument has been that focusing only on potential serial perpetrators in targeted primary prevention efforts or removing the few serial rapists from society would prevent sexual violence. However, given the multiple types and trajectories of sexual violence described above, primary prevention that accounts for and addresses the different developmental stages and trajectories of potential perpetrators is needed to have an impact on rates of sexual violence; these efforts are needed in addition to the criminal justice response that is often a part of secondary and tertiary prevention. Serial Perpetration Hypothesis & Unintended Consequences In addition to promoting a law enforcement response, as opposed to a primary prevention approach to rape prevention, in our experience the serial perpetration hypothesis has led to extreme portrayals of rape perpetrators. For example, the terms “sexual predator” and “predatory behavior” are used to describe all sexual assault perpetrators and all coercive tactics, when in fact these terms refer to a subset of the most pathological perpetrators and assault behaviors. Based on the serial perpetration narrative, rape is stereotypically portrayed as repeated premeditated acts by severely pathological, if not psychopathic, men who also perpetrate other forms of violence towards women and children and who instrumentally use alcohol in their crime. While this characterization may fit a very small number of the most severe rape perpetrators, research suggests that rape may also be impulsive and perpetrated by men without serious pathology or psychopathic traits (see Malamuth, et al 1995 Confluence Model; and, Prentky & Knight, 1991, typology of an opportunistic rapist). In other words, the heterogeneity of sexual assault perpetrators has been masked by the often singular focus on serial perpetrators. Rape is no less significant when perpetrated by less severely pathological men; however, we have found that when sexual assaults occur by perpetrators who are seemingly inconsistent with the extreme portrayal of the serial rapists, there is a reluctance to label an assault as rape. Perhaps as a modern twist on Estrich’s (1987) “real rape” (aggravated assaults by a stranger with a weapon that causes bodily injury to the victim) versus “simple rape” (acquaintance rapes without physical force) dichotomy, the serial rapist hypothesis suggest that alcohol is the weapon of the serial rapist and that he forms relationships with his victims in order to gain their trust, which he will subsequently betray. The idea of premeditated assault with multiple victims has become the “real rape” narrative and opportunistic, impulsive, or offenses committed in intimate or dating relationships are too often seen as “regret sex” or “drunk sex.” An unfortunate consequence of promoting the hypothesis of serial rapists is that it reifies the idea that only “real” perpetrators are those that fit this extreme serial rapist portrayal. This may lead to further marginalization of rape cases in which the perpetrator does not fit that description. Further, these extreme and narrow characterizations obscure the fact that a substantial proportion of college and community men — more than one in three in most studies (DeGue & DiLillo, 2004) — will self-report some form of sexual violence by the end of young adulthood. Characterizing this problem primarily as one of a pathological few rather than something more common masks the need for broader prevention efforts to address the social and structural contexts that facilitate the full range of sexually violent behaviors. The serial perpetration hypothesis, and related characterizations of the pathological repeat rapist, point to a need for primarily psychological and behavioral interventions targeting high-risk individuals. In contrast, the view that many men (and some women) are at risk to perpetrate sexual violence and that risk varies over time suggests a need for multi-level interventions that address variation in individual risk characteristics across the lifespan as well as the social, environmental, and structural influences that create a culture conducive to high rates of sexual violence. Thus, an extreme portrayal of serial rapists, which once helped draw attention to the seriousness of the problem of sexual violence, has had unintended consequences. Alternative Research-Based Conceptualization of Sexually Violent Offending & Prevention The serial perpetration hypothesis is a theory about the pattern of offending over time. It suggests that the majority of perpetrators follow a single trajectory of high-rate perpetration that is consistent across development. An alternative, research-based conceptualization of sexual violence perpetration across time suggests three major developmental pathways: a low or time-limited pathway, a desisting by young adulthood pathway, and an initiating in young adulthood pathway. A theme in all three pathways is that offending is affected by risk factors that occur in close developmental proximity to the offense, rather than risk factors that occurred in the distant past. For example, other research on trajectories of sexual violence suggests offending in adolescence is influenced by experiencing or witnessing violence in the home (Swartout, Swartout, Brennan, & White, 2015), whereas offending in young adulthood is influenced by hostile masculinity and peer norms supportive of sexual assault (Thompson, Swartout, & Koss, 2013). Based on this research, we conjecture alternative, developmental conceptualizations of offending and suggest viable prevention strategies. PHOTO: A pair of red shoes stands at three arrows pointing in different directions.) Although the low or time-limited trajectory generally has a very low likelihood of perpetrating consistently across the college years, this group contains a large proportion of men who commit campus rape, because the men in this group who perpetrate do so in only one academic year. These men — who committed 50% of the college rape acts (7) reported — may be opportunistic and their offenses are likely context-dependent. These offenders may be particularly influenced by substance use, their own or that of their victims. Intoxication or alcohol or drug-related expectancies might temporarily lower these men’s inhibitions; or they might take advantage of an already intoxicated victim. To be clear, this is not to suggest alcohol or drugs cause or excuse sexual assault among these men. As is the case with the general link between substance use and violence, alcohol use can trigger existing risk factors for sexual violence within these time-limited perpetrators, resulting in a greater likelihood of offending when opportunities arise. Desisting offenders perpetrate rape during adolescence and their perpetration may be influenced by maladaptive behaviors and attitudes they have learned from family (Swartout, Swartout, Brennan, & White, 2015) and peers, and attitudes and behaviors that support violence and delinquency. This pathway might be explained with social learning theory that posits that behaviors are shaped over time by patterns of reinforcement and punishment that either promote or extinguish negative behaviors. As such, prevention of sexual violence perpetration in this pathway might involve learning healthy ways of interacting with others, such as learning core social-emotional skills and focusing on healthy relationship and dating skills. This could explain why programs like Safe Dates (Foshee et al., 1998) which teach healthy relationship skills are effective in preventing sexual violence during adolescence. The increasing pathway is comprised of offenders who have not previously offended in adolescence but begin perpetrating in young adulthood. These perpetrators are influenced by personal attitudes (e.g., hostile masculinity) and perceived peer attitudes (Thompson, Swartout, & Koss, 2013). These risk factors may be exacerbated by intoxication. This pathway could be explained with social control theory, which suggests that intrinsic (e.g., values) or external factors (e.g., bystander behavior) serve to control or inhibit negative behaviors and the absence of social controls (e.g., peer norms that support assault, peer pressure to have sex) and the presence of alcohol, which further disinhibits risk, increase the potential for perpetration. Prevention of sexual violence in this pathway would involve enhancing social controls and adjusting social norms to prevent sexual violence. This could explain why programs like Green Dot (Coker et al., 2011) and Bringing in the Bystander (Banyard et al., 2004) that increase social controls via bystanders and changing social norms, in addition to alcohol policies that reduce alcohol consumption (Lippy & DeGue, 2014) show promise in preventing sexual violence among young adults (DeGue et al., 2014). An important aspect of the three pathway conceptualization of perpetration—low, increasing, and decreasing—that differs from the serial perpetration hypothesis is that there are different groups of perpetrators who are offending in adolescence and young adulthood/ adulthood. So, the need for primary prevention remains critical across development in addition to efforts to detect and adjudicate offenders. 7 Does not indicate number of rapes perpetrated, as multiple rape acts can occur within a single assault. Conclusion We acknowledge that the serial perpetration hypothesis was based on the cross-sectional research available at the time it was developed. It played a key role in the rape prevention movement by raising awareness of non- adjudicated offenders. The potential return on investment of focusing on a few offenders who were responsible for the majority of the rapes is attractive to institutions with limited resources for prevention and response. The idea that only a few men perpetrate rape is much more comforting and seemingly manageable than the finding that many men use coercive and aggressive tactics to obtain sex and that patterns of offending vary across time. Although some perpetrators perpetrate repeatedly over time, new research suggests that the majority of rapists do not consistently perpetrate. In addition, the unintended consequences of the serial perpetration narrative have reduced its utility for prevention. Even if all serial offenders were detected and removed from society, a substantial number of rapes and other forms of sexual violence would still be perpetrated. This reality is referred to as the prevention paradox (Rose, 1981) and explains why universal prevention of sexual violence is needed to achieve population level change. Of the three components of the serial perpetration hypothesis — a small number of men perpetrate the vast majority of rapes, these men perpetrate rape consistently over time, and most rapists have numerous victims — using newer analytic techniques, recent research offers empirical evidence of an alternative conceptualization of the first two elements of the hypothesis. This alternative conceptualization provides specific opportunities for prevention with adolescents and young adults. Specifically, the majority of rapists appear to have time limited offending, making it difficult to detect, necessitating universal and targeted prevention approaches. In some ways this more dynamic understanding of offending over time may appear to require a more complex prevention approach; however, it introduces more opportunities for prevention and intervention and holds the potential for greater effectiveness. Given measurement limitations, it remains unclear how many rapes repeat rapists perpetrate, but this new research provides new insights into the magnitude and chronicity of rape perpetration. While it is clear that a subset of perpetrators do consistently perpetrate over time, in light of the new findings we encourage those who espouse the serial perpetration hypothesis to consider a broader conceptualization of sexual violence that addresses the heterogeneity of sexual assault perpetrators. (PHOTO: Two paths diverge into a wooded area. Birds fly in the sky above.) Author Information Andra Teten Tharp, Centers for Disease Control and Prevention; Kevin Swartout, Georgia State University; Mary P. 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