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Sex Offender Management Assessment and Planning Initiative, Office of the Sex Offender Sentencing, Monitoring, Apprehending, Registering, and Tracking (SMART)
Sex Offender Management Assessment and Planning Initiative Office of the Sex Offender Sentencing, Monitoring, Apprehending, Registering, and Tracking (SMART)
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Chapter 2: Etiology of Adult Sexual Offending
by Susan Faupel, M.S.W.

Introduction

The etiology of adult sexual offending refers to the origins or causes of sexually abusive behavior, including the pathways that are associated with the behavior's development, onset, and maintenance. Even though questions about the causes of sexual offending have been asked for many years, they remain important today, primarily because definitive answers have been exceptionally hard to find. While research has generated important insights about the etiology of sexual offending, our understanding of the causes and origins of sexually abusive behavior arguably remains rudimentary.1

There are multiple reasons why it is important to be concerned with the etiology of sexual offending. First, the development of effective prevention strategies is contingent on having credible knowledge about the underlying causes of sexual offending and victimization. Without credible etiological knowledge, prevention efforts are likely to be haphazard and inefficient. Second, knowledge about causes can help sex offender management professionals manage and mitigate risk more effectively. (For a discussion of adult "Sex Offender Risk Assessment," see chapter 6, and for more on "Sex Offender Management Strategies," see chapter 8, both in the Adult section.) Simply put, knowledge about causes and pathways to offending can provide important insights into the characteristics of various sex offending behaviors (including victim preferences) and the likelihood that they will persist over time. Third, knowledge about causes can help sex offender management professionals develop more effective treatment interventions. (For more on "Effectiveness of Treatment for Adult Sex Offenders," see chapter 7 in the Adult section.) Rather than focusing on symptoms or using a one-size-fits-all approach, rehabilitation efforts can target the specific underlying causes and pathways to offending that apply to the individual offender. Fourth, etiological information can inform both discourse and decision-making at the policy level, whether the focus is on sentencing, oversight in the community, civil commitment, or any other criminal justice or societal response to sexual offending. In short, knowledge about origins, causes, and pathways to sexual offending can play a critical role in the development and delivery of effective public safety strategies.

Single-Factor Theories of Sexual Offending Behavior

Biological Theories

Biological theories of sexual offending have centered on abnormalities in the structure of the brain, hormone levels, genetic and chromosomal makeup, and deficits in intellectual functioning. Key research findings concerning the validity of various biological theories are—

  • A number of studies have found abnormalities in the brains of some sexual offenders; however, the evidence is clear that such abnormalities do not exist in the majority of cases (Aigner et al., 2000; Corley et al., 1994; Galski, Thornton, & Shumsky, 1990; Hucker et al., 1986; Langevin et al., 1988, 1989; Wright et al., 1990). 
  • Studies examining the link between hormonal abnormalities and sexual offending have focused on the role of certain hormones (e.g., testosterone) known to be related to physical changes in males. To date, these studies have not found evidence of a clear link between hormone levels and sexual offending (Bain et al., 1987; Hucker & Bain, 1990).
  • Consideration has also been given to the possibility of a genetic defect in sex offenders that makes them more likely to engage in aggressive sexual behavior. The few studies that have examined this issue have been based on a small sample size, and far more research is needed before conclusions about a causal relationship to sex offending can be made (Beckmann et al., 1974; Harrison, Clayton-Smith, & Bailey, 2001). 
  • Links between deficits in intellectual functioning and sexual offending have also been hypothesized, but empirical evidence supporting these theories has not been produced. Moreover, it should be noted that aggression is not the norm in this population (Day, 1994; Murray et al., 2001; O'Callaghan, 1998). 
Summary of the Evidence on Biological Theories

The empirical evidence produced to date does not indicate that the presence of a particular biological phenomenon has a causal relationship with sexual offending. However, biological studies are still relatively new. With improved methodologies, future research may demonstrate that certain aspects of biological theories yield beneficial information for understanding and explaining the origins of sexual offending behavior (Stinson, Sales, & Becker, 2008).

Evolutionary Theories

Evolutionary theories have been proposed to explain a variety of human behaviors, including sexual aggression. Evolutionary theory views human behavior as the result of millions of years of adaptive changes designed to meet ongoing challenges within the environment. 

Several theories rely on evolutionary postulates about sexual selection and sexual strategies to explain sexual aggression. One is that sexual coercion is a conditional sexual strategy. In this theory, sexual coercion is postulated to be merely a type of reproductive strategy, as it is in nonhuman species (Bailey, 1988; Malamuth & Heilmann, 1998; Thornhill & Palmer, 2000). Another evolutionary theory views rape as an outcome of a competitive disadvantage for some men that causes them to lack the resources or ability to obtain a mate by more appropriate means (Figueredo et al., 2000; Lalumiere et al., 1996; Malamuth & Heilmann, 1998; Quinsey & Lalumiere, 1995). Another theory describes rape as a "courtship disorder" that results from an interruption in normal mating processes (Freund, 1990; Freund, Scher, & Hucker, 1983, 1984). 

Summary of the Evidence on Evolutionary Theories

It is very difficult to empirically test the validity of evolutionary theories. They present a unique perspective in that they view sex offending behavior as an adaptation to environmental or interpersonal events. While this is a new direction that may deserve further consideration, researchers in the field have largely disregarded these hypotheses as the cause of sexual offending because of their limitations (Travis, 2003). 

Personality Theories

Personality theories are among the earliest sources of explanation for sexual offending behavior. They emerged based on the work of Sigmund Freud, who believed that sexual deviance is an expression of the unresolved problems experienced during the early stages of an individual's development. Due to a lack of empirical evidence, Freud's personality theories have fallen out of favor with etiological researchers in deference to other theories. Later personality theorists, however, suggested that early childhood relationships involving trauma or mistreatment could lead a child to internalize negative attitudes and beliefs about both the self and relationships with others, thus altering how the child perceives sex and his or her role in sexual relationships (Leguizamo, 2002). 

One of these later personality theories—attachment theory—was first introduced by Bowlby (1988) to explain the relationship between a child and his primary caretaker, and how this early relationship affects later adjustment. According to attachment theory, humans have a propensity to establish strong emotional bonds with others, and when individuals have some loss or emotional distress, they act out as a result of their loneliness and isolation. Later research indicates that there is a relationship between poor quality attachments and sexual offending. Marshall (1989) found that men who sexually abuse children often have not developed the social skills and self-confidence necessary to form effective intimate relations with peers. This failure creates frustration that causes them to seek intimacy with young partners (Marshall, 1989; Marshall and Marshall, 2000). 

Seidman and colleagues (1994) conducted two studies aimed at examining intimacy problems and the experience of loneliness among sex offenders. According to these studies, sex offenders have deficiencies in social skills that seriously restrict the possibility of maintaining intimacy. Ward and colleagues (1995) proposed that sex offenders are likely to have difficulty forming attachments with others and will engage in distorted thinking, such as "courting" a child and treating him or her as his lover.  

Personality theorists also use formulations of personality development based on the results of testing instruments designed to profile personality types. Studies concerning this approach, however, have produced diverse and contradictory findings, and they have been criticized for failing to adequately demonstrate how the results obtained from testing instruments can add to the understanding of the origins of sexually deviant behavior (Stinson, Sales, & Becker, 2008). Further evidence is needed to show how certain personality traits relate specifically to the cause of sexual offending behavior.

Summary of the Evidence on Personality Theories

Personality theories are successful in demonstrating that sex offenders have poor social skills and problems with intimacy, and that there is a connection between poor relationships with others (particularly caregivers) and sexual offending behavior. The primary criticism of personality theories is that while they show that disturbances exist within the personalities of sex offenders, they fail to explain why these disturbances occur. Hence, personality theories alone do not provide a complete explanation of the cause of sexual offending behavior (Stinson, Sales, & Becker, 2008).

Cognitive Theories

Cognitive theories address the way in which offenders' thoughts affect their behavior. It is well documented that when individuals commit deviant sexual acts, they often try to diminish their feelings of guilt and shame by making excuses or justifications for their behavior and rationalizing their actions (Scott & Lyman, 1968; Scully, 1990; Sykes & Matza, 1957). These excuses, justifications, and rationalizations are commonly referred to as "cognitive distortions" or "thinking errors." They allow offenders to absolve themselves of responsibility, shame, or guilt for their actions. Thinking errors on the part of sex offenders have been identified and supported frequently in research. These errors include denial, minimization of harm done, claiming the right or entitlement to the behavior, and blaming the victim (Marshall, Anderson, & Fernandez, 1999; Ward & Keenan, 1999). The literature also suggests that many sex offenders hold feelings of resentment and use these feelings as justification for their behaviors. Marshall, Anderson, and Champaigne (1997) theorized that sex offenders are more likely to be self-protective and self-serving due to low self-esteem, poor relationships with others, and emotional discomfort or anxiety. When challenged about their behavior, sex offenders reframe the situation to maintain feelings of self-worth. 

Another type of cognitive distortion common among sexual offenders is a sense of entitlement, which involves the belief that the need to offend is more important than the negative consequences experienced by the victim (Hanson, Gizzarelli, & Scott, 1994). Hanson, Gizzarelli, and Scott (1994) found that this sense of entitlement in incest offenders led to decreased self-control, while Ward, Hudson, and Keenan (1998) found that thinking errors lead sex offenders to pay attention to information consistent with their distorted beliefs and to reject information that is inconsistent with their beliefs. For example, a child molester may interpret a child's hug as sexual interest because that interpretation conforms to his or her distorted beliefs, or a child molester may ignore a child's crying because it conflicts with his or her beliefs. Further, egocentricity or self-interest allows the sex offender to justify deviant sexual behavior on the basis that it satisfies his or her needs. The offender will see victims as deserving of victimization or may have distorted views of what the victim wants from the offender. He or she may display a consistent tendency to blame others or negate personal responsibility through such statements as "I just couldn't help myself" (Hanson, 1999; Hanson, Gizzarelli, & Scott, 1994: Segal & Stermac, 1990; Ward, 2000; Ward, Hudson, & Keenan, 1998). 

Finally, the way sex offenders process both internal and external cues may explain how and why they manipulate information. Research suggests that sex offenders misinterpret social cues and have difficulty recognizing and interpreting the emotional state of others. Further, they do not make good choices based on the information they perceive and do not consider the perceptions of others in making decisions about their own behavior (Keenan & Ward, 2000; Ward, 2000). 

Summary of the Evidence on Cognitive Theories

Cognitive theories have contributed to a better understanding of sex offenders and their behaviors. There is evidence demonstrating that sex offenders engage in cognitive distortions or thinking errors, and that these distorted thinking patterns have the capacity to drive deviant sexual behavior. Cognitive theories serve as a core component of many of the sex offender treatment programs in existence today, and most treatment programs incorporate some type of intervention to help the perpetrator identify and correct his or her thinking errors. 

Despite the contributions made by cognitive theories and their use in treatment models, these theories have limitations. First, no method has been identified for connecting in a causal manner what the offender reports about his or her thought processes and a sex offending act itself. Second, cognitive theories do not explain where the cognitive distortion thought processes originate. Third, the research that is available on cognitive theories reflects few differences between sex offenders with cognitive distortions and non-sex offenders with cognitive distortions. In short, cognitive theories do not explain why some individuals commit sexually offensive acts specifically (Stinson, Sales, & Becker, 2008).

Behavioral Theories

Behavioral theories explain sexually abusive behaviors as a learned condition. Behavioral theories are based on the assumption that sexually deviant arousal plays a pivotal role in the commission of sex crimes and that people who engage in sex with, or have sexual feelings toward, inappropriate stimuli are more like likely to commit sexual violence than those with appropriate sexual desires (Becker, 1998; Hunter & Becker, 1994; Lalumiere & Quinsey, 1994).

In behavioral theory, the occurrence of continued deviant sexual behavior (as with all behavior) depends on reinforcement and punishment. Sexual gratification and the perceived lack of negative consequences for sexual offending, coupled with a lack of support for not engaging in sexual offending behavior, increases the likelihood for sex offenses to continue. The key factor is that if the negative consequences of the behavior (punishment) are sufficiently strong, the negative behavior (sex offending) is less likely to occur (Laws & Marshall, 1990).

Self-regulation is also a behavioral theory that has been applied to sexually deviant behaviors. Self-regulation involves the selection of a goal and strategies to reach that goal. The goals of sexual satisfaction, intimacy, mood control, or other rewards related to sexual deviance can affect recall, judgment, and information processing (Ward, 2000). According to self-regulation theory, the goal of engaging in sexually deviant behavior and the strategies employed to reach that goal become automatically integrated into the behavior of the offender because they have been consistently reinforced in the past (Ward & Hudson, 1998). 

Summary of the Evidence on Behavioral Theories

Research offers support for sexual abuse being a learned behavior. Acknowledgment of the role of self-regulation also appears to be a necessary component of a thorough understanding of sexual behavior problems. Further research in these areas certainly seems merited. Nonetheless, behavioral theories have limitations. First, it is important to recognize that many male sex offenders lack deviant sexual arousal patterns; in fact, many male sex offenders have arousal patterns similar to those of non-sex-offending men (Looman & Marshall, 2005). This limits the ability to generalize the deviant arousal patterns of some sex offenders to all such offenders. In addition, no research has predicted which reinforcements or consequences are likely to increase or inhibit sexual offending behavior. This seems critical both in understanding etiology and prescribing treatment and public policy. Research is also limited on the effect of "mediators"—such as support for nonoffending behavior, levels of supervision, and restricting access to victims—in the process of sexual offending. Other variables such as the lack of victim empathy, moral values, or remorse in some individuals may also play a role in the development of deviant sexual behavior patterns. Behavioral theories postulated to date do not take these variables into consideration. Additionally, the theories are based on the assumption that individuals are influenced by the threat of negative consequences (punishment). However, no empirical evidence substantiates this assumption consistently. Therefore, sex offenders may not consider the consequences of their behavior as a deterrent to their actions (Stinson, Sales, & Becker, 2008).

Social Learning Theories

Two primary social learning hypotheses have been suggested as possible explanations for sexual offending behaviors. The first is that children who are sexually abused grow into sexually abusive adults, and the second is that sexually explicit material contributes to sexual offending behavior.

Much research has examined the impact of victimization on future victimizing behavior. However, early childhood victimization does not automatically lead to sexually aggressive behavior. While sex offenders have higher rates of sexual abuse in their histories than would be expected in the general population, the majority of perpetrators were not abused as children (Berliner & Elliot, 2002; Putnam, 2003). There is relatively good evidence to support this, including the disproportionate number of women who were victimized as children who do not go on to sexually abuse others (Berliner & Elliot, 2002; Putnam, 2003).

"Negative or adverse conditions in early development have been linked to sexual offending later in life."

Even so, a large percentage of sex offenders do report being sexually abused as children (Becker, 1998; Craissati, McClurg, & Browne, 2002; Graham, 1996; Jonson-Reid & Way, 2001; Seghorn, Prentky, & Boucher, 1987; Veneziano, Veneziano, & LeGrand, 2000; Worling, 1995; Zgourides, Monto, & Harris, 1997). Certain types of offenders, such as those who sexually offend against young boys, have higher rates of child sexual abuse in their histories (Becker & Murphy, 1998; Burgess, Hartman, & McCormack, 1987; Burton, Miller, & Schill, 2002; Freeman-Longo, 1986; Freund & Kuban, 1994; Garland & Dougher, 1990; Ryan, 2002). For those victims who later become perpetrators, the majority are male (Berliner & Elliot, 2002; Stinson, Sales, & Becker, 2008). Therefore, in this regard, researchers have focused on male victims, the way they perceive their abuse, and how it affects them later in life. The aspects of the abusive experience that influenced their learning have been of most interest.

Using social learning theory, researchers have identified the process through which this learning occurs and the key variables that help to determine whether deviant sexual behavior patterns will be adopted. For example, a child who has internalized the victimization experience as normal or pleasurable in some way is more likely to adopt a belief system that is favorable to offending (Briggs & Hawkins, 1996; Burton, Miller, & Schill, 2002; Eisenman, 2000; Freeman-Longo, 1986; Hummel et al., 2000). Several different types of thought patterns may lead more easily to the development of sexually abusive behaviors in victims. For example, the victim may think "this must be normal" or "it isn't a bad thing because someone who loves me is doing it to me" or even "this feels good and I like it" (Briggs & Hawkins, 1996; Burton, Miller, & Schill, 2002; Eisenman, 2000; Freeman-Longo, 1986; Hummel et al., 2000). A child who internalizes these thought processes in reaction to his or her own abuse is more likely to grow into an adult who views sexually abusive acts as less harmful and more pleasurable to the victim.

Studies have identified other factors that can play an important role in the link between being sexually abused and later exhibiting sexually abusive behaviors. These include the age of victimization, the relationship between the perpetrator and the victim, the type of sex act and amount of force used, the sex of the perpetrator, the duration of the abuse, and the number of perpetrators (Burton, Miller, & Schill, 2002; Garland & Dougher, 1990). The younger the victim, the more violent and intrusive the sexual acts, the longer the duration of abuse, and the greater the number of perpetrators, the more likely it is that sexually deviant behavior will develop in victims (Burton, 2000; Burton, Miller, & Schill, 2002; Hummel et al., 2000; Seghorn, Prentky, & Boucher, 1987). 

The manner in which others respond to an individual who discloses victimization is also a factor that has been shown to be related to the social learning process involved in victimization. An indifferent response or a response of disbelief to a disclosure of sexual abuse has been shown to contribute to a victim internalizing negative sexual behaviors and developing future abusive sexual behavior (Burton, Miller, & Schill, 2002; Garland & Dougher, 1990). All of this suggests that the experience of sexual abuse in childhood has some impact on the development of sexually abusive behavior patterns, but exactly how the abuse is modeled and manifested is still somewhat unclear. More research is needed in this area.

Another social learning theory related to sexual offending behavior suggests that pornography serves as a model for sexually aggressive behavior for some individuals, encouraging them to engage in behaviors depicted in pornography that they viewed. The literature defines sexually violent pornography as pornography in which women are portrayed in humiliating or degrading situations or are the victims of forced or coerced sexual interactions (Marshall, 1988).2 Based on this theory, an individual who views sexually violent pornography can experience a change in attitudes toward women and can internalize myths about rape. Burt (1980) defined rape myths as prejudicial, stereotyped, or false beliefs about rape, rape victims, and rapists. Lonsway and Fitzgerald (1994, p. 134) expanded on the concept of rape myths and defined them as "attitudes and beliefs that are generally false but are widely and persistently held, and that serve to deny and justify male sexual aggression against women."

Evidence suggests that repeated exposure to sexually aggressive pornography contributes to increased hostility toward women, acceptance of rape myths, decreased empathy and compassion for victims, and an increased acceptance of physical violence toward women (Check & Guloien, 1989; Knudsen, 1988; Lahey, 1991; Linz, Donnerstein, & Penrod, 1988; Malamuth & Check, 1980, 1981, 1985). From a social learning perspective, the likelihood that these views will lead to abusive behavior depends on the reinforcement in the learning process. One such reinforcer is a core feature of much pornography: the portrayal of women as desiring and enjoying both the sexual activity and degradation involved in the images (Check & Guloien, 1989; Knudsen, 1988; Norris, 1991; Sinclair, Lee, & Johnson, 1995). Another reinforcer lies in social cues from others—both the participants in the pornography and other viewers. If the participants in the pornographic material seem to be enjoying it and watching it appears to be socially acceptable based on the reaction of others, the viewer is more apt to see the sexually aggressive content as positive and desirable to imitate (Norris, 1991; Sinclair, Lee, & Johnson, 1995).

Another type of pornography believed to play a role in the etiology of socially learned sexual aggression is child pornography—material that either uses children or uses technology that makes the participants appear to be children. Social learning theory suggests that individuals use child pornography, internalize this behavior as acceptable, and adopt it into their own behavior. Since child pornography is illegal, research on the role of child pornography is somewhat limited. Nonetheless, it is known that child molesters report increased use of pornography prior to sexually abusing children (Howitt, 1995; Marshall, 1988). Recent research has suggested the use of child pornography as a reliable indicator of sexual interest in children (Seto, Cantor, & Blanchard, 2006). Across multiple studies, offenders have reported the use of pornography to desensitize and arouse them so they can engage in abusive behaviors with children (Knudsen, 1988; Marshall, 1988). Child pornography also appears to reduce empathy toward child victims (Knudsen, 1988). Portrayals of enjoyment on the part of the children and lack of negative consequences may serve as reinforcers of these behaviors. 

Summary of the Evidence on Social Learning Theories

Social learning theories do not offer the only explanation for sexual offending behavior. However, they do provide valuable insights for understanding sexual offending and there is evidence to support various tenets of social learning theory in the context of sexual offending. For example, there is sound empirical evidence that sexual offending is a learned behavior. Also, while it is true that a direct connection between the use of pornography and rape does not exist, research has made it clear that the use of pornography is a factor in shaping the attitudes and behaviors in some men who use it and that it is a factor in some men's sexual aggression. Scholars may differ about the specific nature of pornography's effects, but none have argued about pornography's articulation of the myths about rape and the contributions of these thinking errors to sexual offending behaviors.

Social learning theory also introduces the notion of environmental influences on sexual offending, which is contrary to the notion of other theories that have assumed that abusive behaviors are inherent within some individuals. Insights about the impact of childhood abuse and its ramifications for sexual offending are also valuable contributions.

The most often cited criticism of social learning theory is that there is little evidence that suggests internalized beliefs or attitudes actually result in related behaviors. More research on children who are victimized but do not go on to abuse others may be helpful. Further, much of the research on social learning theory, as in many other theoretical approaches, depends on self-reports of abusers. Because offenders may be motivated to distort stories to place themselves in a more positive light, relying on self-reporting can be problematic. These concerns call into question the validity of social learning theory as the sole explanation of sexually abusive behavior (Stinson, Sales, & Becker, 2008).

Feminist Theories

Although there are many forms of feminist theory, one of the more prominent focuses on the structure of gender relations and the imbalance of power between men and women. This feminist analysis assumes that the elimination of sexual violence is linked to gender equality because it is male power that enables the acceptance and perpetuation of sexual assault. 

Feminists have argued that male sex offenders are no different from "normal" men but rather are conditioned within a culture that accepts, tolerates, condones, and even perpetuates sexual violence toward women and children. Perpetrators within this framework are extended to male partners and acquaintances who cajole, pressure, harass, threaten, coerce, and/or force women into any sexual behavior to which they do not or are unable to consent. This makes it possible to examine acts of sexual coercion that remain hidden or taken for granted as "normal" social practices within the confines of heterosexual dominance (Chung, 2005; Cossins, 2000). 

According to Cossins (2000), child sexual abuse is the way some men alleviate a sense of powerlessness and establish their ideal image of masculinity. Because masculinity is learned, according to feminist theorists, in order for a man to experience power, he must engage in accepted social practices (such as sexual violence) that prove his masculinity. Connell (2000) suggests that there can be different concepts of masculinity with varying degrees of social acceptance and power. Connell proposes this as the foundation for why sexual violence occurs. This perspective has given rise to treatment approaches that shift the focus to positively reconstructing a man's sense of masculinity to exclude the use of sexual violence (White, 2000). Jenkins (1990) also developed an approach to therapy that focuses on what restrains men from engaging in respectful relationships with women, as opposed to what causes them to engage in these relationships. 

Summary of the Evidence on Feminist Theories

Currently, there is insufficient evidence to scientifically support the feminist theory of gender imbalance as the sole cause of sexual violence. However, while the imbalance of power between men and women may not be the sole or direct cause of sexual offending, it is clearly a factor. Psychological theorists have long neglected the fact that an overwhelming number of perpetrators are male, and thus they have failed to explain the role of gender in sexual violence. Additionally, it is important to keep in mind that many feminist theories go beyond the binary of gender and discuss the intersections of gender, race, class, ethnicity, culture, and other factors. This makes the simple gender/power relationship much more complex than that described above, and research that explores both the impact of these interactions and their value for understanding sexual offending is clearly needed.

Multifactor Theories of Sexual Offending Behavior

Believing that single-factor theories are inadequate, a number of scholars have developed theories that combine multiple factors to explain sexual offending behavior. The most prominent of these theories are discussed below.

Finklehor's Precondition Theory

The first integrated theory of sexual offending behavior was put forth by Finkelhor in 1984. Finklehor's theory, which applies only to child sexual abuse, outlines four preconditions that must exist for a sex offense to occur:

  1. The motivation to abuse (e.g., sexual satisfaction, lack of other sexual outlets, a desire to have intimacy, a relationship with the child).
  2. The overcoming of internal inhibitions (e.g., personal sense of morals, values, ethics; fear of being caught). Internal inhibitors may be overcome due to poor impulse control, the use of alcohol or drugs, engaging in excuses and justifications, or impaired mental ability.
  3. The overcoming of external inhibitors (e.g., lack of privacy, adequate supervision, strong personal boundaries of the child, good support system around the child, negative social consequences). For an offender to overcome external inhibitors, he or she must locate both an opportunity for privacy and a child with poor boundaries and inadequate supervision. The offender also must consider that the possibility of negative consequences is unlikely.
  4. The overcoming of victim resistance (e.g., taking advantage of a trusting relationship with the child or caregiver; using bribes, trickery, or manipulation). These strategies are called "grooming behaviors" and are used by the offender to successfully engage the potential victim.
Summary of the Evidence on Finklehor's Precondition Theory

Although the existence of motivating conditions (overcoming internal and external inhibitors as well as victim resistance) has been supported, Finklehor's Precondition Theory never explained why someone would possess such motivation in the first place. For example, Howells (1994) noted that while poor social skills or lack of available sources of sexual gratification (among other factors) may be important, they are not direct causes of sexual offending. It is also unclear whether deviant sexual interest, deficits in intimacy, or a need for power and control may be at work when an individual offends. 

Marshall and Barbaree's Integrated Theory

In this theory, the prominent causal factors for sexual offending are developmental experiences, biological processes, cultural norms, and the psychological vulnerability that can result from a combination of these factors. Marshall and Barbaree (1990) proposed that early negative experiences in childhood (e.g., sexual abuse, physical abuse, neglect) cause children to view their caregivers as emotionally absent, and to see themselves as being unworthy to receive love or be protected. This results in low self-esteem, poor interpersonal skills, and weak coping skills. The presence of antisocial and misogynist attitudes in the home can be aggravating factors. If adolescent males feel inadequate, the theory argues, they are more likely to accept messages that elevate men to positions of power and dominance. Another key feature of the theory is that sex meets a number of psychological needs beyond sexual gratification. These may include an increased sense of competence, elevated self-esteem, personal connection and fulfillment, and a sense of achieving the ideal image of masculinity. 

Marshall and Barbaree suggested that a key developmental task for adolescent boys is to learn to distinguish between sexual impulses and aggression. They argued that this task is difficult because both types of impulses are generated by the same brain structure. Hence, adolescent boys may find it difficult to know when they are angry, sexually aroused, or both, and they must learn how to inhibit aggression in sexual situations. Combined with the influx of hormones that occur in adolescence, these factors render the young male vulnerable to developing sex-offending behaviors. Situational factors such as loneliness, social rejection, or a loss of a relationship may then trigger the sexually abusive acts committed by adolescents. The more vulnerable a person is to committing a sexual offense, the less intense these situational experiences need to be to trigger sexually aggressive behavior. 

A later addition to the theory by Marshall and Barbaree is that mood states initially associated with sexual arousal may later be able to elicit sexual desire on their own through the process of conditioning. For example, if a young man frequently uses masturbation to cope with loneliness, eventually the state of loneliness itself creates sexual arousal. 

Summary of the Evidence on Marshall and Barbaree's Integrated Theory

Marshall and Barbaree's Integrated Theory has been the subject of much research. Many of the theory's hypotheses—such as the presence of poor impulse control and a lack of sufficient social skills in sexual offenders—have been supported through research (Smallbone & Dadds, 2000). Additionally, Smallbone and Dadds (2000) found that insecure childhood attachment, especially parental attachment, can be linked to coercive sexual behavior. Thus, the theory is an important achievement. It is both innovative and has many compelling features. One of its key strengths is its ability to unite multiple influences. Even so, a number of the theory's features merit closer examination (Ward, 2000). One concern is the issue of embedded offense pathways to sexual offending behavior. There are distinct and possibly competing offense pathways (e.g., early exposure to problematic relationships, unsuccessful relationships, negative consequences for masturbation, deviant sexual fantasies to boost self-esteem and a sense of power or worth) in the model. Once these etiological pathways are identified and distinguished from one another, it becomes difficult to explain why a specific pathway leads to specific sexual rather than other offending behavior.

Another weakness relates to impulse control. In their theory, Marshall and Barbaree placed great emphasis on the loss of impulse control, stating that individuals commit sex offenses due to their failure to inhibit deviant impulses. However, the empirical evidence indicates that while some sex offenders have trouble with sexual impulse control, this is not the case for all sexual offenders. In fact, research shows that a comparably small number of sex offenders have problems with self-regulation (Proulx, Perreault, & Ouimet, 1999). Another weakness is the claim that adolescent males have difficulty distinguishing sexual drives from aggression because sexual urges and aggression are generated by the same general neurological structures. The assumption that basic human drives and capacities share neurological structures has been cast into doubt by the results of several studies (Kolb & Whishaw, 1995; Symons, 1979; Tooby & Cosmides, 1992). 

Hall and Hirschman's Quadripartite Model

Hall and Hirschman (1991) grouped sex offender personality traits and characteristics derived from other studies into four factors they believed to be most significant in the etiology of sex offending: 1) sexual arousal, 2) thought processes, 3) emotional control, and 4) personality problems or disorders. Hall and Hirschman proposed that while all four factors are important, one is generally prominent in the individual sexual offender. 

"Many sex offenders have problems with self-regulation and impulse control."

For example, Hall and Hirschman determined that it is not only sexual arousal that is driving the deviant sexual behavior, but the individual's thoughts regarding the arousal. Thought processes—particularly those involving justifications and myths—may disinhibit an individual to such an extent that deviant sexual behavior seems acceptable or even appropriate. Believing rape myths is a prime example. Negative emotional moods also often precede sexual offending, with anger being an important aspect of negative emotion for rapists and depression being the same for child molesters. These emotional states become so uncomfortable that the individual has further difficulty controlling behavior. The final factor includes negative childhood conditions that contribute to personality characteristics highly associated with personality disorders. They include traits such as selfishness, a manipulative and exploitative personality, lack of remorse, and an unstable or antisocial lifestyle. These traits interact with deviant sexual arousal, lack of emotional control, or negative thought processes and intensify their respective impacts.

Summary of the Evidence on Hall and Hirschman's Quadripartite Model

Hall and Hirschman's theory is based on sound empirical research about the traits of sex offenders, including the use of cognitive distortions, the presence of poor impulse control, and problems with self-regulation of emotions and mood. Additionally, the notion that individual offenders display contrasting problems has empirical support. Nevertheless, the theory has serious limitations. One significant shortcoming is the failure of the theory to adequately explain the relationships that exist and interactions that take place among the theory's four etiological factors. Another shortcoming is the theory's inability to identify causal mechanisms behind each factor. A third is the theory's failure to explain how the factors function as motivations to abuse (Ward, 2000; Ward, Polachek, & Beech, 2006; Stinson, Sales, & Becker, 2008). Ward (2001) also argues that Hall and Hirschman seem to confuse typology with theory. (For an explanation of "Sex Offender Typologies," see chapter 3 in the Adult section.) Taken together, these shortcomings significantly limit the theory's etiological and clinical utility.

Ward and Siegart's Pathways Model

Ward and Siegert's Pathways Model attempts to combine the best of all of the integrated theories previously mentioned. The model suggests that a number of different pathways lead an individual to engage in sexually abusive behavior. Within each pathway is a unique set of factors that contribute to the problem of sexual abuse. The theory focuses primarily on the sexual abuse of children by adults. 

Based on different symptom clusters, Ward and Siegert created five different causal pathways for the development of problematic and abusive sexual behavior:

  1. The intimacy deficit pathway describes an offender who takes advantage of an opportunity to offend if a preferred sexual partner is not available. This offender has significant problems with intimacy and turns to sex to ease feelings of loneliness.  
  2. The deviant sexual scripts pathway suggests that sex offenders have distorted thought processes that guide their sexual and intimate behaviors. This involves a fundamental confusion between sex and intimacy as well as difficulty in determining when sexual contact is appropriate or desirable.
  3. The emotional deregulation pathway is the primary cause of abusive sexual behavior with children. Offenders in this category demonstrate significant problems regulating emotional states. In this pathway, the offender experiences negative mood states that he or she is unable to manage. 
  4. The antisocial cognition pathway involves attitudes and beliefs supportive of criminal behavior. Such offenders have an antisocial lifestyle, a significant sense of entitlement, and little regard for the emotional and psychological needs of others. They commonly endorse cultural beliefs consistent with their offending lifestyle.
  5. The multiple dysfunctional mechanisms pathway involves all symptom clusters associated with the previous pathways, with no single prominent feature among them. 

In the pathways model, situational stressors serve as triggers to sexually abuse children. The specific triggers will vary according to the particular profile of causes underlying each individual's pathway. For example, for offenders who have distorted thought processes, the sexual need combined with the judgment that it is safe to abuse will result in a sexual offense. For an offender with deficits in emotional competence, intensely stressful situations can precede an offense (Ward, Polachek, & Beech, 2006).

Summary of the Evidence on Ward and Siegert's Pathways Model

This theory lacks a substantial evidential base. The data supporting the basic tenets came from other areas of psychology and there is little direct support from the sex offender research. It has also yet to be subjected to explicit evaluation. Additionally, there is no empirical justification for grouping offenders into separate categories. In fact, there is research to suggest that individuals in all five pathways share many of the same traits and they are not characteristic of only one pathway (Simon, 1997a, 1997b, 2002). 

The theory also relies heavily on cognitive distortions related to deviant sexual attitudes and beliefs. However, similar to other cognitive theories, Ward and Siegert did not fully explain how an individual moves from a thought to a behavior. Nor did they address the origin of the symptom clusters or the role of each cluster. Finally, Ward and Siegert do not address the role of pedophilia in the sexual abuse of children. They mention that offenders experience deviant sexual arousal but do not explain the origin of this arousal. Rather, they focus on the psychological variables that interact with this arousal to result in sexual offending (Stinson, Sales, & Becker, 2008). 

Nonetheless, the pathways model has a number of strengths. The model addresses some of the issues that have been empirically linked to sex offending behaviors. For example, problems with self-regulation of emotions and a sense of entitlement have been shown to be associated with sex offending behavior, though not in a causal way. Perhaps the theory's greatest strength is its indepth description of the factors involved in sexual offending and the ability to unify promising aspects of other theories. 

Malamuth's Confluence Model

The main idea behind Malamuth's Confluence Model is that two factors—sexual promiscuity and hostile masculinity—merge to result in sexually aggressive behavior. Sexual promiscuity is a preference for impersonal sex with many partners. A desire for intimacy through sex and the development of long-term relationships or monogamous sexual activity is lacking. The relevance of sexual promiscuity to sexually aggressive behavior is related to evolutionary theory. In short, natural selection has created fundamentally different psychological mechanisms in the brains of women and men with regard to sex and intimacy, resulting in the male's preference for short-term over long-term mating patterns. If men are adapted for sexual performance in impersonal contexts, then a disinterested or unwilling partner may fail to inhibit or may even entice sexual aggression. 

Hostile masculinity involves dominating and controlling personality traits, particularly in regard to women. According to Malamuth's theory, it is in women's reproductive interest to withhold sex from insufficiently invested partners. Drawing on an earlier study that found that withholding sex angers men (Buss, 1998), Malamuth theorized that if a woman repeatedly withholds sex from a man, or does so at a developmentally significant time, the male may develop a chronically hostile interpersonal style. Thus, the male will be easily angered and resort to coercion and force to assert his dominance whenever he perceives that a woman is threatening his reproductive success (Malamuth, 1996). 

Dean and Malamuth (1997) introduced a third component to the confluence model—the influence of a high-dominance, low-nurturance approach to interpersonal relationships. This personality style is distinguished by self-interested motives and goals, a lack of compassion or insensitivity, and little concern for potential harm to others (Malamuth, 1998). Malamuth suggested that the level of dominance or nurturance traits develops as a result of early childhood socialization and the incorporation of familial and cultural messages. Malamuth also believed the development of a dominant personality style was due in part to evolutionary processes (Dean & Malamuth, 1997; Malamuth, 1998). 

Summary of the Evidence on Malamuth's Confluence Model

Research on the confluence model suggests that a number of important tenets of the theory are valid. For example, a relationship between dominance and sexual aggression has been documented empirically. There is also empirical evidence that those who use sexual coercion are more likely to endorse short-term mating strategies, and that hostile masculinity is related to negative attitudes toward women (Dean & Malamuth, 1997; Malamuth et al., 1995). Research has also found that men with self-interested motives are far more likely to act on aggressive thoughts than those with more compassion or empathy (Malamuth, 1998). Still, the confluence model has limitations, many of which relate to the shortcoming of evolutionary theory, including using animal models as a basis for modeling human behavior (Stinson, Sales, & Becker, 2008). Also, the confluence model does not take into consideration situational factors, emotional dysregulation, or strong cognitive rationalizations. These and other variables that may contribute to sexual aggression have not been considered in the confluence model, and their absence from the model has not been adequately explained. 

Stinson, Sales, and Becker's Multimodal Self-Regulation Theory

Multimodal Self-Regulation Theory was recently introduced as an etiological explanation of sexual offending by Stinson, Sales, and Becker (2008). The theory integrates various psychological perspectives and implicates self-regulatory deficits as a key variable in the development of sexually inappropriate interests and behaviors. As part of the theory, Stinson, Sales, and Becker (2008) argue that significant self-regulatory deficits resulting from negative childhood experiences combine for the development of deviant sexual interest and arousal. When certain biological and temperamental vulnerabilities are also present, the individual is unable to manage his or her behavior and sexual offending can result.

Key to this theory is the premise that sexual arousal becomes linked with a deviant or inappropriate stimulus at some early point in sexual development. This occurs through the mind's attempt to label the experience of sexual arousal and to associate a source with the arousal. Since this scenario is unlikely to occur on its own, other dynamics are necessary for the connection to occur. The individual would have to normalize the experience in some way and also lack other sources to achieve the same results. Stinson, Sales, and Becker (2008) suggested that behavioral conditioning in the development of abusive sexual behaviors also occurs, as sexual gratification coupled with a lack of corrective action helps to solidify the behavior. Over time, the reinforcing effects of these practices, combined with a lack of negative consequences, will contribute to the development of a deviant sexual interest. Stinson, Sales, and Becker (2008) also suggested that cognitive beliefs and personality traits could serve as mediators in the development of deviant sexual behaviors. These include egocentricity, a need for excitement and sensation, resentment and a sense of entitlement, impulsivity, and irresponsibility. Finally, external factors (e.g., parental support for violence against women) and the development of offense-supportive cognitive beliefs (e.g., a man's right to control a woman) solidify the behavior in the individual.

Summary of the Evidence on Stinson, Sales, and Becker's Multimodal Self-Regulation Theory

Given the relatively recent introduction of the multimodal self-regulation theory, there is a paucity of empirical research regarding its validity. However, there is empirical support for many tenets of the theory, including the roles that negative developmental experiences, cognitive distortions, and a lack of emotional control play in sexual offending. Still, some of the linkages hypothesized in the theory have been criticized for being implausible (a criticism the authors themselves acknowledge) because deviant sexual interests are not found among all sex offenders, making it difficult to generalize the theory to the larger sex offender population (Stinson, Sales, & Becker, 2008). Far more evaluative research needs to be undertaken before the validity and utility of the multimodal self-regulation theory can be determined.   

"There is no simple answer to the question of why people engage in sexual offending behavior. The problem of sexual offending is too complex to attribute solely to a single theory. Multifactor theories provide greater insight into the causes of sexual offending."

Summary

The field of sex offender management has yet to find a clear explanation or cause for sexual offending behavior. Despite many unanswered questions, research has produced a number of important findings about the etiology of sexual offending:  

  1. No single factor or cause of sexual offending has yet been identified. Research suggests that a combination of factors likely contribute to sexual offending behavior.
  2. Negative or adverse conditions in an individual's early development lead to poor attachment to others, particularly caregivers, and these conditions contribute to the development of sexual offending behaviors. These negative or adverse conditions may include sexual and/or physical abuse, as well as emotional neglect or absence. 
  3. Like other behaviors, sexual abuse appears to be a learned behavior. Further, the learning of sexually abusive behavior is influenced by reinforcement and punishment. If the perceived punishment for sex offending is sufficient, the behavior is less likely to occur. However, the specific punishments needed to mitigate sexual offending remain unclear, particularly in light of the cognitive distortions maintained by many sex offenders.
  4. Many sex offenders have cognitive distortions or thinking errors, and these distorted thinking patterns appear to be involved in maintaining deviant sexual behavior. Many child victims of sexual assault who have thinking errors related to their own assault develop sexual offending behaviors as adults. These thinking errors often parallel common myths about sexual assault (e.g., there's nothing wrong with it, no harm is done, the victim wants it and enjoys it). 
  5. Repeated exposure to sexually violent pornography may contribute to hostility toward women, acceptance of rape myths, decreased empathy and compassion for victims, and an increased acceptance of physical violence toward women. Positive reinforcement for the behavior, coupled with thinking errors, increases the likelihood that these beliefs will lead to sexually abusive behaviors.
  6. Sex offenders appear to have a problem with self-regulation of emotions and moods as well as with impulse control. Self-regulation and impulse control problems both appear to be related to sexual offending behavior. However, a causal relationship has not been clearly established. 
  7. Men who use sexual coercion are more likely to engage in short-term relationships and maintain negative attitudes toward women. Men with self-interested motives are more likely to act on aggressive thoughts than those with more compassion or empathy.

It also should be noted that other etiological variables that are not addressed in this chapter have been linked to sexual offending. These include alcohol and drugs, domestic violence, and mental illness. These variables have been found to be factors in sex offending in some cases; however, there is no scientific evidence that any of these factors are the cause of sexual violence. In addition, there is evidence that some individuals who are already prone to sexual offending behavior become more likely to engage in that behavior when certain situational factors or variables are present. These factors may include limited intellectual functioning, the use of alcohol or drugs, stress within the family/home, or loss of a relationship or job. These situational factors, however, do not cause the sexual offending behavior but may increase the likelihood that it will occur in an individual who is already prone to the problem. 

Although numerous theories concerning the etiology of sexual offending have been proposed and empirically tested, knowledge about the causes of sexual offending remains somewhat rudimentary. This is due, at least in part, to two sets of factors—one related to etiological research and the other to etiological theories themselves. Two major, overwhelming shortcomings are noted from this review of the literature: the problem of sampling used in the research and a lack of intersection and balance among the different theoretical perspectives.

Much of the etiological research undertaken to date is based on populations of sex offenders who are either in treatment, in prison, or both. This is problematic because the evidence is clear that many sex offenders are never identified by authorities; hence, these studies generally represent a very small percentage of individuals who engage in sexually aggressive or abusive behavior. Many etiological studies also rely on data self-reported by sexual offenders. Because sex offenders are commonly known to engage in cognitive distortions, the validity of their self-reporting remains questionable. There may also be incentives for cooperation in treatment, such as reduced sentencing. Offenders who deny their offenses altogether typically are not included in research. Because many perpetrators who engage in sexually aggressive and abusive behaviors deny it, this implies that a large percentage of the population is ignored in research.

Equally important is the propensity of etiological theories to focus on explanations for sexual offending that reside within the individual. Most etiological theories are steeped in the traditional scientific fields of biology, psychology, and psychiatry. Hence, the focus largely has been on psychopathological and cognitive-behavioral causes of sex offending. These perspectives, in turn, have strongly influenced policy debates regarding sex offender management and intervention. Few of the integrated theories that have been proposed consider the ways in which social structures and cultural phenomena contribute to sexual offending behavior. Some theories acknowledge situational and environmental factors as related variables or mediators, but the overwhelming emphasis is related to problems within the individual. Consideration of a broader range of theoretical perspectives may be necessary to understand and effectively combat sexual offending behavior. Ending sexual violence may require knowledge and change at the individual, social, and institutional levels.

Several other dynamics identified in etiological research warrant further study. They include:

  1. Early maltreatment in childhood development and its impact on attachment.
  2. The role of distorted thinking, how thinking errors originate, and why some individuals act on these thoughts and others do not. 
  3. How sexual behavior is learned and, more specifically, the role of punishment (e.g., what punishment is most effective, when and how punishment should be administered) and reinforcement (including the lack of reinforcement for nonoffending sexual behaviors).
  4. The impact of sexually violent and exploitive images in the culture, not only in pornography but also in advertising, videos, and music (among others).

Because much of the etiological research undertaken to date is retrospective in nature, there is a clear need for prospective, longitudinal research, particularly to explore antecedents to sex offending and changes in sexually aggressive behavior over time. Efforts to employ samples that are more representative of the range of individuals who commit sex crimes also are needed, along with studies that include samples of nonoffenders and studies that incorporate the experiences of victims. Victims—both female and male—could contribute valuable information about offender motivations and behaviors through detailed disclosures of their interactions with offenders. This would also allow more opportunity to include the experiences of female victims, as opposed to the current focus on male victims who become sexual abusers. Rather than focusing on why some male victims go on to abuse others, perhaps it is time to ask why most victims, particularly females, do not go on to engage in offending behavior. Including family members associated with the offender could be useful as well. More research into the area of gender relations within the culture is also merited. There also is a need for further study regarding the integration of theories and the ways that different factors involved in sexual offending relate to one another. This need was identified by the national experts at the SOMAPI forum. Success in this area, however, requires more openness and collaboration among researchers with different theoretical perspectives and less loyalty to a particular focus or field of study.  

Notes

1 This chapter does not distinguish between offenders who sexually abuse adults and those who sexually abuse children. However, when a theory focuses specifically on one of those populations, it is noted in the discussion. In addition, this chapter does not present research findings on the etiology of sexual offending perpetrated by juveniles. (For that discussion, see chapter 2, "Etiology and Typologies of Juveniles Who Have Committed Sexual Offenses," in the Juvenile section.)

2 Feminist theorists argue that all pornography is violent because it is based on the sexual exploitation and degradation of women.

References

Aigner, M., Eher, R., Fruehwalk, S., Forttier, P., Gurierrez-Lobos, K., & Dwyer, S.M. (2000). Brain abnormalities and violent behavior. Journal of Psychology and Human Sexuality, 11, 57–64. 

Bailey, R.C. (1988). The significance of hypergyny for understanding subsistence behavior among contemporary hunters and gatherers. In B.V. Kennedy & G.M. LeMoine (Eds.), Diet and Subsistence: Current Archaeological Perspectives (pp. 57–65). Calgary, AB: University of Calgary Press.

Bain, J., Langevin, R., Dickey, R., Dickey, R., & Ben-Aron, M. (1987). Sex hormones in murderers and assaulters. Behavioral Science and the Law, 5, 95–101. 

Becker, J.V. (1998). What we know about the characteristics and treatment of adolescents who have committed sexual offenses. Child Maltreatment:  Journal of the American Professional Society on the Abuse of Children, 3, 317–329. 

Becker, J., & Murphy, W. (1998). What we know and don't know about assessing and treating sex offenders. Psychology, Public Policy and Law, 4, 116–137.

Beckmann, J., Dupont, A., Erling, I., Jacobsen, P., Mikkelsen, M., & Theilgaard, A. (1974). Report of sex chromosome abnormalities in mentally retarded male offenders including a psychological study of patients with XYY and XXYY karyo-types. Journal of Mental Deficiency Research, 18, 331–353.  

Berliner, L., & Elliot, D.M. (2002). Sexual abuse of children. In J.E.B. Meyers, L. Berliner, J. Briere, C.T. Hendriz, C. Jenny, & T.A. Reid (Eds.), The APSAC Handbook on Child Maltreatment, 2d ed. (pp. 55–78). Thousand Oaks, CA: Sage. 

Bowlby, J. (1988). Developmental psychiatry comes of age. American Journal of Psychiatry, 145, 1–10.

Briggs, F., & Hawkins, R.M.F. (1996). A comparison of the childhood experiences of convicted male child molesters and men who were sexually abused in childhood and claimed to be non-offenders. Child Abuse & Neglect, 20, 221–233.

Burgess, A.W., Hartman, C.R., & McCormack, A. (1987). Abused to abuser: Antecedents of socially deviant behaviors. American Journal of Psychiatry, 144, 1431–1436. 

Burt, M.R. (1980). Cultural myths and supports for rape. Journal of Personality and Social Psychology, 38, 217–230.

Burton, D.L. (2000). Were adolescent sex offenders children with sexual behavior problems? Sexual Abuse: A Journal of Research and Treatment, 12, 37–48.

Burton, D.L., Miller, D.L., & Schill, C.T. (2002). A social learning theory comparison of the sexual victimization of adolescent sex offenders and nonsexual male delinquents. Child Abuse & Neglect, 26, 893–907.

Buss, D.M. (1998). The psychology of human mate selection: Exploring the complexity of the strategic repertoire. In C. Crawford & D.L. Krebs (Eds.), Handbook of Evolutionary Psychology: Ideas, Issues, and Applications (pp. 405–429). Mahwah, NJ: Erlbaum. 

Check, J.V.P., & Guloien, T.H. (1989). Reported proclivity for coercive sex following repeated exposure to sexually violent pornography, nonviolent dehumanizing pornography, and erotica. In D. Zillman & J. Bryant (Eds.), Pornography: Research Advances and Policy Considerations (pp. 159–184). Hillsdale, NJ: Erlbaum. 

Chung, D. (2005). Violence, control, romance and gender equality: Young women and heterosexual relationships. Women's Studies International Forum, 28, 445–455.

Connell, R.W. (2000). Masculinities. Cambridge, England: Polity Press. 

Corley, A., Corley, M.D., Walker, J., & Walker, S. (1994). The possibility of organic left posterior hemisphere dysfunction as a contributing factor in sex offending behavior. Sexual Addiction and Compulsivity, 1, 337–346. 

Cossins, A. (2000). Masculinities, Sexualities and Child Sexual Abuse. The Hague: Kluwer Law International. 

Craissati, J., McClurg, G., & Browne, K. (2002). Characteristics of perpetrators of child sexual abuse who have been sexually victimized as children. Sexual Abuse: A Journal of Research and Treatment, 14, 225–239.

Day, K. (1994). Male mentally handicapped sex offenders. British Journal of Psychiatry, 165, 630–639. 

Dean, K.E., & Malamuth, N.M. (1997). Characteristics of men who aggress sexually and of men who imagine aggressing: Risk and moderating variables. Journal of Personality and Social Psychology, 72(2), 449–455.

Eisenman, R. (2000). Explaining sex offenders: The concept of imprinting. International Journal of Adolescence and Youth, 8, 1–9. 

Figueredo, A.J., Sales, B.D., Becker, J.V., & Kaplan, M. (2000). A Brunswikian evolutionary-developmental theory of adolescent sexual offending. Behavioral Sciences and the Law, 18, 309–329. 

Freeman-Longo, R.E. (1986). The impact of sexual victimization on males. Child Abuse & Neglect, 10, 411–414. 

Freund, K. (1990). Courtship disorder. In W.L. Marshall, D.R. Laws, & H.E. Barbaree (Eds.), Handbook of Sexual Assault:  Issues, Theories, and Treatment of the Offender (pp. 195–207). New York: Plenum Press.

Freund, K., & Kuban, M. (1994). The basis of the abused abuser theory of pedophilia: A further elaboration on an earlier study. Archives of Sexual Behavior, 23, 553–563. 

Freund, K., Scher, H., & Hucker, S. (1983). The courtship disorders: A further investigation. Archives of Sexual Behavior, 27, 433–443.

Freund, K., Scher, H., & Hucker, S.J. (1984). The courtship disorders: A further investigation. Archives of Sexual Behavior, 13, 133–139.

Galski, T., Thornton, K.E., & Shumsky, D. (1990). Brain dysfunction in sex offenders. Journal of Offender Rehabilitation, 16, 65–79.

Garland, R.J., & Dougher, M.J. (1990). The abused/abuser hypothesis of child sexual abuse: A critical review of theory and research. In J.R. Feierman (Ed.), Pedophilia: Biosocial Dimensions (pp. 488–509). New York: Springer.

Graham, K. (1996). The childhood victimization of sex offenders: An under-estimated issue. International Journal of Offender Therapy and Comparative Criminology, 40(3), 192–203.

Hall, G.C.N., & Hirschman, R. (1991). Toward a theory of sexual aggression: A quadripartite model. Journal of Consulting and Clinical Psychology, 59, 662–669.

Hanson, R.K. (1999). Working with sex offenders: A personal view. Journal of Sexual Aggression, 4, 81–93. 

Hanson, R.K., Gizzarelli, R., & Scott, H. (1994). The attitudes of incest offenders: Sexual entitlement and acceptance of sex with children. Criminal Justice and Behavior, 21, 187–202.

Harrison, L.E., Clayton-Smith, J., & Bailey, S. (2001). Exploring the complex relationship between adolescent sexual offending and sex chromosome abnormality. Psychiatric Genetics, 11, 5–10. 

Howells, K. (1994). Child sexual abuse: Finkelhor's precondition model revisited. Psychology, Crime and Law, 1, 201–214.

Howitt, D. (1995). Pornography and the paedophile: Is it criminogenic? British Journal of Medical Psychology, 68(1), 15–27.

Hucker, S., & Bain, J. (1990). Androgenic hormones and sexual assault. In W.L. Marshall & D.R. Laws (Eds.), Handbook of Sexual Assault: Issues, Theories and Treatment of the Offender (pp. 93–102). New York: Plenum Press.

Hucker, S., Langevin, R., Wortman, G., Bain, J., Handy, L., Chambers, J., & Wright, S. (1986). Neuropsychological impairment in pedophiles. Canadian Journal of Behavioral Science, 18, 440–448.

Hummel, P., Thomke, V., Oldenburger, H.A., & Specht, F. (2000). Male adolescent sex offenders against children: Similarities and differences between those offenders with and those without a history of sexual abuse. Journal of Adolescence, 23, 305–317.

Hunter, J.A., Jr., & Becker, J.V. (1994). The role of deviant sexual arousal in juvenile sexual offending: Etiology, evaluation, and treatment. Criminal Justice and Behavior, 21, 132–149. 

Jenkins, A. (1990). Invitations to Responsibility: The Therapeutic Engagement of Men Who Are Violent and Abusive. Adelaide, South Australia: Dulwich Centre Publications.

Jonson-Reid, M., & Way, I. (2001). Adolescent sexual offenders: Incidence of childhood maltreatment, serious emotional disturbance, and prior offenses. American Journal of Orthopsychiatry, 71(1), 120–130.

Keenan, T., & Ward, T. (2000). A theory of mind perspective on cognitive, affective, and intimacy deficits in child sex offenders. Sexual Abuse: A Journal of Research and Treatment, 12, 49–60.

Knudsen, D.D. (1988). Child sexual abuse and pornography: Is there a relationship? Journal of Family Violence, 3, 253–267.

Kolb, B., & Whisaw, I.W. (1995). Fundamentals of Human Neuropsychology, 4th ed. New York: W.H. Freeman & Co.

Lahey, K.A. (1991). Pornography and harm: Learning to listen to women. International Journal of Law & Psychiatry, 14, 117–131.

Lalumiere, M.L., Chalmers, L.J., Quinsey, V.L., & Seto, M.C. (1996). A test of the mate deprivation hypothesis of sexual coercion. Ethology and Sociobiology, 17, 299–318.

Lalumiere, M.L., & Quinsey, V.L. (1994). The discriminability of rapists from non-sex offenders using phallometric measures: A meta-analysis. Criminal Justice and Behavior, 21, 150–175.

Langevin, R., Bain, J., Wortzman, G., Hucker, S., Dickey, R., & Wright, P. (1988). Sexual sadism:  Brain, blood, and behavior. Annals of the New York Academy of Sciences, 528, 163–171. 

Langevin, R., Wortzman, G., Dickey, R., Wright, P., & Handy, L. (1988). Neuropsychological impairment in incest offenders. Annals of Sex Research, 1, 401–415. 

Laws, D.R., & Marshall, W.L. (1990). A conditioning theory of the etiology and maintenance of deviant sexual preference and behavior. In W.L. Marshall, D.R. Laws, & H.E. Barbaree (Eds.), Handbook of Sexual Assault: Issues, Theories, and Treatment of the Offender (pp. 209–230). New York: Plenum Press.

Leguizamo, A. (2002). The object relations and victimization histories of juvenile sex offenders. In B.K. Schwartz (Ed.), The Sex Offender: Current Treatment Modalities and Systems Issues, vol. 4 (pp. 4-1– 4-39). Kingston, NJ: Civic Research Institute. 

Linz, D.G., Donnerstein, E., & Penrod, S. (1988). Effects of long-term exposure to violent and sexually degrading depictions of women. Journal of Personality and Social Psychology, 55, 758–768. 

Lonsway, K.A., & Fitzgerald, L.F. (1994). Rape myths: In review. Psychology of Woman Quarterly, 18, 133–164.

Looman, J., & Marshall, W.L. (2005). Sexual arousal in rapists. Criminal Justice and Behavior, 32, 367–389.

Malamuth, N.M. (1996). The confluence model of sexual aggression: Feminist and evolutionary perspectives. In D.M. Buss & N.M. Malamuth (Eds.), Sex, Power, Conflict: Evolutionary and Feminist Perspectives (pp. 269–295). New York: Oxford University Press. 

Malamuth, N.M. (1998). The confluence model as an organizing framework for research on sexually aggressive men: Risk moderators, imagined aggression, and pornography consumption. In R.G. Green & E. Donnerstein (Eds.), Human Aggression: Theories, Research, and Implications for Social Policy (pp. 229–245). San Diego, CA: Academic Press. 

Malamuth, N.M., & Check, J.V.P. (1980). Penile tumescence and perceptual responses to rape as a function of victim's perceived reactions. Journal of Applied Social Psychology, 10(6), 528–547.

Malamuth, N.M., & Check, J.V.P. (1981). The effects of mass media exposure on acceptance of violence against women: A field experiment. Journal of Research in Personality, 15, 536–446. 

Malamuth, N.M., & Check, J.V.P. (1985). The effects of aggressive pornography on beliefs in rape myths: Individual differences. Journal of Research in Personality, 19, 299–320.

Malamuth, N.M., & Heilmann, M.F. (1998). Evolutionary psychology and sexual aggression. In C. Crawford & D.L. Krebs (Eds.), Handbook of Evolutionary Psychology: Ideas, Issues, and Applications (pp. 515–542). Mahwah, NJ: Erlbaum.

Malamuth, N.M., Linz, D., Heavey, C.L., Barnes, G., & Acker, M. (1995). Using the confluence model of sexual aggression to predict men's conflict with women: A 10 year follow-up study. Journal of Personality and Social Psychology, 69, 353–369.

Marshall, W.L. (1988). The use of sexually explicit stimuli by rapists, child molesters, and nonoffenders. Journal of Sex Research, 25, 267–288.

Marshall, W.L. (1989) Intimacy, loneliness, and sex offenders. Behavior Research and Therapy, 27, 491–504. 

Marshall, W.L., Anderson, D., & Champaigne, F. (1997). Self-esteem and its relationship to sexual offending. Psychology, Crime, & Law, 3, 161–186.

Marshall, W.L., Anderson, D., & Fernandez, Y.M. (1999). Cognitive Behavioral Treatment of Sex Offenders. Chichester, England: Wiley.

Marshall, W.L., & Barbaree, H.E. (1990). An integrated theory of the etiology of sexual offending. In W.L. Marshall, D.R. Laws, & H.E. Barbaree (Eds.), Handbook of Sexual Assault: Issues, Theories, and Treatment of the Offender (pp. 257–275). New York: Plenum Press.

Marshall, W.L., & Marshall, L.E. (2000). The origins of sex offending. Trauma, Violence, and Abuse, 1, 250–263.

Murray, G.C., McKenzie, K., Quigley, A., Matheson, E., Michie, A.M., & Lindsay, W.R. (2001). A comparison of the neuropsychological profiles of adult male sex offenders and non-offenders with a learning disability. Journal of Sexual Aggression, 7, 57–64.

Norris, J. (1991). Social influence effects on responses to sexually explicit material containing violence. Journal of Sex Research, 28, 67–76.

O'Callaghan, D. (1998). Practice issues in working with young abusers who have learning disabilities. Child Abuse Review, 7, 435–448.

Proulx, J., Perreault, C., & Ouimet, M. (1999). Pathways in the offending process of extrafamilial sexual child molesters. Sexual Abuse: A Journal of Research and Treatment, 11, 117–129.

Putnam, F.W. (2003). Ten year research updates review: Child sexual abuse. Journal of the American Academy of Child and Adolescent Psychiatry, 42, 269–278.

Quinsey, V.L., & Lalumiere, M.L. (1995). Evolutionary perspectives on sexual offending. Sexual Abuse: A Journal of Research and Treatment, 7, 301–315.

Ryan. G. (2002). Victims who go on to victimize others: No simple explanations. Child Abuse & Neglect, 26, 891–892.

Scott, M.B., & Lyman, S.M. (1968). Accounts. American Sociological Review, 33, 46–61.

Scully, D. (1990). Understanding Sexual Violence: A Study of Convicted Rapists. Boston: Unwin Hyman.

Segal, Z.V., & Stermac, L.E. (1990). The role of cognition in sexual assault. In W.L. Marshall, D.R. Laws, & H.E. Barbaree (Eds.), Handbook of Sexual Assault: Issues, Theories, and Treatment of the Offender (pp. 161–174). New York: Plenum Press.

Seghorn, T.K., Prentky, R.A., & Boucher, R.J. (1987). Childhood sexual abuse in the lives of sexually aggressive offenders. Journal of the American Academy of Child and Adolescent Psychiatry, 26, 262–267.

Seidman, B.T., Marshall, W.L., Hudson, S.M., & Robertson, P.J. (1994). An examination of intimacy and loneliness in sex offenders. Journal of Interpersonal Violence, 9, 518–534.

Seto, M.C., Cantor, J.M., & Blanchard, R. (2006). Child pornography offenses are a valid diagnostic indicator of pedophilia. Journal of Abnormal Psychology, 115, 610–615.

Simon, L.M.J. (1997a). Do criminal offenders specialize in crime types? Applied and Preventative Psychology, 6, 35–53.

Simon, L.M.J. (1997b). The myth of sex offender specialization: An empirical analysis. New England Journal on Criminal and Civil Commitment, 23, 387–403.

Simon, L.M.J. (2002). An examination of the assumptions of specialization, mental disorder, and dangerousness in sex offenders. Behavioral Sciences and the Law, 18, 275–308.

Sinclair, R.C., Lee, T., & Johnson, T.E. (1995). The effect of social-comparison feedback on aggressive responses to erotic and aggressive films. Journal of Applied Social Psychology, 25, 818–837.

Smallbone, S.W., & Dadds, M.R. (2000). Attachment and coercive sexual behavior. Sexual Abuse Journal of Research and Treatment, 12(1), 3–15.

Stinson, J.D., Sales, B.D., & Becker, J.V. (2008). Sex Offending: Causal Theories to Inform Research, Prevention and Treatment. Washington, DC: American Psychological Association. 

Sykes, G., & Matza, D. (1957). Techniques of neutralization: A theory of delinquency. American Sociological Review, 22, 664–670.

Symons, D. (1979). The Evolution of Human Sexuality. New York: Oxford University Press.

Thornhill, R., & Palmer, C.T. (2000). A Natural History of Rape: Biological Bases of Sexual Coercion. Cambridge, MA: MIT Press.

Tooby, J., & Cosmides, L. (1992). The psychological foundations of culture. In J.H. Barkow, L. Cosmides, & J. Tooby (Eds.), The Adapted Mind: Evolutionary Psychology and the Generation of Culture (pp. 19–36). New York: Oxford University Press.

Travis, C.B. (2003). Evolution, Gender, and Rape. Cambridge, MA: MIT Press.

Veneziano, C., Veneziano, L., & LeGrand, S. (2000). The relationship between adolescent sex offender behaviors and victim characteristics with prior victimization. Journal of Interpersonal Violence, 15, 363–371.

Ward, T. (2000). Sex offenders' cognitive distortions as implicit theories. Aggression and Violent Behavior, 5, 491–507.

Ward, T. (2001). A critique of Hall & Hirschman's quadripartite model of child sexual abuse. Psychology, Crime, & Law, 7, 333–350.

Ward, T., & Hudson, S.M. (1998). A model of the relapse process in sex offenders. Journal of Interpersonal Violence, 13, 700–725.

Ward, T., Hudson, S.M., & Keenan, T. (1998). A self-regulation model of the sexual offense process. Sexual Abuse: A Journal of Research and Treatment, 10, 141–157.

Ward, T., Hudson, S., Marshall, W., & Siegert, R. (1995). Attachment styles and intimacy deficits in sexual offenders: A theoretical framework. Sexual Abuse: A Journal of Research and Treatment, 7(4), 317–335.

Ward, T., & Keenan, T. (1999). Child molesters' implicit theories. Journal of Interpersonal Violence, 14, 821–838.

Ward, T., Polachek, D.L.L., & Beech, A.R. (2006). Theories of Sexual Offending. Chichester, England: Wiley.

White, M. (2000). Reflections on Narrative Practice: Essays and Interviews. Adelaide, South Australia: Dulwich Centre Publications. 

Worling, J.R. (1995). Adolescent sex offenders against females: Differences based on the age of their victims. International Journal of Offender Therapy and Comparative Criminology, 39, 276–293.

Wright, P., Nobrega, J., Langevin, R., & Wortzman, G. (1990). Brain density and symmetry in pedophilic and sexually aggressive offenders. Annals of Sex Research, 3, 319–328.

Zgourides, G., Monto, M., & Harris, R. (1997). Correlates of adolescent male sexual offense: Prior adult sexual contact, sexual attitudes, and use of sexually explicit materials. International Journal of Offender Therapy and Comparative Criminology, 41, 272–283.