undermines their belief that intimate partner violence is an extension of men's desire to subjugate women; "one of the explanations for denying the evidence on gender symmetry is to defend feminism in general. this is because a key step in the effort to achieve an equalitarian society is to bring about recognition of the harm that a patriarchal system causes. the removal of patriarchy as the main cause of ipv weakens a dramatic example of the harmful effects of patriarchy." straus also points out that despite being critical of the cts, numerous feminist researchers use it for their own research, and that it was cts based studies which first illustrated and brought to the public's attention the extent of the battered women problem in the 1970s. battered husband syndrome the most controversial aspect of female perpetrated intimate partner violence is the theory of "battered husband syndrome". in reaction to the findings of the u.s. national family violence survey in 1975, suzanne k. steinmetz wrote an article in 1977 in which she coined the term as a correlative to "battered wife syndrome". steinmetz conducted several empirical investigations prior to writing her article. using a broad-based non-representative sample of fifty-four couples, steinmetz found male perpetrated intimate partner violence at a rate of 47% and female perpetrated intimate partner violence at a rate of 43%. she further found that while 39% of husbands had thrown objects, 31% of wives had done likewise; 31% of husbands had pushed or shoved their partner, compared to 32% of wives; 20% of husbands had hit their wives, 20% of wives had hit their husbands; 10% of husbands had hit their wives with an object, 10% of wives had hit their husbands with an object. in another study, using a sample of fifty-two canadian college students, steinmetz found male perpetrated ipv at a rate of 23% and female perpetrated intimate partner violence at a rate of 21%. further investigation found that 21% of both husbands and wives had thrown objects; 17% of husbands had pushed or shoved, compared to 13% of wives; 13% of husbands had hit their wives, 13% of wives had hit their husbands; 10% of husbands had hit their wives with an object, 12% of wives had hit their husbands with an object.: 501–503 in a third study, using a random sample of ninety-four people, steinmetz found male perpetrated intimate partner violence at a rate of 32% and female perpetrated intimate partner violence at a rate of 28%. further investigation found that 31% of husbands had thrown objects compared to 25% of wives; 22% of husbands had pushed or shoved, compared to 18% of wives; 17% of husbands had hit their wives, 12% of wives had hit their husbands; 12% of husbands had hit their wives with an object, 14% of wives had hit their husbands with an object. these findings led steinmetz to conclude that intimate partner violence was roughly reciprocal between husbands and wives, with a similar level of intentionality between men and women; "women are as likely to select physical conflict to resolve marital conflict as are men ... women have the potential to commit acts of violence and under certain circumstances, they do carry out these acts".: 505 according to malcolm j. george, steinmetz' article "represented a point of departure and antithetical challenge to the otherwise pervasive view of the seemingly universality of female vulnerability in the face of male hegemony exposed by the cases of battered wives". steinmetz' colleague, richard j. gelles, publicly addressed confusion caused by the research and father's rights groups "significant distortion" of the data in his public response domestic violence: not an even playing field, "indeed, men are hit by their wives, they are injured, and some are killed. but, are all men hit by women battered? no. men who beat their wives, who use emotional abuse and blackmail to control their wives, and are then hit or even harmed, cannot be considered battered men. a battered man is one who is physically injured by a wife or partner and has not physically struck or psychologically provoked her." steinmetz' claims in her article, and her use of the phrase "battered husband syndrome" in particular, aroused a great deal of controversy, with many scholars criticizing research flaws in her work. in particular, she was criticized for not differentiating between verbal and physical aggression or between intentionality and action (wanting to hit was considered the same as actually hitting). for example, david finkelhor argues that steinmetz' methodology was unacceptably unscientific. he argues that her work looks at all violence as fundamentally similar; there is no differentiation between male and female violence, or violence against a child and violence against a wife, such as a mother spanking a child and a father breaking a mother's ribs. finkelhor sees this as especially important insofar as it does not allow a differentiation between ongoing systemic abuse and once-off violence, or between disciplining a child and beating a partner. causes of female-perpetrated ipv linda kelly writes that "in conceding that women do engage in acts of domestic violence, female use of violence is justified as self-defense—a lifesaving reaction of women who are being physically attacked by their male partners. the development of the battered woman syndrome as a defense for crimes committed against abusive male partners, including homicide, evidences the wide acceptance of a woman's use of violence as self-defense." the theory is that when women commit intimate partner violence, it is probably justified because they were previously victims and, therefore, the male was the "primary aggressor." thus, the woman's violent behavior is caused by her background as a victim. juan carlos ramírez explains that given the socially accepted model of femininity as one of submission, passivity and abnegation, whatever behavior does not follow this stereotype will be perceived in an exaggerated manner as abnormal and violent. thus, women will be perceived as disproportionately aggressive even if merely defending themselves. multiple studies indicate that the majority of women's intimate partner violence against male partners is in the context of being victimized. a 2010 systematic review of the literature on women's perpetration of intimate partner violence found that anger, self-defense and retaliation were common motivations but that distinguishing between self-defense and retaliation was difficult. other studies indicate that only a small proportion of women identify their intimate partner violence as self-defense. for example, in a 1996 study of 1,978 people in england, 21% of women who admitted to committing intimate partner violence gave self-defense as a reason. more prevalent reasons were "get through to" (53%), "something said" (52%) and "make do something" (26%). in a five-year study of 978 college students from california, concluded in 1997, martin s. fiebert and denise m. gonzalez found an intimate partner violence rate amongst women of 20%. within this group, perpetrators were asked to select reasons as to why they assaulted their partner, with the option to choose multiple reasons. the breakdown of reasons had "my partner wasn't sensitive to my needs" as the most prevalent (46%). also found more frequently than self-defense were "i wished to gain my partner's attention" (44%) and "my partner was not listening to me" (43%). looking beyond self-defense, studies have found a range of causes for female-perpetrated intimate partner violence. writing of the feminist theory which regards reinforcement of patriarchy as a primary cause of intimate partner violence, murray a. straus writes "patriarchy and male dominance in the family are clearly among the causes of intimate partner violence, but there are many others. however, with rare exceptions, current offender treatment programs are based on the assumption that the primary cause is male dominance. thus, they proceed under an erroneous assumption. illustrative of this fallacious single-cause approach are the state-mandated offender treatment programs that forbid treating other causes, such as inadequate anger management skills." in 2006, rose a. medeiros and murray a. straus conducted a study using a sample of 854 students (312 men and 542 women) from two american universities. they identified fourteen specific risk factors common amongst both males and females who had committed intimate partner violence; poor anger management, antisocial personality disorders, borderline personality disorders, pattern of dominating relationships, substance abuse, criminal history, posttraumatic stress disorders, depression, communication problems, jealousy, sexual abuse as a child, stress, and a general attitudinal approval of partner violence. straus states that most female perpetrated intimate partner violence is not motivated by self-defense, but by a desire to control their partners. in 2014, a study involving 1,104 male and female students in their late teens and early twenties found that women are more likely than men to be controlling and aggressive towards their partners, more likely to demonstrate a desire to control their partners, and more likely to use physical aggression in ensuring that control. the main author of the study, elizabeth bates, wrote "this suggests that intimate partner violence may not be motivated by patriarchal values and needs to be studied within the context of other forms of aggression, which has potential implications for interventions." other explanations for both male and female-perpetrated intimate partner violence include psychopathology, anger, revenge, skill deficiency, head injuries, biochemical imbalances, feelings of powerlessness, lack of resources, and frustration. researchers have also found a correlation between the availability of domestic violence services, increased access to divorce, higher earnings for women, and improved laws and enforcement regarding domestic violence with declines in female perpetrated intimate partner violence. criticism many critics have rejected the research cited by men's rights activists and dispute their claims that such violence is gender symmetrical, arguing that mras' focus on women's violence against men stems from a misogynistic political agenda to minimize the issue of men's violence against women and to undermine services to abused women. current literature on intimate partner violence has alternative viewpoints in relation to gender symmetry theory. a 2008 review published in journal of violence and victims found that although less serious situational violence or altercation was equal for both genders, more serious and violent abuse was perpetrated by men. it was also found that women's physical violence was more likely motivated by self-defense or fear while men's was more likely motivated by control. a 2011 systematic review from the journal of trauma violence abuse also found that the common motives for female on male domestic violence were anger, a need for attention, or as a response to their partner's own violence. another 2011 review published in the journal of aggression and violent behavior also found that although minor domestic violence was equal, more severe violence was perpetrated by men. it was also found that men were more likely to beat up, choke or strangle their partners, while women were more likely to throw things at their partner, slap, kick, bite, punch, or hit with an object. researchers have also found different outcomes in men and women in response to intimate partner violence. a 2012 review from the journal psychology of violence found that women suffered disproportionately as a result of ipv especially in terms of injuries, fear, and posttraumatic stress.: 42–45 the review also found that 70% of female victims in one of their studies were "very frightened" in response to intimate partner violence from their partners, but 85% of male victims cited "no fear". the review also found that intimate partner violence mediated the satisfaction of the relationship for women but it did not do so for men. gender asymmetry is also consistent with government findings. according to government statistics from the us department of justice, male perpetrators constituted 96% of federal prosecution on domestic violence. another report by the us department of justice on non-fatal domestic violence from 2003 to 2012 found that 76 percent of domestic violence was committed against women and 24 percent were committed against men. dr. ruth m. mann of the university of windsor, an expert on sociology and criminology, stated her opposition to the gender symmetry theory of domestic violence on the grounds that women as well as children are the main victims in the "annual pile up" (coyle, 2001) of victims being murdered by intimate partners and fathers throughout canada (aucoin, 2005; ogrodnik, 2006). legal activism in 2005, the national coalition for men filed a lawsuit against the state of california for funding domestic violence shelters for women only. in 2008,