Gender asymmetry and symmetry in Brazilian intimate partner violence research

This study aims to analyze intimate partner violence from the gender symmetry and asymmetry concepts. Seventy-nine papers were selected for analysis, and most were published in the 2006-2014 period (78.5%). The fields of journals that addressed the subject were psychology (32.9%) followed by public health (27.9%) and nursing (27.6%). Of the researchers, 46.8% work with the feminist theoretical line discourse, whose gender approach is asymmetrical. They mostly produce qualitative research with a sample consisting of women only (81.1%), and 78.3% collected data from violence victims’ support services. When looking at the characteristics of the studies conducted by researchers from the theoretical line of family sociologists who advocate gender symmetry (25.3%), qualitative and quantitative approaches were used in similar proportions. Bidirectional violence was identified in 80% of this research. We noted a strong leadership of the feminist theoretical line, which was identified in the discourses of the researchers. We stress the relevance of the discussion of the data with different theoretical frameworks, since analysis in isolation, regardless of the field, runs the risk of being biased and thus weaken the results.


Introduction
Intimate partner violence (IPV) is understood as any behavior in an intimate relationship that causes physical, psychological or sexual harm to those involved in the relationship 1 .A historical path of the feminist and women's movements for legislation against impunity in the national and international setting seeking to give visibility to this problem 2,3 to make this violence become the object of public coping policies.
It is an area of technical-scientific knowledge, relevant to the point of generating intervention tools, based on its social relevance, figures and vulnerabilities 4 .In the United States, 24% of intimate relationships report some violence, and in half of these cases, acts are reciprocal between men and women.In cases of non-reciprocity, women were the perpetrators in about 70% of the cases 5 .
In Latin America, domestic violence affects 25% to 50% of women, while in Brazil, 23% of women are subjected to domestic violence, with an estimate of women suffering an assault every four minutes, and in 85.5% of the cases of physical violence against women, perpetrators are their partners 6 .Studies conducted in Canada and the United States, IPV by victim's gender shows that women are more likely than men to be injured and suffer more severe forms of violence during assaults 7,8 .
Women experiencing partner violence are more likely to report frequent headaches, chronic pain, sleeping disorders, limited activities, and poorer physical health compared to those who do not.Despite the severe consequences of IPV in both genders, most research investigating intimate partner violence 9,10 is geared to women as victims and men as perpetrators 11,12 , and are mostly carried out in developed countries 4,10,13 .
Although the predominance of women who suffer intimate partner violence compared to men is evident 14,15 , few studies are investigating men involved in intimate partner violence in Brazil.Heterosexual men have difficulty admitting the violence suffered 16 , and women, as perpetrators, use psychological violence more, through manipulation and threats, which hinders identification 17 .
Two theoretical conceptions are considered to understand the dynamics of intimate partner violence: the feminist theory, which focuses on violence as an asymmetrical gender issue, and family sociologists, whose central focus is the dynamics of the marital relationship, symmetri-cally considering the couple relationship aspects.Casimiro 18 emphasizes the relevance of explaining that this perspective includes sociologists and authors of related areas, such as psychologists, family therapists, criminologists, among others.
In studying the international scene of IPV, Michael P. Johnson warned that the feminist theoretical line and that of family sociologists discreetly follow a research type pattern, in which the research profile is often a determining factor of the results found.He also stresses the need to show the relevance of making distinctions in studies and theoretical lines, so that researchers do not generalize information carelessly from one context to another 19 , given that the research produced underpins the formulation of public policies and care programs.
Thus, recognizing and understanding each theoretical line will enable the development of more sensitive and comprehensive theories, since the differentiation may force us to question the tendency, as well as provide us with a better theoretical and practical understanding of the nature of intimate partner violence.
Given the above, this study aims to analyze intimate partner violence based on the conceptions of gender symmetry and asymmetry shown in Brazilian research.

Selection of material
A systematic review was carried out from June to October of 2015 in the databases MEDLINE (Medical Literature Analysis and Retrieval System Online), PsycINFO (Psychological Abstracts), LILACS (Latin American and Caribbean Literature in Health Sciences), SciELO (Scientific Electronic Library Online), Sociological Abstracts, Scopus, and Web of Science.The search used combinations in Portuguese, English and Spanish of the terms "Battered Women", "Domestic Violence", "intimate partner violence", "conjugal violence", "Conjugal Ill-Treatment", "gender asymmetry" and "gender symmetry".
Paper inclusion criterion for review were: (1) original papers investigating intimate partner violence; (2) the language of publication should be Portuguese, English or Spanish; (3) papers that had been published in these databases in the period 2000-2014; and (4) research should have been conducted with the Brazilian population.
The exclusion criteria were: (1) investigating other types of violence, such as that committed by women against children, the elderly, animals, by gangs or war-related; (2) violence in the context of mental health and alcohol/drugs; (3) programs of care and services for victims; (4) violence against the LGBTQ community; (5) violence in the context of STD/AIDS; (6)  research on the social representation of IPV for partners or professionals; (7) focus on specific groups, indigenous, military, people living in the streets and sex workers (8) intimate partner violence against pregnant women or puerperae (9)  other exclusion, such as violence committed by persons with other relationships with the victim other than intimate partner, femicide, product disclosure, presentation of questionnaires and IPV measurement scales, among others; (10) literature reviews, editorials, communications, and book summaries; and (11) papers not located by the authors (Figure 1).

Data review
Seventy-four papers were selected based on the inclusion and exclusion criteria.The references for these studies were analyzed to identify other studies that met the established inclusion criteria.In this process, five papers were included, resulting in 79 papers for reading.The analysis of the studies occurred in two stages, as described below.
In the first stage, the papers were analyzed under the following aspects: • Year of publication; • Knowledge area of the journal; • Brazilian regions where research is conducted: the states surveyed were grouped in macro-regions (South, Southeast, Midwest, North and Northeast), in multiple states and not informed; • Language: the language in which the paper was published; • Types of violence: all types of violence mentioned by the researchers were included: physical, psychological, sexual, property-related violence, destructive acts, controlling behavior, threat, jealousy and false imprisonment; • Methodological approach: studies were considered quantitative when involving statistical inferences; they were qualitative when they included human relationships and activities represented in collective or individual consciences; and qualitative-quantitative when both approaches were used in a complementary way, according to the concepts of Minayo & Sanches 20 ; • Place of research: health service, residence, NGOs, private practice, universities, workplace and support services for victims of violence (houses shelters, police stations, forum, Women's Care Integrated Center (CERAM) and Special Criminal Courts); • Gender of the respondents; • Directional characterization of violence perpetrated: men against women, women against men or bidirectional.
In the second step, the papers were divided into gender asymmetry and symmetry as per Johnson [21][22][23][24][25] , configured in two categories defined a priori for analysis.
The first category, called "gender asymmetry", is based on the feminist perspective that identifies the root of violence in patriarchal power, which promotes male inequality and domination in gender relationships 26 .The phenomenon is considered asymmetrical and unidirectional, of men against women.Thus, intergender relationships, both in the domestic private space and the public space of civil relationships, are characterized by an asymmetrical relationship, in which inequality is explained by physical, sexual and biological differences, justifying the "nature" of female subjection 27 .Thus studies are governed by ideas that men use violence to gain control of their partners.The main theoretical current advocating the perspective in which intimate partner violence is influenced by gender asymmetry is the feminist.Papers for this category were selected when the following topics were identified: • The asymmetric power between genders manifests violence; • They consider that men use violence as a way of controlling women; • They argue that women use violence as a way of resisting or protection; • They believe that violence against women is influenced by the macho culture of a patriarchal society; The other category of analysis, called "gender symmetry", developed by family sociologists, states that violence is rooted in the structure of society and in the family system itself, and violence is an aspect of how to relate 28 .Thus, they believe that violence is caused by sociostructural factors, including stress, unemployment, financial insecurity, health problems and permissive social norms that tolerate violence as a means of resolving conflicts.The term "symmetry" describes that both men and women can exercise violence since both can be perpetrators in a con-jugal relationship.However, it is important to emphasize that this is not a "radial" or "radiated" symmetry, as if the types and ways of violence, their frequency, objectives and consequences 1,520 papers for analysis were identical 18 .Based on this, papers with the following topics were identified as belonging to this category: • They believe that both men and women can use violence; • They believe that violence arises from the power play between couples; • They understand that conflicts are naturalized in today's society; • They consider the use of violence as a way of resolving conflicts; • The associated factors are strong determinants of violence.

Results
Seventy-nine papers were selected for analysis, with the highest prevalence between 2006 and 2014 (78.5%).Among the 48 journals that addressed the topic of violence, the majority occurred in journals of psychology (32.9%) followed by public health (27.9%) and nursing (27.6%).In isolation, the Revista de Saúde Pública had the highest number of publications, with seven papers.As for the language of the publications, 93.7% were in Portuguese, followed by English (5.1%) and Spanish (1.3%), totaling 6.4% of articles in foreign languages and without translation into Portuguese, and of these, four were published in international journals and one in the Cadernos de Saúde Pública.
The surveys were concentrated in the Northeast and Southeast regions of Brazil, both with 27.9%, followed by the South with 22.8%.When the state is observed, São Paulo stands out with 15 studies, followed by Rio Grande do Sul with 12.In the Midwest region, all the surveys occurred in the Federal District.Physical and psychological violence was reported in 31.6% and 27.0% of publications, respectively, followed by sexual violence (18.1%) and property-related violence (4.7%) (Table 1).
Table 2 below shows the theoretical trend identified in the researchers' discourse: 46.8% described that violence occurred asymmetrically in power between the genders, whose phenomenon is derived from the historical process produced and reproduced by social structures of domination fueled by patriarchal ideology, while 25.3% identified in the literature a symmetric tendency, based on gender equality, in which the gender issue is not taken into account in the discussion of intimate partner violence.
In 21.5% of the scientific works, it was not possible to identify a trend in any of the two the- We observed that researchers working with the feminist theoretical line discourse, whose gender approach is asymmetrical, produce mostly qualitative research with a sample consisting only of women (81.1%), and men were interviewed 16,2% of the time.In total, 54.1% of the participants were selected in services providing care to victims of domestic violence and 18.9% in health services.
It is important to note that in the asymmetric studies, 83.8% of the victims are women, and in 16.2% of them, violence occurs bidirectionally, that is, both men and women reported committing some violence against their partners.The fact that no study of this theoretical line referred to the violence that women commit against their partners causes a stir.
When observing whether the characteristics of the studies carried out by researchers of the theoretical line of family sociologists who advocate for gender symmetry, we note that the qualitative and quantitative approaches were used in similar proportions.Research subjects were well diversified: couples represented 35%, women 25%, men only and both genders 20% each, respectively.The places for selecting and collecting information from the participants were residence (30%), private practices (20%) and services for the care and protection of victims of violence (20%).The direction of violence was more evident in the bidirectional category, totaling 80% of the studies (Table 3).
The studies that traverse the two categories are scarce (n = 5), they have a qualitative approach (n = 4) and evidence bidirectional violence (n = 4).Studies that did not specify either the symmetric or asymmetric category had a quantitative approach in 58.2% of the cases, and 82.3% were performed with female subjects.Men were pointed out as the perpetrators of violence in 88.2% of these surveys.Psychology, public health and nursing stood out among the knowledge areas of the journals that published papers on the subject, together accounting for 87.4% of the areas identified; the Revista de Saúde Pública alone led with seven papers.However, these data contrast when the systematic review includes publications outside Brazil, findings by Lourenço et al. 31 , in a review of papers on international intimate partners published between 2006 and 2011, which identified only 5.4% of published studies in journals in the area of psychology and 1.9% in public health, while 44.3% were published in journals specialized in violence.Worth noting is the lack of specific Brazilian journals on violence.
Of the 79 publications, five papers were found in foreign languages, four in English and one in Spanish.It should be noted that the studies described in the papers were carried out in Brazil, predominantly in the Southeast, Northeast and South regions, accounting for 78.6%.Noteworthy is the lack of research on IPV in the northern region, in the databases and periods studied.This fact can be explained, in part, by the higher concentration of research centers in other regions.Physical (31.6%), psychological (27%) and sexual (18.1%) violence was the most evident in the papers analyzed.These acts are usually the most studied when investigating IPV, as shown in research conducted in the urban region of Brasília 32 , which showed the psychological violence among the most prevalent types in women for episodes during life (80.2%).
Compared to physical and sexual violence, data from the National Survey on Violence Against Women in the United States 33 show that most rape victims know their rapist.Among all the female victims identified by the survey, 43% were raped by the current or former intimate partner.Another study 10 , also conducted in the U.S., which included men in their sample, found that one in seven men and one in four women reported episodes of physical violence and (or) forced sex by an intimate partner during life.It should be noted that, in this study, the prevalence of physical violence by intimate partners always shows the highest rates for females.
As shown, women are subjected to the most severe forms of violence and a significant part of the papers addresses women as victims and men as aggressors, but also considers the possibility of two-way violence.This issue raises a discussion on the conceptions of gender symmetry and asymmetry in violence, identified in 72% of the papers under study.
Gender asymmetry was the most evidenced (46.8%) in all the papers analyzed.This discourse is supported by the feminist theoretical line researchers, who understand that the hierarchy of gender and power influence the experiences, the consequences and the context where IPV occurs.In this conception, the qualitative approaches were the most used (81.1%), as well as data collection techniques through semi-structured interviews, case studies and focus groups, where the places of research were the services providing care to victims of domestic violence, health services, private practice and NGOs (78.3%), interviewing mainly women.
The findings of this study are consistent with Johnson's contention that there is a trend for this group to undertake studies in public agencies, such as police stations, therapeutic groups, NGOs, health services, and shelters [21][22][23] .Archer 34 compared samples of women residing in shelters and the general population in order to perceive the reported differences in conjugal violence, concluding that women interviewed at these locations reported much higher rates of aggression by partners than women in the general population.
Generally, the profile of surveys conducted with samples from these places is qualitative with a woman-centered analysis, since they are considered the primary target of conjugal violence.This set of factors can influence the final result of research, mainly because these places share the function of providing care to victims of violence, either in health rehabilitation or life protection.Studying the violence by intimate partners in samples from these services reveals many cases of asymmetric violence 25 .
In the papers that follow the feminist theoretical line, the male subject was studied separately in six papers, five of which were selected from services providing care and protection to victims of violence, since they were previously identified as perpetrators.This shows that research with men is scarce, as evidenced by Grossi et al. 35 : from the 286 publications shown, only 7% (16) investigate men or masculinities, although they have been emerging in the international scene since the 1980s.
In this logic, men are doomed to strengthen the hardened role of perpetrator, reinforcing the results of the surveys, which could demonstrate nothing other than the asymmetric violence of men against women.As evidenced by the current research, whose asymmetric papers pointed almost exclusively to unidirectional violence from men to women (83.8%).
Although the theoretical feminist line has found two-way violence in six studies, they do not recognize the possibility of women committing violence against their partners.For this reason, the authors' main discussions were that the violent acts practiced by the women were intended for self-defense [36][37][38][39] .
However, in the United States, authors 13,40 affirm that IPV in men is a reality when 26.8% of men suffered physical violence from intimate partners.Research in this area is recent in Brazil; however, the informants of this type of violence are women who claim attacking their partners, as evidenced by Anacleto et al. 41 , who found a prevalence of 13.7% for moderate physical violence in men and 9.8% in women.
Lindner et al. 42 affirms that it is essential to study this type of violence.Recognizing men not only as authors but also as people who suffer will allow the knowledge of factors that permeate violent marital relationships, culminating in the development of models of care and public policies aimed at men and women in intimate partner violence situations.
The theoretical perspective that recognizes the possibility of men being victims is that of family sociologists, who show gender symmetry in the violent relationships.In this study, it was possible to identify 25.3% of the publications as belonging to this group.
Internationally, studies of this theoretical line are structured in quantitative approaches, using random sampling method through population surveys, with unintentional and representative samples 43,44 , unlike that found in this study, whose qualitative and quantitative approaches were used in similar proportions (50% and 45%, respectively).This can be explained by the fact that conducting these types of studies requires a significant infrastructure with human and financial resources that often do not match the reality of the financing of research of this magnitude in the country.Unicamp's thematic journal draws attention to the difficulty faced by Brazilian scholars in research, enumerating a series of issues that hinder research activities; these are issues related organization, institutional culture and infrastructure 45 .
Another characteristic of these theoretical lines is the use of validated instruments to obtain the data; this pattern was found in this review, which found that 83.3% of the surveys that used a validated instrument opted for the Conflict Tactic Scale (CTS) 36,41,[46][47][48][49][50][51][52][53] to identify gender symmetry.In 1990, Straus 28 pointed to this direction, in which CTS was the most widely used instrument for investigating issues related to intimate and family violence.The same is found 10 years later in a review of the literature elaborated by Archer 34 , in which 76 of the 82 studies that this author examines resorted to the CTS.
It is important to highlight the limitations of this instrument, given its extensive use.Feminist authors criticize the inability of the document to consider the context, motivations, meanings and consequences of the violence.Thus, the inferences made by researchers who collect their data end up tampering with the role of gender in the victimization and aggression of what has occurred 54 .The criticisms are in the interpretations of the results, and not in the reliability of the instrument; the decontextualization of inferences become dangerous.
The proportions of the place and gender of the respondents found in the papers aimed at gender symmetry, in general, were homogeneous in their proportions, unlike the direction of violence, in which 80% of the authors pointed to bidirectional IPV.Thus, attention is focused on the dynamics of family or conjugal unity, which differs from what was found in studies conducted by the feminist line, which addressed violence bidirectionality in only 16.2% of the studies.When, in feminist studies, women were found to commit violent acts against their partners, the authors justify the use of these acts in self-defense, without discussing the possibility of women committing the violent act without holding the position of a victim.There are indeed differences between the experiences of women and men experiencing violence, both sides of the issue should be accepted as viable fields of investigation, thus considering possibilities for the problem of conjugal violence to be fully understood 18 .
This review showed the strong leadership of the feminist theoretical line identified in the researchers' discourses.It is observed that, in both theoretical lines, the chosen method, place of study and research subjects may influence the results obtained.At this moment, the relevance of data contextualization with several theoretical references is emphasized, because the separate analysis, by whatever the area, risks being weak.
The main limitations of this study are the selection of a limited number of databases and the use of grouped descriptors to set a more approximate set of studies by theme.Even using a large number of databases and combinations of descriptors and keywords, we cannot affirm that the topic has been exhausted in the face of relevant publications in manuals, books, theses and dissertations that were not researched.
It is believed that there are different causal factors of intimate partner violence, one of which is defined in the gender oppression, which characterizes the asymmetric violence advocated by feminist theorists, and another one defined by relational dynamics, in which violence is a phenomenon beyond itself, as something that transcends what is called "victim" and "perpetrator".It is suggested that the research encompasses the situations experienced by those involved, trying to understand the dynamics of the couple because it is considered that this is the methodological path that can elucidate the understanding and ways of preventing violence by intimate partners.

Collaborations
TB Conceição and EBS Coelho worked on the design of the research, methods and drafting of the paper, and CC Bolsoni and SR Lindner worked on the methods and final drafting of the paper.

Figure 1 .
Figure 1.Flowchart of the systematic review on intimate partner violence.

Table 1 .
Characterization of articles according to year of publication, study areas of journals, research site, language of publication and types of violence researched.

Table 2 .
Violence according to the theoretical line of gender.The researchers' discourse addressed factors and theories of both theoretical lines in only 6.3% of the works.
oretical lines surveyed; the papers had a descriptive, comparative character, addressing violence as pathology, focusing a discussion on the asso-ciated factors or consequences.

Table 3 .
Asymmetry and gender symmetry, according to the approach, place of participant selection, sex of the interviewees and direction of violence in the researches conducted in Brazil, 2016.