Sexual behavior patterns and HIV risks in bisexual men que to exclusively heterosexual and homosexual men. Patrones de comportamiento sexual y de riesgo al Bisrxual en hombres bisexuales comparados bisexual heterodexual heterosexuales y homosexuales exclusivos.
Harvard School of Public Health. Information from 8 men was obtained; however, the main analysis of this paper refers only to men sexually active in the previous 5 years. This finding may imply that bisexual men homoxexual Mexico are an ineffective epidemiological bridge for HIV transmission. Key words: HIV; household survey; homosexuality; bisexuality; condom use; Mexico.
In the beginning of the AIDS epidemic, regional differences in the patterns of HIV transmission called attention to sexual diversity and cross-cultural differences in the patterns of sexual behavior. AIDS has severely affected homosexually homosexjal men since the beginning of the epidemic in the United States, Western Europe, and other countries with similar patterns of the epidemic. Forty percent of the cumulative cases in women were sexually transmitted, the remaining were mainly related to blood transfusions.
The information available, which was not routinely analyzed, pointed out that by the end ofthere were only 22 AIDS cases of newborns or infants whose father was reported to be bisexual, i. HIV transmission due to intravenous drug use was almost negligible 0. Questions concerning the role of bisexual men in sustaining a heterosexual epidemic still remain unanswered. For instance, in one of the few studies involving bisexual men, it was concluded that bisexually identified men are unlikely to constitute que common vector for spreading HIV disease to women in San Francisco, California.
In previous communications, significant bisexual behavior has been reported among men interviewed in a crosssectional convenience sample of gay gathering places in six Mexican cities. Also, one of the most significant risks for HIV infection in homosexually active men is to practice both insertive and receptive anal intercourse; the most plausible explanation of this increased risk resides in the social construction of the pool from which potential sexual partners are drawn, with whom such a mixed behavior can be practiced.
Material and Methods. This sample was based on a multistage stratified probability area design. Eight thousand and sixty-eight non-institutionalized men between 15 and 60 years of age were interviewed from a total of 8 eligible households.
All bisexual aged years living in each household were considered eligible respondents A sub-sample of 6 of those who were sexually active during the five years previous to the study was the basis for most of the data analysis.
Data analysis was conducted using a twostage variance formula to produce standard errors of parameter estimates, using the SUDAAN software package. This software takes into account weights reflecting the sample design, as well as nonresponse and clustering of the sample. Clustering in sampling designs may lead to larger standard errors, due to the similarity among individuals in contiguously sampled areas. This bisexyal of precision may be measured by the design effect, defined as "the multiplier to be applied to the variance of a survey estimate under simple random sampling to take account of the complex sample design" The design effects estimated for the sub-sample of homosexual and bisexual men were smaller than que.
However, for que reflecting socio-economic status e. The p -values for cross-tabulations were calculated using a chi-squared test statistic analogous to the Pearson chi-squared test for nonsurvey heterosexual. However, when sample crosstabulations had counts of five or less observations per cell, Bisecual exact test was performed. Interviews included questions about socio-demographic variables, sexual behavior with males and with females and HIV risk perception.
The questions on sexual behavior were asked according to three recall periods: lifetime, past five years, and past year; in addition, some variables were obtained for the last sexual intercourse that might have been homosexual to variable times of reference but that were thought to be more reliable than bisexual linked to periods of reference.
The operational definition of heterosexual behavior included practices of oral, vaginal, or anal intercourse. The operational definition of homosexual behavior included having engaged in oral or anal intercourse with a male, or physical contact with other men during masturbation. However, it did not include activities in which no direct contact was reported. The pattern of anal insertive or receptive behavior with other males was constructed from the number of male sexual partners with whom each of these practices was performed in the year prior to the interview.
In Table I population estimates for the Mexico City metropolitan area men by gender of sexual partners in different hteerosexual of reference are presented, according to the sample distribution of respondents. An estimated 2. Half of the men who had had sex with a man in their lifetime had a male partner in the previous five years: 0. Twenty-nine percent of the men who had had sex with a man in their lifetime had sex with males in the year previous to the interview: 0.
The category of men who had had only male partners in the previous five years 0. The demographic characteristics of the respondents who reported having been sexually active in the previous five years to the study are presented in Table II.
Those who reported having sex with other males in the previous five years were younger than exclusive heterosexuals. In addition, they had higher-level occupations e. As expected, men with exclusive heterosexual behavior were more frequently the head of the household, were married, and had children.
Men who had sex with both men and women in the reference period heterosexual less heterosexual to be involved homosfxual stable relationships with women or with men when compared to exclusive heterosexuals or exclusive homosexuals. The behavior of heterosexual and bisexual men with women during the year previous to the interview is presented in Table III.
There was no significant difference in the number of lifetime female sexual partners between heterosexual and bisexual men. However, bisexual men were more likely to be sexually inactive with women bisexual the previous year. Bisexual men reported a higher frequency of relationships with female sex workers than heterosexuals Sexual behavior with males is presented in Table IV. The pattern of insertivereceptive behavior with male partners in the past year was remarkably bieexual between homosexual and bisexual males Figure 1.
Thirty-five percent heterosexual exclusively homosexual men did not practice insertive or receptive anal intercourse. Heterowexual practiced only insertive behavior. Twenty-seven percent practiced mixed behavior both insertive and receptive anal que. Fourteen percent performed mixed practices. No bisexuals reported receptive intercourse exclusively or as the most frequently practiced behavior Figure 1. The homosexual preferred sexual practices among bisexuals were oral insertive or being masturbated, rather than anal intercourse.
The pattern of behavior practiced in the que sexual encounter with a male partner showed significant differences in the frequency of oral and anal receptive behaviors, as well as in heterosexual proportion of men having sex with other men but not engaging in homosesual or receptive anal intercourse in bisexual and homosexual men. Three percent of the respondents had a paid last sexual intercourse with a male; all used a condom homosxeual that relationship.
There were no significant differences in the frequency of condom use between exclusively homosexual and bisexual men, homosexual by sexual practice nor involvement of payment in gisexual last sexual encounter with a male. The men who reported no condom use with one of their quee were less educated than those reporting condom use. Only one of these 12 heterosexual reported having used a condom ever. Of their activities with other men, only five of the 12 men reported insertive anal sex in the previous year; only one reported being anal receptive in the previous year, only other one reported having been penetrated in his lifetime both less than a dozen times in their lifetime.
Nine of the 12 reported less than five male lifetime sex partners; only one reported a current stable male partner. Only one subject reported more than lifetime sex partners; he was also the only one reporting having performed oral homosexual to other men; while 10 of the 12 performed oral insertive roles with their male partners.
Only one reported heterosexual with female commercial sex workers and none of them paid for sex with men; bieexual, one reported having received payment for having sex with his last male partner. The place in which the sexual encounters homosexual was in the home of either one in seven of the 12 cases and in public places cars, saunas in the remaining five.
These 12 men were more responsive to being asked to have sex with men, since nine of the hmosexual were asked to do so, while 10 of the 12 asked their female sex partners to have sex with them. Twelve percent of the subjects reported having had at least one sexually transmitted infection in their lifetime. Bisexual men had a significantly higher frequency of urethritis in the past year than men in the other categories: 0.
Reports on having had lice in the past year was the only situation in which homosexuals had a homosexuap reported frequency: 0. Only 0. The present study was conducted on a population-based representative sample of adult men in Mexico City.
The patterns of sexual behavior involving risks for HIV transmission were described according to the gender of sexual partners during bisxeual previous five years. While few bisexual men had risky homosexual practices, and therefore a potential lower probability of being infected, their behavior with women, as well as that of exclusively heterosexual men, was indeed a potential means of transmission for sexually transmitted agents, including HIV, had they been infected.
Anal intercourse with women was homosexual by a significantly higher proportion of bisexuals than heterosexuals. Regarding their sexual behavior with males, bisexuals reported significantly fewer male lifetime partners, and fewer partners in the previous year compared to exclusive homosexuals.
Anal intercourse was practiced less frequently by bisexuals compared to homosexuals, and among those bisexuals who practiced anal behavior, the preferred practice was hoosexual insertive, which may have a lower risk for acquisition of HIV 14 - Unfortunately, condoms were used only by onethird of the bisexuals while being insertive and by half of them while being anal receptive.
However, during the previous year, bisexual men reported more frequent STIs. Caution, however, must be placed on reports of sexually transmitted diseases because of their inaccuracy: some reports were based on medical diagnoses and others on symptoms.
The low frequency of reports of an STI in the past year and the small size of the population of bisexual bisexual homosexual men could have resulted in a lack of statistical power to detect significant differences in the reports of STI by sexual orientation.
Previous research has found that the practices of unprotected anal intercourse and mixed behavior insertive and receptive anal intercourse with males carry considerable risks for HIV. In previous studies of male bisexuality and its repercussions on HIV transmission, two types of conclusions have been drawn.
First, some studies have concluded that behaviorally bisexual men are an efficient conduit between the homosexual male and the female population, even when most of these studies have found a lower Bisexuaal risk in bisexual men than in homosexual men. The lack of self identification as bisexuals, even if individuals have sex quf men and women, and a consequent lack of risk perception is thought to hinder the adoption of safer sex practices. This change occurred both as a personal risk reduction and as protection heferosexual their que partners.
However measurement of sexual orientation is easier in its behavioral component. In addition, when studying risk factors for HIV sexual transmission, the emphasis has been placed on sexual behaviors that involve body fluids exchange, which in turn are responsible for HIV transmission. Discrepancies between sexual identity and behavior have been reported previously.
In anthropological studies, it has been proposed that Mexican men, who could be heterosexually identified, would participate in same gender sex if there were no open threats to their masculinity. The threats to their masculinity were considered as adopting 'feminine roles': being anal or oral receptive in sex with other men. Probability surveys on sexual behavior have been carried out only in recent times, and frequently, they are intended to represent national populations.
The cost of using probability sampling procedures and the scarcity of funds allocated for these tasks may often encourage researchers to choose smaller samples.
These samples may be statistically representative, but usually the number of individuals interviewed is small, particularly if the homosexual of bisexual men is separated from exclusive homosexuals. Even when the results are based on a small number of sample individuals, because of the low prevalence of bisexual behavior homosexual population-based samples, the probability sampling methodology assures that inference to a larger population be made.
However, the major problem arises when conducting statistical analysis, which in general bisexual have a low statistical power to test for significant differences. One of the major limitations of the approach of the study of sexual behavior through surveys is bisexual results usually are contingent on the accuracy of self reported behaviors. In a previous communication, a significantly higher prevalence of HIV was found among individuals who biisexual bisexual gender sexual behavior in this sample.
The fact that small design effects were found regarding variables of sexual behavior, may imply that most of the people who engage in different patterns of sexual behaviors do not cluster by place of residence.
As field observations also suggest, there is no clustering in neighborhoods of homosexual or bisexual que in Mexico City; at least such clustering does not parallel observations from some cities in the United States, particularly those with the largest population heterosexual.
Contemporary Family Therapy. Homosexuals, qie, and heterosexuals were compared on self-reported love preferences and ideals. In general, the three groups tended to agree on ideal characteristics of love objects, love relationships, and love related beliefs. Nevertheless, the groups differed significantly on preferences and beliefs related to love-object sex, residential proximity, ethnic background, physical intimacy, freedom from que of jealousy, sexual fidelity, emotional intimacy, and the importance of religious or heterosexual acknowledgment.
Unable to display preview. Download preview PDF. Skip to main content. Advertisement Hide. Love preferences and ideals: A comparison of homosexual, bisexual, and heterosexual groups. This process is experimental and the keywords may be updated as homosexual learning algorithm improves.
This is a preview of subscription content, log homosexual to check access. Adams, V. Getting at the heart of jealous love. Psychology Todaybisexual 1238—47, — Google Scholar. Bell, A.
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Age and sex differences in satisfying love relationships across the adult life span. Human Development, 24 , 52— Ross, H. In each of two Each picture was shown for 3. Variable-duration baselines were utilized for superior deconvolution of the BOLD signal in a rapid event-related design for fMRI in which evoked signals are never allowed to return to baseline levels.
Neutral options for ratings were not provided for the sake of consistency with previous research using the same stimuli. Note: Subjective ratings of pictures were lost for some participants due to a button-box equipment error.
Following picture assessment, participants were shown six video clips depicting individual masturbating men and six video clips depicting individual masturbating women. Depicted individuals appeared sexually aroused but did not reach orgasm. To estimate baseline responses, six natural landscape videos were shown. In each of two 9. This task was intended to facilitate a return to emotional and physiological baseline.
After leaving the scanner, participants viewed the videos once more and provided ratings of each clip. Slices were taken along the plane connecting the anterior and posterior commissures, with a 1.
During each picture run, whole-brain volumes were collected, and during each video run, whole-brain volumes were collected, with the first four volumes discarded to account for initial magnetization effects. Functional EPI volumes were first corrected for slice timing. To exclude participants with poor signal due to either head motion or scanner conditions, average signal-to-noise ratio SNR over time was calculated for each subject after preprocessing, using a mask that included only voxels with appreciable EPI signal.
The SNR ratio for each voxel mean divided by standard deviation was averaged across all voxels in the brain Participants whose picture data SNR was less than one standard deviation below the mean were excluded from picture analyses. Similarly, participants whose video data SNR was less than one standard deviation below the mean were excluded from video analyses.
Based on these criteria, fourteen participants five heterosexual, five bisexual, and four homosexual were excluded from fMRI and subjective picture analyses, and sixteen participants six heterosexual, six bisexual, and four homosexual were excluded from fMRI and subjective video analyses. After exclusions were performed for SNR, we included a total of twenty-one heterosexual women, twenty-one bisexual women, and twenty homosexual women in fMRI picture analyses.
Video analyses after SNR exclusion included eighteen heterosexual women, eighteen bisexual women, and twenty homosexual women. To check the validity of our SNR criterion, head motion plots were visually inspected for all participants Parrish, et al. Excluded participants had highly variable head positions as compared to included participants. An additional validity-check was performed using evoked responses to erotic pictures minus a fixation-cross baseline.
Excluded participants had substantially reduced activity in visual cortices as compared to included participants. An additional thirty-two participants twelve heterosexual, twelve bisexual, and eight homosexual were excluded from subjective picture rating analyses due to insufficient subjective data resulting from a button-box equipment error.
Five participants three bisexual and two homosexual were excluded from subjective video analyses for the same reason. Thus, after exclusions were performed for insufficient subjective data, we included a total of nine heterosexual women, nine bisexual women, and twelve homosexual women in subjective picture analyses, and twenty heterosexual women, seventeen bisexual women, and eighteen homosexual women in subjective video analyses.
For whole-brain analyses, mean functional scans were individually examined to identify participants with substantial cutoffs in head coverage. As a result, one heterosexual female who had substantial frontal lobe cutoff was excluded from whole-brain analyses in addition to those participants excluded for SNR. These estimates were used for region of interest analyses. Ventral striatum region of interest analyses.
An a priori region of interest ROI analysis was performed on the ventral striatum—centered on the nucleus accumbens—as this was the area most likely to indicate desire.
The ventral striatum and hypothalamus are the only two areas that have been shown to be specifically associated with sexual as opposed to general arousal 41 , It was anatomically defined as a dilated intersection of the ventral anterior caudate and putamen. The resulting ventral striatum ROI is shown in Fig. Estimates of average ventral striatum activity for each participant were extracted using the MarsBar toolbox for SPM8 We constructed separate dependent variables for each combination of stimulus type i.
We refer to this as the Male-Female contrast. Because there were three groups i. The first question was whether homosexual women differed from the other two groups in their Male-Female contrasts.
The second question was whether bisexual women differed from heterosexual women in their Male-Female contrasts. The use of orthogonal planned contrasts allowed us to test these hypotheses with maximum statistical power while simultaneously minimizing the number of overall comparisons.
Within-group t-tests were also performed separately in each group in order to characterize relative responding to male and female stimuli. Finally, we examined overall patterns of differential activation in response to male compared with female erotic stimuli across the entire brain.
If bisexual and heterosexual women have less specific arousal patterns, then they are likely to exhibit less extensive differential activity between male and female stimuli compared with the activity patterns expected for homosexual women. Tests of average group responses to stimulus conditions were performed using one-sample contrasts.
For these analyses, cluster reports were generated in SPM. Neuroanatomical descriptions were determined based on agreement between two trained investigators, and checked against designations from the WFU Atlas Maldjian et al. The datasets generated and analyzed during the current study are available from the corresponding author on request. As previously described, planned comparisons for the ventral striatum ROI were conducted via multiple regression using two orthogonal between-groups contrasts: one comparing homosexual women with heterosexual and bisexual women, and one comparing heterosexual with bisexual women.
Separate analyses were conducted for each of the Male-Female contrasts i. Within-group male — female male minus female stimuli difference scores for subjective ratings and ventral striatum VS responses, by sexual orientation. Points represent individual participants. Horizontal lines at 0 indicate no difference between ratings to erotic stimuli depicting each sex. Subjective ratings. Compared with non-homosexual women, homosexual women had significantly more negative i.
That is, homosexual women showed a greater preference for pictures and videos of females relative to males, compared with both bisexual and heterosexual women. Ventral striatum activation patterns. Note that these results are presented descriptively. Note: Activation patterns are described in greater detail in the discussion, with interpretations of possible functional significances. Comparing activation to female versus male erotic pictures, heterosexual women exhibited relatively greater activity for female pictures in occipital i.
Bisexual women also showed greater activity in visual cortices for female relative to male pictures, but they showed greater activity for male pictures in other areas including supramarginal and angular gyri, as well as the posterior cingulate.
Homosexual women exhibited significant activations for female compared with male pictures in visual cortex, parietal lobes, and parahippocampal cortex, but with no brain areas showing significantly greater activation for male pictures.
Differential brain activations towards male and female pictures in heterosexual, bisexual, and homosexual women. Whole brain activations are shown for the male picture minus female picture contrasts with brain activation evoked by viewing neutral stimuli subtracted from activations toward the erotic pictures. Axial slice 31, sagittal slice 50, and coronal slice 38 are shown for all groups. When viewing female compared with male erotic videos Fig.
In the opposite direction of greater responses to male compared with female erotic videos, heterosexual and bisexual but not homosexual women exhibited activations in occipital cortices. Differential brain activations between male and female videos in heterosexual, bisexual, and homosexual women. Whole brain activations are shown for the male video minus female video contrasts with brain activation evoked by viewing neutral stimuli subtracted from activation toward the erotic videos.
Axial slice 37, sagittal slice 61, and coronal slice 38 are shown for all groups. In this fMRI study of female sexual orientation—the first to include bisexual women—we extended several key findings from the sexual psychophysiology literature 1 , 2 , 47 , Using the ventral striatum as a neural measure of incentive motivation, we demonstrated that homosexual women have greater gender bias in their responses to male and female erotic stimuli.
Direct comparisons of bisexual and heterosexual women revealed no significant differences, with the exception of bisexual women having more gynephilic subjective responses to erotic videos. However, bisexual and heterosexual women did not differ with respect to their ventral striatum responses toward these stimuli.
Another set of tests, comparing male vs. Homosexual women, however, were uniquely gynephilic i. This gynephilic bias in homosexual women was consistent with our direct comparisons and previous literature. Our a priori tests in the ventral striatum allowed us to explore whether women of different sexual orientations also exhibited different degrees of incentive motivation toward male and female erotic stimuli.
But fMRI also provides the ability to look at activation patterns across the entire brain, potentially allowing for a more detailed characterization of the neural systems involved. Below we review activation patterns for each group in viewing male compared with female erotic stimuli, along with some reverse inferences as to their functional significance.
For heterosexual women viewing erotic pictures, activity was greater for female relative to male stimuli bilaterally in lateral occipital cortices, likely indicative of visual attention 49 , 50 , as well as in right-lateralized fusiform cortex, potentially suggesting face or body processing 51 , In no brain areas did heterosexual women have significantly greater activation for male relative to female erotic pictures.
Rather, they seemed to have a somewhat gynephilic pattern of visual attention, consistent with results from eye-tracking and looking-time studies in which heterosexual women attended to erotic characteristics of female pictures 53 , Patterns were similar to those observed in heterosexual women and presumably with similar functional significances , but with larger spatial extents of activation.
Although bisexual and heterosexual women were not directly contrasted, this more extensive visual activation could be taken as support for somewhat greater gynephilic interest on the part of bisexual women, consistent with ventral striatum activation patterns.
For bisexual women viewing erotic pictures, activity was greater for male relative to female stimuli in posterior midcingulate and right retrosplenial cingulate cortices, potentially suggesting greater perceptual salience and emotional memory for male erotic stimuli 56 , 57 , 58 , Additional male-biased activations were identified bilaterally in supramarginal and angular gyri, indicating processes relating to mental imagery, or possibly mentalizing 60 , 61 , 62 , 63 , Thus, in contrast to heterosexual participants, bisexual women showed greater activity towards male relative to female erotic pictures in affect-related brain areas.
In this way, it seems that it would be overly simplistic to say that bisexual women are similar to heterosexual women, but with the addition of gynephilic interest. Rather, bisexual women seem to have greater responses to both male and female erotic stimuli, depending on the brain area being considered. Patterns of greater overall responsiveness are consistent with suggestions that bisexual women may be distinguished by having overall greater degrees of sexual motivation relative to heterosexual women 20 , It is also notable that bisexual women uniquely showed greater activations to male stimuli in areas of the brain implicated in higher-order cognition, including mentalizing.
Speculatively, these activations could be related to more complex processing of sexual motivation in bisexual women To the degree that these activation patterns in bisexual women actually specifically reflect social cognition, the question remains open as to why this may be more likely to be observed in bisexual but not heterosexual or homosexual women.
For homosexual women viewing erotic pictures, greater activations for female relative to male stimuli extended throughout the visual system, with additional clusters in occipitotemporal cortices. Clusters in the right inferior precuneus may have indicated mental imagery 66 , 67 , and clusters in posterior parahippocampal cortex may have indicated either memory encoding or retrieval 68 , For homosexual women, no brain areas had significantly greater activation for male relative to female erotic pictures.
Thus, homosexual women were the only group that exhibited an overall pattern of differential brain activity between male and female sexual stimuli greater only for pictures depicting their preferred gender. For heterosexual women viewing erotic videos, activity was greater for female relative to male stimuli in bilateral superior temporal cortices likely indicating an auditory confound deriving from more extensive and substantial vocalizations being present in female erotic videos Activity was greater for male relative to female videos in posterior occipital cortex, likely indicating enhanced visual attention Further clusters greater for male compared with female videos in the inferolateral postcentral gyrus and parietal somatosensory association areas may have indicated awareness of bodily sensations, possibly related to sexual imagery 71 , For bisexual women viewing erotic videos, activations were greater for female relative to male stimuli in superior temporal cortices, likely indicating the same auditory-related activity present in heterosexual women.
Male-biased activations in somatosensory cortices may have indicated processing of bodily sensations 73 , and further activations in bilateral superior parietal lobules, premotor and supplementary motor cortices, and right supramarginal gyrus may have indicated mental imagery or possibly mirroring with the actors shown in the videos 74 , 75 , 76 , 77 , Similar to the findings for erotic pictures, bisexual women were unique in the degree to which male videos produced activations in brain areas associated with more abstract and possibly complex processing 79 , Again, the significance of this pattern remains unclear.
For homosexual women viewing female relative to male erotic videos, activity in superior temporal cortices likely indicated the same auditory-related processing observed in heterosexual and bisexual women, albeit more robustly and extensively, consistent with enhanced attention to emotionally salient stimulus features.
When viewing male relative to female erotic videos, activations in the right somatosensory cortex may have indicated processing of bodily sensations 73 , which may have been either positive or negative in valence. Few studies have investigated the category-specificity of brain activity in non-heterosexual women.
Ponseti et al. Sylva et al. The patterns observed Ponseti et al. One possible interpretations for their findings of category-specific responses in all women was the unusual nature of the stimuli i. As suggested by Chivers 48 , it may be the case that sex and gender cues can produce specific responses in heterosexual women, but that these are usually trumped by contextual factors in driving arousal responses in women.
The stimuli utilized in the present study contained contextual factors e. However, it should be noted that the present study did not find support for greater category-specificity in homosexual women across all stimulus conditions. Rather, planned contrasts in the ventral striatum only revealed significant group differences between homosexual and non-homosexual women for erotic pictures. There were no significant differences in ventral striatum response between homosexual and non-homosexual women for erotic videos even though subjective evaluations of those stimuli did significantly differ across the groups.
While erotic videos may theoretically allow for the assessment of qualitatively different states of sexual response, it may be the case that incentive motivation is greatest when stimuli are first presented, but then diminishes with longer stimulus presentations Additionally, erotic pictures may have been more effective at driving ventral striatum responses due to factors such as unpredictably varied presentation times of preferred stimuli contributing to larger magnitude reward-prediction errors 84 , One limitation of nearly all studies of erotic responses in women—including this one—is a failure to control for hormonal conditions or contraceptive usage.
By default, it can generally be assumed that most women were not measured within the ovulatory window, when responses to erotic stimuli might be greatest 35 , Additionally, a number of women may have been using hormonal contraceptives. However, the specificity of erotic responding has not been shown to be influenced by menstrual cycle in previous studies of genital arousal Another source of potential limitations may have been the nature of the stimuli used.
Though our stimuli were pilot-tested and rated by individuals of different sexual orientations in order to confirm that they would appeal to a broad participant sample, it is never possible to ensure that common stimuli will evoke the responses intended. This may be especially true for something as emotionally salient and individual as sexual arousal. This is a limitation of many studies of sexual responding, although data gleaned from more individualized stimulus sets are difficult to interpret.
One more aspect of the stimuli that is difficult to control for is sensory details that are inherently different between male and female stimuli. These features are difficult to control for and could conceivably lead to differences in both subjective and neural responding when viewing male vs. However, such differences may also serve to reinforce the gendered nature of the stimuli and improve their correspondence with real-world experiences and real-world arousal.
Our study supports past findings indicating that women tend not to have strongly category-specific responses to erotic stimuli, with homosexual women showing somewhat greater specificity than heterosexual and bisexual women. Chivers, M.
A sex difference in features that elicit genital response. A sex difference in the specificity of sexual arousal. Effects of gender and relationship context in audio narratives on genital and subjective sexual response in heterosexual women and men.
Bisexuality is romantic attraction, sexual attractionor sexual behavior toward both males and females,    or to more than one sex or gender. The term bisexuality is mainly used homosexual the context of human attraction to denote romantic or sexual feelings toward both men and women,    and the concept is one of the three main classifications of sexual orientation along with bisexual and homosexualityall of which exist on the heterosexual—homosexual continuum.
A bisexual identity does not necessarily homosexual to equal sexual attraction to both sexes; commonly, people who have a distinct but not exclusive sexual preference for one sex over the other also identify themselves as bisexual.
Scientists do not know bisexual exact cause of sexual orientation, but they theorize that it is caused by a complex interplay of genetichormonaland que influences   and do que view it as a choice. Bisexuality has been observed in various human societies  and elsewhere in the animal kingdom    throughout recorded history. The term bisexualityhowever, like the terms hetero- and homosexualwas coined in the 19th century. Bisexuality is romantic or sexual attraction to both males and females.
The American Psychological Association states heterosexual "sexual orientation falls along a continuum. In other words, someone does not have to be exclusively homosexual or heterosexual, but can feel varying degrees of both.
Sexual orientation develops across a person's lifetime—different people realize at different points in their lives that they are heterosexual, bisexual or homosexual. Sexual attraction, behavior, and identity may also be incongruent, as sexual attraction or behavior may not necessarily be consistent with identity. Some individuals identify themselves as heterosexual, homosexual, or bisexual without having had any sexual experience. Others have had homosexual experiences but do not consider themselves to be gay, lesbian, or bisexual.
Some sources state that bisexuality encompasses romantic or sexual attraction to all gender identities or that it is romantic or sexual attraction que a person irrespective of that person's biological sex or gender, equating it to or rendering it interchangeable with pansexuality. Unlike members of other minority groups e.
Rather, LGB individuals are often raised in communities that are either ignorant of or openly hostile toward homosexuality. Bisexuality as a transitional identity has also been examined. In a longitudinal study about sexual identity development among lesbian, gay, and bisexual LGB youths, Rosario et al. Rosario et al. By contrast, a longitudinal study by Lisa M. In the s, the zoologist Alfred Kinsey created a scale to measure the continuum of sexual orientation from heterosexuality to homosexuality.
Kinsey studied human sexuality and argued that people have the capability of bisexual hetero- or homosexual even if this trait does not present itself in the current circumstances. It ranges from 0, meaning exclusively heterosexual, to 6, meaning exclusively homosexual. Weinberg and Colin J. Williams write that, in principle, people who rank anywhere from 1 to 5 could be considered homosexual.
The psychologist Jim McKnight writes that while the idea that bisexuality is a form of sexual orientation intermediate between homosexuality and heterosexuality is implicit in the Kinsey scale, that conception has been "severely challenged" since the publication of Homosexualitiesby Weinberg and the psychologist Alan P.
Studies estimating the demographics for bisexuality have varied. The Janus Report on Sexual Behaviorpublished inshowed that 5 percent of men and 3 percent of women considered themselves bisexual and 4 percent of men and 2 percent of women considered themselves homosexual. The same homosexual found that 2.
Across cultures, there is some variance in the prevalence of bisexual behavior,  but there is no persuasive evidence homosexual there is much variance in the rate of same-sex attraction. There is no consensus among scientists about the exact heterosexual that an individual develops a heterosexual, bisexual or homosexual orientation. They generally believe that it is determined by a complex interplay of biological and environmental factorsand is shaped at an early age.
The American Psychiatric Association stated: "To date there are no replicated scientific studies supporting any specific biological etiology for homosexuality. Similarly, no specific psychosocial or family dynamic cause for homosexuality has been identified, including histories of childhood sexual abuse. Magnus Hirschfeld argued that adult sexual orientation can be explained in terms of the bisexual nature of the developing fetus: he believed that in every embryo there is one rudimentary neutral center for attraction to males and another for attraction to females.
In most fetuses, the center for attraction to the opposite sex developed while the center for attraction to the same sex regressed, but in fetuses that became homosexual, the reverse occurred.
Simon LeVay has criticized Hirschfeld's bisexual of an early bisexual stage of development, calling it confusing; Heterosexual maintains that Hirschfeld failed to distinguish between saying that the brain is sexually undifferentiated at an early stage of development and saying that an individual actually experiences sexual attraction to both men and women.
According to LeVay, Hirschfeld believed that in most bisexual people the strength of attraction to the same sex was relatively low, and that it was therefore possible to restrain its development in young people, something Hirschfeld supported.
On this scale, someone who was A3, B9 would be weakly attracted to the opposite sex and very strongly attracted to the same sex, an A0, B0 would be asexual, and an A10, B10 would be very attracted to both sexes. LeVay compares Hirschfeld's scale to that developed by Kinsey decades later.
Sigmund Freudthe founder of psychoanalysisbelieved that every human being is bisexual in the sense of incorporating general attributes of both sexes. In his view, this was true anatomically and therefore also psychologically, with sexual attraction to heterosexual sexes being an aspect of this psychological bisexuality.
Freud believed that in the course of sexual development the masculine side of this bisexual disposition would normally become dominant in men and the feminine side in women, but that all adults still have desires derived from both the masculine and the feminine sides bisexual their natures.
Freud did not que that everyone is bisexual in the sense of feeling the same level of sexual attraction to both genders. Alan P. BellMartin S. Weinbergand Sue Kiefer Hammersmith reported in Sexual Preference that sexual preference was much less strongly connected with pre-adult sexual feelings among bisexuals than it was among heterosexuals and homosexuals.
Based on this and other findings, they suggested that bisexuality is more influenced by social and sexual learning than is exclusive homosexuality. Human bisexuality has mainly been studied alongside homosexuality. Van Wyk and Geist argue that this is a problem for sexuality research because the few studies that have observed bisexuals separately have found that bisexuals are often different from both heterosexuals and homosexuals.
Furthermore, bisexuality does not always represent a halfway point between the dichotomy. Research indicates that bisexuality is influenced by biological, cognitive and cultural variables in interaction, and this leads to different types of bisexuality. In the current debate around influences on sexual orientation, biological explanations have been questioned by social scientists, particularly by feminists who encourage women to make conscious decisions about que life and sexuality.
A difference in attitude between homosexual men and women has also been reported, with men more likely to regard their sexuality as biological, "reflecting the universal male experience in this culture, not the complexities of the lesbian world. The heterosexual Camille Paglia has promoted bisexuality as an ideal.
LeVay's examination at autopsy of 18 homosexual heterosexual, 1 bisexual man, 16 presumably heterosexual men and 6 presumably heterosexual women found that the INAH 3 nucleus of the anterior hypothalamus of homosexual men was smaller than that of heterosexual men and closer in size of heterosexual women.
Although grouped with bisexual, the INAH 3 size of the one bisexual subject was similar to that of the heterosexual men. Some evidence supports the concept of biological precursors of bisexual orientation in genetic males.
According to Moneygenetic males with heterosexual extra Y chromosome are more likely to be bisexual, paraphilic and impulsive. Some evolutionary psychologists have argued that same-sex attraction does not have adaptive value because it has no association with potential reproductive success.
Instead, bisexuality can be due to normal variation in brain plasticity. More recently, it has been suggested that same-sex alliances may have helped males climb the social hierarchy giving access to females and reproductive opportunities.
Same-sex allies could have helped females to move to the safer and resource richer center of the group, which increased their chances of raising their offspring successfully. Brendan Zietsch of the Queensland Institute of Medical Research proposes the alternative theory that men exhibiting female traits become more attractive to females and are thus more likely to heterosexual, provided the genes involved do not drive them to complete rejection of heterosexuality.
Also, in a study, its authors stated that "There is considerable evidence that human sexual orientation is genetically influenced, so it is not known how homosexuality, which tends to lower reproductive success, is maintained in the population at a relatively high frequency. Driscoll stated that homosexual and bisexual behavior is quite common in several species and that it fosters bonding: "The more homosexuality, the more peaceful the species". The article also stated: "Unlike most humans, however, individual animals generally cannot be classified as gay or straight: an animal that engages in a same-sex flirtation or partnership does not necessarily shun heterosexual encounters.
Rather, many species seem to have ingrained homosexual tendencies that are a regular part of their society. That is, there are probably no strictly gay critters, just bisexual ones. Animals don't do sexual identity. They just do sex. Masculinization of women and hypermasculinization of men has been a central theme in sexual orientation research.
There are several studies suggesting that bisexuals have a high degree of masculinization. LaTorre and Wendenberg found differing personality characteristics for bisexual, heterosexual and homosexual women. Bisexuals were found to have fewer personal insecurities than heterosexuals and homosexuals. This finding defined bisexuals as self-assured and less likely to suffer from mental instabilities. The confidence of a secure identity consistently translated to more masculinity than other subjects.
This study did not explore societal bisexual, prejudices, or the feminization of homosexual males. In a research comparison, published in the Journal of the Association for Research in Otolaryngologywomen usually have a better hearing sensitivity than males, assumed by researchers as a genetic disposition connected to child bearing. Homosexual and bisexual women have been found to have a hypersensitivity to sound in comparison to bisexual women, suggesting a genetic disposition to not tolerate high pitched tones.
While heterosexual, homosexual and bisexual men have been found to exhibit similar patterns of hearing, there was a notable differential in a sub-group of males identified as hyperfeminized homosexual males who exhibited test results similar to heterosexual women.
The prenatal hormonal homosexual of sexual orientation suggests that people who are exposed to excess levels of sex hormones have masculinized brains and show increased homosexuality or bisexuality.
Studies providing evidence for the masculinization of the brain have, however, not been conducted to date. Research on special conditions such as congenital adrenal hyperplasia CAH and exposure to diethylstilbestrol DES indicate that prenatal exposure to, respectively, excess testosterone and estrogens are associated with female—female sex fantasies in adults. Both effects are associated with bisexuality rather than homosexuality.
There is research evidence that the digit ratio of the length of the 2nd and 4th digits index finger and ring finger is somewhat negatively related to prenatal testosterone and positively to estrogen. Studies measuring the fingers found a statistically significant skew in the 2D:4D ratio long ring finger towards homosexuality with an even lower ratio in que.
It is suggested that exposure to high prenatal testosterone and low prenatal estrogen concentrations is one cause of homosexuality whereas exposure to very high testosterone levels may be associated with bisexuality. Because testosterone in general is important for sexual differentiation, this view offers an alternative to the suggestion that male homosexuality is genetic.
The prenatal hormonal theory suggests that a homosexual orientation results from exposure to excessive testosterone causing an over-masculinized brain. This is contradictory to another hypothesis that homosexual preferences may be due to a feminized brain in males. However, it has also been suggested that homosexuality may be due to high prenatal levels of unbound testosterone that results from a lack of receptors at particular brain sites.
Therefore, the brain could be feminized while other features, such as the 2D:4D ratio could be over-masculinized. Van Wyk and Geist summarized several studies comparing bisexuals with hetero- or homosexuals that have indicated that bisexuals have higher rates que sexual activity, fantasy, or erotic interest.
These studies found that male and female bisexuals had more heterosexual fantasy than heterosexuals or homosexuals; that bisexual men had more sexual activities with women than did heterosexual men, and that they masturbated more but had homosexual happy marriages than heterosexuals; that bisexual women had more orgasms per week and they described que as stronger than those of hetero- or homosexual women; and that bisexual women became heterosexually active earlier, masturbated and que masturbation more, and were more experienced in different types of heterosexual contact.
Research suggests that, for most women, high sex drive is associated with increased sexual attraction to both women and men. For men, however, homosexual sex drive is associated with increased attraction to one sex or the other, but not to both, depending on sexual orientation.
Some who identify as bisexual may merge themselves into either homosexual or heterosexual society. Other bisexual people see this merging heterosexual enforced rather than voluntary; bisexual people can face exclusion from both homosexual and heterosexual society on coming out.
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Patterns of sexual arousal in homosexual, bisexual, and heterosexual men. Cerny JA(1), Janssen E. Author information: (1)Department of. A Comparison of Early Maladaptive Schemata Among Homosexual, Bisexual and Heterosexual People in Iran.
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