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Gender and Sexuality Differences in the Brain

kbrown's picture

Gender and Sexuality Differences in the Brain:Should we study them?

Kara BrownApril 21, 2008            

    The study of sex and sexuality has been a topic of both hot dispute and increasing interest in the past century.  The first studies involving differences between both between males and females and people of different sexual orientation were fraught with faulty data collection and inaccurate conclusions.  These early days of gender and sexuality studies signify a time in which women and homosexuals were treated as inferior and defective versions of the heterosexual male norm.  However, studies such as those performed during this period have become almost obsolete, replaced by both new methods and by a more tolerant and progressive view of females and homosexuals.   In the field of psychology especially, increasingly modern and innovative technology such as the use of functional magnetic resonance imaging (fMRI) has allowed researchers in the field to no longer base their predictions and theories on simple speculation, but rather to peer within the confines of this extremely complex organ and examine physical differences between males and females, homosexuals and heterosexuals.  Of course, with this profoundly influential ability comes an increasingly loud voice calling into question both the validity and the double-edged significance of recent data supporting the concept of sex and sexuality differences in the brain.  This voice has led to an examination of the benefits and consequences of the examination of psychological gender differences in search for an answer to the question; should we study gender and sexuality differences in the brain?           

    Historically, women by and large have been treated in many fields as inferior.  In the field of psychology in particular, however, perhaps because of the inherent temptation to make generalizations about intelligence and worth from studies of the brain, studies of women in its early stages were particularly unjust.  In fact, many scholars have deemed the era surrounding the early 1800’s as the “women as problem” era.  Studies of women at this time can be classified in general as focusing on the deficiencies of women in comparison to their superior male counterparts. (Unger, 2001)  The psychoanalytic work of Freud can be seen as an accurate representation of the way in which women were portrayed in psychological studies at the time.  Freud used women mostly as subjects of his discussions, and many of his theories were directly centered on unraveling the secrets of the female psyche.  Many of Freud’s theories focused on the inability of women to sexually equal the man’s penis, and the mental disconnection and behavioral correlates that followed such a deficiency.  Freud’s theory of “penis envy” in the female, that the female child blames her mother for her lack of a penis during the “phallic stage” of development (4-7 years of age), therefore withdrawing from her mother and attempting to be closer to her father, is just one example of such a theory (Van Wagner, 2008).  Freud’s work with hysteria in women contributed to a different type of stereotype of women at the time.  Freud saw hysteria as psychosomatic symptoms including paralysis that was exhibited by women due to some form of mental anguish.  These symptoms could, according to Freud, be treated with talk therapy alone (Van Wagner, 2008). This notion seemed to portray women as both mentally and physically “weak”, as well as unable to maintain their own stability of mind without the help of a more rational male counterpart. Clearly Freud’s work today has been largely disregarded as unfounded as well as contributing to an attitude towards females at the time that could be largely characterized as sexist and demeaning.             

    Apart from Freud’s work on women subjects, studies of gender differences in psychological processes were also problematical from a more modern day viewpoint.  Studies by Sir Francis Galton, whose work centered mostly on measurements of hereditary traits such as intelligence, once wrote that one conclusion he had drawn from his studies of gender differences was that “women tend in all their capacities to be inferior to men.” (Unger, 2001)  A study by r. Jastrow in 1891 depicts the methods used in the early stages of gender studies of psychology to measure differences among the sexes in cognition.  In his study, he sought to compare the mental processes of men and women by asking a group of 50 males and females to record a list of 100 disconnected words (Nevers et al., 1895).  From the types of words used, as well as the amounts these words were used, Jastrow drew conclusions about the ways in which female and male brains processed information.  From this data, Jastrow concluded that females and males could be given a set of definable traits that distinguished them from one another (Nevers et al., 1895.  Female traits included attention to the immediate surrounds and the ornamental, whereas male traits comprised of attention to the constructive, useful and abstract (Nevers et al., 1895).             

    Current day gender psychology, known to many as the “psychology of gender” era, prompted a transition from the focus of case studies of women to studies of women as a social structure and larger group instead.  Feminist psychology is now regarded as worthy of specialized focus for many researchers, and courses in women’s psychology are taught in more than 50% of undergraduate and graduate programs in the United States (Unger, 2001).  Today, our knowledge of sex differences in the brain has exceeded far above that known by researchers during the 19th and early 20th century, in large part due to our ability to visualize these differences with technology such as PET and fMRI.  A vast array of biological differences have been found to occur within the male and female brain, including structural asymmetries in the corpus collosum and the planum temporale (involved in language production) just to name a few (Wisniewski, 1998; Kimura, 1987).  In addition, researchers have found differences in brain lateralization in the two hemispheres of male and female brains, with specialization of the two hemispheres being less pronounced in women than in men (Kimura, 1987).  Male and female brains also differ spatially in the allotment of total brain space.  Furthermore, studies of the male and female brain have revealed hormone differences within the brain, specifically in levels of the gonadal hormones estrogen and testosterone.           

    With these studies the field of gender in psychology has blossomed to include the cognitive, the social, and the biological correlates of such differences in the brain, and with this increasing knowledge, a rapidly increasing controversy has surfaced.  Many feel that increasing data on the differences between males and females, gender stereotypes are being fed and propagated by scientific evidence.  Especially within the realm of differences between males and females in cognitive ability, the waters begin to get decidedly murkier as to whether this information will help equalize or segregate genders.  Current evidence demonstrates that women tend to have better visual memory, better word and landmark recall, and are better at math calculations, whereas men are predisposed to a greater ability to perform mental rotation of objects, better spatial perception and visualization, as well as better math problem solving (Kimura, 2002).   It is of course important to note, as in many cases this point is not properly emphasized, that these differences are general tendencies, and do not in any way predict whether one man will be better or worse than one woman at any one task.  In addition, there are no mean differences in intelligence between men and women.  This data has prompted further questions regarding cognitive ability differences such as whether these differences are socially are biologically based.           

    Some feel that knowledge of these cognitive strengths and weakness of men and women will only serve to enhance the prejudice of the populace against women in holding jobs which necessarily entail large amounts of spatial and mathematical skills.  On the other hand, knowledge of the ways in which girls and boys are able to relate to information and use it might prove helpful to educators in managing curriculum, and might even provide incentive for single sex education.  The statements made by former Harvard president on the possibility of a difference in natural ability between males and females in high end science and engineering positions embodies the dilemma surrounding cognitive gender studies (Summers, 2005).  A recent panel of educators released a report stating that women are still severely outnumbered in the upper echelons of the science and engineering field not because of an innate lack of ability but because of a bias burned into the brains of society that women are simply not capable of performing at the same high level in these fields as men (Dean, 2006).  The report went on to say that as we further examine sex differences in cognitive ability, these differences seem to disappear, even at very high levels (Dean, 2006).  If women and men are truly different in their cognitive abilities, is it wrong to make such information available to the public, and are there ways in which this data could help our understanding of men and women, or will studies that emphasize difference always be translated into deficiency?           

    Homosexuals as a group were treated in similar ways to that of women in the early phases of gender and sexuality studies, and often parallels are drawn between the two groups in their unjust and often inhumane treatment by the psychological community.  Kurt Freund was one of the first psychologists to focus on homosexuals as a subject of psychological study.  His experiments utilized methods such as plethysmonography, or enlargement of the blood vessels to the pelvic area due to sexual arousal (Dynes, 1992).  Studies involving this method were used by Freund to demonstrate that aversion therapy as a treatment for homosexuality was ineffective.  Other methods in sexuality studies involved pupil dilation and patterns of pleasure experience in brain activation (Dynes, 1992).  All of the aforementioned tools were utilized to detect whether a person was aroused or found a visual stimulus pleasurable, therefore attempting to determine a person’s sexual partner preference.  Clearly these types of studies are extremely susceptible to misuse by both the government and private agencies seeking to determine the sexual orientation of their employees (Dynes, 1992).  Since then, studies of homosexuality have grown past simple detection and moved towards the determination of neurological correlates of homosexuality.  Simon LeVay has performed some of the most controversial research in the 20th and 21st century regarding homosexuality and the brain.  In his study, he found that there is a section of the brain, namely the anterior hypothalamus which is thought to be involved in sexual urges, of homosexuals is physiologically more similar to females than males (Barinaga, 1991).             

    Studies have also been performed involving the presence of animal homosexuality as a means of examining the biological correlates of homosexuality, as well as the possibility that homosexuality can be produced sans the influence of certain social protocols which seem to be associated with homosexuality in humans (the overbearing mother seems to be a favorite of pop psychology).  A study performed by Charles Roselli recently investigated the neurological correlates of homosexuality in sheep.  Results of the study revealed that rams that preferred to have sexual relations with other rams instead of ewes when given a choice between the two had distinctly different brains than heterosexual rams (Cloud, 2007).  Many, however, fear that studies of these differences and the hormonal or biological causes for sexuality in both animals and humans may lead to the production of “cures” for homosexuality.Studies such as those performed by LeVay and his colleagues lead us to question the validity of research on sexuality differences in the brain.  Like gender studies in the brain, there are both benefits and drawback to such a study, and as yet it has not been determined whether the benefits outweigh the disadvantages in such data.  The natural question following studies such as these demonstrating neural correlates of sexuality is whether there is a biological reason for the existence of homosexuality.  Of course, from this question there follows two opposing mindsets.  Some believe that the existence of a biological reason for the existence of homosexuality would lead the populace to believe that homosexuality is a defect, one which in the future we could develop the technology to screen for (Barinaga, 1991).  The proliferation of such ideas is a clear downside to the study of such brain differences in sexuality.  However, another faction of the population maintains that this data could instead help to explain homosexuality as a natural variation in the population, thereby squelching the proclamations of many that homosexuality is a flaw in the human makeup (Barinaga, 1991).             

    Therefore, the consequences of gender and sexuality studies in psychology can be broken into the positive and negative; the positive being educational implications with increased knowledge of the differences in male and female cognition, and the argument that a biological basis for homosexuality could help to explain homosexuality as a natural variant in the human population instead of a defect.  However, with these benefits come a fair amount of risks, those being that people will misuse information on gender and sexuality differences to enhance stereotypes and promote intolerance for minority groups (namely homosexuals).             

    Whether the costs outweigh the benefits gained from these studies is something yet to be reconciled, leaving the individual to make up his or her own mind on the matter.  However, questioning the validity of studies on gender and sexuality progress past simple disillusionment with the possibility that this data could propagate stereotypes.  The entire theory behind studying gender and sexuality differences begins to break apart when we question the bimodal distribution of gender throughout the human population.  Studies of gender presuppose that humans can be classified into two different categories: male and female.  Some may argue, however, that instead people on the whole will largely fall in between these two categories (and will be evenly distributed) on a variety of measures which we commonly see as “sex determination” measures, including chromosomal makeup (XX/XY), sexual organs (testicles, uterus etc.), levels of specific hormones such as estrogen and testosterone, and various other characteristics.  Statistically speaking, the frequency of babies born with inter-sex qualities such as non-XX or XY chromosomes, XXY, full and partial androgen insensitivity syndrome, adrenal hyperplasia, vaginal agenesis, ovotestes, complete gonadal dysgenesis, hypospadias (urethral opening along shaft of penis), general deviation from the standard male or female body, and receiving surgery to normalize genital appearance only sums to approximately 1 in 22,000 babies who have one of these characteristics (Intersex Society of Utah).             

    It seems therefore, that at least with the knowledge and data that researchers have collected, humans do not seem to be evenly distributed across sex, as there are vastly more individuals who do fit standard descriptions of male and female on a number of different levels.  Of course, there is always the possibility that researchers do not have sophisticated enough tools to measure all variables corresponding to sex determination in humans, and therefore we really cannot ever know whether sex is evenly or bimodally distributed, however, I would argue that with the aforementioned data, we can at least tentatively say that current data suggest a bimodal and not even distribution.  That said I do not discount the importance of avoiding the type of black and white categorization that seems to predominate the sciences when studying sex as well as sexuality in psychology.  In all probability, both sex and sexuality are a continuum, and the presence of a substantial, if not vast, number of humans who do not fit at either end of the spectrum but instead fall somewhere in between seem to support the continuous nature of both.  However, I do not personally feel that because not everyone fits into these two discrete categories, male or female, heterosexual or homosexual, that the study of the extremes of these two variables are not valid.  It is possible that through the study of neurological correlates of these extremes, we could benefit a large portion of the population, and with the creation of more exact means of determining sex, such as using a visual analogue scale allowing people to report their own sex on a continuous scale, or measuring variables other than simply sexual organs, we could begin to determine biological correlates for the entire range of sexes and sexualities.    


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Paul Grobstein's picture

sex/gender: dichotomies, bimodal, even distributions

Why should one pay special attention to the "extremes" in any case?