{"id":275,"date":"2015-02-06T23:15:45","date_gmt":"2015-02-06T23:15:45","guid":{"rendered":"https:\/\/courses.candelalearning.com\/ospsych\/?post_type=chapter&#038;p=275"},"modified":"2024-05-17T15:09:15","modified_gmt":"2024-05-17T15:09:15","slug":"sexual-behavior","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/waymaker-psychology\/chapter\/sexual-behavior\/","title":{"raw":"Sexual Behavior","rendered":"Sexual Behavior"},"content":{"raw":"<div>\r\n<div class=\"textbox learning-objectives\">\r\n<h3>Learning Objectives<\/h3>\r\n<ul>\r\n \t<li>Understand basic biological mechanisms regulating sexual behavior and motivation<\/li>\r\n \t<li>Explain the contributions of Alfred Kinsey\u2019s and William Masters and Virginia Johnson\u2019s research made to our understanding of\u00a0sexual behavior<\/li>\r\n<\/ul>\r\n<\/div>\r\n\r\n[caption id=\"\" align=\"alignleft\" width=\"325\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/902\/2015\/02\/23224943\/CNX_Psych_10_03_Rats.jpg\" alt=\"A photograph shows two rats.\" width=\"325\" height=\"226\" data-media-type=\"image\/jpeg\" \/> <strong>Figure 1<\/strong>. A male rat that cannot engage in sexual behavior still seeks receptive females, suggesting that the ability to engage in sexual behavior and the motivation to do so are mediated by different systems in the brain. (credit: Jason Snyder)[\/caption]\r\n\r\nLike food, sex is an important part of our lives. From an evolutionary perspective, the reason is obvious\u2014perpetuation of the species. Sexual behavior in humans, however, involves much more than reproduction. This section provides an overview of research that has been conducted on human sexual behavior and motivation. This section will close with a discussion of issues related to gender and sexual orientation.\r\n\r\n<\/div>\r\n<section data-depth=\"1\">\r\n<h2>Physiological Mechanisms of Sexual Behavior and Motivation<\/h2>\r\nMuch of what we know about the physiological mechanisms that underlie sexual behavior and motivation comes from animal research. As you\u2019ve learned, the hypothalamus plays an important role in motivated behaviors, and sex is no exception. In fact, lesions to an area of the hypothalamus called the medial preoptic area completely disrupt a male rat\u2019s ability to engage in sexual behavior. Surprisingly, medial preoptic lesions do not change how hard a male rat is willing to work to gain access to a sexually receptive female (Figure 1). This suggests that the ability to engage in sexual behavior and the motivation to do so may be mediated by neural systems distinct from one another.\r\n\r\nAnimal research suggests that limbic system structures such as the amygdala and nucleus accumbens are especially important for sexual motivation. Damage to these areas results in a decreased motivation to engage in sexual behavior, while leaving the ability to do so intact (Figure 2) (Everett, 1990). Similar dissociations of sexual motivation and sexual ability have also been observed in the female rat (Becker, Rudick, &amp; Jenkins, 2001; Jenkins &amp; Becker, 2001).\r\n<figure>\r\n\r\n[caption id=\"attachment_6892\" align=\"aligncenter\" width=\"487\"]<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03203531\/88954174d88ba86f35ceaee3b5d220a7dec7a7f4-1.jpeg\"><img class=\"wp-image-6892 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03203531\/88954174d88ba86f35ceaee3b5d220a7dec7a7f4-1.jpeg\" alt=\"An illustration of the brain labels the locations of the \u201cnucleus accumbeus,\u201d \u201chypothalamus,\u201d \u201cmedial preoptic area,\u201d and \u201camygdala.\u201d\" width=\"487\" height=\"408\" \/><\/a> <strong>Figure 2<\/strong>. The medial preoptic area, an area of the hypothalamus, is involved in the ability to engage in sexual behavior, but it does not affect sexual motivation. In contrast, the amygdala and nucleus accumbens are involved in motivation for sexual behavior, but they do not affect the ability to engage in it.[\/caption]<\/figure>\r\nAlthough human sexual behavior is much more complex than that seen in rats, some parallels between animals and humans can be drawn from this research. The worldwide popularity of drugs used to treat erectile dysfunction (Conrad, 2005) speaks to the fact that sexual motivation and the ability to engage in sexual behavior can also be dissociated in humans. Moreover, disorders that involve abnormal hypothalamic function are often associated with hypogonadism (reduced function of the gonads) and reduced sexual function (e.g., Prader-Willi syndrome). Given the hypothalamus\u2019s role in endocrine function, it is not surprising that hormones secreted by the endocrine system also play important roles in sexual motivation and behavior. For example, many animals show no sign of sexual motivation in the absence of the appropriate combination of sex hormones from their gonads. While this is not the case for humans, there is considerable evidence that sexual motivation in humans varies as a function of circulating testosterone levels (Bhasin, Enzlin, Coviello, &amp; Basson, 2007; Carter, 1992; Sherwin, 1988).\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/1f1e683c-8b3d-4abd-bd52-50a8c62ad194\r\n\r\n<\/div>\r\n<\/section><section data-depth=\"1\">\r\n<h2>Kinsey's Research<\/h2>\r\nBefore the late 1940s, access to reliable, empirically-based information on sex was limited. Physicians were considered authorities on all issues related to sex, despite the fact that they had little to no training in these issues, and it is likely that most of what people knew about sex had been learned either through their own experiences or by talking with their peers. Convinced that people would benefit from a more open dialogue on issues related to human sexuality, Dr. Alfred Kinsey of Indiana University initiated large-scale survey research on the topic (Figure 3). The results of some of these efforts were published in two books\u2014<em data-effect=\"italics\">Sexual Behavior in the Human Male <\/em>and <em data-effect=\"italics\">Sexual Behavior in the Human Female<\/em>\u2014which were published in 1948 and 1953, respectively (Bullough, 1998).\r\n<figure>\r\n\r\n[caption id=\"\" align=\"alignleft\" width=\"325\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/902\/2015\/02\/23224946\/CNX_Psych_10_03_Kinsey.jpg\" alt=\"A photograph shows Morrison Hall, the building that houses the Kinsey Institute for Research in Sex, Gender, and Reproduction.\" width=\"325\" height=\"212\" data-media-type=\"image\/jpeg\" \/> <strong>Figure 3<\/strong>. In 1947, Alfred Kinsey established The Kinsey Institute for Research, Sex, Gender and Reproduction at Indiana University, shown here in 2011. The Kinsey Institute has continued as a research site of important psychological studies for decades.[\/caption]<\/figure>\r\nAt the time, the Kinsey reports were quite sensational. Never before had the American public seen its private sexual behavior become the focus of scientific scrutiny on such a large scale. The books, which were filled with statistics and scientific lingo, sold remarkably well to the general public, and people began to engage in open conversations about human sexuality. As you might imagine, not everyone was happy that this information was being published. In fact, these books were banned in some countries. Ultimately, the controversy resulted in Kinsey losing funding that he had secured from the Rockefeller Foundation to continue his research efforts (Bancroft, 2004).\r\n\r\nAlthough Kinsey\u2019s research has been widely criticized as being riddled with sampling and statistical errors (Jenkins, 2010), there is little doubt that this research was very influential in shaping future research on human sexual behavior and motivation. Kinsey described a remarkably diverse range of sexual behaviors and experiences reported by the volunteers participating in his research. Behaviors that had once been considered exceedingly rare or problematic were demonstrated to be much more common and innocuous than previously imagined (Bancroft, 2004; Bullough, 1998).\r\n\r\nAmong the results of Kinsey\u2019s research were the findings that women are as interested and experienced in sex as their male counterparts, that both males and females masturbate without adverse health consequences, and that homosexual behavior is fairly common (Bancroft, 2004). Kinsey also developed a continuum known as the Kinsey scale that is still commonly used today to categorize an individual\u2019s sexual orientation (Jenkins, 2010).\r\n\r\n<\/section><section data-depth=\"1\">\r\n<h2>Masters and Johnson's Research<\/h2>\r\nIn 1966, William Masters and Virginia Johnson published a book detailing the results of their observations of nearly 700 people who agreed to participate in their study of physiological responses during sexual behavior. Unlike Kinsey, who used personal interviews and surveys to collect data, Masters and Johnson observed people having intercourse in a variety of positions, and they observed people masturbating, manually or with the aid of a device. While this was occurring, researchers recorded measurements of physiological variables, such as blood pressure and respiration rate, as well as measurements of sexual arousal, such as vaginal lubrication and penile tumescence (swelling associated with an erection). In total, Masters and Johnson observed nearly 10,000 sexual acts as a part of their research (Hock, 2008).\r\n\r\nBased on these observations, Masters and Johnson divided the <strong>sexual response cycle<\/strong> into four phases that are fairly similar in individuals regardless of the individual's sex assigned at birth: excitement, plateau, orgasm, and resolution (Figure 4). The <strong>excitement<\/strong> phase is the arousal phase of the sexual response cycle, and it is marked by the erection of the penis or clitoris and lubrication and expansion of the vaginal canal. In the <strong>plateau<\/strong> phase, individuals experience a full erection of the penis often accompanied by pre-ejaculatory fluid or further swelling of the vagina and increased blood flow to the labia minora. For individuals with female sex organs, <strong>orgasm<\/strong> is marked by rhythmic contractions of the pelvis and uterus along with increased muscle tension. For individuals with male sex organs, pelvic contractions are accompanied by a buildup of seminal fluid near the urethra that is ultimately forced out by contractions of genital muscles (i.e., ejaculation).\u00a0<strong>Resolution<\/strong> is the relatively rapid return to an unaroused state accompanied by a decrease in blood pressure and muscular relaxation. While many individuals with female sex organs can quickly repeat the sexual response cycle, those with male sex organs commonly pass through a longer refractory period as part of resolution. The refractory period is a period of time that follows an orgasm during which an individual is incapable of experiencing another orgasm. For those with male sex organs, the duration of the refractory period can vary dramatically from individual to individual with some refractory periods as short as several minutes and others as long as a day. As these people age, their refractory periods tend to span longer periods of time.\r\n<figure>\r\n\r\n[caption id=\"attachment_6897\" align=\"aligncenter\" width=\"487\"]<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03203928\/8779b02770677c3a72128d975437df4299869513.jpeg\"><img class=\"size-full wp-image-6897\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03203928\/8779b02770677c3a72128d975437df4299869513.jpeg\" alt=\"A graph titled \u201cSexual response cycle\u201d has an x-axis labeled \u201ctime\u201d and a y-axis labeled \u201carousal.\u201d Four phases are depicted. In the \u201cexcitement\u201d phase the arousal level increases from the bottom to midway on the graph. In the \u201cplateau\u201d phase the arousal level remains mostly steady at the midpoint of the graph and then begins to rise at the end of the plateau phase. At the \u201corgasm\u201d phase, the arousal level sharply increases, peaks at the top of the graph, and then declines to the midway point. In the \u201cresolution\u201d phase the graph drops from the midway point to the bottom.\" width=\"487\" height=\"349\" \/><\/a> <strong>Figure 4<\/strong>. This graph illustrates the different phases of the sexual response cycle as described by Masters and Johnson.[\/caption]<\/figure>\r\nIn addition to the insights that their research provided with regards to the sexual response cycle and the multi-orgasmic potential of those with female sex organs, Masters and Johnson also collected important information about reproductive anatomy. Their research demonstrated the oft-cited statistic of the average size of a flaccid and an erect penis (3 and 6 inches, respectively) as well as dispelling long-held beliefs about relationships between the size of an individual's erect penis and their ability to provide sexual pleasure to their partner. Furthermore, they determined that the vagina is a very elastic structure that can conform to penises of various sizes (Hock, 2008).\r\n\r\n<\/section><section data-depth=\"1\">\r\n<div class=\"textbox examples\">\r\n<h3>Link to Learning<\/h3>\r\nWatch\u00a0the following episode of Crash Course Psychology in which Hank talks about Kinsey, Masters and Johnson, sexuality, gender identity, hormones, and even looks into the idea of why people have sex.\r\n<iframe src=\"https:\/\/www.youtube.com\/embed\/Qymp_VaFo9M?list=PL8dPuuaLjXtOPRKzVLY0jJY-uHOH9KVU6\" width=\"853\" height=\"480\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe>\r\n\r\nYou can <a href=\"https:\/\/oerfiles.s3-us-west-2.amazonaws.com\/Psychology\/Transcriptions\/LetsTalkAboutSexCrashCoursePsychology27.txt\" target=\"_blank\" rel=\"noopener\">view the transcript for \"Let's Talk About Sex: Crash Course Psychology #27\" here (opens in new window)<\/a>.\r\n\r\n<\/div>\r\n<\/section><section data-depth=\"1\"><section>\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/d12fffa1-db04-438d-b786-e798bfa3d08b\r\n\r\nhttps:\/\/assess.lumenlearning.com\/practice\/f5485313-d7f9-4263-b8f1-87289d56d2ad\r\n\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Glossary<\/h3>\r\n<div data-type=\"definition\"><strong>excitement:\u00a0<\/strong>phase of the sexual response cycle that involves sexual arousal<\/div>\r\n<div data-type=\"definition\"><strong>heterosexual:\u00a0<\/strong>emotional and erotic attractions to individuals of another sex<\/div>\r\n<div data-type=\"definition\"><strong>homosexual:\u00a0<\/strong>emotional and erotic attractions to same-sexed individuals<\/div>\r\n<div data-type=\"definition\"><strong>orgasm:\u00a0<\/strong>peak phase of the sexual response cycle associated with rhythmic muscle contractions (and ejaculation)<\/div>\r\n<div data-type=\"definition\"><strong>plateau:\u00a0<\/strong>phase of the sexual response cycle that falls between excitement and orgasm<\/div>\r\n<div data-type=\"definition\"><strong>refractory period:\u00a0<\/strong>time immediately following an orgasm during which an individual is incapable of experiencing another orgasm<\/div>\r\n<div data-type=\"definition\"><strong>resolution:\u00a0<\/strong>phase of the sexual response cycle following orgasm during which the body returns to its unaroused state<\/div>\r\n<\/div>\r\n<\/section><\/section>","rendered":"<div>\n<div class=\"textbox learning-objectives\">\n<h3>Learning Objectives<\/h3>\n<ul>\n<li>Understand basic biological mechanisms regulating sexual behavior and motivation<\/li>\n<li>Explain the contributions of Alfred Kinsey\u2019s and William Masters and Virginia Johnson\u2019s research made to our understanding of\u00a0sexual behavior<\/li>\n<\/ul>\n<\/div>\n<div style=\"width: 335px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/902\/2015\/02\/23224943\/CNX_Psych_10_03_Rats.jpg\" alt=\"A photograph shows two rats.\" width=\"325\" height=\"226\" data-media-type=\"image\/jpeg\" \/><\/p>\n<p class=\"wp-caption-text\"><strong>Figure 1<\/strong>. A male rat that cannot engage in sexual behavior still seeks receptive females, suggesting that the ability to engage in sexual behavior and the motivation to do so are mediated by different systems in the brain. (credit: Jason Snyder)<\/p>\n<\/div>\n<p>Like food, sex is an important part of our lives. From an evolutionary perspective, the reason is obvious\u2014perpetuation of the species. Sexual behavior in humans, however, involves much more than reproduction. This section provides an overview of research that has been conducted on human sexual behavior and motivation. This section will close with a discussion of issues related to gender and sexual orientation.<\/p>\n<\/div>\n<section data-depth=\"1\">\n<h2>Physiological Mechanisms of Sexual Behavior and Motivation<\/h2>\n<p>Much of what we know about the physiological mechanisms that underlie sexual behavior and motivation comes from animal research. As you\u2019ve learned, the hypothalamus plays an important role in motivated behaviors, and sex is no exception. In fact, lesions to an area of the hypothalamus called the medial preoptic area completely disrupt a male rat\u2019s ability to engage in sexual behavior. Surprisingly, medial preoptic lesions do not change how hard a male rat is willing to work to gain access to a sexually receptive female (Figure 1). This suggests that the ability to engage in sexual behavior and the motivation to do so may be mediated by neural systems distinct from one another.<\/p>\n<p>Animal research suggests that limbic system structures such as the amygdala and nucleus accumbens are especially important for sexual motivation. Damage to these areas results in a decreased motivation to engage in sexual behavior, while leaving the ability to do so intact (Figure 2) (Everett, 1990). Similar dissociations of sexual motivation and sexual ability have also been observed in the female rat (Becker, Rudick, &amp; Jenkins, 2001; Jenkins &amp; Becker, 2001).<\/p>\n<figure>\n<div id=\"attachment_6892\" style=\"width: 497px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03203531\/88954174d88ba86f35ceaee3b5d220a7dec7a7f4-1.jpeg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-6892\" class=\"wp-image-6892 size-full\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03203531\/88954174d88ba86f35ceaee3b5d220a7dec7a7f4-1.jpeg\" alt=\"An illustration of the brain labels the locations of the \u201cnucleus accumbeus,\u201d \u201chypothalamus,\u201d \u201cmedial preoptic area,\u201d and \u201camygdala.\u201d\" width=\"487\" height=\"408\" \/><\/a><\/p>\n<p id=\"caption-attachment-6892\" class=\"wp-caption-text\"><strong>Figure 2<\/strong>. The medial preoptic area, an area of the hypothalamus, is involved in the ability to engage in sexual behavior, but it does not affect sexual motivation. In contrast, the amygdala and nucleus accumbens are involved in motivation for sexual behavior, but they do not affect the ability to engage in it.<\/p>\n<\/div>\n<\/figure>\n<p>Although human sexual behavior is much more complex than that seen in rats, some parallels between animals and humans can be drawn from this research. The worldwide popularity of drugs used to treat erectile dysfunction (Conrad, 2005) speaks to the fact that sexual motivation and the ability to engage in sexual behavior can also be dissociated in humans. Moreover, disorders that involve abnormal hypothalamic function are often associated with hypogonadism (reduced function of the gonads) and reduced sexual function (e.g., Prader-Willi syndrome). Given the hypothalamus\u2019s role in endocrine function, it is not surprising that hormones secreted by the endocrine system also play important roles in sexual motivation and behavior. For example, many animals show no sign of sexual motivation in the absence of the appropriate combination of sex hormones from their gonads. While this is not the case for humans, there is considerable evidence that sexual motivation in humans varies as a function of circulating testosterone levels (Bhasin, Enzlin, Coviello, &amp; Basson, 2007; Carter, 1992; Sherwin, 1988).<\/p>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_1f1e683c-8b3d-4abd-bd52-50a8c62ad194\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/1f1e683c-8b3d-4abd-bd52-50a8c62ad194?iframe_resize_id=assessment_practice_id_1f1e683c-8b3d-4abd-bd52-50a8c62ad194\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe><\/p>\n<\/div>\n<\/section>\n<section data-depth=\"1\">\n<h2>Kinsey&#8217;s Research<\/h2>\n<p>Before the late 1940s, access to reliable, empirically-based information on sex was limited. Physicians were considered authorities on all issues related to sex, despite the fact that they had little to no training in these issues, and it is likely that most of what people knew about sex had been learned either through their own experiences or by talking with their peers. Convinced that people would benefit from a more open dialogue on issues related to human sexuality, Dr. Alfred Kinsey of Indiana University initiated large-scale survey research on the topic (Figure 3). The results of some of these efforts were published in two books\u2014<em data-effect=\"italics\">Sexual Behavior in the Human Male <\/em>and <em data-effect=\"italics\">Sexual Behavior in the Human Female<\/em>\u2014which were published in 1948 and 1953, respectively (Bullough, 1998).<\/p>\n<figure>\n<div style=\"width: 335px\" class=\"wp-caption alignleft\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/902\/2015\/02\/23224946\/CNX_Psych_10_03_Kinsey.jpg\" alt=\"A photograph shows Morrison Hall, the building that houses the Kinsey Institute for Research in Sex, Gender, and Reproduction.\" width=\"325\" height=\"212\" data-media-type=\"image\/jpeg\" \/><\/p>\n<p class=\"wp-caption-text\"><strong>Figure 3<\/strong>. In 1947, Alfred Kinsey established The Kinsey Institute for Research, Sex, Gender and Reproduction at Indiana University, shown here in 2011. The Kinsey Institute has continued as a research site of important psychological studies for decades.<\/p>\n<\/div>\n<\/figure>\n<p>At the time, the Kinsey reports were quite sensational. Never before had the American public seen its private sexual behavior become the focus of scientific scrutiny on such a large scale. The books, which were filled with statistics and scientific lingo, sold remarkably well to the general public, and people began to engage in open conversations about human sexuality. As you might imagine, not everyone was happy that this information was being published. In fact, these books were banned in some countries. Ultimately, the controversy resulted in Kinsey losing funding that he had secured from the Rockefeller Foundation to continue his research efforts (Bancroft, 2004).<\/p>\n<p>Although Kinsey\u2019s research has been widely criticized as being riddled with sampling and statistical errors (Jenkins, 2010), there is little doubt that this research was very influential in shaping future research on human sexual behavior and motivation. Kinsey described a remarkably diverse range of sexual behaviors and experiences reported by the volunteers participating in his research. Behaviors that had once been considered exceedingly rare or problematic were demonstrated to be much more common and innocuous than previously imagined (Bancroft, 2004; Bullough, 1998).<\/p>\n<p>Among the results of Kinsey\u2019s research were the findings that women are as interested and experienced in sex as their male counterparts, that both males and females masturbate without adverse health consequences, and that homosexual behavior is fairly common (Bancroft, 2004). Kinsey also developed a continuum known as the Kinsey scale that is still commonly used today to categorize an individual\u2019s sexual orientation (Jenkins, 2010).<\/p>\n<\/section>\n<section data-depth=\"1\">\n<h2>Masters and Johnson&#8217;s Research<\/h2>\n<p>In 1966, William Masters and Virginia Johnson published a book detailing the results of their observations of nearly 700 people who agreed to participate in their study of physiological responses during sexual behavior. Unlike Kinsey, who used personal interviews and surveys to collect data, Masters and Johnson observed people having intercourse in a variety of positions, and they observed people masturbating, manually or with the aid of a device. While this was occurring, researchers recorded measurements of physiological variables, such as blood pressure and respiration rate, as well as measurements of sexual arousal, such as vaginal lubrication and penile tumescence (swelling associated with an erection). In total, Masters and Johnson observed nearly 10,000 sexual acts as a part of their research (Hock, 2008).<\/p>\n<p>Based on these observations, Masters and Johnson divided the <strong>sexual response cycle<\/strong> into four phases that are fairly similar in individuals regardless of the individual&#8217;s sex assigned at birth: excitement, plateau, orgasm, and resolution (Figure 4). The <strong>excitement<\/strong> phase is the arousal phase of the sexual response cycle, and it is marked by the erection of the penis or clitoris and lubrication and expansion of the vaginal canal. In the <strong>plateau<\/strong> phase, individuals experience a full erection of the penis often accompanied by pre-ejaculatory fluid or further swelling of the vagina and increased blood flow to the labia minora. For individuals with female sex organs, <strong>orgasm<\/strong> is marked by rhythmic contractions of the pelvis and uterus along with increased muscle tension. For individuals with male sex organs, pelvic contractions are accompanied by a buildup of seminal fluid near the urethra that is ultimately forced out by contractions of genital muscles (i.e., ejaculation).\u00a0<strong>Resolution<\/strong> is the relatively rapid return to an unaroused state accompanied by a decrease in blood pressure and muscular relaxation. While many individuals with female sex organs can quickly repeat the sexual response cycle, those with male sex organs commonly pass through a longer refractory period as part of resolution. The refractory period is a period of time that follows an orgasm during which an individual is incapable of experiencing another orgasm. For those with male sex organs, the duration of the refractory period can vary dramatically from individual to individual with some refractory periods as short as several minutes and others as long as a day. As these people age, their refractory periods tend to span longer periods of time.<\/p>\n<figure>\n<div id=\"attachment_6897\" style=\"width: 497px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03203928\/8779b02770677c3a72128d975437df4299869513.jpeg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-6897\" class=\"size-full wp-image-6897\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03203928\/8779b02770677c3a72128d975437df4299869513.jpeg\" alt=\"A graph titled \u201cSexual response cycle\u201d has an x-axis labeled \u201ctime\u201d and a y-axis labeled \u201carousal.\u201d Four phases are depicted. In the \u201cexcitement\u201d phase the arousal level increases from the bottom to midway on the graph. In the \u201cplateau\u201d phase the arousal level remains mostly steady at the midpoint of the graph and then begins to rise at the end of the plateau phase. At the \u201corgasm\u201d phase, the arousal level sharply increases, peaks at the top of the graph, and then declines to the midway point. In the \u201cresolution\u201d phase the graph drops from the midway point to the bottom.\" width=\"487\" height=\"349\" \/><\/a><\/p>\n<p id=\"caption-attachment-6897\" class=\"wp-caption-text\"><strong>Figure 4<\/strong>. This graph illustrates the different phases of the sexual response cycle as described by Masters and Johnson.<\/p>\n<\/div>\n<\/figure>\n<p>In addition to the insights that their research provided with regards to the sexual response cycle and the multi-orgasmic potential of those with female sex organs, Masters and Johnson also collected important information about reproductive anatomy. Their research demonstrated the oft-cited statistic of the average size of a flaccid and an erect penis (3 and 6 inches, respectively) as well as dispelling long-held beliefs about relationships between the size of an individual&#8217;s erect penis and their ability to provide sexual pleasure to their partner. Furthermore, they determined that the vagina is a very elastic structure that can conform to penises of various sizes (Hock, 2008).<\/p>\n<\/section>\n<section data-depth=\"1\">\n<div class=\"textbox examples\">\n<h3>Link to Learning<\/h3>\n<p>Watch\u00a0the following episode of Crash Course Psychology in which Hank talks about Kinsey, Masters and Johnson, sexuality, gender identity, hormones, and even looks into the idea of why people have sex.<br \/>\n<iframe loading=\"lazy\" src=\"https:\/\/www.youtube.com\/embed\/Qymp_VaFo9M?list=PL8dPuuaLjXtOPRKzVLY0jJY-uHOH9KVU6\" width=\"853\" height=\"480\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>You can <a href=\"https:\/\/oerfiles.s3-us-west-2.amazonaws.com\/Psychology\/Transcriptions\/LetsTalkAboutSexCrashCoursePsychology27.txt\" target=\"_blank\" rel=\"noopener\">view the transcript for &#8220;Let&#8217;s Talk About Sex: Crash Course Psychology #27&#8221; here (opens in new window)<\/a>.<\/p>\n<\/div>\n<\/section>\n<section data-depth=\"1\">\n<section>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_d12fffa1-db04-438d-b786-e798bfa3d08b\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/d12fffa1-db04-438d-b786-e798bfa3d08b?iframe_resize_id=assessment_practice_id_d12fffa1-db04-438d-b786-e798bfa3d08b\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe><\/p>\n<p>\t<iframe id=\"assessment_practice_f5485313-d7f9-4263-b8f1-87289d56d2ad\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/f5485313-d7f9-4263-b8f1-87289d56d2ad?iframe_resize_id=assessment_practice_id_f5485313-d7f9-4263-b8f1-87289d56d2ad\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe><\/p>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Glossary<\/h3>\n<div data-type=\"definition\"><strong>excitement:\u00a0<\/strong>phase of the sexual response cycle that involves sexual arousal<\/div>\n<div data-type=\"definition\"><strong>heterosexual:\u00a0<\/strong>emotional and erotic attractions to individuals of another sex<\/div>\n<div data-type=\"definition\"><strong>homosexual:\u00a0<\/strong>emotional and erotic attractions to same-sexed individuals<\/div>\n<div data-type=\"definition\"><strong>orgasm:\u00a0<\/strong>peak phase of the sexual response cycle associated with rhythmic muscle contractions (and ejaculation)<\/div>\n<div data-type=\"definition\"><strong>plateau:\u00a0<\/strong>phase of the sexual response cycle that falls between excitement and orgasm<\/div>\n<div data-type=\"definition\"><strong>refractory period:\u00a0<\/strong>time immediately following an orgasm during which an individual is incapable of experiencing another orgasm<\/div>\n<div data-type=\"definition\"><strong>resolution:\u00a0<\/strong>phase of the sexual response cycle following orgasm during which the body returns to its unaroused state<\/div>\n<\/div>\n<\/section>\n<\/section>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-275\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Sexual Behavior. <strong>Authored by<\/strong>: OpenStax College. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/10-3-sexual-behavior\">https:\/\/openstax.org\/books\/psychology-2e\/pages\/10-3-sexual-behavior<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Download for free at https:\/\/openstax.org\/books\/psychology-2e\/pages\/1-introduction<\/li><\/ul><div class=\"license-attribution-dropdown-subheading\">All rights reserved content<\/div><ul class=\"citation-list\"><li>Let&#039;s Talk About Sex: Crash Course Psychology #27. <strong>Authored by<\/strong>: Hank Green. <strong>Provided by<\/strong>: CrashCourse. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/www.youtube.com\/watch?v=Qymp_VaFo9M&#038;feature=youtu.be&#038;list=PL8dPuuaLjXtOPRKzVLY0jJY-uHOH9KVU6\">https:\/\/www.youtube.com\/watch?v=Qymp_VaFo9M&#038;feature=youtu.be&#038;list=PL8dPuuaLjXtOPRKzVLY0jJY-uHOH9KVU6<\/a>. <strong>License<\/strong>: <em>Other<\/em>. <strong>License Terms<\/strong>: Standard YouTube License<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":5797,"menu_order":12,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Sexual Behavior\",\"author\":\"OpenStax 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