Human sexuality is incredibly complex, and, as with anything complicated, there are countless opportunities for dysfunction to occur. Despite decades of research by doctors and psychologists – to say nothing of the millions of books, websites, and magazines which have been devoted to the topic – we’re still “groping in the dark,” so to speak, when it comes to unraveling its deepest mysteries. Sitting at the nexus of emotion and science, erectile dysfunction (ED) and female sexual dysfunction (FSD) – along with sexuality in general – will probably always defy cut-and-dried explanation. However, that doesn’t mean we haven’t tried. In this article, we’ll explain the four different models of human sexuality – and why they’re important for understanding (and treating) sexual dysfunction in men and women.

The Four Scientific Models of Human Sexuality and Sexual Response

In order to conceptualize how and why ED and FSD occur in the most objective light possible, scientists have developed at least four basic models of sexual function, beginning with:

  • The linear model. Developed by Masters and Johnson, this model looks a little like a line graph. In the linear model, phases of the human sexual response cycle – excitement, plateau, and orgasm – are neatly sequential.

Before we discuss the other models (or elaborate further on the linear model), let’s take a moment to explain the four-stage human sexual response cycle the linear model depicts:

  1. Excitement Phase – Also called the arousal phase, the excitement phase causes increased heart rate, blood pressure, and respiration. In men, the penis becomes erect. In women, the clitoris and labia minora begin to engorge, and the vaginal walls begin to produce lubricating fluid. The process of tissue becoming swollen and engorged with blood is referred to as vasocongestion.

Note: The arousal/excitement phase is frequently mentioned in discussions of treatment of ED with Viagra type drugs. However, because, in most cases, ED is mechanical bloodflow problem, these medicines are pertinent only to men, and have no effect on FSD.

2. Plateau Phase – The plateau phase is marked by increased heart rate and circulation. Men begin to produce pre-ejaculatory fluid, while swelling and lubrication continue in women.

3. Orgasmic Phase – Male and female orgasm is caused by rapid muscle contractions in the lower pelvis. Women also experience vaginal contractions.

4. Resolution Phase – After orgasm, both genders experience gradual muscle relaxation and drop in blood pressure. Unlike men, women do not experience a “refractory period,” which allows them to have multiple orgasms or orgasms in quick succession.

Familiarity with these four phases is instrumental when it comes to understanding both healthy and dysfunctional human sexuality.

Now, to return to the remaining three models, researchers have posited the following:

  • The “circular” model. Developed by Whipple and Brash-McGreer. In the circular model, the stages of sexual response exist within a cycle of “seduction,” “sensations,” “surrender,” and “reflection.” The circular model also adds a few phases to the human sexual response cycle, placing “desire” before excitement and adding “resolution” after orgasm. The circular model posits that, if the chain is disrupted – for instance, if the woman did not experience satisfaction during the reflection stage – she may not want to repeat the experience again.

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  • The “non-linear” model. Developed by Basson. In the non-linear model, different components of sexuality interact and branch out in several directions. In the non-linear model, “emotional intimacy” leads to “sexual stimuli,” which leads to “sexual arousal,” which leads to “arousal and sexual desire,” which leads to “emotional and physical satisfaction,” which leads back to “emotional intimacy.” The non-linear model is not quite “circular,” because at the same time this cycle is occurring, the factor of “spontaneous sexual drive” branches out toward several other parts of the cycle. The non-linear model emphasizes personal satisfaction over orgasm, noting that satisfaction may be derived from orgasm and/or emotions of intimacy and connection.

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  • The “biopsychosocial” model. Put forth by Rosen and Barsky in Obstetrics & Gynecology Clinics of North America. In the biopsychosocial model, biological, psychological, sociocultural, and interpersonal factors all overlap (hence the name). For example, an interpersonal factor would be the quality of the woman’s past and current relationships.

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Why Does the Linear Model Fail to Explain Female Sexual Dysfunction?

All of these models can tell us something about human sexuality, but some are more comprehensive (and helpful) than others. For instance, while the linear model might be sufficient to summarize sexual response in healthy men and women, its accuracy is greatly diminished where ED and FSD are concerned. The linear model, though far from being useless, represents merely one section of the complicated cycle depicted by the non-linear model, which describes all the precursors to the linear model in which things can go awry, leading to failure in the linear model. Put simply, the linear model is only the tip of the iceberg.

This shortcoming was actually noted by a 2009 study published in the Journal of Sexual Medicine, which stated the following:

“The linear model was a more accurate representation of sexual response for women with normal sexual function than [it was for] women with FSD… The modified circular model was a more accurate representation of the sexual response of women with FSD than women with normal sexual function.”

But what are the actual problems with the linear model, particularly when it comes to accurately depicting the sexual cycle in women with FSD? Why, exactly, is it arguably less accurate than its counterparts? Well, as the Association of Reproductive Health Professionals (ARHP) points out, the linear model suffers from three major issues:

  1. It works on the assumption that males and females “have similar sexual responses,” which is not necessarily the case.
  2. It’s a little too tidy. “Many women,” according to ARHP, “do not move progressively and sequentially through the phases as described.” The ARHP here notes Rutgers researcher Beverly Whipple, PhD, who found that many women do not experience all four phases. Rosemary Basson, MB, of the University of British Columbia, theorizes that female sexual desire tends to be responsive (to a partner) rather than spontaneous.
  3. It fails to account for “non-biologic experiences” (e.g. satisfaction), nor does it consider the context of the couple’s sexual relationship (unlike the biopsychosocial model). Men seem to have an innate drive for sex that often (but not always) overrides the biopsychosocial model as it would apply to men. However, in certain circumstances – particularly in long-term relationships – the biopsychosocial aspect becomes more important in men.

So, why take the time to discuss sexual dysfunction on a website about medical marijuana? The short answer is that women (and men) in long-term relationships often report experiencing less spontaneous sex drive, which can lead to diminished sexual and emotional fulfillment. For some people, Cannabis has the potential to help awaken that drive – not to mention heighten the satisfaction experienced by both partners.

As for the long answer? You’ll have to come back for the next article in our series exploring the fascinating links between marijuana and sexuality. For our next installment, we’ll be taking a look at the aphrodisiac qualities of Cannabis – and how marijuana could improve your sex life.

Author’s Note: The images used in this post are from ARHP and This content is not to be redistributed for non-commercial use.

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