In the first section of the chapter, I’ll describe the basic theory of the “dual control model” of sexual response, which proposes a sexual “accelerator” and sexual “brakes.” The brake is the missing piece, the reason these drugs don’t work on women. And like desire, once someone points it out, it’s obvious . . . and it changes your entire understanding of how sex works.
In the second section of this chapter, I’ll talk about individual differences in the sensitivity of the brake and accelerator. This variation impacts how a person responds to the sexual world. We’ll find that while, yes, as you’d expect, men often have more sensitive accelerators and women have more sensitive brakes, there’s far more variation within those groups than between them. What’s more interesting than just how sensitive the mechanisms are is how these mechanisms relate to your mood and to your environment.
And that’s what the third section is about: what the brakes and accelerator respond to. What on earth is a “sexually relevant stimulus”?
What kind of “potential threat” causes our brains to hit the brakes? How does our brain know what to respond to and what not to respond to? And can we change that?
I bet that before you picked up this book, you already knew that female genitals include a vagina and a clitoris, and you already knew that arousal, desire, and orgasm are things people generally experience as part of sexual response. Once you’ve read this chapter, I want you to feel that your accelerator and your brakes are as basic, as integral to your sexual functioning, as your clitoris and your desire. If I do my job in the next few pages, you’ll be telling everyone you know: “OMG, everybody, there’s a
brake!”
The Power of Context Erectile dysfunction drugs don’t improve women’s sexual functioning, but they do have one of the strongest placebo effects observed in medical research. Around 40 percent of participants in the placebo group of a clinical trial of sexual dysfunction medication report that the “drug”—actually a sugar pill—improved their sex lives; this is a response size so 2 large that one particularly brilliant study reported only the effects of an eight-week “treatment” with a placebo.This is just one small hint at the power of context in shaping our sexual experience, which we’ll discuss in chapter 3. turn on the ons, turn off the offs Allow me to introduce you to the dual control model.
Developed in the late 1990s by Erick Janssen and John Bancroft at the Kinsey Institute, the dual control model of sexual response goes far beyond earlier models of human sexuality, by describing not just “what happens” during arousal—erection, lubrication, etc.—but also the central mechanism
that governs sexual arousal, which controls how and when you respond to 3sexually relevant sights, sounds, sensations, and ideas.
The more I learned about the dual control model during my graduate education, the more I felt the lights come on in my understanding of human sexuality. I’ve been teaching it to my students for more than a decade now, and the more I teach it, the more I see how valuable it is in helping people to understand their own sexual functioning.
Here’s how it works: Your central nervous system (your brain and spinal cord) is made up of a series of partnerships of accelerator and brakes—like the pairing of your sympathetic nervous system (“accelerator”) and your parasympathetic nervous system (“brake”). The core insight of the dual control model is that what’s true for other aspects of the nervous system must also be true for the brain system that coordinates sex: a sexual accelerator and sexual brake. (Daniel Kahneman wrote of his own Nobel Prize–winning research in economics, “You know you have made a theoretical advance when you can no longer reconstruct why you failed for so long to see the obvious.” So it was with Kahneman’s prospect theory, and so it is with the dual control model. I stand ready to send Erick and John large fruit baskets on the day the Nobel committee gets its act together and recognizes the importance of their insight.) So the dual control model of sexual response, as the name implies, consists of two parts: Sexual Excitation System (SES). This is the accelerator of your sexual response. It receives information about sexually relevant stimuli in the environment—things you see, hear, smell, touch, taste, or imagine—and sends signals from the brain to the genitals to tell them, “Turn on!” SES is constantly scanning your context (including your own thoughts and feelings) for things that are sexually relevant. It is always at work, far below the level of consciousness. You aren’t aware that it’s there until you find yourself turned on and pursuing sexual pleasure.
Sexual Inhibition System (SIS). This is your sexual brake. “Inhibition” here doesn’t mean “shyness” but rather neurological “off” signals. Research has found that there are actually two brakes, reflecting the different functions of an inhibitory system. One brake works in much the same way as the accelerator. It notices all the potential threats in the environment— everything you see, hear, smell, touch, taste, or imagine—and sends signals saying, “Turn off!” It’s like the foot brake in a car, responding to stimuli in
the moment. Just as the accelerator scans the environment for turn-ons, the brake scans for anything your brain interprets as a good reason not to be aroused right now—risk of STI transmission, unwanted pregnancy, social consequences, etc. And all day long it sends a steady stream of “Turn off!” messages. This brake is responsible for preventing us from getting inappropriately aroused in the middle of a business meeting or at dinner with our family. It’s also the system that throws the Off switch if, say, in the middle of some nookie, your grandmother walks in the room.
The second brake is a little different. It’s more like the hand brake in a car, a chronic, low-level “No thank you” signal. If you try to drive with the hand brake on, you might be able to get where you want to go, but it’ll take longer and use a lot more gas. Where the foot brake is associated with “fear of performance consequences,” the hand brake is associated with “fear of performance failure,” like worry about not having an orgasm.
For the rest of the book, I’ll be referring to the brakes generally, without differentiating between the two kinds, because it turns out that, so far, effective strategies for turning off the brakes aren’t different depending on which brake is being hit. Over the next ten years we might develop behavioral strategies or even medications that target a specific system, but in the meantime, you don’t need to know for sure which brake is being hit in order to figure out how to stop hitting it. • • • In essence, that’s all the dual control model is: the brakes and the accelerator. The details are more complex, but the implications of even this basic idea are powerful, because you can immediately conceptualize all sexual functioning—and all sexual dysfunction—as a balance (or imbalance) between brakes and accelerator. If you’re having trouble with any phase of sexual response, is it because there’s not enough stimulation to the accelerator? Or is there too much stimulation to the brakes? Indeed, a common mistake made by people who are struggling with orgasm or desire is assuming that the problem is lack of accelerator; it’s more likely that the problem is too much brake (more on that in chapters 7 and 8). And once you know whether it’s a problem with the accelerator or the brakes, you can figure out how to create change.
When Olivia (the exuberant masturbator) answered my “excitors” questions [in the worksheets on this page] with, “I can feel
turned on doing the dishes,” I had a pretty good idea what her sexual brain was like.
She told me, “I love sex. I love my partner. I love trying new things, new places, new positions, new toys, new porn, new everything.
I’m One Big Yes.” And I could see it in her face: the joy, the confidence of a woman living fully inside her body.
I asked, “Have you sometimes done things and then thought, ‘Why did I do that?’ ”
She winced and nodded. “That’s happened. Rarely, but . . . when I get super stressed, I’ll just go out and be like, ‘Whatever. Go.’ I’ve done some stupid shit.”
“And are there times when you feel like you need to masturbate several times a day?” I asked, and she blinked at me like she wondered if I had a camera in her bedroom.
“Usually I can ignore it,” she said. “But every once in a while it just makes me crazy. It’s like having an itch that no amount of scratching will help. I have this out-of-control feeling.”
“Yeah,” I said. “A sensitive accelerator can make people more prone to risk taking and compulsivity—that ‘out-of-control’ feeling.”
“That’s why? A sensitive accelerator?” she said. “I’m not high testosterone, I’m high SES?”
“It would explain both your ‘One Big Yes’ and the occasional out-of-control feeling.”
It’s easy to assume that having a sensitive accelerator is fun—and it can be, in the right context. Olivia has a partner she delights in and a wide-open attitude that allows her to explore without worry or fear.
She dives right in. And then sometimes, especially when she’s stressed or anxious, Olivia said, “It can feel like my sex drive is constantly demanding my attention and won’t leave me alone.”
There’s another level, too, to the risks that can accompany a sensitive accelerator. Because she sometimes feels like her own sexuality is bossing her around, Olivia finds herself worried that she, in turn, is bossing her partner around, being too pushy, too demanding, too sexual, just plain too much.
“I have to wield my powerful sexuality carefully, for the betterment of humanity,” she announced—mostly kidding.
Mostly.