the explanation I've been looking for?

I’ve long wondered about the physiological underpinnings of the sexual appeal of the forbidden, the unattainable, and the mysterious.

Relying as I do on the dual control model of sexual response to explain why and how and when we get aroused (or fail to get aroused), it’s a puzzle, especially this thing about “the forbidden.”

Because the forbiddenness of something SHOULD be an inhibitory factor, right? But somehow if a forbidden stimulus (like an unavailable partner) is also sexually appetitive, the very forbiddenness seems to make it more appetitive! This is a paradox!

Well. There are some theories about crossed wiring that I find fairly unsatisfactory, but then I read this article in WIRED (of all places), which discusses the neural and evolutionary origins of curiosity, in terms of the “information gap theory.”

Here’s how the article puts it:

It comes when we feel a gap “between what we know and what we want to know”. This gap has emotional consequences: it feels like a mental itch, a mosquito bite on the brain. We seek out new knowledge because we that’s how we scratch the itch.

(Nerdy nitpicking: It’s not actually like scratching a mosquito bite or any itch, since an itch is an aversive stimulus motivating behavior to return the organism to baseline – a drive, in other words. Curiosity, as explained by the information gap theory and elsewhere (see Toates, 1986), is an incentive motivation system [like sex!])

The article explains the results of a fMRI study:

The first thing the scientists found is that curiosity obeys an inverted U-shaped curve, so that we’re most curious when we know a little about a subject (our curiosity has been piqued) but not too much (we’re still uncertain about the answer)


The most interesting finding is the activation of the caudate, which seems to sit at the intersection of new knowledge and positive emotions. (For instance, the caudate has been shown to be activated by various kinds of learning that involve feedback, while it’s also been closely linked to various parts of the dopamine reward pathway.) The lesson is that our desire for abstract information – this is the cause of curiosity – begins as a dopaminergic craving, rooted in the same primal pathway that also responds to sex, drugs and rock and roll.

As a chronically curious person, I can relate.

Indeed, as a highly persistent person who MUST finish every book and movie I start, I can REALLY relate. If I’ve started to read a good book and have to put it down because, you know, I have a job and a life etc, all that job and life is just exceedingly tedious interruption to my reading! It’s all I can think about! The longer I’m deprived of my book, the more I want it!

So suppose – like an itch, but not quite like an itch, like the craving for a new technological toy, like the yearning for a loved one who’s away – deprivation increases desire. Indeed, we know that deprivation (by some definition or other) results in increased sensitivity of SES, the sexual gas pedal. So the presence of an appetitive but inaccessible stimulus would generate increasing desire/arousal, eh?

(Another thing that might be explained by an “information gap theory” type story about sex is the phenomenon of wanting someone until you have them. With satisfaction of the desire comes a lack of desire.)

The test of this would be in the nature of the forbiddenness or inaccessibility. If you can’t have someone because they’re monogamously partnered, that’s maybe not that likely to be experienced as an inhibitor. You’ve got stimulus for the gas, but the reason to put on the brakes doesn’t actually mean a whole lot to your sexual motivation system. I mean, so what? They’re partnered already. That’s not a consequence, that’s a fact, unless you associate some soon, certain, and negative consequence with it; so it won’t really work as an inhibitor.

But if you can’t have someone because, I don’t know, you feel likely to experience STI transmission or unwanted pregnancy or serious social stigmatization or other soon, certain, and highly negative consequences, that would legit turn on the brakes and, even if it didn’t stop you from wanting the person, wouldn’t actively INCREASE your desire for that person.

The test then, is of the relationship between the nature of the inaccessibility of a sexually appetitive stimulus and a person’s experience of wanting that appetitive stimulus more in relation to its inaccessibility.

Someone go test this please.