The Science of Spanking #2: Good Vibrations

A new discovery explains the puzzle of sensual pleasure

This article has a companion post:

The Science of Spanking #1: Heat Without Fire

---

The Puzzle of Pleasure

One might think that after centuries of detailed anatomical study, and technological advances in scanning that enable us to peer deep beneath our skin, that we’d know exactly how our own bodies work. You might be surprised.

Through observation and meticulous experiments, science has been able to establish how much of our bodies work, yet blank spaces remain where we still don’t truly understand why our bodies work as they do. And inhibited by a shroud of our own prudishness, our ignorance is at its greatest when it comes to knowing how sexual pleasure emerges.

Why, for example, do vibrators feel more intensely pleasurable than dildos? Think about it, and it seems pretty weird. The vibrator is entirely artificial, nothing like it exists in nature, whilst the dildo mimics anatomy commonly used for penetration. Even so, buzzy toys provide far more intense sensations than the substitute phallus.

In this post, we’re going to go down a scientific rabbit hole, and learn how our most intimate places work. By the end of this article, you’re going to know something really rather cool: how and why sexual stimulation results in pleasurable sensations.

And it’s not just sex. Consider the surprisingly enjoyable experience of bottom smacking. A similar slap delivered anywhere else on the body would feel like an injurious insult — but if you’ve ever participated in a spanking, you’ll know how unexpectedly good it feels. Stranger still, you may have noticed how the smacks aren’t just felt where they land on the buttocks, there’s an accompanying echo in the genitals too, far beyond the point of impact.

We know enough about our anatomy to explain how impacts are felt, there are several nerves that serve the skin and transmit sensations from smacks on the bum towards our brains. The superior, middle, and inferior cluneal nerves act as conduits for “stingy” and “thuddy” sensations from each cheek. Whilst the gluteal nerves only transmit the “thuddy” impacts felt deeper in the big gluteal muscles. No mystery there.

But what about the pleasurable sensations? What’s interesting about sensations of sexual pleasure is, despite the physical proximity of the genitals and the buttocks, they’re transmitted along a different pathway - the pudendal nerve and its sub-branches, namely the perineal nerve, and the dorsal nerve of the penis or clitoris.

So spanking involves an intriguing puzzle, impacts are felt as blows where they land, then separately as arousingly tingly sensations in faraway places that were never actually touched. There’s quite a distance between where a cane lands on a man’s bum and where it’s felt at the tip of his penis. And women commonly feel the echoes of spankings in their clitoris, and inside their vaginas. 

What is happening here? Clearly something quite different to our normal experience of touch. The whole point of our sense of touch is to be super-specific about the part of our body that’s currently feeling some physical contact. Nowhere else in the body are you touched somewhere and yet feel it in a completely different place entirely. 

To solve this conundrum, we’re going to need more science.

---

A New Discovery about How We Feel

Let’s start with a quick primer on the biological basis of sensations. I covered this in the previous post, but here’s a quick recap.

We have three classes of sensors in our skin. Pressure sensors (of which there are at least six different kinds) detect various types of contact and movement, and generate the nerve signals that we ultimately interpret as touching, caressing and rubbing. Pain sensors detect physical injury to our skin, such as cuts, slaps, and scratches, which we perceive as painful and alarming. And Temperature sensors detect variations of hot and cold, allowing us to distinguish between the pleasantly comfortable and the dangerously extreme.

All three kinds of sensors are location specific, they’re intended to tell where something is touching us, so we know immediately where we’ve been hurt, or are at risk of being frozen or burned. But have you noticed how sexual sensations feel different? They feel diffuse, like a glow, radiating beyond where we were originally touched, which is likely why they’re so unusually satisfying. 

The mystery of why certain touches were felt so far beyond the site of touching led scientists to investigate the microscopic structures within the skin. It led to a discovery, reported recently in the prestigious scientific journal Nature, that studied tiny mysterious bulbs called Krause corpuscles, which are found throughout the skin of mammals. 

Krause corpuscles are different in structure from the much more widespread Meissner's corpuscles, which are our most common kind of mechanoreceptor (pressure sensor). Previously scientists had suspected the Krause were a kind of temperature sensor or light-touch pressure sensor, but this new research presents evidence that they are in fact vibration sensors.

Experiments revealed Krause corpuscles are sensitive to different (higher) frequencies (50-80 Hz) than Meissner corpuscles (10-50 Hz). Intriguingly, the Krause also occur in their greatest concentration in the penis and clitoris, so the pulses they emit are ultimately transmitted through the pudendal nerve. Their prevalence in these specific locations - but not elsewhere - strongly suggests they have an important role to play in perceiving sexual sensations.

The emerging evidence indicates that the sensitivity of the genital regions to vibrations isn't an incidental side-effect, but a crucial part of how motion gets transformed into something we perceive as sexually arousing.

Note that a sensitivity to 50-80 Hertz doesn’t mean the skin is being rubbed 50-80 times a second, that would be preposterous, no one rubs that fast. What it means is that new incoming pressure waves are being detected around 50-80 times a second. Our skin is what’s known as a viscoelastic material. Stretchy collagen fibres give it the ability to stretch and return to its original shape (elasticity), while the amorphous gel that fills the spaces between our cells (called the ground substance) makes the skin act like viscous solid that resists deformation. 

Imagine a penis being gripped by a hand, or sucked by a mouth. Or imagine a vagina being penetrated. In all these cases, highly sensitive flesh is being repeatedly dragged and stretched, then springing back to its natural shape chaotically. Imagine the tiny wobbles of plates of jelly. These repeated erratic deformations, occurring at miniscule scales many times per second, are what give rise to the vibrations that we perceive as pleasurable sensations.

That vibrations feel arousing is hardly a ground-breaking discovery, otherwise much of the sex toy industry wouldn't exist. But what’s so interesting about this new research is it provides an explanation for why vibrations feel pleasurable. The tiny Krause structures seem to be the missing link that translate rubbing motions to low-frequency vibrations, which we perceive as sexual sensations.

When you think about it, our responsiveness to vibration makes perfect sense. If we only felt sexual pleasure at the point of touching, sex would feel quite superficial, akin to being patted or lightly tapped. But intimate rubbing and stroking feels inexplicably different from every other kind of everyday touch, it makes us glow in a way no other physical contact ever does.

There’s a cliche in bad sex scenes, where one character (almost always female, often sexually naive) moans to her lover: “Touch me, just there!” - as if he’s just discovered the long lost hidden button that finally ignites the blazing beacon of her sexuality. It’s a lame trope, because it suggests good sex involves finding the right spot, or being an “expert lover” who knows all the “right” techniques. In reality, touching any spot can feel good, and sometimes people can even climax with barely any touches at all. 

Of course, sex is far more than an emotionally satisfying activity, it’s also of fundamental importance biologically. The researchers reported that the sensations felt in the penis were vital to ejaculation, and deliberately blocking the Krause bodies inhibited mating between lab rats. There are strong evolutionary advantages to having super-sensitive vibration sensors in the genitals that make sexual activity as pleasurable, and effective, as possible. 

Whether it’s through a thrusting penis, a licking tongue, or stroking fingers, the rhythmic rubbing of the genitals produces miniscule ripples within our bodies. We have been blessed with special sensors concentrated in that region that pick up these vibrations like an antenna.

Our sensors do their duty of reporting regardless of what caused the vibrations, operating at the molecular level, they have no way to distinguish the source. The stream of sensations are ever-changing in tempo and abstract in their meaning. Perhaps that’s why our experience of sex feels more like music than the staccato blips of Morse Code.

---

What exactly are vibrations anyway?

Let’s return to that original mystery, why spankings can feel so sexually satisfying despite involving no direct genital contact at all.

To explain this, we need to step away from Biology for a moment and talk Physics. If you remember the basic principles of science from school, you’ll know that energy can not be created or destroyed, only transformed. So what happens to the energy of a moving hand that suddenly encounters a firm fleshy bottom? The kinetic energy of the hand will have to be transmuted, of course.

As the hand can’t move any further, its energy is going to need new vehicles for its travels. Some of the energy will create acoustic waves, which will propagate through the surrounding air, and that’s what we hear as the familiar slap. Some of the energy will be transformed into heat through friction, and whilst this may marginally raise the skin temperature, it’s not responsible for the fiery heat felt during a spanking, which is a phantom heat generated by our own nerves. 

Some of the incoming energy will briefly deform both the shape of the hand (the spanker will feel a force pushing their fingers back) and the recipient’s bottom (by squashing the fleshy parts flat), and then be transformed into vibrations - minuscule repercussions within the two colliding regions. 

Newton’s Third Law of Motion states that to every action, there is always an equal but opposite reaction. So the moving hand is going to stop, and impart a force to the recipient’s cheek. Bums, being mostly composed of fatty flesh and water, are excellent mediums for the propagation of what are known as mechanical waves. So the energy radiates out from the point of impact through the recipient's body.

To use another analogy, this is exactly what happens when a drum is struck. The kinetic energy of the drumstick deforms the drum-skin, which causes it to vibrate, and we hear those vibrations as sound. Drums are instruments for highly efficiently converting impacts into vibrations. And, so it turns out, bottoms are too.

And would you believe it? In women, just a short distance away from the point of impact, right between the buttocks, is an extraordinarily sensitive vibration sensor: the clitoris. This isn’t just the visible little bump, but also two bulbs of spongy tissue that straddle the vagina. Like an iceberg, most of the clitoris is invisible, hidden beneath the surface of the skin, its wishbone shape even looks like an antenna. By now, it should be obvious why it’s buried out of sight, it’s designed to sense vibrations, rather than be directly touched.

In a drum, the rigid outer case reflects sound waves internally, when waves of complementary frequencies meet, they are reinforced, resulting in a louder sound. The clitoris also sits in the centre of the pelvis, so exactly the same thing happens within the lower torso, vibrations are reflected back off nearby bones and amplified before being felt between the legs. 

These might be quirks of anatomy, or an evolution-selected design, but whatever the origins, we can be grateful that the vibrations of a spanking travel through the flesh of the bottom, and ultimately end up focused on the clitoris, like the collector on a satellite dish.

And, as a woman is aroused, her clitoris swells and grows, literally increasing the volume of her pleasure receiver. No wonder women say spankings feel even better when they’re at their most excited.

In men, the receiving area is the tip (glans) of the penis, but the same principle applies. The whole penis serves as a receiving and focusing antenna, so picks up different frequencies of vibrations when it’s soft and flaccid to when it’s swollen and erect. Hence there’s a sweet spot of erectile stiffness, unique to every man, that feels just right.

These quirks of sensitivity explain why spankings that are delivered ‘cold’, (without giving the recipient the chance to become fully aroused), feel less pleasurable and more like “punishments”. A sudden unexpected bottom smacking is therefore much more likely to generate pouts and pleas than mews and moans. 

---

The Rattan Vibrator

Those who enjoy spanking have long known that the vibrations of spankings seem to echo through their genitals. There’s an excellent description of the kind of feelings a caning induces in this essay by Conrad Hudson:  

“The shock waves made by a cane are directional - they tend to continue through the target in the general direction the cane was moving when it hit. In fact, if you slide a hand under your partner's thigh or belly, you can feel the shock of a medium cane stroke go right through them. The "sweet spot" in the lower butt, to either side of the crack, is sweet for this reason; blows here can send waves up into a whole complex of muscles, nerves, and engorged tissue that is directly involved with sexual excitement. Many bottoms will enjoy a steady rhythm of light or medium blows on the sweet spot - especially if they are angled to send their shock waves up and forward. At least one lady I know has called the effect a ‘rattan vibrator’.”

That essay also contains the interesting anecdote that “perhaps a quarter of women, and a very few men, can actually get orgasms from the cane. There will be others who may not actually climax, but get extremely turned on.”

This claim is consistent with my experience. Spanking is not just psychologically arousing, it is definitely physically arousing too. That impacts produce sexually pleasurable sensations is likely a happy coincidence. When delivered with the right force, impacts generate miniscule ripples in our bodies, just like the continuous stretching and deformation of intercourse does. 

This explanation of pleasure being vibration-centric rather than touch-centric also explains why different spanking implements feel good to different people. In Physics, there’s a concept called resonance. When an oscillating force (something that causes vibrations) is applied at a resonant frequency, which is different for every substance, the oscillations will be amplified. Everyone’s body will be physically attuned to resonate at specific frequencies, unique to their own particular anatomy, and some implements will happen to match that perfectly.

And if you’ve read the previous part, you’ll know vibrations are just one of the flavours our bodies can “taste” — along with pain, stinginess, impacts, and heat. Together these sensations can be blended into quite delicious recipes, but I’ll save that discussion for another post.

---

Vibrations in Stardust 

The beauty of Science is the deeper we look, the more elegant everything appears. It seems appropriate that vibrations are the medium of sexual interaction, given how fundamental vibrations are to nature. The energy in our food that powers us is captured sunlight, beamed across the void of space as oscillations in the fabric of reality.

Cosmology tells us that every non-Hydrogen atom in our bodies was manufactured in the stellar furnaces of long-dead stars. I think it’s rather romantic that the sensations that intimately connect us to our lovers are, at the very deepest level, vibrations in our stardust.

Whilst there’d been plenty of anecdotal evidence that spankings felt sexually arousing, until recently the physical pathways involved weren't obvious. For years, the prevailing wisdom was "sex was in the head", as if the brain acted like a DJ's mixing desk, receiving disparate physical signals and somehow sexualising them into a banging erotic remix.

Thanks to this new research, we now know the same exquisite sensitivity to vibrations that makes sex pleasurable is also responsible for making spanking enjoyable too. Our genital areas have miniature sensors that collectively form an internal antenna, so they don’t even need to be touched directly.

The sensors within us aren’t judgemental, they don’t care what causes the vibrations, whether it’s a penetrating penis or the smack of a slipper. The sensors simply report what they feel, and leave it up to our brains to eroticise it. That’s why a spanking, or grinding against a pillow, or any number of other non-penetrative activities can feel just as good as any conventional fucking. 

It’s a shame so many struggle with opening up and sharing the actual activities that turn them on. It’s as if we’ve internalised the belief that there’s only a few officially approved ways of achieving sexual enjoyment, and anything outside that is somehow weird and deviant.

If we hide our interests we make ourselves less interesting. How often do we lament the erotic spark we crave seems missing — and yet, how often do we honestly reveal what truly turns us on?

I think this last point may be the most important lesson in this post. However you choose to make the microscopic cells of your own body vibrate is perfectly acceptable. Whether it’s a tongue or a penis, a strap or a strap-on, a vibrator or a hairbrush, or a slipper or a cane — there’s no need to be ashamed of it. 

Because, when you think about it, being able to generate pleasure from smacks on the bottom — without ever even touching the genitals — is pretty damn ingenious. It’s almost like a magic trick.

Just like a bell, everybody has a special frequency that makes them sing.

Do more of the things that make you quake and quiver. 

Until next time - stay curious!

— spankingtheatre