Autumn rain: being damp is inferred rather than truly felt. Photo: Getty
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On our nerves: what makes us itch or feel wet?

Michael Brooks’s science column. 

We’re all going to feel some unwanted damp on the skin over the next few weeks – welcome to autumn. But for those who feel wet due to a medical condition rather than the weather, researchers at Loughborough University have made what might just prove to be a welcome breakthrough.

It starts with a seemingly innocuous question: what makes wet stuff feel wet? By the end of this exploration, we will have encountered Joni Mitchell, patients with multiple sclerosis (MS) and a host of people suffering in ways that evoke Dante’s Inferno.

To some animal species, wetness is so critical to survival that evolution has equipped them to determine their state of external hydration: insects have humidity sensors. Human beings, however, don’t have wetness sensors on their skin, so understanding how we differentiate the sense of wetness from other sensations is a puzzle.

We have found clues in some of the tricks one can play on our species. The Loughborough researchers have shown that if you reduce the skin’s temperature using a dry cooling method, people feel as though their skin is wet. If you put something wet in contact with the skin, but at a temperature warmer than it, people don’t perceive it as wet.

So, clearly, we don’t feel wetness, we infer it. Our skin has an array of sensors for temperature and pressure, and it is a combination of these senses which tells us that something we are touching is wet. To find out what that combination might be, the Loughborough team experimented on 13 students, blocking and releasing their nerve sensitivities.

It turns out that crucial to wetness perception are nerves known as A-nerve fibres. Block the blood supply to these – using something like a blood-pressure cuff – and you become far worse at sensing wetness. Unsurprisingly, it is easier to sense cold wetness than warm wetness. The interplay of these different sensitivities enabled the researchers to create a model for the brain’s interpretation of wetness; in essence, it applies a weighting to each set of inputs in order to come to a probability-based conclusion on the body’s state.

This is more than an academic discovery because skin sensitivity is a serious medical issue. People suffering with MS frequently report an unpleasant feeling of cold wetness on their skin. It is a couple of short steps from feeling cold wetness to pain. One side effect of diabetes, for instance, can be dysaesthesia, when diabetics experience a burning or stabbing sensation on their skin, or feel the slightest touch from clothing or bedlinen as excruciating pain. In other cases, some diabetics can’t feel heat or touch sensitively enough to avoid injuring themselves.

It’s not just about the side effects of recognised diseases, though. There are various medical conditions associated with nerves sending pain signals in response to (apparently) nothing. Sufferers of central pain syndrome can report sensations such as being torn apart with hot knives, or being burned alive. No wonder it gets referred to as a Dante-type condition. Another oddity is Morgellons Disease. Joni Mitchell is perhaps the best-known sufferer of this unstoppable itching, which feels as if something is crawling under the skin. The medical orthodoxy is that the condition is indicative of a psychiatric disorder. However, if we knew more precisely what our skin’s nerve endings transmit to the brain, we might be able to help sufferers, delusional or not. 

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 08 October 2014 issue of the New Statesman, Grayson Perry guest edit

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A quote-by-quote analysis of how little Jeremy Hunt understands technology

Can social media giants really implement the health secretary’s sexting suggestions? 

In today’s “Did we do something wrong? No, it was social media” news, Health Secretary Jeremy Hunt has argued that technology companies need to do more to prevent sexting and cyber-bullying.

Hunt, whose job it is to help reduce the teenage suicide rate, argued that the onus for reducing the teenage suicide rate should fall on social media companies such as Facebook and Twitter.

Giving evidence to the Commons Health Committee on suicide prevention, Hunt said: “I think social media companies need to step up to the plate and show us how they can be the solution to the issue of mental ill health amongst teenagers, and not the cause of the problem.”

Pause for screaming and/or tearing out of hair.

Don’t worry though; Hunt wasn’t simply trying to pass the buck, despite the committee suggesting he direct more resources to suicide prevention, as he offered extremely well-thought out technological solutions that are in no way inferior to providing better sex education for children. Here’s a quote-by-quote analysis of just how technologically savvy Hunt is.

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“I just ask myself the simple question as to why it is that you can’t prevent the texting of sexually explicit images by people under the age of 18…”

Here’s Hunt asking himself a question that he should be asking the actual experts, which is in no way a waste of anybody’s time at all.

“… If that’s a lock that parents choose to put on a mobile phone contract…”

A lock! But of course. But what should we lock, Jeremy? Should teenager’s phones come with a ban on all social media apps, and for good measure, a block on the use of the camera app itself? It’s hard to see how this would lead to the use of dubious applications that have significantly less security than giants such as Facebook and Snapchat. Well done.

“Because there is technology that can identify sexually explicit pictures and prevent it being transmitted.”

Erm, is there? Image recognition technology does exist, but it’s incredibly complex and expensive, and companies often rely on other information (such as URLs, tags, and hashes) to filter out and identify explicit images. In addition, social media sites like Facebook rely on their users to click the button that identifies an image as an abuse of their guidelines, and then have a human team that look through reported images. The technology is simply unable to identify individual and unique images that teenagers take of their own bodies, and the idea of a human team tackling the job is preposterous. 

But suppose the technology did exist that could flawlessly scan a picture for fleshy bits and bobs? As a tool to prevent sexting, this still is extremely flawed. What if two teens were trying to message one another Titian’s Venus for art or history class? In September, Facebook itself was forced to U-turn after removing the historical “napalm girl” photo from the site.

As for the second part of Jezza’s suggestion, if you can’t identify it, you can’t block it. Facebook Messenger already blocks you from sending pornographic links, but this again relies on analysis of the URLs rather than the content within them. Other messaging services, such as Whatsapp, offer end-to-end encryption (EE2E), meaning – most likely to Hunt’s chagrin – the messages sent on them are not stored nor easily accessed by the government.

“I ask myself why we can’t identify cyberbullying when it happens on social media platforms by word pattern recognition, and then prevent it happening.”

Jeremy, Jeremy, Jeremy, Jeremy, can’t you spot your problem yet? You’ve got to stop asking yourself!

There is simply no algorithm yet intelligent enough to identify bullying language. Why? Because we call our best mate “dickhead” and our worst enemy “pal”. Human language and meaning is infinitely complex, and scanning for certain words would almost definitely lead to false positives. As Labour MP Thangam Debbonaire famously learned this year, even humans can’t always identify whether language is offensive, so what chance does an algorithm stand?

(Side note: It is also amusing to imagine that Hunt could even begin to keep up with teenage slang in this scenario.)

Many also argue that because social media sites can remove copyrighted files efficiently, they should get better at removing abusive language. This is a flawed argument because it is easy to search for a specific file (copyright holders will often send social media giants hashed files which they can then search for on their databases) whereas (for the reasons outlined above) it is exceptionally difficult for algorithms to accurately identify the true meaning of language.

“I think there are a lot of things where social media companies could put options in their software that could reduce the risks associated with social media, and I do think that is something which they should actively pursue in a way that hasn’t happened to date.”

Leaving aside the fact that social media companies constantly come up with solutions for these problems, Hunt has left us with the burning question of whether any of this is even desirable at all.

Why should he prevent under-18s from sexting when the age of consent in the UK is 16? Where has this sudden moral panic about pornography come from? Are the government laying the ground for mass censorship? If two consenting teenagers want to send each other these aubergine emoji a couple of times a week, why should we stop them? Is it not up to parents, rather than the government, to survey and supervise their children’s online activities? Would education, with all of this in mind, not be the better option? Won't somebody please think of the children? 

“There is a lot of evidence that the technology industry, if they put their mind to it, can do really smart things.

Alas, if only we could say the same for you Mr Hunt.

Amelia Tait is a technology and digital culture writer at the New Statesman.