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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Forget fake news on Facebook – the real filter bubble is you

If people want to receive all their news from a single feed that reinforces their beliefs, there is little that can be done.

It’s Google that vaunts the absurdly optimistic motto “Don’t be evil”, but there are others of Silicon Valley’s techno-nabobs who have equally high-flown moral agendas. Step forward, Mark Zuckerberg of Facebook, who responded this week to the brouhaha surrounding his social media platform’s influence on the US presidential election thus: “We are all blessed to have the ability to make the world better, and we have the responsibility to do it. Let’s go work even harder.”

To which the only possible response – if you’re me – is: “No we aren’t, no we don’t, and I’m going back to my flowery bed to cultivate my garden of inanition.” I mean, where does this guy get off? It’s estimated that a single message from Facebook caused about 340,000 extra voters to pitch up at the polls for the 2010 US congressional elections – while the tech giant actually performed an “experiment”: showing either positive or negative news stories to hundreds of thousands of their members, and so rendering them happier or sadder.

In the past, Facebook employees curating the site’s “trending news” section were apparently told to squash stories that right-wingers might “like”, but in the run-up to the US election the brakes came off and all sorts of fraudulent clickbait was fed to the denizens of the virtual underworld, much – but not all of it – generated by spurious alt-right “news sites”.

Why? Because Facebook doesn’t view itself as a conventional news provider and has no rubric for fact-checking its news content: it can take up to 13 hours for stories about Hillary Clinton eating babies barbecued for her by Barack Obama to be taken down – and in that time Christ knows how many people will have not only given them credence, but also liked or shared them, so passing on the contagion. The result has been something digital analysts describe as a “filter bubble”, a sort of virtual helmet that drops down over your head and ensures that you receive only the sort of news you’re already fit to be imprinted with. Back in the days when everyone read the print edition of the New York Times this sort of manipulation was, it is argued, quite impossible; after all, the US media historically made a fetish of fact-checking, an editorial process that is pretty much unknown in our own press. Why, I’ve published short stories in American magazines and newspapers and had fact-checkers call me up to confirm the veracity of my flights of fancy. No, really.

In psychology, the process by which any given individual colludes in the creation of a personalised “filter bubble” is known as confirmation bias: we’re more inclined to believe the sort of things that validate what we want to believe – and by extension, surely, these are likely to be the sorts of beliefs we want to share with others. It seems to me that the big social media sites, while perhaps blowing up more and bigger filter bubbles, can scarcely be blamed for the confirmation bias. Nor – as yet – have they wreaked the sort of destruction on the world that has burst from the filter bubble known as “Western civilisation” – one that was blown into being by the New York Times, the BBC and all sorts of highly respected media outlets over many decades.

Societies that are both dominant and in the ascendant always imagine their belief systems and the values they enshrine are the best ones. You have only to switch on the radio and hear our politicians blithering on about how they’re going to get both bloodthirsty sides in the Syrian Civil War to behave like pacifist vegetarians in order to see the confirmation bias hard at work.

The Western belief – which has its roots in imperialism, but has bodied forth in the form of liberal humanism – that all is for the best in the world best described by the New York Times’s fact-checkers, is also a sort of filter bubble, haloing almost all of us in its shiny and translucent truth.

Religion? Obviously a good-news feed that many billions of the credulous rely on entirely. Science? Possibly the biggest filter bubble there is in the universe, and one that – if you believe Stephen Hawking – has been inflating since shortly before the Big Bang. After all, any scientific theory is just that: a series of observable (and potentially repeatable) regularities, a bubble of consistency we wander around in, perfectly at ease despite its obvious vulnerability to those little pricks, the unforeseen and the contingent. Let’s face it, what lies behind most people’s beliefs is not facts, but prejudices, and all this carping about algorithms is really the howling of a liberal elite whose own filter bubble has indeed been popped.

A television producer I know once joked that she was considering pitching a reality show to the networks to be called Daily Mail Hate Island. The conceit was that a group of ordinary Britons would be marooned on a desert island where the only news they’d have of the outside world would come in the form of the Daily Mail; viewers would find themselves riveted by watching these benighted folk descend into the barbarism of bigotry as they absorbed ever more factitious twaddle. But as I pointed out to this media innovator, we’re already marooned on Daily Mail Hate Island: it’s called Britain.

If people want to receive all their news from a single feed that constantly and consistently reinforces their beliefs, what are you going to do about it? The current argument is that Facebook’s algorithms reinforce political polarisation, but does anyone really believe better editing on the site will return our troubled present to some prelap­sarian past, let alone carry us forward into a brave new factual future? No, we’re all condemned to collude in the inflation of our own filter bubbles unless we actively seek to challenge every piece of received information, theory, or opinion. And what an exhausting business that would be . . . without the internet.

Will Self is an author and journalist. His books include Umbrella, Shark, The Book of Dave and The Butt. He writes the Madness of Crowds and Real Meals columns for the New Statesman.

This article first appeared in the 24 November 2016 issue of the New Statesman, Blair: out of exile