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Now you see it, now you don't: what optical illusions tell us about our brains

Illusions can offer insights into how the visual system processes images.

Maurits Escher: where do the staircases lead?

The human brain is a network of about 20 billion neurons – nerve cells – linked by several trillion connections. Not to mention glial cells, which scientists used to think were inactive scaffolding, but increasingly view as an essential part of how the brain works. Our brains give us movement, language, senses, memories, consciousness and personality. We know a lot more about the brain than we used to, but it still seems far too complicated for human understanding.

Fortunately, the brain contains many small networks of neurons that carry out some specific function: vision, hearing, movement. It makes sense to tackle these simple modules first. Moreover, we have good mathematical models of nerve cell behaviour. In 1952, Alan Hodgkin and Andrew Huxley wrote down the “Hodgkin-Huxley equations” for the transmission of a nerve impulse, which won them the 1963 Nobel Prize in Medicine. We also have effective techniques for understanding small networks’ components and how they are linked.

Many of these simple networks occur in the visual system. We used to think that the eye was like a camera, taking a “snapshot” of the outside world that was stored in the brain like a photo stuck in an album. It uses a lens to focus an image on to the retina at the back of the eye, which functions a bit like a roll of film – or, in today’s digital cameras, a charge-coupled device, storing an image pixel by pixel. But we now know that when the retina sends information to the brain’s visual cortex, the similarity to a camera ends.

Although we get a strong impression that what we are seeing is “out there” in front of us, what determines that perception resides inside our own heads. The brain decomposes images into simple pieces, works out what they are, “labels” them with that information, and reassembles them. When we see three sheep and two pigs in a field, we “know” which bits are sheep, which are pigs, and how many of each there are. If you try to program a computer to do that, you quickly realise how tricky the process is. Only very recently have computers been able to distinguish between faces, let alone sheep and pigs.

Probing the brain’s detailed activity is difficult. Rapid progress is being made, but it still takes a huge effort to get reliable information. But when science cannot observe something directly, it infers it, working indirectly. An effective way to infer how something functions is to see what it does when it goes wrong. It may be hard to understand a bridge while it stays up, but you can learn a lot about strength of materials when it collapses.

The visual system can “go wrong” in several interesting ways. Hallucinogenic drugs can change how neurons behave, producing dramatic images such as spinning spirals, which originate not in the eye, but in the brain. Some images even cause the brain to misinterpret what it’s seeing without outside help. We call them optical illusions.

One of the earliest was discovered in Renaissance Italy in the 16th century. Giambattista della Porta was the middle of three surviving sons of a wealthy merchant nobleman who became secretary to the Holy Roman emperor Charles V. The father was an intellectual, and Giambattista grew up in a house in Naples that hosted innumerable mathematicians, scientists, poets and musicians. He became an outstanding polymath, with publications on secret codes (including writing on the inside of eggshells), physiology, botany, agriculture, engineering, and much else. He wrote more than 20 plays.

Della Porta was particularly interested in the science of light. He made definitive improvements to the camera obscura, a device that projects an image of the outside world into a darkened room; he claimed to have invented the telescope before Galileo, and very likely did. His De refractione optices of 1593 contained the first report of a curious optical effect. He arranged two books so that one was visible to one eye only and the other to the other eye. Instead of seeing a combination of the two images, he perceived them alternately. He discovered that he could select either image at will by consciously switching his attention. This phenomenon is known today as binocular rivalry.

Two other distinct but related effects are impossible figures and visual illusions. In rivalry, each image appears unambiguous, but the eyes are shown conflicting images. In the other two phenomena, both eyes see the same image, but in one case it doesn’t make sense, and in the other it makes sense but is ambiguous.

Impossible figures at first sight seem to be entirely normal, but depict things that cannot exist – such as Roger Shepard’s 1990 drawing of an elephant in which everything above the knees makes sense, and everything below the knees makes sense, but the two regions do not fit together correctly. The Dutch artist Maurits Escher made frequent use of this kind of visual quirk.

In 1832, the Swiss crystallographer Louis Necker invented his “Necker cube” illusion, a skeletal cube that seems to switch its orientation repeatedly. An 1892 issue of the humorous German magazine Fliegende Blätter contains a picture with the caption “Which animals are most like each other?” and the answer “Rabbit and duck”. In a 1915 issue of the American magazine Puck, the cartoonist Ely William Hill published “My wife and my mother-in-law”, based on an 1888 German postcard. The image can be seen either as a young lady looking back over her shoulder, or as an elderly woman facing forwards. Several of Salvador Dalí’s paintings include illusions; especially Slave Market With the Apparition of the Invisible Bust of Voltaire, where a number of figures and everyday objects, carefully arranged, combine to give the impression of the French writer’s face.

Illusions offer insights into how the visual system processes images. The first few stages are fairly well understood. The top layer in the visual cortex detects edges of objects and the direction in which they are pointing. This information is passed to lower layers, which detect places where the direction suddenly changes, such as corners. Eventually some region in the cortex detects that you are looking at a human face and that it belongs to Aunt Matilda. Other parts of the brain are alerted, and you belatedly remember that tomorrow is her birthday and hurry off to buy a present.

These things don’t happen by magic. They have a very definite rationale, and that’s where the mathematics comes in. The top layer of the visual cortex contains innumerable tiny stacks of nerve cells. Each stack is like a pile of pancakes, and each pancake is a network of neurons that is sensitive to edges that point in one specific direction: one o’clock, two o’clock and so on.

For simplicity, call this network a cell; it does no harm to think of it as a single neuron. Roughly speaking, the cell at the top of the stack senses edges at the one o’clock position, the next one down corresponds to the two o’clock angle, and so on. If one cell receives a suitable input signal, it “fires”, telling all the other cells in its stack: “I’ve seen a boundary in the five o’clock direction.” However, another cell in the same stack might disagree, claiming the direction is at seven o’clock. How to resolve this conflict?

Neurons are linked by two kinds of connection, excitatory and inhibitory. If a neuron activates an excitatory connection, those at the other end of it are more likely to fire themselves. An inhibitory connection makes them less likely to fire. The cortex uses inhibitory connections to reach a definite decision. When a cell fires, it sends inhibitory signals to all of the other cells in its stack. These signals compete for attention. If the five o’clock signal is stronger than the seven o’clock one, for instance, the seven o’clock one gets shut down. The cells in effect “vote” on which direction they are detecting and the winner takes all.

Many neuroscientists think that something very similar is going on in visual illusions and rivalry. Think of the duck and rabbit with two possible interpretations. Hugh R Wilson, a neuroscientist at the Centre for Vision Research at York University, Toronto, proposed the simplest model, one stack with just two cells. Rodica Curtu, a mathematician at the University of Iowa, John Rinzel, a biomathematician then at the National Institutes of Health, and several other scientists have analysed this model in more detail. The basic idea is that one cell fires if the picture looks like a duck, the other if it resembles a rabbit. Because of the inhibitory connections, the winner should take all. Except that, in this illusion, it doesn’t quite work, because the two choices are equally plausible. That’s what makes it an illusion. So both cells want to fire. But they can’t, because of those inhibitory connections. Yet neither can they both remain quiescent, because the incoming signals encourage them to fire.

One possibility is that random signals coming from elsewhere in the brain might introduce a bias of perception, so that one cell still wins. However, the mathematical model predicts that, even without such bias, the signals in both cells should oscillate from active to inactive and back again, each becoming active when the other is not. It’s as if the network is dithering: the two cells take turns to fire and the network perceives the image as a duck, then as a rabbit, and keeps switching from one to the other. Which is what happens in reality.

Generalising from this observation, Wilson proposed a similar type of network that can model decision-making in the brain – which political party to support, for instance. But now the network consists of several stacks. Maybe one stack represents immigration policy, another unemployment, a third financial regulation, and so on. Each stack consists of cells that “recognise” a distinct policy feature. So the financial regulation stack has cells that recognise state regulation by law, self-regulation by the industry, or free-market economics.

The overall political stance of any given political party is a choice of one cell from each stack – one policy decision on each issue. Each prospective voter has his or her preferences, and these might not match those of any particular party. If these choices are used as inputs to the network, it will identify the party that most closely fits what the voter prefers. That decision can then be passed to other areas of the brain. Some voters may find themselves in a state akin to a visual illusion, vacillating between Labour and Liberal Democrat, or Conservative and Ukip.

This idea is speculative and it is not intended to be a literal description of how we decide whom to vote for. It is a schematic outline of something more complex, involving many regions of the brain. However, it provides a simple and flexible model for decision-making by a neural network, and in particular it shows that simple networks can do the job quite well. Martin Golubitsky of the Mathematical Biosciences Institute at Ohio State University and Casey O Diekman of the University of Michigan wondered whether Wilson’s networks could be used to model more complex examples of rivalry and illusions. Crucially, the resulting models allow specific predictions about experiments that have not yet been performed, making the whole idea scientifically testable.

The first success of this approach helped to explain an experiment that had already been carried out, with puzzling results. When the brain reassembles the separate bits of an image, it is said to “bind” these pieces. Rivalry provides evidence that binding occurs, by making it go wrong. In a rivalry experiment carried out in 2006 by S W Hong and S K Shevell, the subject’s left eye is shown a horizontal grid of grey and pink lines while the right eye sees a vertical grid of grey and green lines. Many subjects perceive an alternation between the images, just as della Porta did with his books. But some see two different images alternating: pink and green vertical lines, and pink and green horizontal lines – images shown to neither eye. This effect is called colour misbinding; it tells us that the reassembly process has matched colour to grid direction incorrectly. It is as if della Porta had ended up seeing another book altogether.

Golubitsky and Diekman studied the simplest Wilson network corresponding to this experiment. It has two stacks: one for colour, one for grid direction. Each stack has two cells. In the “colour” stack one cell detects pink and the other green; in the “orientation” stack one cell detects vertical and the other horizontal. As usual, there are inhibitory connections within each stack to ensure a winner-takes-all decision.

Following Wilson’s general scheme, they also added excitatory connections between cells in distinct stacks, representing the combinations of colour and direction that occur in the two “learned” images – those actually presented to the two eyes. Then they used recent mathematical techniques to list the patterns that arise in such a network. They found two types of oscillatory pattern. One corresponds to alternation between the two learned images. The other corresponds precisely to alternation between the two images seen in colour misbinding.

Colour misbinding is therefore a natural feature of the dynamics of Wilson networks. Although the network is “set up” to detect the two learned images, its structure produces an unexpected side effect: two images that were not learned. The rivalry experiment reveals hints of the brain’s hidden wiring. The same techniques apply to many other experiments, including some that have not yet been performed. They lead to very specific predictions, including more circumstances in which subjects will observe patterns that were not presented to either eye.

Similar models also apply to illusions. However, the excitatory connections cannot be determined by the images shown to the two eyes, because both eyes see the same image. One suggestion is that the connections may be determined by what your visual system already “knows” about real objects.

Take the celebrated moving illusion called “the spinning dancer”. Some observers see the solid silhouette of a dancer spinning anticlockwise, others clockwise. Sometimes, the direction of spin seems to switch suddenly.

We know that the top half of a spinning dancer can spin either clockwise or anticlockwise. Ditto for the bottom half. In principle, if the top half spins one way but the bottom half spins the other way, you would see the same silhouette, as if both were moving together. When people are shown “the spinning dancer”, no one sees the halves moving independently. If the top half spins clockwise, so does the bottom half.

Why do our brains do this? We can model that information using a series of stacks that correspond to different parts of the dancer’s body. The brain’s prior knowledge sets up a set of excitatory connections between all cells that sense clockwise motion, and another set of excitatory connections between all “anticlockwise” cells. We can also add inhibitory connections between the “clockwise” and the “anticlockwise” cells. These connections collectively tell the network that all parts of the object being perceived must spin in the same direction at any instant. Our brains don’t allow for a “half and half” interpretation.

When we analyse this network mathematically, it turns out that the cells switch repeatedly between a state in which all clockwise cells are firing but the anticlockwise ones are quiescent, and a state in which all anticlockwise cells are firing but the clockwise ones are quiescent. The upshot is that we perceive the whole figure of the dancer switching directions. Similar networks provide sensible models for many other illusions, including some in which there are three different inputs.

These models provide a common framework for both rivalry and illusion, and they unify many experiments, explain otherwise puzzling results and make new predictions that can be tested. They also tell us that in principle the brain can carry out some apparently complex tasks using simple networks. (What it does in practice is probably different in detail, but could well follow the same general lines.)

This could help make sense of a real brain, as new experiments improve our ability to observe its “wiring diagram”. It might not be as ambitious as trying to model the whole thing on a computer, but modesty can be a virtue. Since simple networks behave in strange and unexpected ways, what incomprehensible quirks might a complicated network have?

Perhaps Dalí, and Escher, and the spinning dancer can help us find out. 

Ian Stewart is Emeritus Professor of Mathematics and Digital Media Fellow at the University of Warwick

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Losing Momentum: how Jeremy Corbyn’s support group ran out of steam

Tom Watson says it is destroying Labour. Its supporters say it is a vital force for change. Our correspondent spent six months following the movement, and asks: what is the truth about Momentum?

1. The Bus

 The bus to the Momentum conference in Liverpool leaves at seven on a Sunday morning in late September from Euston Station, and the whole journey feels like a parody of a neoliberal play about the failings of socialism. We depart an hour late because activists have overslept and we cannot go without them. As we wait we discuss whether Jeremy Corbyn will be re-elected leader of the Labour Party this very day. One man says not; a young, jolly girl with blonde hair cries: “Don’t say that on Jezmas!” She is joking, at least about “Jezmas”.

A man walks up. “Trots?” he says, calmly. He is joking, too; and I wonder if he says it because the idea of Momentum is more exciting to outsiders than the reality, and he knows it; there is an awful pleasure in being misunderstood. Momentum was formed in late 2015 to build on Corbyn’s initial victory in the Labour leadership election, and it is perceived as a ragtag army of placard-waving Trots, newly engaged clicktivists and Corbyn fanatics.

We leave, and learn on the M1 that, in some terrible metaphor, the coach is broken and cannot drive at more than 20mph. So we wait for another coach at a service station slightly beyond Luton. “Sabotage,” says one man. He is joking, too. We get off; another man offers me his vegan bread and we discuss Karl Marx.

A new coach arrives and I listen to the others discuss Jeremy Corbyn’s problems. No one talks about his polling, because that is depressing and unnecessary for their purpose – which, here, is dreaming. They talk about Corbyn as addicts talk about a drug. Nothing can touch him, and nothing is ever his fault. “There are problems with the press office,” says one. “Perhaps he needs better PAs?” says another.

One man thinks there will be a non-specific revolution: “I hope it won’t be violent,” he frets. “There have been violent revolutions in the past.” “I stuck it out during Blair and it was worth it,” says another. “They’ve had their go.” “We don’t need them [the Blairites],” says a third. “If new members come in, it will sort itself out,” says a fourth.

I have heard this before. Momentum supporters have told me that Labour does not need floating voters, who are somehow tainted because they dare to float. This seems to me a kind of madness. I do not know how the Labour Party will win a general election in a parliamentary democracy without floating voters; and I don’t think these people do, either.

But this is a coach of believers. Say you are not sure that Corbyn can win a general election and they scowl at you. That you are in total agreement with them is assumed, because this is the solidarity bus; and if you are in total agreement with them they are the sweetest people in the world.

That is why I do not tell them that I am a journalist. I am afraid to, and this fear baffles me. I have gone everywhere as a journalist but with these, my fellow-travellers on the left, I am scared to say it; and that, too, frightens me. MSM, they might call me – mainstream media. What it really means is: collaborator.

The man beside me has been ill. He talks sweetly about the potential renewal of society under Corbyn’s Labour as a metaphor for his own recovery, and this moves him; he has not been involved in politics until now. I like this man very much, until I mention the Jewish Labour MP Luciana Berger and the anti-Semitism she has suffered from Corbyn supporters and others; and he says, simply, that she has been employed by the state of Israel. He says nothing else about her, as if there were nothing else to say.

We listen to the results of the leadership election on the radio; we should be in Liverpool at the Black-E community centre to celebrate, but the solidarity bus is late. Corbyn thanks his supporters. “You’re welcome, Jeremy,” says a woman in the front row, as if he were on the coach. She nods emphatically, and repeats it to the man who isn’t there: “You’re welcome, Jeremy.”

In Liverpool, some of the passengers sleep on the floor at a community centre. The venue has been hired for that purpose: this is Momentum’s commitment to opening up politics to the non-connected, the previously non-engaged, and the outsiders who will attend their conference in a deconsecrated church, even as the official Labour conference convenes a mile away. But never mind that: this is the one that matters, and it is called The World Transformed.


2. The Conference

Later that day, outside the Black-E, a man comes up to me. Are you happy, he asks, which is a normal question here. These are, at least partly, the politics of feelings: we must do feelings, because the Tories, apparently, don’t. I say I’m worried about marginal seats, specifically that Jeremy – he is always Jeremy, the use of his Christian name is a symbol of his goodness, his accessibility and his singularity – cannot win them.

“The polls aren’t his fault,” the man says, “it’s [Labour] people briefing the Tories that he is unelectable.” I do not think it’s that simple but it’s easy to feel like an idiot – or a monster – here, where there is such conviction. As if there is something that only you, the unconvinced, have missed: that Jeremy, given the right light, hat or PA, could lead a socialist revolution in a country where 13 million people watched Downton Abbey.

But the man does say something interesting which I hope is true. “This is not about Jeremy, not really,” he says. “It is about what he represents.” He means Momentum can survive without him.

There is a square hall with trade union banners and a shop that sells Poems for Jeremy Corbyn, as well as a Corbyn-themed colouring book. When I am finally outed as a journalist, and made to wear a vast red badge that says PRESS, I attempt to buy one. “That’s all journalists are interested in,” the proprietor says angrily. That is one of our moral stains, apparently: a disproportionate (and sinister) interest in colouring books.

I go to the Black Lives Matter event. A woman talks about the experience of black students in universities and the impact of austerity on the black community. Another woman tells us that her five-year-old son wishes he was white; we listen while she cries. I go to the feminism meeting and change my mind about the legalisation of prostitution after a woman’s testimony about reporting an assault, and then being assaulted again by a police officer because of her legal status. Then I hear a former miner tell a room how the police nearly killed him on a picket line, and then arrested him.

This, to me, a veteran of party conferences, is extraordinary, although it shouldn’t be, and the fact that I am surprised is shameful. Momentum is full of the kinds of ­people you never see at political events: that is, the people politics is for. Women, members of minority communities (but not Zionist Jews, naturally), the disabled: all are treated with exaggerated courtesy, as if the Black-E had established a mirror world of its choosing, where everything outside is inverted.

When Corbyn arrives he does not orate: he ruminates. “We are not going to cascade poverty from generation to generation,” he says. “We are here to transform society and the world.” I applaud his sentiment; I share it. I just wish I could believe he can deliver it outside, in the other world. So I veer ­between hope and fury; between the certainty that they will achieve nothing but an eternal Conservative government, and the ever-nagging truth that makes me stay: what else is there?

There is a rally on Monday night. Momentum members discuss the “purges” of socialist and communist-leaning members from Labour for comments they made on social media, and whether détente is possible. A nurse asks: “How do we know that ‘wipe the slate clean’ means the same for us as it does for them? How on Earth can we trust the likes of Hilary Benn who dresses himself up in the rhetoric of socialism to justify bombing Syria? The plotters who took the olive branch offered by Jeremy to stab him in the back with another chicken coup?” I am not sure where she is going with that gag, or if it is even a gag.

The next man to speak had been at the Labour party conference earlier in the day; he saw Len McCluskey, John McDonnell and Clive Lewis on the platform. “Don’t be pessimistic, folks,” he cries. “On the floor of conference today we owned the party. Progress [the centrist Labour pressure group] are the weirdos now. We own the party!”

A man from Hammersmith and Fulham Momentum is next. “The national committee of Momentum was not elected by conference,” he says. “It’s a committee meeting knocked up behind closed doors by leading people on the left, including our two heroes.” He means Jeremy Corbyn and John McDonnell. This is explicit heresy, and the chair interrupts him: “Stan, Stan . . .” “I’m winding up!” he says. “We need a central committee of Momentum elected by conference,” he says, and sits down.

The following day Corbyn speaks in the hall in front of golden balloons that spell out S-H-E-E-P. It may be another gag, but who can tell, from his face? This is his commitment to not doing politics the recognisable way. He is the man who walks by himself, towards balloons that say S-H-E-E-P. (They are advertising the band that will follow him. They are called, and dressed as, sheep.) The nobility of it, you could say. Or the idiocy. He mocks the mockers of Momentum: is it, he was asked by the mainstream media, full of extremists and entryists? “I’m not controlling any of it,” he says calmly, and in this calmness is all the Twitter-borne aggression that people complain of when they talk about Momentum, for he enables it with his self-satisfied smile. “It’s not my way to try and control the way people do things. I want people to come together.” He laughs, because no one can touch him, and nothing is ever his fault.

I meet many principled people in Liverpool whose testimony convinces me, and I didn’t need convincing, that austerity is a national disaster. I meet only one person who thinks that Momentum should take over the Labour Party. The maddest suggestion I hear is that all media should be state-controlled so that they won’t be rude about a future Corbyn government and any tribute colouring books.


3. The HQ

Momentum HQ is in the TSSA transport and travel union building by Euston Station in London. I meet Jon Lansman, Tony Benn’s former fixer and the founder of Momentum, in a basement room in October. Lansman, who read economics at Cambridge, lived on the fringes of Labour for 30 years before volunteering for Corbyn’s campaign for the leadership.

The terms are these: I can ask whatever I want, but afterwards James Schneider, the 29-year-old national organiser (who has since left to work for Corbyn’s press team), will decide what I can and cannot print. ­Momentum HQ wants control of the message; with all the talk of entryism and infighting reported in the mainstream media, the movement needs it.

There is a civil war between Jon Lansman and the Alliance for Workers’ Liberty (AWL) and other far-left factions, which, I am told, “wish to organise in an outdated manner out of step with the majority of Momentum members”. Some of the Momentum leadership believe that the AWL and its allies want to use Momentum to found a new party to the left of Labour. Jill Mountford, then a member of Momentum’s steering committee, has been expelled from Labour for being a member of the AWL. It screams across the blogs and on Facebook; more parody. We don’t talk about that – Schneider calls it “Kremlinology”. It is a problem, yes, but it is not insurmountable. We talk about the future, and the past.

So, Lansman. I look at him. The right considers him an evil Bennite wizard to be feared and mocked; the far left, a Stalinist, which seems unfair. It must be exhausting. I see a tired, middle-aged man attending perhaps his fifteenth meeting in a day. His hair is unruly. He wears a T-shirt.

The last Labour government, he says, did one thing and said another: “Wanting a liberal immigration policy while talking tough about refugees and migrants. Having a strong welfare policy and generous tax credits while talking about ‘strivers’ and ‘scroungers’ unfortunately shifted opinion the wrong way.”

It also alienated the party membership: “Their approach was based on ensuring that everyone was on-message with high levels of control.” It was an “authoritarian structure even in the PLP [Parliamentary Labour Party]. Even in the cabinet. It killed off the enthusiasm of the membership. They never published the figures in 2009 because it dropped below 100,000. We’ve now got 600,000.” (The membership has since dropped to roughly 528,000.)

And the strategy? “If you have hundreds of thousands of people having millions of conversations with people in communities and workplaces you can change opinion,” he says. “That’s the great advantage of ­having a mass movement. And if we can change the Labour Party’s attitude to its members and see them as a resource – not a threat or inconvenience.”

That, then, is the strategy: street by street and house by house. “We can’t win on the back of only the poorest and only the most disadvantaged,” he says. “We have to win the votes of skilled workers and plenty of middle-class people, too – but they are all suffering from some aspects of Tory misrule.”

I ask about polling because, at the time, a Times/YouGov poll has Labour on 27 per cent to the Tories’ 41 per cent. He doesn’t mind. “It was,” he says, “always going to be a very hard battle to win the next election. I think everyone across the party will privately admit that.” He doesn’t think that if Yvette Cooper or Andy Burnham were leader they would be polling any better.

Upstairs the office is full of activists. They are young, rational and convincing (although, after the Copeland by-election on 23 February, I will wonder if they are only really convincing themselves). They talk about their membership of 20,000, and 150 local groups, and 600,000 Labour Party members, and the breadth of age and background of the volunteers – from teenagers to people in their eighties. One of them – Ray Madron, 84 – paints his hatred of Tony Blair like a portrait in the air. He has a ­marvellously posh voice. Most of all, they talk about the wounds of austerity. Where, they want to know, is the anger? They are searching for it.

Emma Rees, a national organiser, speaks in the calm, precise tones of the schoolteacher she once was. “A lot of people are sick and tired of the status quo, of politics as usual, and I think trying to do things differently is hard because there isn’t a road map and it’s not clear exactly what you’re supposed to do,” she says. She adds: “It is a coalition of different sorts of people and holding all those people together can sometimes be a challenge.”

Is she alluding to entryism? One activist, who asks not to be named, says: “I don’t want to insult anyone, but if you rounded up all the members of the Socialist Workers Party [SWP] and the Socialist Party and any other ultra-left sect, you could probably fit them in one room. Momentum has 20,000 members.”

The SWP were outside at The World Transformed in Liverpool, I say, like an ambivalent picket line. “Well,” James Schneider says pointedly, “they were outside.”

Momentum, Emma Rees says, “is seeking to help the Labour Party become that transformative party that will get into government but doesn’t fall back on that tried and failed way of winning elections”.

They tell me this repeatedly, and it is true: no one knows what will work. “The people who criticised us don’t have any route to electability, either,” says Joe Todd, who organises events for Momentum. He is a tall, bespectacled man with a kindly, open face.

“They lost two elections before Jeremy Corbyn. It’s obvious we need to do something differently,” he says. “Politics feels distant for most people: it doesn’t seem to offer any hope for real change.

“The left has been timid and negative. More and more people are talking about how we can transform society, and how these transformations link to people’s everyday experience. Build a movement like that,” Todd says, and his eyes swell, “and all the old rules of politics – the centre ground, swing constituencies to a certain extent – are blown out of the water.”

Momentum sends me, with a young volunteer as chaperone, to a rally in Chester in October to watch activists try to muster support for local hospitals. They set up a stall in the centre of the shopping district, with its mad dissonance of coffee shops and medieval houses. From what I can see, people – yet far too few people – listen politely to the speeches about austerity and sign up for more information; but I can hear the hum of internal dissent when an activist, who asks not to be named, tells me he will work for the local Labour MP to be deselected. (The official Momentum line on deselection is, quite rightly, that it is a matter for local parties.)

We will not know what matters – is it effective? – until the general election, because no one knows what will work.


4. The Fallout

Now comes the result of the by-election in Copeland in the north-west of England, and the first time since 1982 that a ruling government has taken a seat from the opposition in a by-election. Momentum canvassed enthusiastically (they sent 85 carloads of activists to the constituency) but they failed, and pronounce themselves “devastated”. The whispers – this time of a “soft” coup against Corbyn – begin again.

Rees describes calls for Jeremy Corbyn to resign as “misguided. Labour’s decline long pre-dates Corbyn’s leadership.”

This produces a furious response from Luke Akehurst, a former London Labour ­councillor in Hackney, on He insists that Labour’s decline has accelerated under Corbyn; that even though Rees says that “Labour has been haemorrhaging votes in election after election in Copeland since 1997”, the majority increased in 2005 and the number of votes rose in 2010, despite an adverse boundary change. “This,” he writes, “was a seat where the Labour vote was remarkably stable at between 16,750 and 19,699 in every general election between 2001 and 2015, then fell off a cliff to 11,601, a third of it going AWOL, last Thursday.”

And he adds that “‘85 carloads of Mom­entum activists’ going to Copeland is just increasing the party’s ability to record whose votes it has lost”.

But still they plan, and believe, even if no one knows what will work; surely there is some antidote to Mayism, if they search every street in the UK? Momentum’s national conference, which was repeatedly postponed, is now definitively scheduled for 25 March. Stan who complained about a democratic deficit within Momentum at The World Transformed got his way. So did Lansman. In January the steering committee voted to dissolve Momentum’s structures and introduce a constitution, after consulting the membership. A new national co-ordinating group has been elected, and met for the first time on 11 March – although, inevitably, a group called Momentum Grassroots held a rival meeting that very day.

I go to the Euston offices for a final briefing. There, two young women – Sophie and Georgie, and that will make those who think in parodies laugh – tell me that, in future, only members of the Labour Party will be allowed to join Momentum, and existing members must join Labour by 1 July. Those expelled from Labour “may be deemed to have resigned from Momentum after 1 July” – but they will have a right to a hearing.

More details of the plan are exposed when, a week later, a recording of Jon Lansman’s speech to a Momentum meeting in Richmond on 1 March is leaked to the Observer. Lansman told the Richmond branch that Momentum members must hold positions within the Labour Party to ensure that Corbyn’s successor – they are now talking about a successor – is to their liking. He also said that, should Len McCluskey be re-elected as general secretary of Unite, the union would formally affiliate to Momentum.

Tom Watson, the deputy leader of the party, was furious when he found out, calling it “a private agreement to fund a political faction that is apparently planning to take control of the Labour Party, as well as organise in the GMB and Unison”.

There was then, I am told, “a short but stormy discussion at the away day at Unison” on Monday 20 March, where the inner circle of John McDonnell, Diane Abbott and Emily Thornberry “laid into” Watson, but Shami Chakrabarti made the peace; I would have liked to see that. Watson then released a bland joint statement with Corbyn which mentioned “a robust and constructive discussion about the challenges and opportunities ahead”.

Jon Lansman, of course, is more interesting. “This is a non-story,” he tells me. “Momentum is encouraging members to get active in the party, to support socialist policies and rule changes that would make Labour a more grass-roots and democratic party, and to campaign for Labour victories. There is nothing scandalous and sinister about that.” On the Labour right, Progress, he notes, does exactly the same thing. “Half a million members could be the key to our success,” he says. “They can take our message to millions. But they want to shape policy, too. I wouldn’t call giving them a greater say ‘taking over the party’” – and this is surely unanswerable – “it’s theirs to start with.”

Correction: This article originally named Luke Akehurst as a Labour councillor. Akehurst stood down in 2014.

This article first appeared in the 23 March 2017 issue of the New Statesman, Trump's permanent revolution