Simulating the Mafia

I’ve just found this fascinating paper that used game theory to model why a Mafia protection racket inevitably leads to violence that neither the mob nor the shopkeepers can keep a lid on.

It turns out, fakers who pretend to be the Mafia to extort additional money throw a spanner in the works, as it reduces ‘trust’ between the real Mafia and the small business owners.

The full paper is available online as a pdf file but the abstract is reproduced below:

Payment, Protection and Punishment: The Role of Information and Reputation in the Mafia

Rationality and Society, 2001, 13(3), 349–393.

Alistair Smith and Federico Varese

A game theoretic model is used to examine the dynamics governing repeated interaction between Mafiosi running extortion rackets and entrepreneurs operating fixed establishments. We characterize the conditions under which violence occurs. Entrepreneurs pay protection money to the Mafia because they fear the Mafia’s ability to punish. However, the entrepreneurs’ willingness to pay encourages opportunistic criminals (fakers) to use the Mafia’s reputation and also demand money. We show that two phenomena drive the repeated interaction between criminals and entrepreneurs: reputation-building and readiness to use violence on the part of the Mafiosi, and attempts to filter out fakers on the part of entrepreneurs.

These two phenomena lead to turbulence: as entrepreneurs filter out fakers by not paying some of the times, some real Mafiosi are not paid and punish non-payment to establish their reputation. As Mafia reputation is re-established, fakers have again an incentive to emerge, setting in motion a spiral of never-ending filtering and violence. We also show how external shocks to this relationship, such as changes in policing practices, succession disputes within the Mafia or inflation, often lead to violence until beliefs are re-established. We conclude that a world where mafias operate is inherently turbulent. This conclusion goes against the widespread perception that racketeers are able to perfectly enforce territorial monopolies.

pdf of full-text paper.

A blind man hallucinating

NPR has an brief but interesting piece on a blind man who has visual hallucinations.

Stewart, the person in question, lost his sight due to hereditary sight-loss, but has developed Charles Bonnet syndrome, a curious condition where playful visual hallucinations are common.

Two things about this condition are striking: firstly, the hallucinations are typically complex and intricate but the damage is typically only to the retina, the cortex remains intact.

Secondly, unlike many other conditions where hallucinations are common, the person typically retains complete insight. They know they are hallucinating and typically don’t mistake hallucinations for the real world.

While the person interviewed in this radio segment is blind, Charles Bonnet syndrome can occur in people with partial sight, who may have only lost vision in one part of their visual field (often due to macular degeneration). In these cases, even when the hallucinations can ‘blend in’ with true vision, the person usually knows the difference.

One of the most remarkable things about the interview is that the Stewart’s hallucinations can be triggered by quite idiosyncratic things (such as foods and thoughts) and that he takes such joy in the experience.

If you want to read more about the syndrome, the Fortean Times published a great article on it back in 2004.

Link to NPR segment on Charles Bonnet syndrome.
Link to FT article on the same.

Illegal ink: reading meaning in criminal tattoos

Until fashions changed in recent decades, a tattoo was widely considered the mark of the soldier, the sailor or the criminal. The tattoos of offenders have sparked particular interest as they can be highly symbolic coded messages that have been thought to be a glimpse into the psychology of the criminal underworld.

The interest in ‘criminal ink’ stretches back to the 19th century when Italian criminologist Cesare Lombroso started collecting pictures of tattoos from captured or murdered Mafiosos.

Lombroso believed that persistent offenders were biologically defective who reflected an ‘atavistic‘ throwback to a primitive stage of human development.

He further believed that criminal tendencies could be seen in the shape of the face, skull and body, and could be divined by studying tattoos, which were a reflection of the “fierce and obscene hearts of these unfortunates”.

While Lombroso’s ideas on criminality and the body proved to be little more than prejudice and conclusions drawn from poorly guided research (he failed to compare how often the same traits appear in non-criminals) the idea that criminal tattoos were a sort of ‘symbolic code’ proved to be closer to the mark.

Russian prison tattoos from the Soviet era are some of the most complex of these symbolic codes and determine an offender’s place within the strictly organised and brutally enforced criminal social order.

Russian prison guard Danzig Baldaev collected pictures of these tattoos for over 40 years, mostly during the period of Soviet-run gulags, and carefully documented the images and their meanings.

He published a Russian book on the tattoos in 2001 and later his work was re-published in English in two volumes of the Russian Criminal Tattoo Encyclopaedia.

Racist, graphically pornographic and violent images are common but apparently accurately reflect the vicious and oppressive nature of the prison camps. Others are political, some romantic, and many a combination of a number of these themes.

The images are satirical, offensive and disturbing both in their explicit content and their implicit meaning. While some are ‘earned’, others are forcibly applied and intended as punishments.

The tattoos are intended to reflect the life, status and experiences of the prisoner, and most importantly, they allow others to ‘read’ the person in the most literal sense.

The Russian criminal tattoo is a means of secret communication, an esoteric language of representational images which the thief’s body uses to inform the world of thieves about itself. This language resembles thieves’ argot and it performs a similar function – encoding secret thieves’ information to protect it from outsiders (fraera). In exactly the same way as argot endows standard, neutral words with ‘strictly professional’ meanings, the tattoo also conveys ‘secret’ symbolic knowledge through the use of ordinary allegorical images which at first glance seem familiar to everyone. Even the tattoo ‘Heil Hitler!’, when applied to the body of a Russian ‘legitimate thief’ (vor v zakone) may have absolutely nothing to do with Hitler or National Socialism in general. As a rule it is a sign of a thief’s attitude of denial (otritsalovka) or the symbol of a refusal to submit to the prison and camp administration and also, in a broader sense, a total refusal to cooperate in any way with the Soviet authorities. (p33, Russian Criminal Tattoo Encyclopaedia Vol II).

In effect, these tattoos embody a thief’s complete ‘service record’, his entire biography. They detail all of his achievements and failures, his promotions and demotions, his ‘secondments’ to jail and his ‘transfers’ to different types of work. A thief’s tattoos are his ‘passport’, ‘case file’, ‘awards record’, ‘diplomas’ and ‘epitaphs’. In other words, his full set of official bureaucratic documents… Tattoos acts as symbols of public identity, social self-awareness and collective memory. They shape stereotypes of group behaviour and set out the rules and rituals necessary for maintaining order in the world of thieves. (p27, Russian Criminal Tattoo Encyclopaedia Vol I).

The symbols are extensive and complicated, and owing to their importance, the penalty for faking an unearned tattoo could be a swift and brutal death.

There is a grim irony in the fact that many in the Russian criminal underworld saw themselves as rebelling against the Soviet system while creating a subculture which was more oppressive and almost as bureaucratic. I suspect, however, the irony was lost on many.

The tattoos from the Soviet gulags are not the sole examples, of course. Many criminal gangs use tattoos as a pledge of allegiance and a record of past experience, to the point where Mara Salvatrucha gang members are now trying to avoid getting their distinctive tattoos so the authorities can’t identify and ‘read’ them so easily.

Link to NSFW info/images from Russian Criminal Tattoo Encyclopaedia I.
Link to NSFW info/images from Russian Criminal Tattoo Encyclopaedia II.
Link to SFW images from the same collection.
pdf of good essay on Cesare Lombroso, his theories and influence.


I’ve been enjoying the Neuroanthropology blog recently which discusses how the cognitive and neurosciences can help us understand culture and social diversity.

For example, trance states are common in some cultures, where they may form the part of certain religious rituals or spirit possession experiences.

There is now increasing interest in understanding the neuroscience of trance states, with a view to better understanding both how they occur and how they are used as key parts of social life by cultures across the world.

The Neuroanthropology blog disusses how culture shapes and interacts with brain function, and what new research tell us about our cultural quirks.

Link to Neuroanthropology blog.

An embuggerance

Author Terry Pratchett recently announced that he has early onset Alzheimer’s disease, a form of the brain disorder that strikes before the age of 65.

In typical Pratchett style, he described the news as ‘an embuggerance’ but still continues to work on his comic novels.

He’s just given an audio interview to the BBC where he discusses his diagnosis, how he views the future, and how the brain changes are affecting his day-to-day life.

He is wonderfully open and optimistic, and quite inspiring, in his usual quiet, humorous way.

Link to BBC audio interview with Terry Pratchett.

Deep brain stimulation opens memory floodgates

Neurophilosophy has a great write-up of the recent finding that deep brain stimulation boosted memory function in a patient undergoing brain surgery to treat morbid obesity.

I’ve only just got round to having a look at the scientific paper myself, and the summary on Neurophilosophy captures the main themes beautifully, and is some of the best coverage I’ve read so far.

A couple of things stand out for me.

Firstly, the patient was given a last-ditch experimental treatment for obesity by having an electrode planted in the ventral hypothalamus, a deep brain structure, to try and reduce his appetite.

The hypothalamus is involved in regulating a number of essential bodily functions and most pertinently, contains glucoreceptors – cells that detect levels of glucose in the body to regulate feeding and appetite.

A lot has been written about the role of ‘mechanical’ models of the mind and brain in undermining our sense of free will and responsibility for our actions.

This case suggests that we’ve now got to the stage where an inability to control a biological urge which negatively affects few people except the patient himself, is reason enough to consider neurosurgery.

I wonder whether deep brain stimulation for people who can’t give up cigarettes, alcohol or self-harm will be next.

Secondly, the immediate effect of the stimulation on the patient, who was flooded with numerous vivid memories, is quite striking:

Unexpectedly, the patient reported sudden sensations that he described as déjà vu with stimulation of the first contact tested (contact 4: 3.0 volts, 60-microsecond pulse width [pw], and 130Hz). He reported the sudden perception of being in a park with friends, a familiar scene to him. He felt he was younger, around 20 years old. He recognized his epoch-appropriate girlfriend among the people. He did not see himself in the scene, but instead was an observer. The scene was in color; people were wearing identifiable clothes and were talking, but he could not decipher what they were saying. As the stimulation intensity was increased from 3.0 to 5.0 volts, he reported that the details in the scene became more vivid.

This is a strikingly similar experience to the memories triggered by electrical stimulation of the surface of the temporal lobe reported by legendary Canadian neurosurgeon Wilder Penfield in the 50s and 60s:

The other response is an activation of the stream of past experience. This is what the patient often refers to as a ‘flash-back’ to his own past. When the electrode is applied, he may exclaim in surprise, as the young secretary, M M, did: ‘Oh, I had a very, very familiar memory, in an office somewhere. I could see the desks. I was there and someone was calling to me, a man leaning on a desk with a pencil in his hand.’ Or the patient may call out in astonishment, as J T did (when the current was switched on without his knowledge): ‘Yes, Doctor, yes, Doctor! Now I hear people laughing – my friends in South Africa … Yes, they are my two cousins, Bessie and Ann Wheliaw.’

However, despite testing over 600 patients in this way, less than 8% had the experience of electrically triggered memories, and the effect has not been reliably replicated by modern researchers.

This suggests that the flood of memories triggered by stimulating the hypothalamus in this new study, perhaps may not happen in all people.

Of course the big finding in this new study was not the triggered memories, but that when the stimulation was switched on for longer periods, the patient did much better in memory tests.

It will be interesting to see whether this general effect on memory is perhaps as unpredictable across individuals as electrically evoked memories have proved to be in the past.

Link to Neurophilosophy post on the new study.
Link to abstract of scientific paper.
Link to Penfield’s paper (with evoked memory memory examples).

2008-02-01 Spike activity

Quick links from the past week in mind and brain news:

Best Life magazine has probably one of the most sensible articles I’ve yet come across on back pain. Another good read by Jonah Lehrer, who you may know from the Frontal Cortex blog.

Morons and Idiots Buy a Brain! Omni Brain finds an odd hip-hop video that encourages us to purchase a new cerebrum.

Sharp Brains has a fantastic review of its most popular recent articles.

Mobile phones disrupt sleep (lectures, movies, funerals).

The San Francisco Chronicle discusses the new exhibits at the SF Exploratorium that allow you to watch your own mind at work.

People use the internet to confirm their pre-existing beliefs. So, no different from any other source of information then.

SciAm discusses ‘evolutionary economics‘ and what it tells us about how we reason about money.

A fantastically comprehensive article on the treatment of multiple sclerosis made it to the front page of Wikipedia this week.

Cognitive Daily has an article on the cognitive psychology of film. Interestingly, in the Richard Gregory talk I linked to the other day, he notes very little is known about how we comprehend film across shots. This post covers exactly this process!

This history of theories about mind over medical matters and the psychology of illness is covered in an article from Slate.

BBC News reports on a new study that has found that world-wide, the risk of depression peaks at 44, except in America.

The Wall Street Journal look at studies that cite head injuries as a factor in antisocial behaviour, offending and other social ills.

Salon has a polemic piece on antidepressants and the ‘medicalisation of misery’.

A special infrared hat that cures Alzheimer’s? Respectful Insolence has a rightly sceptical look at the odd contraption.

The Phineas Gage Fan Club discusses a recent study showing suggesting that sleep ‘disconnects’ the brain’s emotional circuits.

National Geographic has a fun and beautiful interactive brain demo.

An article in The Atlantic argues that multitasking is dumbing us down and driving us crazy.

Frontiers in Neuroscience is a new open-access neuroscience journal. Bravo!