Behavioral Game Theory

The basic idea behind a linear public good game is as follows: You have a group of people, typically four in the lab, who are endowed with a certain of money, say $5. Each group member is independently asked how much they want to contribute towards a public good. Any dollar that is contributed results in everyone in the group getting a return of, say, $0.40.           From an individual's perspective contributing towards the group looks like a bad deal because you contribute $1 and only get back $0.40. Note, however, that from the group's perspective a contribution of $1 results in a total return of 4 x 0.4 = $1.60. So, from the group's perspective it is good to contribute. For instance, if all four group members contribute $5 then each gets 4 x 5 x 0.4 = $8. And $8 is better than $5.            'Standard economic theory' gives a very simple prediction in a linear public good game. Namely, the game has a unique Nash equilibrium in which everyone should contri

One of the more bizarre aspects of the recent US Presidential election campaign was the ability of Donald Trump to tell more lies and half-truths than most of us would do in a lifetime and yet still claim that Hilary Clinton could not be trusted in office. Even more bizarre, was the fact that he got away with it! How can we possible make sense of this? Some might point to a dumb electorate. I think we can learn more by looking at guilt aversion.              The concept of guilt aversion was formally introduced into game theory by Pierpaolo Battigalli and Martin Dufwenberg with a paper published in the American Economic Review in 2007. (I should also mention a paper  by Gary Charness and Martin Dufwenberg in Econometrica in 2006.) The basic idea is that a person only needs to feel guilt if they disappoint the expectations of others . To illustrate, consider Donald Trump's 'promise' to lock up Hilary Clinton. Nobody realistically expects Trump to fulfil this promise. Bu

A few days ago we heard the story of how a waitress rescued an 86 year old lady who been stuck in her bath for four days. The waitress contacted the police after becoming concerned that Doreen had not come in for her usual lunch and wine. A story with a happy ending.          A story with a not so happy ending is the infamous murder of Kitty Genovese in 1964 in New York. This murder caught the public's attention because of the supposed number of witnesses who did nothing to stop the crime. The exact details of what happened are debated . One thing is, however, for certain: Several people must have seen or heard the attack and  none of them called the police.         To try and make sense of these conflicting stories let us look at simple game theoretic model. Suppose that there is someone called Doreen that needs rescuing and there are n witnesses who can call the police. If (at least) one person calls the police then Doreen is rescued and all the witnesses feel relief equa

In economics there are two diametrically opposed ways of viewing politicians. For the most part we assume the benevolent social planner who acts to maximize social welfare. But, when it comes to specifically analysing political decision making we typically assume that politicians are just like everyone else - out to maximize their own payoff. If a politician's objectives coincide with those of society then we have no problem. But, there are, of course, lots of reasons to suppose that political and societal objectives do not coincide.           A particularly important issue is that of electoral survival. Clearly, a politician needs to get elected in order to make a living. That means it is in a politicians interest to do things that go down well with the electorate. At first sight you might think that this aligns the incentives of the politician with those of society because the politician needs to do good things to get elected. There is, however, a problem of asymmetric informa

Standard economic theory takes a very deterministic view of the world in that we solve for a unique equilibrium and expect that to describe what will happen. Game theory offers an alternative perspective in that most games have multiple equilibria and there is no reason to suppose that one of these equilibria is any more likely to describe what will happen than another.               For a long while the existence of multiple equilibria was seen as a 'problem'; surely the objective of economics was to say what would happen and not what might happen? Experimental economics, however, has shown that multiple equilibria are not so much a problem as a reflection on reality. When we observe two seemingly identical groups of people we often find they end up doing very different things. For instance, one group might end up cooperating and other not cooperating.              Another way of looking at the multiple equilibrium problem is to say that small, hidden, seemingly irrelev

One thing that causes a lot of confusion, both in popular and academic debate, is the distinction between a pure public good and common resource good. Concepts like tragedy of the commons, prisoners dilemma, and free-riding get used far too liberally, and often incorrectly. So, here is one way of trying to untangle the differences:           Suppose that I decide, out of the goodness of my heart, to provide a 'gift' to my local community. For example, I build a children's play-area, or renovate the village hall, or play very loud grunge music. This is a form of public good in the sense that it is non-excludable - anyone in the village is free to enjoy my gift. What distinguishes between a pure public good and common resource good is rivalry in consumption - does one person's enjoyment of my gift depend on the number of other people who make use of the good. Here are some examples: Loud music is a pure public good (or public bad) because one person opening (or

The Paris Climate Change Conference last December was hailed as a great success. As countries signed the Agreement in April there seemed an even stronger sense of optimism. UN Secretary-General Ban Ki-moon was quoted as saying: "Paris will shape the lives of all future generations in a profound way - it is their future that is at stake."  A recent article in Nature entitled 'Paris Agreement climate proposals need a boost to keep warming well below 2°C' provides a more sombre and depressing view. And the sad reality, is that the Paris Agreement is probably a step backwards, not a historic step forwards, in the fight against climate change.           The goal of previous climate agreements, like the Kyoto Protocol, was to provide binding commitments to reduce dangerous emissions. Kyoto, and all attempts at a follow up agreement, failed dismally to work. But, at least the objective was a sound one - to tackle the problem . In Paris the objectives were far less ambi

On the 23rd June the UK held a referendum on its membership of the EU and 52% of voters decided we should leave. To put things bluntly - this was the wrong decision. Politicians of all persuasions, however, have been queuing up after the vote to say that we must respect the 'democrat will' of the people. Clearly they do not have much choice, at this stage, given that a majority voted to leave. But, can we really talk of this referendum result as 'democratic'? I don't think so.           To make the case we can start with the impossibility theorems. These theorems, of which Kenneth Arrow's is the most famous prove that there is no voting mechanism that is guaranteed to produce outcomes satisfying some basic desirable properties. For instance, the choice made can be critically influenced by the options on the ballot paper (even if we add options people do not like). There are two basic ways to interpret the impossibility theorems. One is to say that they show

At the heart of game theory is the notion that we can strip away details of a particular setting to focus on the key strategic incentives that matter. Hence, two very different looking settings can give rise to the same game. For example, contributing to charity may be strategically equivalent to not dropping litter. This stripping away of detail makes game theory a 'general theory' rather than a list of case studies. But, the constant danger is to strip away details that matter.       Framing effects are one illustration of this danger. Daniel Kahneman and Amos Tversky very powerfully illustrated that people can make different decisions depending on how a decision is framed. (See, for example, their 1981 article in Science on ' the framing of decisions and psychology of choice '.) Strategically irrelevant aspects of a setting may, therefore, matter. Recent years have seen a burgeoning number of studies looking at framing effects in public good games. The basic ques

In 2013 a system was introduced in Wales where restaurants and food outlets were required to display food hygiene ratings for all to see. This has seemingly led to an increase in food hygiene , prompting calls for the system to be extended across the UK. But is it necessary to force restaurants to display the rating? Textbook models of signalling would suggest not. Here's why:           Restaurants are rated on a 6 point scale ranging from a cockroach infested 0 to very good 5. All restaurants have to be rated and so this is not at issue. The question is whether they should be forced to prominently display the rating. With that in mind, consider the incentives of restaurant owners:         It is easiest to start with a restaurant that got a top, 5 rating. Clearly the owners have an incentive to display the high rating and show off how good the are. So they will likely display the rating whether forced to or not.           What about a restaurant with a 4 rating? You might th

There has been a lot of media coverage recently on the cost of attending Premier League football matches. One particular focal point was a protest by Liverpool supporters over plans to charge £77 for a ticket. In response to this protest the owners of Liverpool back-tracked and said they would keep prices pegged at current levels (where the highest price is £59). But, why should prices not go higher?           The data on Premier League attendances shows that, for the vast majority of games, stadia are full. And there is no doubt that many more would attend if they could get tickets. Such excess demand clearly means that plenty of people are willing to pay high prices. This gives a strong rationale for clubs to push prices higher and increase profit. Indeed, it is what the economic textbook says they should do.         But, the main consequence of an increase in prices is to extract surplus from supporters. Essentially supporters are pushed to the point where they are only just

A recent  study by Maxwell Burton-Chelle, Claire El Mouden and Stuart West, published in the Proceedings of the National Academy of Sciences , challenges one of experimental economics most robust findings. They argue that conditional cooperation reflects subjects confusion over experimental instructions and not social preferences. So, what to make of this result?        Let me begin by providing a little background on conditional cooperation. A  study by Urs Fischbacher, Simon Gachter and Ernst Fehr, published in Economics Letters 2001, looked at how people behave in a pubic good game when they get to see the contributions of others. More specifically:         They considered a setting with 4 people. Each person could contribute up to 20 tokens into a public project. Any tokens not contributed were worth, say, $1 to that person. Any tokens contributed were worth $0.40 to everyone in the group. For example, if a person keeps 5 tokens and total contributions to the group (includ

Evidence (albeit somewhat anecdotal) suggests than women are being asked to pay considerably more than men for almost identical consumer products. This seems to apply to clothing, toiletries, toys, even pens. Why? It is hard to believe that it costs more to produce products for women than men. So, I think we can safely discount the idea that the difference is being driven by costs. The far more likely explanation is price discrimination.       To illustrate consider a very simple example. Imagine you are the owner of a company making jeans. It costs £25 to produce a pair of jeans and you are currently selling them at £50 a pair. At this price you sell 100 a week to men and 50 a week to women. The key question you have to consider is what would happen to sales if you increase (or decrease) the price? Suppose that at a price of £55 a pair you estimate you would sell 80 to men and 45 to women. On the male side this is a bad deal because profit falls from (50 - 25)(100) = £2,500 to (55

On Saturday rail fares in the UK rose by an average of 1.1%. This is the latest instalment in a long running trend of fair increases. Indeed, average fares have risen by around 40% over the last decade. As usual passengers were queuing up to say how disgraceful it all is. This year the opposition leader Jeremy Corbyn joined the fray with his standard call for a renationalisation of the railways. But what is the problem with high rail fares?        The main reason I ask this question is one of revealed preference . At the same time as complaining about high fares, most passengers also complain about having to stand on over-crowded trains. Indeed, use of the railway has soared , with over 70% more journeys now than in 2002. Moreover, I don't think that anyone would seriously dispute that the UK rail network has just about reached the limit of its capacity in terms of the number of trains operating.         If a price rise is accompanied by a reduction in demand then we can sta