According to a new study, there are four kinds of people

According to a new study, 90% of people fall into one of four categories: optimists, pessimists, trusting or envious. Which one are you?

Game theory and prisoners

Humans interact with each other all the time, but those interactions are very difficult to study with consistency. In recent years, game theory has emerged as a great tool to study human interactions. It is “the study of mathematical models of conflict and cooperation between intelligent rational decision-makers.” Simply put, you simulate different game-like scenarios for people, give them options with rewards and punishments for their decisions, and see how it pans out. The most classical example is the Prisoner’s Dilemma. The game basically says:

Two people are arrested and put in solitary confinement, without being able to talk to each other. There’s not enough evidence to convict them, so they are given a deal. The deal is:.

  • If they both betray each other, they each serve two years in prison
  • If A betrays B but B remains silent, A will be set free and B will serve three years in prison (and vice versa).
  • If both of them remain silent, both of them will only serve one year in prison (on the lesser charge).

It seems pretty simple – if they just stay quiet, they will both get one year in prison, which is the best deal they can get together. If they go for the first option, that’s a total of four prison years, and the second one is a total of three prison years – two prison years is the best deal they have.

But think like you’d be one of the prisoners. From your point of view, there are two possible outcomes:

  1. Your friend betrays.
  2. Your friend doesn’t betray.

If your friend betrays you, then you’re better off snitching too – otherwise, you’d get three years in prison and he’d go free. If your friend doesn’t betray, you’re also better off snitching – you’ll go free, as opposed to staying one year in prison. So no matter what he does, you’re always better off betraying. So logically, they will both betray and end up spending two years in prison, which is the worst possible outcome for the two as a group.


Four kinds of people

Games like the Prisoner’s Dilemma are studied on a great scale and with several degrees of complexity higher. In this study, researchers from several universities in Spain analyzed the responses of 541 subjects to a variety of social scenarios, grouping them and seeing if they’d rather cooperate or defect.

“Those involved are asked to participate in pairs, these pairs change, not only in each round, but also each time the game changes,” explained one of the authors of the study, Anxo Sánchez

The games were designed in a similar fashion to the Prisoner’s Dilemma, in a way where cooperating would yield the best outcome, but there was a strong incentive to defect.

“So, the best option could be to cooperate or, on the other hand, to oppose or betray…In this way, we can obtain information about what people do in very different social situations.”

They then put the results into a computer algorithm. The algorithm could have come up with any form of classification with any number of groups, but it found that four is truly enough.

“The really funny thing is that the classification was made by a computer algorithm which could have obtained a larger number of groups, but which has, in fact, produced an “excellent “rating in four personality types,” explains Yamir Moreno. Jordi Duch, a researcher at Universitat Rovira i Virgili in Tarragona, and one of the authors of this study.

The four groups are:

  1. Optimists: The people who work on the assumption that their partner will make the right decision.
  2. Pessimists: The people who expect the worst from their partner.
  3. Trustful: Those who cooperate out of goodwill, even if there’s nothing in it for them.
  4. Envious: The people who don’t care what they achieve, as long as it’s better than the others.

The surprising part is that the last group was also the biggest one, with over 30% of all participants being envious. The last 10% of participants had behaviors which were too inconsistent to be grouped in any of the groups.

Better game theory could help us understand what motivates people to be better citizens and valuable members of their community. Image by Benjamin Combs.

Better game theory could help us understand what motivates people to be better citizens and valuable members of their community. Image by Benjamin Combs.

Better models, better citizens

The study aims to understand how we can encourage citizen participation. If we know how willing people are to collaborate with other people (and with a framework), then we can better motivate them to engage in civic activities. This is what can be accomplished through such a study using game theory.

“One of main principles of this study is the fact that the experiment has been developed in such a way to encourage the participation of citizens within the framework of one of the city’s public activities,” explains Josep Perelló, leader of the group, OpenSystems in the Condensed Matter Physics Department at Universitat de Barcelona, and also coordinator of the Barcelona Citizen Science Office.

Results aren’t looking too good, though – a majority of envious people are not what you want to have in a healthy society.

Journal Reference: Humans display a reduced set of consistent behavioral phenotypes in dyadic games

6 thoughts on “According to a new study, there are four kinds of people

  1. Airis Damon

    I am neither one of those, but I am pretty sure most people would be a little pessimistic after being forcibly put in solitary for any amount of time. As Dr. Feynman would say, if the theory does not conform to the results of the experiment, it is wrong. 90% is great and all, but we a talking about prison and solitary confinement, right? Those situations are not under natural conditions, and they put a great amount of stress on those subject to them. The results will be skewed and quite unreliable for most cases.

  2. Brian

    It would be interesting see the variation between cultures. While it's not prisoners, we do have many opportunities to work together or step on others thinking we will win. Cultures that betray each other will probably do poorly.

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