Culture Community Researchers Identify 4 Basic Personality Types By Melissa Breyer Editorial Director Hunter College F.I.T., State University of New York Cornell University Melissa Breyer is Treehugger’s editorial director. She is a sustainability expert and author whose work has been published by the New York Times and National Geographic, among others. our editorial process Melissa Breyer Updated October 11, 2018 CC BY 2.0. Wikimedia Commons Share Twitter Pinterest Email Culture History Travel Sustainable Fashion Art & Media Holidays Community Study on human behavior finds 90% of the population falls into 4 categories; researchers say results are useful for negotiating or for when people need to help each other. Most things work best when all of its parts are getting along – humanity included. But human behavior is complicated and the battle between power and altruism seems a chronic one, and one that also seems at odds with the longevity of our species, not to mention countless others. Which is why a new study on human behavior is so interesting. It reveals that 90 percent of us can be classified into four basic personality types: Optimistic, Pessimistic, Trusting and Envious. This study was published in the journal Science Advances by researchers from Universidad Carlos III de Madrid, along with collaborators from the universities of Barcelona, Rovira i Virgili and Zaragoza. The study looked at how 541 volunteers responded to hundreds of social dilemmas, "with options leading to collaboration or conflict with others, based on individual or collective interests." The experiments relied on elements of game theory, which analyses the behavior of people when faced with a dilemma and need to make decisions. It kind of sounds like the reality show, Survivor. "Those involved are asked to participate in pairs, these pairs change, not only in each round, but also each time the game changes. 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," explained study author Anxo Sánchez from Universidad Carlos III de Madrid (UC3M). Once the experiments were completed, the team developed a computer algorithm to classify people according to their behavior. Ninety percent of the people fell into the four distinct groups, even though the algorithm allowed for many more. • Envious: The largest group, accounting for 30 percent. These people don't actually mind what they achieve, as long as they're better than everyone else.• Optimists: Accounting for 20 percent, optimists believe that they and their partner will make the best choice for the team.• Pessimists: Twenty percent select the option which they see as the lesser of two evils.• Trusting: Another 20 percent are born collaborators who will always cooperate; they don't really mind if they win or lose. The remaining 10 percent comprise a fifth, undefined group that the algorithm was unable to classify in relation to a clear type of behavior. An example of a specific dilemma from the study: Two people can hunt deer together, but if they are alone, they can only hunt rabbits. The person belonging to the Envious group will choose to hunt rabbits because he or she will be at least equal to the other hunter, or maybe even better; the Optimist will choose to hunt deer because that is the best option for both hunters; the Pessimist will go for rabbits because that way he or she is sure to catch something; and the hunter who belongs to the Trusting group will cooperate and choose to hunt deer, without a second thought. According to Yamir Moreno, president of the Sociedad de Sistemas Complejos (Complex Systems Society), "The results go against certain theories; the one which states that humans act purely rationally for example, and, therefore, they [the results] should be taken into consideration in redesigning social and economic policies, as well as those involved in cooperation." Adding, "these types of studies are important because they improve existing theories on human behavior by giving them an experimental base." Now if researchers could just figure out how to help everyone get along ... imagine the potential we could have.