People are always coming up with new theories on how to divide us all into categories according to our personality, most of which use broad terms to make sure everyone fits in to the system.
But when the people creating this personality division system are psychologists we should probably take note, because even if doesn't change our own minds it may teach us about how others think.
Researchers from the Universidad Carlos III de Madrid believe 90% of people belong to four basic personality groups- Optimists, Pessimists, Trusting and Envious.
The Envious are the largest group, with 30 percent, while the other three groups have twenty percent each, with ten percent of people fitting into the category they haven't figured out yet.
The system is based on the way 541 volunteers responded to hundreds of different social situations and whether they chose to conflict or collaborate with others.
Here's more from head researcher Anxo Sánchez:
“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.”