Human behaviour classified into four basic personality types

Human behaviour is affected by several factors viz. personality traits, feelings, instincts, etc.
Researchers at Universidad Carlos III de Madrid and University of Barcelona using computer algorithm with applications in sociology and economics found that human behaviour can be categorized into four basic personality types: optimistic, pessimistic, trusting and envious.
Majority of the population, accounting for 30%, falls under envious group compared to 20% for each of the other groups. The fifth group, representing 10%, failed to get classified by the algorithm suggesting that some individuals do not respond in a determined way to any of the outlined models.