The psychology behind irrational decisions

Often people make decisions that are not "rational" from a purely economical point of view — meaning that they don't necessarily lead to the best result. Why is that? Are we just bad at dealing with numbers and odds? Or is there a psychological mechanism behind it? Sara Garofalo explains heuristics, problem-solving approaches based on previous experience and intuition rather than analysis. [Directed by TOGETHER, narrated by Pen-Pen Chen].