Human brains are incredible organs capable of amazing feats of information processing, pattern recognition, judgment, and split-second reaction. But there are situations in which the mind is prone to errors. These errors occur when we make decisions, which has led researchers to study decision making extensively.
In Thinking Fast and Slow , describes two modes of thinking and making decisions.
System 1: The fast-thinking, intuitive system that uses simple mental shortcuts ( heuristics ) based on experience to make decisions. This system is prone to errors, particularly when confronted with unfamiliar situations.
System 2: The slow-thinking, deliberate system that is triggered when people are faced with complex problems. It is much less prone to error than the intuitive System 1.
Kahneman specifies that the two systems are metaphors or ways of thinking about how the mind works rather than actual systems that could be found within the brain.
We can think of System 1 as an energetic and enthusiastic individual that is always willing to help solve a problem. System 1 springs into action to deal with the vast majority of decisions people make every day. System 2 is a very different beast. It likes to wrestle with hard problems and think them through. But this hard thinking takes a lot of effort, so System 2 is reluctant to get involved in too many decisions and leaves most of the easy ones to System 1.