Dual process thinking is a psychological concept that describes two distinct modes of cognitive processing, in other words, how humans process information and make decisions. Daniel Kahneman wrote in his best selling book, “Thinking, Fast and Slow” about System 1 and System 2 thinking.

System 1:
This is often referred to as the "fast" or "automatic" thinking system. It involves quick, intuitive, and often emotional responses. System 1 thinking doesn't require conscious effort and is responsible for making rapid judgments and decisions based on instinct and previous experiences.
System 2:
This is the "slow" or "deliberative" thinking system. It involves analytical, rational, and logical thinking. System 2 thinking requires conscious effort and is used for more complex decision-making, problem-solving, and critical thinking.