The table below contains a list of features and activities that have been attributed to System 1. Each of the active sentences replaces a statement, technically more accurate but harder to understand, to the effect that a mental event occurs automatically and fast. My hope is that the list of traits will help you develop an intuitive sense of the “personality” of the fictitious System 1. As happens with other characters you know, you will have hunches about what System 1 would do under different circumstances, and most of your hunches will be correct.

Characteristics of System 1

• generates impressions, feelings, and inclinations; when endorsed by System 2 these become beliefs, attitudes, and intentions

• operates automatically and quickly, with little or no effort, and no sense of voluntary control

• can be programmed by System 2 to mobilize attention when a particular pattern is detected (search)

• executes skilled responses and generates skilled intuitions, after adequate training

• creates a coherent pattern of activated ideas in associative memory

• links a sense of cognitive ease to illusions of truth, pleasant feelings, and reduced vigilance

• distinguishes the surprising from the normal

• infers and invents causes and intentions

• neglects ambiguity and suppresses doubt

• is biased to believe and confirm

• exaggerates emotional consistency (halo effect)

• focuses on existing evidence and ignores absent evidence (WYSIATI)

• generates a limited set of basic assessments

• represents sets by norms and prototypes, does not integrate

• matches intensities across scales (e.g., size to loudness)

• computes more than intended (mental shotgun)

• sometimes substitutes an easier question for a difficult one (heuristics)

• is more sensitive to changes than to states (prospect theory)*• overweights low probabilities*

• shows diminishing sensitivity to quantity (psychophysics)*

• responds more strongly to losses than to gains (loss aversion)*

• frames decision problems narrowly, in isolation from one another*

*Feature introduced in detail in part 4.