Insensitivity to Sample Size and Reliability

Key Insight

People are often insufficiently sensitive to sample size when evaluating information, primarily focusing on the message's content rather than its source's reliability. For instance, upon hearing a poll that '300 seniors support the president,' the mind extracts the gist ('elderly support president') and largely disregards the sample size, unless it is absurdly small or large.

System 1, the automatic intuitive system, is inherently not prone to doubt; it suppresses ambiguity and constructs coherent stories. Unless a message is immediately negated as false or biased, its evoked associations spread as if true. System 2, capable of doubt, finds sustaining it more effortful than defaulting to certainty, making people less critical of information reliability.

This bias is a manifestation of 'What You See Is All There Is' (WYSIATI), where judgments are based solely on the information at hand, regardless of its completeness or quality. It contributes to an exaggerated faith in the consistency and coherence of perceived reality, leading people to construct rich narratives from scraps of evidence and operate as if they believe in the law of small numbers, forming an overly simplified world view.