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By far the greatest impediment and aberration of the human understanding arises from [the fact that] . . . those things which strike the sense outweigh things which, although they may be more important, do not strike it directly. Hence, contemplation usually ceases with seeing, so much that little or no attention is paid to things invisible.
- Sir Francis Bacon
According to Sir Francis Bacon (1620), insensitivity to missing information is the single most important source of bias and error in human judgment and choice. Recently, extensive research on omission neglect has supported Bacon's keen observation (e.g., Kardes et al. 2006; Kardes and Sanbonmatsu 1993, 2003; Sanbonmatsu et al. 1991, 1992, 1997, 2003). Omission neglect refers to insensitivity to missing or unknown attributes, features, properties, qualities, alternatives, options, cues, stimuli, or possibilities. Insensitivity to omissions occurs for several reasons: Omissions are typically not salient, singular judgment tasks frequently mask omissions, presented information can inhibit consideration of omissions, and people often anchor on the implications of presented information and adjust insufficiently for the implications of omissions.
Omission neglect influences all stages of information processing -including perception (change blindness, errors of omission and self- assessment, attributions for inactions), learning (feature-positive effect, insensitivity to cause-absent and effect-absent cells in covariation estimation), evaluation (absence of between-subjects set-size effects, presence of within-subject set-size effects, overweighing presented attributes), persuasion (cross-category set-size effect, tip-of-the-iceberg effect, insensitivity to non-gains, non-losses, and hidden fees), and decision making (omission neglect contributes to overconfidence, intransitive preference, the Ellsberg paradox, and subadditivity). Increasing sensitivity to omissions is often a useful debiasing technique for improving a wide variety of judgments and decisions (Kardes et al. 2006).
In everyday life, people typically receive limited information about just about everything - including political candidates, public policies, job applicants, defendants, potential dating partners, business deals, consumer goods and services, healthcare products, medical procedures, and other important topics. News reports, advertisements, group meetings, conversations, and other sources of information typically provide only limited information. When people overlook important missing information, even a little presented information can seem like a lot. Ideally, people should form stronger beliefs when a large amount of relevant information is available than when only a small amount is available. However, when people are insensitive to omissions,...