Omission Neglect in Consumer Psychology

Field: Psychology (Social Sciences)

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 BaconAccording 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, they form strong beliefs regardless of how little is known about a topic. Furthermore, in rare instances in which a large amount of information is available, forgetting occurs over time and insensitivity to information loss from memory, another type of omission, leads people to form beliefs that increase in strength over time.For example, consumers should form more favorable evaluations of a new camera when the camera performs well on eight attributes rather than only four attributes. However, research shows that consumers form equally favorable evaluations of the camera regardless of how much attribute information was presented (Sanbonmatsu et al. 1992). The amount of information presented matters only when consumers were warned that information might be missing. This warning increased sensitivity to omissions and lead consumers to form more favorable evaluations of the camera described by a greater amount of information.Similar results are observed in inferences, or judgments that go beyond the information given (Sanbonmatsu et al. 1991). Consumers received a brief description of a new ten-speed bicycle and were asked to rate its durability even though no information about durability was provided. …