Extension Neglect

What is Extension Neglect?

Extension neglect occurs when an evaluation gives too little weight to a relevant quantity, such as the size of a group, the scope of a benefit, or the duration of an experience. It does not simply mean underestimating how many objects are present.

How it works

Kahneman and Frederick (2002) discuss cases in which judgments rely heavily on a representative example while responding weakly to the extent of the whole. They propose this as an account of related findings, not as the only possible mechanism.

An example of extension neglect

For illustration, valuing protection for a small and a much larger number of otherwise comparable birds almost identically could indicate weak sensitivity to scope.

The relevant comparison depends on the judgment. Greater quantity need not imply a strictly proportional valuation, and explicit comparisons can change sensitivity to scope.

Scope neglect, also called scope insensitivity, concerns weak responsiveness to the scale of an outcome. It is one form of the broader extension-neglect problem described here.

Why it matters

An appealing example can dominate a decision while the scale of the problem receives little attention. Extension neglect asks whether the evaluation responds to how much is at stake, not merely to how vivid one part of it is.