Neglect of probability
We weigh how bad an outcome would be while ignoring how likely it is.
What it means
The tendency to disregard probability altogether when making decisions under uncertainty, so that judgment is driven by the magnitude or emotional charge of an outcome rather than by its odds. Rather than over- or under-weighting probabilities (as probability weighting describes), people here treat them as nearly irrelevant, collapsing a continuum of risk into a crude 'could it happen or not.' The neglect is strongest for vivid, dread-laden, or affect-rich outcomes — kidnapping, contamination, a freak accident — where the imagery swamps any number attached to it. It is closely tied to the affect heuristic and to scope insensitivity, and it explains why people will pay sharply more to reduce a tiny risk to zero than to make a far larger dent in a bigger one. It matters because real-world risk decisions, from parenting to public safety, are frequently made as if likelihood barely entered the calculus.
Examples
Parents may obsess over a statistically negligible threat like abduction by a stranger while underreacting to far likelier dangers such as car accidents.
A shopper pays a steep premium to remove a trace contaminant from her water entirely, yet would not pay half as much to cut a far larger contaminant risk in half.
After a shark attack makes the news, swimmers stay out of the sea all summer. The horror of the image does the work; nobody looks up the odds.
First described in Discussed by Sunstein (2002); Rottenstreich & Hsee (2001).