Prominence effect
The attribute that seems most important dominates choices more than trade-offs.
What it means
The tendency for the most prominent or important attribute of the options to weigh more heavily when people make a direct choice than when they evaluate the options separately or set a matching price. Because choice is a qualitative, comparative task, it invites lexicographic reasoning in which the dimension judged most important serves as the decisive criterion, whereas pricing and matching force quantitative trade-offs that let lesser attributes contribute. The effect is a leading explanation for choice-versus-matching preference reversals and is linked to the compatibility principle. It surfaces uncomfortable cases where a prominent moral or safety dimension dominates choice — people choose to save more lives even at greater cost when choosing, but trade lives against money when pricing. It matters because the response mode determines how much the 'important' attribute counts, so the same person can reveal different value trade-offs depending on how the question is posed.
Examples
Choosing between two candidates, the panel takes the one strongest on technical skill, the thing they call most important; asked what salary would make the two equal, communication suddenly counts.
Asked to choose, the parent picks the safest family car outright; asked how many pounds the extra safety is worth, they name a figure that lets fuel economy back in.
First described in Tversky, Sattath & Slovic (1988).