Matching bias
We gravitate to the items explicitly named in a rule, ignoring logical relevance.
What it means
Matching bias is the tendency, in conditional reasoning, to select or judge relevant the items that are lexically mentioned in a statement, regardless of whether logic actually makes them relevant. It explains the classic pattern of errors in the Wason selection task, where people flip the named cards rather than the logically required falsifier. The bias is amplified by affirmative phrasing and largely neutralized by negations, suggesting it reflects a low-effort, linguistic relevance heuristic rather than genuine analysis of the conditional. It is often read as a System 1 default that frames which information even reaches deliberate scrutiny. Recognizing it clarifies why surface wording, not logical form, drives so many reasoning mistakes.
Examples
Told 'if there is not a circle then there is a triangle,' people still fixate on cards bearing circles and triangles — the named shapes — rather than tracking the negations.
Told 'if an order is not urgent, it ships Friday,' staff inspect the urgent orders and the Friday shipments, while the case that could break the rule sits in Tuesday's non-urgent pile.
A sign reads 'if you are not a member, you must pay at the desk.' The steward checks members' cards and the queue at the desk — never the non-member who walked straight in.
First described in Evans (1972, 1998).