Fan Effect
A psychological phenomenon where recognition times or error rates for a particular concept increases as more information about the concept is acquired. The word "fan" refers to the number of associations correlated with the concept.
Origin
American cognitive psychologist John R. Anderson discovered the effect in 1974 experiments where participants learned 26 sentences pairing people with locations (e.g., "A hippie is in the park"). Anderson found that retrieval time increased when a person or location appeared in multiple sentences—the more associations "fanned out" from a concept, the longer recognition took. This demonstrated that multiple mental associations compete during memory retrieval. The effect became a cornerstone of Anderson's ACT-R theory of cognitive architecture.