Fan effect
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The fan effect[1] is a psychological phenomenon under the branch of cognitive psychology where recognition times or error rate 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.
The fan effect first appeared in a series of experiments conducted by John R. Anderson, a cognitive psychologist, in 1974.[2] The three experiments he conducted involved participants learning 26 sentences that paired a person with a location. Additionally, they were asked to determine whether or not a particular sentence that was given to them belonged to the 26 they were asked to study. An example of a sentence Anderson used in his experiment was: "A hippie is in the park." Some sentences seemed similar in the sense that a person was paired with another location. For instance, "A hippie is in the church." Results revealed that participants produced a longer retrieval time when a person was paired with more than one location. Overall, these experiments demonstrated that multiple associations, such as including a large number of nouns in a sentence, interfered with the recognition time by producing a much slower effect.[3] Association splitting, a self-help technique devised for individuals with obsessive-compulsive disorder (OCD), builds upon the fan-effect. In OCD, associations are typically constricted to OCD-related meanings (e.g., fire = danger, cancer = death). Patients are taught to contemplate alternative meanings to reduce the strength of fearful associations (e.g., fire = diamond, cancer = zodiac sign). According to a systematic review, the technique leads to a significant reduction of OCD symptoms relative to control conditions. [4]