Social osmosis

Social osmosis is the indirect infusion of social/cultural knowledge. Effectively, social content is diffused, and by happenstance authentic experience is displaced by degrees of mediated separation before a subject acquires knowledge of a social phenomenon.

An example of social osmosis would be knowing a show exists that you have never seen, yet possessing detailed information concerning aspects of the show without actively acquiring this knowledge, such as the main character's stage name and the actor/actress who plays him/her.

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Wikipedia