A fact checker is the person or organization that checks factual assertions in non-fictional text, either before (ante hoc) or after (post hoc) the text has been published or otherwise disseminated, in both cases to determine the veracity and correctness of the factual statements in the text. Fact checking before dissemination (ante hoc checking) has been a mainstay of serious publishers of non-fiction since the advent of modern journalism, and aims to remove errors and allow text to proceed to dissemination (or to rejection if it fails confirmations or other criteria). Post hoc checking most often is followed by a written report of inaccuracies, sometimes with a visual metric from the checking organization (e.g., Pinocchios from the The Washington Post Fact Checker, or TRUTH-O-METER ratings from PolitiFact). The aim for ante hoc analyzed text is often external publication, as in journalistic endeavors. Studies of post hoc fact checking have made clear that such efforts often result in changes in the behaviour, as speakers and writers become more careful in their statements and of the listeners and readers become more discerning with regard to the factual accuracy of content. As well, the studies have provided an array of nuanced insights relevant to theories of human persuasion.