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The retraction count for former psychology professor Diederik Stapel just hit 50: Social Psychology is revoking a 2008 paper by the Dutch researcher after an investigation found “strong indications” that the results had been manipulated and faked. Stapel, who has had 49 other papers retracted since December 2011, said he wasn’t sure whether the study was fraudulent or not. Suppose it’s hard to keep count!

All of Stapel’s 130 articles and 24 book chapters are under investigation by his former employer, Tilburg University in the Netherlands. The university suspended him in September 2011 and later discovered that, in addition to making up data, Stapel had allowed many of his students to graduate without ever completing an experiment.

The co-author of the 2008 paper, titled “The impact of comprehension versus self-enhancement goals on group perception,” said he was unaware of Stapel’s actions and was not involved in data collection.

Other results faked by Stapel include the widely reported findings that meat eaters are more selfish than vegetarians and that chaotic environments promote stereotyping and discrimination. The New York Times and TIME were both fooled by fake Stapel experiments in 2010, and in May 2008, Popular Science posted an article about one of Stapel’s later-retracted studies. (Sorry readers!)

Last November, Stapel published a memoir called “Derailed,” in which he admitted to years of scientific fraud and apologized to his former colleagues. Dutch reviewers described the book as “revealing” but noted the last chapter contains lines plagiarized from James Joyce and Raymond Carver.