 Empirical research on the norm of assertion was initiated by Turri. His (2013) study aims to determine whether people’s assertability judgments are better predicted by a factive norm, like  (KNA)  or  (TNA),  or a non-factive one, like  (JNA)  or  (BNA).  Turri reports the results of six experiments, primarily investigating judgments about unlucky assertions (false assertions that the speaker reasonably believes to be true). In the first experiment, Maria incorrectly thinks that she has a 1990 Rolex in her watch collection, because this is what her inventory says. When a friend asks Maria if she has that particular Rolex, participants are asked: “Should Maria tell her guest that she has a 1990 Rolex in her collection?” [Yes/No]. Participants overwhelmingly selected the negative option (No), even when different factors were manipulated (the control questions, what is at stake, the response options, etc.), apparently providing robust evidential support for factive accounts. Turri has since conducted several more studies, accumulating an impressive body of evidence supporting factive accounts of assertion in general and the knowledge-norm in particular (for a review, see Turri 2017), including studies on other potential counterexamples to  (KNA),  like selfless assertions (2015a), and Gettiered assertions (2016).