In a typical conversation, Speakers are assumed to be committed to the content of their utterances. Recent research has uncovered several linguistic expressions or prosodic contours that convey subtle interactions between the commitments of discourse agents and the presumed source of the information. Another such case is that of Transparent Free Relatives, as in That’s an instance of what pragmaticians call ‘implicature’, which provide a systematic way to explicitly introduce a source (pragmaticians) into an attribution statement (call ‘implicature’), but may also leave the source unexpressed, as in That’s an instance of what is called ‘implicature’. We explore the factors that give rise to Non-Speaker commitment in a novel two-person experimental paradigm, finding that (i) the presence of an explicit third person source and (ii) the tense of the attribution statement provide reliable cues to Non-Speaker commitment.