The Effect of Hearsay on Speaker Commitment: An fEMG Study

When reporting speech, speakers not only relay information, but may also signal their degree of commitment to that information. This study aims to gather reliable empirical data on the role of so-called reportative evidentials (like 'I heard that Jack is a bachelor') in impacting the degree of perceived speaker commitment (here, their commitment to the truth of Jack being a bachelor). To measure perceived speaker commitment we use the physiological method of facial electromyography or fEMG. We show how this method can be used to trace perceived norm violations in conversation, from which we can then derive the commitments attributed to the discourse participants. In addition to comparing assertions with and without the use of reportative evidentials, we zoom in on the differences between two common reportative constructions: embedding ('I heard that Jack is a bachelor') versus parenthetical ('Jack is a bachelor, I heard'). In the literature there is controversy as to whether these two constructions have the same effect on speaker commitment. Results show that the use of reportative evidentials indeed lowers (but does not fully remove) perceived speaker commitment, but do not provide evidence that the two constructions have different effects. The findings can be understood within discourse frameworks that both model the contents of what is said and the degree of commitment to these contents.