By speaking we undertake commitments. But what exactly is the role of the hearer? Does their silence mean assent? And sometimes we want to ‘put something on the table’ without taking on a commitment, for example by saying that someone else said it. What does that mean for our commitments? We answer these questions by means of a new experimental method where we measure the activity of the frowning muscle, which is known to become active in the case of moral indignation. In this way, we will come to a better understanding of what happens when we communicate.