In this article we describe the preliminary results of our experiment conducted with the PRESEMO. PRESEMO is a system that makes it possible for an audience to interact during a presentation. The system uses the Nokia N900 devices with heart rate monitors to create an interactive presentation and displays the heart rate of four participants in real time. Over all we measured 70 participants. During the presentation the participants were able to communicate with each other via the mobile devices and answer questions that were presented interactively. In the experiment, short movie clips were presented to the participants during which their interbeat interval, electrodermal activity and blood volume pulse were measured. Some feedbacks (chat conversation, answers to the questions and biofeedback) were visible to the participants during the presentation. We wanted to know whether it had an impact on emotions, inter-personal attraction, physical presence and social presence. We found that feedback had a positive effect on the dependent variables.