The basic definition of distance learning (DL) considers that the teacher and the students are separate in the spatial dimension and that this distance is filled by using technological resources.
Recent technological developments, allowing an increasing level of interaction between users, have implicated a deep change in the educational system. Aim of these studies was to analyze the implementation of interaction in a DL system with one-way video and two-way audio channels and to investigate the effect of interaction on psychological variables. Final results suggest that the possibility of interaction in distance learning arouses a greater degree of attention, interest, participation, concentration, satisfaction and perceived efficacy. The distance modality with interaction takes his place at the intermediate level between the traditional face to face lesson and video-recorded lesson or distance learning without interaction. The possibility of interaction during the lesson is a basic factor for the success of a distance course.