Abstract
This paper introduces an experimental study performed to investigate the usability aspects of e-learning interfaces that incorporate the use of avatar as a virtual lecturer. A within-subject experiment has been conducted using three different e-learning interfaces which were developed from scratch and tested by a group of 48 users. Each of these three interfaces involved the use of a human-like avatar as a virtual lecturer to present one of three different lessons about class diagram notation usually used in the software engineering process. The scope of this paper is to report and discuss the experimental results related to users' satisfaction and views in regard to a set of facial expressions and body gestures when used by a virtual lecturer in the presence and absence of interactive context in e-learning interfaces. These results highlighted that some facial expressions as well as some body gestures were perceived by the users more positively than other expressions and gestures. Consequently, it could be used to improve the attractiveness of virtual lecturers which in turn will be reflected in increasing users' motivation and interest about the presented learning material.