  In order to evaluate the contribution of Embodied (Animated) Conversational
Agents (ECAs) to the effectiveness and usability of human-computer interaction,
we developed a software platform meant to collect usage data. This platform,
which implements the wizard of Oz paradigm, makes it possible to simulate user
interfaces integrating ACAs for any Windows software application. It can also
save and "replay" a rich interaction trace including user and system events,
screen captures, users' speech and eye fixations. This platform has been used
to assess users' subjective judgements and reactions to a multimodal online
help system meant to facilitate the use of software for the general public
(Flash). The online help system is embodied using a 3D talking head (developed
by FT R&D) which "says" oral help messages illustrated with Flash screen
copies.
