The 4 scenarios : Assertiveness, Intimacy, Scrutiny and Performance We used two main software tools to create the 3D virtual exposure environments in the treatment of social phobia. We designed the objects, the visual effects, and the virtual worlds with Discreet 3D Studio Max 4. We also created animated characters with Character Studio 3, an extension of 3DS Max. The 3D design is then integrated in a behavior-based interactive 3D development tool, Virtools Dev. Virtools Dev is an authoring application that allows to create interactive, 3D content; that brings to life imported media; that allows the creation of simple media such as cameras, lights, curves, interface elements, and 3D frames. A behavioral engine processes behaviors, which are descriptions of interactions of elements in an environment. These behaviors are realized by building blocks, which can be combined to create complex interactive behaviors. A rendering engine draws the image seen on-screen, according to the information supplied by the behavioral engine. Virtools Dev is finally a software development kit that allows, for example, to create and modify behaviors. The environment is running on PC and can be viewed with the Virtools Web Player .

    

Assertiveness	Intimacy
Scrutiny	Performance