In this paper we present a novel interaction framework for augmented reality, and demonstrate its application in an interactive AR exposure treatment system for the fear of spiders. We use data from the Microsoft Kinect to track and model real world objects in the AR environment, enabling realistic interaction between them and virtual content. Objects are tracked in three dimensions using the Iterative Closest Point algorithm and a point cloud model of the objects is incrementally developed. The approximate motion and shape of each object in the scene serve as inputs to the AR application. Very few restrictions are placed on the types of objects that can be used. In particular, we do not require objects to be marked in a certain way in order to be recognized, facilitating natural interaction. To demonstrate our interaction framework we present an AR exposure treatment system where virtual spiders can walk up, around, or behind real objects and can be carried, prodded and occluded by the user. We also discuss improvements we are making to the interaction framework and its potential for use in other applications.