This invention relates to a computer simulated environment, such as a virtual world, and to the identification of a user entering the virtual world and user context in the virtual world model. An output of the virtual world model may be rendered using objects in the virtual world model. Previous versions of the rendered objects may then be located in associated user memory and specified differences between the rendered objects and the previous versions of the objects may be identified. A layer of the identified differences may then be rendered on the rendered output of the virtual world model.