A system for controlling presentation of information to a user based on the user's current condition. In particular, the system monitors the user and the user's environment, and creates and maintains an updated model of the current condition of the user. The user condition can include a variety of condition variables, including abstract concepts such as the user's current cognitive load, desired level of privacy for output information, and desired scope of audience for output information. Upon receiving output information to be presented to the user (e.g., from an application program), the system determines an appropriate output device and an appropriate format with which to present the information to the user, and then presents the output information. The system can also receive description information about the output information that describes relevant factors for determining when and how to present the output information (e.g., the importance and urgency of the output information, the consequences of the user not receiving or ignoring the output information, etc.). Some versions of the system execute on a wearable computer having a variety of available output display devices.