As human computer interface gets more immersive, it will need to explicitly draw upon cognitive science as a basis for understanding what people are capable of doing. User experience and situation should be integrated into the computer system design process. Situational awareness can be used to reduce the amount of explicit input a person has to give a computer. Contextual information of where and what the user task is, what the user knows and what the system is capable of can greatly simplify the user scenario. Such use of contextual models in computers can also reduce the teaching needed to accomplish tasks. An approach for contextual-computing framework for design is illustrated though examples.