Before beginning the discussion of the GOMS concept, it is useful to understand the motivation for developing such techniques.

The overall philosophy behind GOMS and other HCI cognitive modeling efforts is to provide engineering models of human performance. Engineering models seek to optimize several criteria that distinguish them from traditional, psychologically-oriented cognitive models: (1.) the ability to make a priori predictions; (2) the ability to be learned and used by practitioners as well as researchers; (3) coverage of relevant tasks; and (4) approximation.