When should usability testing be done?

Usability should be built into a new product from the analysis phase. Critical features and interactions should be identified and usability goals developed to interpret the findings of usability tests. Usability testing should be done on the earliest phases of design and prototypes. Usability evaluation is most beneficial when it is iterative and used in all parts of the development cycle. Findings from usability testing lead to changes in the product. The changed product should then be tested to determine how the changes impact the user and if the changes solved the identified problem. Usability testing facilitates decision making and allows developers to obtain more of a user perspective of their product. Instructional products that are developed and tested for usability will hopefully enable the learner to devote more cognitive power to the content and learning and less brain power and time trying to figure out navigation and how to control the product (Reeves & Hedberg, 2001).

What are the usability testing methods?