The Value of Usability Testing

Usability testing answers four key questions about an application.

• Can people use it?

• Do they form a correct mental model of the application so they can continue to use it? That is, do the people using the system form images in their heads (about the way to navigate through the system, the commands to use in particular situations, and so on) that matches the way the system actually works?

• Can they extend their mental model so that they're confident to interact with other areas of the system?

• Do they enjoy using it?

Each successive question demands a higher standard of usability. If people can use an application once, they may or may not be able to use it successfully the next time they call. If they can use it successfully on subsequent attempts, then they probably have formed an accurate mental model of how the system works. And if they actually enjoy using the application well, then the designer has hit the jackpot .