What is primarily being measured in a usability test?

In a usability test, the focus is on evaluating how effectively and efficiently users can complete specific tasks using a product or system. This involves understanding how easily users can navigate through the interface, achieve their objectives, and how well the overall design supports their interactions.

Primary metrics in usability testing often include task completion rates, time taken to complete tasks, and user satisfaction levels, all of which fall under the umbrella of user efficiency. By observing users as they interact with a system, researchers can identify areas where users struggle, leading to insights that can improve the design and functionality of the application for better usability.

The other options, while relevant in different contexts, do not align with the primary focus of usability testing. Memory usage pertains to system performance rather than user experience, speed of data processing relates to how quickly a system can handle operations, and vulnerability to hacking concerns security rather than how user-centric and effective the interface is during interactions.