Antradar Software develops it in an attempt to benchmark the ease of use of open source CMS products and to monitor the trend of UI designs.
It is usually measured by the number of page refreshes or the amount of hand–eye coordination required to complete a task.
It is observed that when the users are presented with more than 4 choices at a time, their decisions tend to base on random guess instead of reasoning.
Because of the nature of some application logic, the overall attention stress bears a lower bound.
This limit is termed "UI capacity" in the principles of attention stress.