Computer-based HSIs should support users in rapidly assessing the status of sequential actions in progress.
Additional Information:
An action sequence is a set of operations that must be performed in a specific order. Errors involving misordering the components of an action sequence include skipped, reversed, and repeated steps. Soft controls may be more prone to this type of slip than conventional controls because they introduce additional operations for accessing controls and displays and providing inputs that also often have sequential constraints on their execution. In addition, many control operations must be performed in particular sequences. For example, when configuring a fluid system, it may be necessary to establish the flow path, control mode, and setpoint of a flow controller in a specific sequence of operations (e.g., A, B, C, D, and E). One form of error occurs when a user skips a step thinking that it was completed. For example, a user may perform operations A, B, and C and after some delay or interruption, may perform operation E thinking that D already was finished. The repetitiveness of the task is a factor in this type of error. If a user has performed a set of operations repeatedly on several identical controllers, the memory of performing a particular operation on the other controllers may increase the likelihood of the user incorrectly concluding that the operation was completed on the present controller. Thus, the sequentiality of soft controls can interact with repetitive, sequential tasks to increase the probability of errors involving misordering the components of the action sequence. The display design of computer- based HSIs should support users in identifying tasks that are in progress; ideally, they should be designed so that the status of related operations (e.g., A, B, C, D, and E) can be checked at a glance from a single display.