2.2 Ensure that the user interface and task flow is similar across different functions and remains the same across repeated visits
A uniform presentation and interaction style should be used for all functions of the device or service. This should not change between visits. This applies equally to telephone interfaces and Interactive Voice Response (IVR) or voicemail services.
The steps required to complete a task should also remain the same between visits. This includes the instructions, the choices provided, what inputs are required and how these are made. Having completed one task, the user should be able to complete a second task by carrying out a similar sequence of steps. Having carried out a task once, the user should be able to repeat the task by carrying out the same sequence of steps.
People with cognitive or learning disabilities find it difficult when the interaction style or task flow varies. Consistency helps enormously by making procedures easier to understand and enabling users to transfer the skills learnt on one task to other tasks. If there is no consistency between tasks or, even worse, if there is no consistency over time for a given task, users will have to repeatedly relearn the procedure.
Directions and Techniques
Define and follow a standard style.
Consistency is achieved by defining a standard style and following it. This can outline standards for aspects such as colours, control sizes, positioning of controls and menu items, task order, navigation options and writing or speaking style for instructions and information. Standards should be written down in the form of a style guide. One or more members of the development team should be assigned to act in a quality assurance role, reviewing the design to ensure that it adheres to the style guide.
For IVR systems and voicemail services, it may be possible to enforce the standard automatically, by using templates or some kind of content management system.
Do not insert extra steps into a process
Avoid inserting extra steps into the sequence, such as advertising or promotion messages.
How you could check for this:
Try to repeat a task by using a standard sequence of operations
While carrying out a task, write down the sequence of operations you perform, in terms of physical actions such as keypad presses. Try to repeat the task a number of times by following this sequence exactly, without looking at or listening to the instructions. If the result is in any way different, then there is inconsistency.