1. Yonglei Tao School of Computing & Info Systems GVSU Ch 7 Design Guidelines

2. Guidelines 1. Help the user build and use a workable mental model 2. Minimize modal interaction 3. Reduce the cognitive workload of the user 4. Let the user be in charge 1-2

3. Guideline 1 Help the user build and use a workable mental model ◦ Consistent with the intended tasks ◦ Consistent representations ◦ Use concrete and familiar ideas for metaphors ◦ Use the user’s language ◦ Guide new users through normal and reasonable patterns of usage ◦ Provide feedback 1-3

4. 4 Consistency Functional consistency ◦ The same action should have the same result regardless of the mode the application is in Consistent appearance/behavior ◦ comparable operations should be expressed in the same way Consistency within and among applications

5. Benefits Predictable in appearance and behavior throughout the application’s display of information, manner of manipulating information, and methods of navigation Facilitating user’s learning ◦ Result in great productivity and efficiency Reusable design ◦ Increase productivity and product quality 1-5

6. 6 Consistent Appearance and Behavior

7. 7 User Familiarity Do not force users to adapt to an interface just because it is convenient to implement ◦ Use terms and concepts from the experience of users ◦ Hide the underlying implementation of interfaces (such as files and data structures) Consistency with the real world ◦ base interface design on a real-world metaphor

8. 8 Minimal Surprise Users get irritated when a system behaves in an unexpected way Need to ensure that comparable actions have comparable effects Users become confused or panic if no response to their actions from the system

9. Guideline 2 Minimize modal interaction Visibility 1-9

10. Visibility Making the user aware of the system’s components and processes, including all possible functionality and feedback from user actions. ◦ Reduce memory load Recognition/Recall ◦ the principle of visibility is based on the fact that we are better at recognition than we are at recall 1-10 Show everything at once, and the result is chaos. Don’t show everything, and then stuff gets lost. (Norman, 1998, 74)

11. 11 Can You Tell between Edit and Preview ?

12. 12 Excel Mode

13. 13 Excel Mode (Cont.)

14. Mode of a Mobile Phone 1-14

15. Guideline 3 Reduce the cognitive workload of the user ◦ Present options clearly and explicitly without multiple, reasonable interpretations ◦ Reduce the number of cognitive transformations or translations from the interface to the user’s mental model 1-15

16. 16 Clarity Visual clarity ◦ graphical representations can be clearly identified Conceptual clarity ◦ behavior of control is clear ◦ the metaphor is easily recognized Linguistic clarity ◦ meaning of labels and static text clarify contents

17. 17 Visual Clarity

18. Reduce the User’s Info Load Users should not be required to remember information from one screen for use on another screen. Tasks should be arranged such that completion occurs with few actions, minimizing the chance of forgetting to perform a step. 1-18

19. Common Techniques Recognition, rather than recall Allow users to perform actions by choosing alternatives presented on the screen, as opposed to remember particular command or name Build on user's frame of reference Labels and common formats should be provided for users 1-19

20. Techniques - Simplicity Simple things are easy to understand and, therefore, easy to learn and remember ◦ 80/20 Rule - 80% of an application’s usage involves 20% of its functionality ◦ Combines the conflicting needs of finding the optimal solution that satisfies all the requirements 1-20

21. 1-21 Example

22. 1-22 Example

23. Techniques - Progressive Disclosure 1-23

24. Constraints Limiting the actions that can be performed in a particular design  Controls the design’s simplicity 1-24

25. Guideline 4 Let the user be in charge ◦ Allow users to accomplish tasks directly ◦ Allow users to try again ◦ Provide appropriate feedback to users 1-25

26. 26 Make the Interface Forgiving Users inevitably make mistakes when using a system Users should be able to explore without fear of causing an irreversible mistake ◦ Prevention ◦ Toleration ◦ Recovery

27. Common Techniques Allow the user to select instead of typing Disable improper menu items or buttons by graying the option Confirm destructive actions or actions that result in an unexpected loss of user info (such as Cancel, OK command buttons) Provide undo and redo facilities 1-27