1. Design Principles Review

2. Objectives
Design principles

3. Four basic activities in Interaction Design
Establishing requirements
Designing alternatives
Prototyping
Evaluating

4. Common Design Principles
Visibility
Feedback
Constraints
Consistency
Affordances
Mapping
See Norman (1998), The design of everyday things and Chapter 1, Rogers, Sharp, Peerce (2011)

5. From, Lidwell, W. , Holden, K. , & Butler, J
From, Lidwell, W., Holden, K., & Butler, J. (2010), Universal Principles of Design.

6. Core cognitive aspects
Attention
Perception and recognition
Memory
Reading, speaking and listening
Problem-solving, planning, reasoning and decision-making, learning
Most relevant to interaction design are attention, perception and recognition, and memory

7. Gestalt Principles of Perception
A premise of Gestalt psychology is the idea that humans strive to find the simplest solutions to incomplete visual information.

8. Principles Humans organize things into meaningful units using:
Chapter 4: Content Organization
Principles
Humans organize things into meaningful units using:
Proximity: we group by distance or location
Similarity: we group by type
Symmetry: we group by meaning
Continuity: we group by flow of lines (alignment)
Closure: we perceive shapes that are not (completely) there
Copyright © 2004 by Prentice Hall

9. Design Principles Design Principles Fitts’ law 80/20 Rule Alignment
Aesthetic-Usability Effect
Flexibility-Usability Tradeoff
Elegance and simplicity

10. Fitts’ law
Time required to move to a target is a function of the target size and the distance to the target.
Smaller and more distant a target, longer it takes to move to the resting position over the target.
Faster movement and smaller targets, greater error rate due to the speed-accuracy tradeoff.

11. Fitts’ law Implications
When rapid movements are required and accuracy is important, controls are near or large.
When controls not used frequently or when they cause problems if accidently activated, more distant and smaller.
Use large objects for important functions (Big buttons are faster).
Use pinning actions of the sides, bottom, top, and corners of your display.

12. Tapping Experiment
When controls not used frequently or when they cause problems if accidently activated.
When rapid movements are required and accuracy is important.

13. Fitts’ law Implications
Single-row toolbar with tool icons that "bleed" into the edges of the display is faster than a double row of icons.
Faster
Slower

15. 80/20 Rule
Approximately 80% of effects generated by any large system are caused by 20% of the variables in that system.
80 percent of a product's usage involves 20 percent of its features.
80 percent of a town's traffic is on 20 percent of its roads.
80 percent of a company's revenue comes from 20 percent of its products.
80 percent of innovation comes from 20 percent of the people.
80 percent of progress comes from 20 percent of the effort.
80 percent of errors are caused by 20 percent of the components.
The first recognition of the 80/20 rule is attributed to Vilfredo Pareto, an Italian economist who observed that 20 percent of the Italian people possessed 80 percent of the wealth. The seminal work on the 80/20 rule is Quality Control Handbook by Joseph M. Juran (Ed.), McGraw-Hill, 1951.

16. 80/20 Rule
Design and testing should focus on 20% of features used 80% of the time.
Identify the critical 20% of the functions that are used 80% of the time and…
make them readily available to users.
Noncritical functions part of the less-important 80% should be minimized or removed from the design.

17. Alignment It is easier to perceive a structured layout.
Place elements so edges line up along common rows or columns.
Nothing should be placed arbitrarily.

18. Alignment
Every item should have a visual connection with something else on screen (Williams, R. p. 27)
Alignment can help lead person through a design.

19. Alignment In text Left-aligned and right-aligned text blocks
better than center-aligned text.
presents clear, visual cue against which other elements of the design can be aligned.
Center-aligned text
has more visually ambiguous alignment cues, and can be difficult to connect with other elements.

20. You are looking at center alignment.By
Susan Fitzgerald
February 06, 2015

21. Alignment You are looking at left alignment. By Susan Fitzgerald
February 06, 2015

22. Hello World

23. Hello world It is easier to perceive a structured layout. SEARCH
Section Headings
Navigation
It is easier to perceive a structured layout.
Navigation

24. 50 px
50 px
50 px
100X100 px
100X100 px
50 px
50 px
50 px
50 px
50 px
100X100 px
100X100 px

25. Alignment
Source:

26. Alignment

27. Alignment

28. Alignment - numbers Think purpose! Which is biggest?

29. Aesthetic-Usability Effect
Aesthetic designs are perceived as easier to use than less-aesthetic designs.

30. Good usability is inherent in good design because people think well designed things work better, whether they do or not.
Source:
Aesthetics and Apparent Usability: Empirically Assessing Cultural and Methodological Issues

31. Flexibility-Usability Tradeoff
As the flexibility of a system increases, the usability of the system decreases.

32. Elegance and simplicity
The most powerful designs are always the result of a continuous process of simplification and refinement.
Source:

33. Elegance and simplicity
Before you do anything else to improve the quality of a design…
reduced its formal and conceptual elements to the absolute minimum.
Source:

34. Elegance and simplicity
Anything that is not essential to the communication task must be removed.

35. Elegance and simplicity
Whenever a single part plays more than one role, the unity of the overall design is enhanced.
Elegant solutions produce a maximum of satisfaction from an absolute minimum of components.

36. Whenever a single part plays more than one role, the unity of the overall design is enhanced.
Used to view next image and to navigate to a larger view of an image.

37. Elegance and simplicity
Remember…
Designs succeed or fail on the basis of how well they solve a particular problem.

38. Additional Items

39. Provide Clarity
Use plenty of negative or white space - area of page not occupied by content. Space between specific items on page.
Negative space does not have to be white.
Makes important content and functionality noticeable and easier to understand.
Source:

40. Provide Clarity
Use plenty of negative or white space - area of page not occupied by content.
Space between specific items on page.
Items equally spaced and aligned.

41. physical controls grouping of items order of items decoration
alignment
white space
gaps to aid grouping
gaps to aid grouping

42. Speaking of Goals
Adults’ perception & attention focuses almost totally on goals.
Adults tend NOT to notice things unrelated to goals.
Align our interfaces with users goals, or they won’t perceive most of what we put in front of them.

43. Speaking of Goals On the next slide there are many different tools.
Find a saw

45. Research and design issues
Need to consider how best to design, present, and structure information and system behavior;
Veen’s design principles
(1) Where am I? (2) Where can I go? (3) What’s here? 45

46. Research and design issues
Finger-flicking, stroking and touching a screen result in new ways of consuming, reading, creating and searching digital content
Touch areas min. 44px X 44px

47. Principles
Consistency: Since users find it difficult to handle the unexpected, it is important to be consistent throughout the interface.
Exploiting prior knowledge: provide user opportunity to draw on their prior knowledge.

48. Principles Recognition versus recall to reduce cognitive load Recall
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