Design Principles Review

Objectives Design principles

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

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

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

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

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

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

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

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.

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.

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

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

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.

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.

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.

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.

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.

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

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

Hello World

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

50 px 50 px 50 px 100X100 px 100X100 px 50 px 50 px 50 px 50 px 50 px 100X100 px 100X100 px

Alignment Source: http://msdn.microsoft.com/en-us/library/system.windows.controls.grid(v=vs.95).aspx

Alignment

Alignment

Alignment - numbers Think purpose! Which is biggest? 532.56 179.3 256.317 15 73.948 1035 3.142 497.6256 532.56 179.3 256.317 15 73.948 1035 3.142 497.6256

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

Good usability is inherent in good design because people think well designed things work better, whether they do or not. Source: http://www.markboulton.co.uk/journal/comments/aesthetic-usability-effect Aesthetics and Apparent Usability: Empirically Assessing Cultural and Methodological Issues http://www.sigchi.org/chi97/proceedings/paper/nt.htm

Flexibility-Usability Tradeoff As the flexibility of a system increases, the usability of the system decreases. http://www.youtube.com/watch?v=9pr1vOt21qQ

Elegance and simplicity The most powerful designs are always the result of a continuous process of simplification and refinement. Source: http://usabilitynews.usernomics.com/2008/05/simplicity-functionally-and-visually.html

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: http://usabilitynews.usernomics.com/2008/03/usability-and-simplicity.html

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

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.

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.

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

Additional Items

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: http://sixrevisions.com/web_design/negative-space-in-webpage-layouts-a-guide/

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.

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

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.

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

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

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

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.

Principles Recognition versus recall to reduce cognitive load Recall Visited Links