Design Guidelines, Principles, and Theories

• The chapter discusses guidelines, principles, and theories in the context of design.

Introduction to Guidelines, Principles and Theories

• Guidelines are low-level focused advice regarding good practices and potential dangers.
• Principles are mid-level strategies or rules used to analyze and compare different design options.
• Theories are high-level, widely applicable frameworks that inform design and evaluation, as well as support teaching and communication.

Guidelines

• Shared language promotes consistency among various designers in terminology, appearance, and action sequences.
• Guidelines are rooted in best practices.
• Critics note they can be too specific, incomplete, hard to apply, or even incorrect.
• Proponents suggest that building on the experience of design leaders fosters steady improvements.

Guidelines continued

• Early guidelines from Apple and Microsoft for desktop interfaces have been widely followed in web and mobile device design.
• Apple's guidelines for iWatch menu design provides options for designing menus, including different styles to display items.
• Example of Apple iWatch menu design styles: List, stack and sequence styles for the navigation of menu items.
• Guidelines are also used for navigating interfaces.
• Guidelines are further used in organizing displays.
• Guidelines are used to facilitate data entry.

Navigating the interface

• The National Cancer Institute's guidelines can be found at www.usability.gov.
• Task sequences are standardized for easier navigation.
• Embedded links should be descriptive.
• Unique and descriptive headings enhance navigability.
• Check boxes are used for binary choices.
• Pages need to be developed to ensure printability.
• Thumbnail images are used to preview larger images.

Accessibility guidelines

• Text equivalents are to be provided for all non-text elements.
• Time-based multimedia presentations require synchronized equivalent alternatives.
• Information conveyed through color should also be accessible without color.
• Each frame has to have a descriptive title to ease identification and navigation.
• More information can be found at: U.S. Access Board http://www.access-board.gov/508.htm or World Wide Consotrium Web (W3C) http://www.w3.org/TR/WCAG20/

Organizing the display

• Smith and Mosier (1986) proposed five high-level goals for organizing displays.
• Data display should be consistent in formats, colors, and capitalization.
• Information assimilation from the user should be efficient.
• Memory load on the user is minimal.
• There has to be Compatibility of data display with data entry.
• Users must have flexibility for user control of how data are displayed.

Mobile HCI Design Constraints/Guidelines

• Smaller screen sizes are a constraint for mobile HCI design.
• Touch data entry can cause errors
• Battery-power limitations affect design.
• Data download speed or access issues need to be considered.
• Design guidelines include spatial consistency.
• Show high-level information.
• Minimize the number of steps in a given task.
• Minimize data entry requirements.
• Focus on objectives and streamline processes.
• Look at emerging design standards from manufacturers.

Getting the user’s attention

• Intensity should be limited to two levels, with high intensity reserved for drawing attention.
• Items can be underlined, put in a box, or pointed to with an arrow.
• Size can be varied up to four levels, with larger sizes grabbing more attention.
• Choice of font can be used to get the attention of the user.
• Inverse video can be used for attention.
• Display items can blink Use blinking displays within a range if 2-4 Hz.
• Up to four standard colors can be used.
• Audio can be used, incorporating soft tones for regular positive feedback.

Facilitate data entry

• Similar action sequences speed up learning.
• Fewer input actions usually leads to increased operator productivity, and usually less error.
• Users shouldn't need to remember lengthy lists of codes.
• The format of data-entry information should be linked to the displayed information.
• Experienced users prefer to enter information in a personally controlled sequence.
• Cerner has guidelines for designers/developers in electronic health records available at https://design.cerner.com/.

Principles

• Principles are enduring than guidelines.
• Principles need more clarification than the guidelines.
• Determine user's skill levels.
• Identify the tasks
• 5 primary interaction styles.
• 8 golden rules of interface design.
• Prevent errors.
• Automation and human control.

Determine user's skill levels

• It’s important to "Know thy user".
• Factors include age, gender, physical and cognitive abilities, education, cultural or ethnic background, training, motivation, goals, and personality.
• Design goals need to be based on the user's skill level.
• Novice or first-time users.
• Expert frequent users.
• Multi-layer designs are good to implement.

Identify the tasks

• Task Analysis usually involve long hours observing and interviewing users.
• Tasks should be decomposed into high level tasks and then broken down.
• Relative task considerations

Choose an interaction style

• Direct manipulation visually presents task concepts and allows easy learning.
• Menu selection shortens learning and reduces keystrokes, but presents danger of many menus.
• Form fill-in simplifies data entry.
• Command language is flexible and appeals to "power" users, but has poor error handling.
• Natural language relieves the burden of learning syntax, but may not show context.

8 Golden Rules of Interface Design

• Strive for consistency.
• Cater to universal usability.
• Offer informative feedback.
• Design dialogs to yield closure.
• Prevent errors.
• Permit easy reversal of actions.
• Keep users in control.
• Reduce short-term memory load.

Prevent errors

• Error messages should be specific, positive in tone, and constructive.
• Correct actions by: Graying out inappropriate actions and selection rather focusing on freestyle typing.
• Automatic completion can aid in the prevention of errors.
• Complete sequences.

Automation and human control

• Humans are generally better in sense-making from hearing, sight, touch, etc.
• Machines are generally better to Sense stimuli outside human's range.
• Successful integration Users being able to avoid routine, tedious, and error prone tasks.
• Successful integration users should be able to concentrate on making critical decisions, coping with unexpected situations, and planning future actions.

More on Automation and human control

• Supervisory control is needed to deal with real world open systems.
• E.g. air-traffic controllers with low frequency, but high consequences of failure air-traffic.
• Autonomous Agents are one goal for automation.
• Autonomous Agents should aim to knows user's likes and dislikes.
• Autonomous Agents should aim to makes proper inferences.
• Autonomous Agents should aim to Performs competently with little guidance.
• An Alternative is by creating User models to allow for adaptive interfaces.
• Downside can be Users that may make surprising changes, they need to pause to see what has happened and it is problematic for them to predict changes that may happen..
• Alternative is to look to alternatives such as user control,expand use of control panels and information visualization tools.

Theories

• Theories go beyond guidelines.
• Principles are used to develop theories.
• Some theories are descriptive.
• Some theories are also exploratory.
• Some theories are prescriptive.
• There are also predictive theories.
• Some theories are based on human capacity.
• Motor Task, for example skill in pointing, clicking, dragging, or other movements.
• Perceptual, involving the aditory and tactile senses.
• Cognitive processes, such as problem solving with short- and long-term memory.

Stages of action models

• Norman's seven stages of action: Forming the goal, forming the intention, specifying the action, executing the action, perceiving the system state, interpreting the system state, and evaluating the outcome.
• Contributes to the context of cycles of action and evaluation.
• Gulf of execution: Mismatch between the user's intentions and the allowable actions.
• Gulf of evaluation: Mismatch between the system's representation and the user's expectations.

Stages of action models (concluded)

• Four principles of good design: Visibility: State and alternatives are visible, Conceptual Model: Good system image, Good Mappings: Interface reveals relationships, Feedback: User receives continuous communication.
• Failures points and Users forming on inadequate goal.
• Users finding the correct interface object.
• User specifications for executing a desired action.
• User receiving inappropriate or misleading feedback.