Design Principles – Part 1 of 3

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Design Principles – Part 1 of 3

Introduction

This material has been developed by Georgia Tech HCI faculty, and continues to evolve. Contributors include Gregory Abowd, Jim Foley, Diane Gromala, Elizabeth Mynatt, Jeff Pierce, Colin Potts, Chris Shaw, John Stasko, and Bruce Walker. Comments directed to [email protected] are encouraged. Permission is granted to use with acknowledgement for non-profit purposes. Last revision: February 2012.UI Design - Georgia Tech

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UI Design - Georgia Tech 2

Outline

• Introduction• Guidelines / Principles

Learnability– Support for learning for users of all levels

Flexibility– Support for multiple ways of doing tasks

Robustness– Support for recovery

• Design Patterns• Styleguides• Summary


What are Design Principles?

• Rules of thumb to help with the design process

• AKA Design Guidelines, Design Rules


Design Principles - Overview

• Become obvious to user of poorly-designed UIs

• Are easy to ignore• Apply at multiple levels of design• Are neither complete nor orthogonal

Can all be “broken”, often to satisfy another rule

• Have underpinnings in psychology or experience or common sense


Why we Need Design Principles

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Many Sets of Design Principles

• Norman, Design of Everyday Things• Shneiderman, Designing the User

Interface• Dix, Finlay, Abowd, Beale (DFAB),

Human-Computer Interaction DFAB Taxonomy/terminology used here

• Foley et al, Computer Graphics: Principles and Practice

• And many more - including in styleguides, discussed later

Norman’s Guidelines

• Bridge the gulf of execution and evaluation• Provide affordances• Provide user with a conceptual model that is consistent with

system operation• Make current state visible• Make action alternatives visible• Provide natural mappings• Provide continuous feedback• Use constraints• Use knowledge in the head and knowledge in the world• Design for error• When all else fails, standardize

Shneiderman’s Guidelines

1. Strive for consistency 2. Enable frequent users to use shortcuts3. Offer informative feedback 4. Design dialogs to yield closure 5. Offer error prevention and simple error handling 6. Permit easy reversal of actions 7. Support internal locus of control 8. Reduce short-term memory load

Foley’s Guidelines

• Be consistent• Provide feedback• Minimize error possibilities – don’t

set the user up for a fall• Provide error recovery• Accommodate multiple skill levels• Minimize memorization



DFAB’s Principles (1 of 3)

• Learnability - Ease with which new users can begin effective interaction and achieve maximal performance Predictability Synthesizability Familiarity Generalizability Consistency



• Flexibility - Multiplicity of ways that users and system exchange information Dialog Initiative Multithreading Task migratability Substitutivity Customizability



• Robustness - Supporting user in determining successful achievement and assessment of goals Observability Recoverability Responsiveness Task Conformance


Concepts, Principles, Guidelines

• No “cookbooks”• No simple, universal checklists• There are many concepts, principles, and

guidelines• Understand the higher level principles that

apply across situations, display types, etc.• Implement the standards and guidelines

…a few details…


Many Principles Apply at Multiple Levels

1. Conceptual (model)2. Semantic (meanings of actions & visual

organizations/encodings - or auditory)3. Syntactic (input sequencing,output

organization)4. Lexical (physical actions, visual encodings)

• Similar toNorman’s,especiallysyntactic & lexical

GoalsWhat we

want to happen

Evaluation of the interpretationswith what we expected to happen

Interpreting the perception accordingto our expectations

Perceiving the stateof the world

An intention to actso as to achieve the goal

The actual sequence of actionsthat we plan to do

The physical execution of that action sequence


The End

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Design Principles – Part 1 of 3