05-knowledge of user interface design · 2011-07-01 · 4 Psychological Principles It Is Easier to Recognize Something Than to Recall It C. Patanothai 2110646:04-Knowledge of User

User Interface Design

Lecture 4

Requirements Gathering: Knowledge of User Interface Design

What to click, Yes or No?

C. Patanothai 2110646:04-Knowledge of User Interface Design 2

Knowledge Types for UI Design

• Information-gathering activities

• User interface design knowledge, from theory

(cognitive psychology), and experience


Minimizing work

• Cognitive work – comprehension of product behaviors

• Memory work – recall of product behaviors, commands, names and

locations of objects and controls and other relationships between objects

• Visual work – where the eye should start on a screen, finding object,

decoding layouts

• Physical work – keystrokes, mouse movement, gesture (click, drag, double-

click), switching between input modes, # of clicks required


Design Knowledge

• Design Principles – derived from experience – abstract, high-level guides – general, difficult to apply – First Principles of Interactive Design

• Design Rules

– low-level – high specific instruction – 8 Golden Rules


http://www.asktog.com/basics/firstPrinciples.html

http://www.usask.ca/education/coursework/skaalid/theory/interface.htm

4 Psychological Principles

• Users see what they expect to see

• Users have difficulty focusing on more than one activity at a time

• It is easier to perceive a structured layout

• It is easier to recognize something that to recall it




Users See What They Expect to See

What do you see?

• Principle of consistency

– throughout the UI

• Principle of exploiting prior knowledge

– users perceive the screen using their prior knowledge



Users Have Difficulty Focusing on More Than One Activity at a Time


– The Cocktail Party Effect

– Principle of Perceptual Organization

• Group like things together

– Principle of Importance

• Prominent display for important items



It Is Easier to Perceive a Structured Layout


Gestalt principles

a. Proximity

b. Similarity

c. Closure

d. Continuity

e. Symmetry


Figure-Ground Segregation


Exercise (5 minutes)


How well does this web sites support the principles of proximity, similarity, closure, and continuity?


It Is Easier to Recognize Something Than to Recall It


• Knowledge in the head & Knowledge in the world

• Principle of recognition

exceptions

• expert prefer key combinations

• routine operator don’t like to read the same info. repeatedly

Three Principles from Experience: Visibility, Affordance, and Feedback


The Principle of Visibility: It Should Be Obvious What a Control Is Used For



The Principle of Affordance: It Should Be Obvious How a Control Is Used

- affordance: strong clues to

operations of things - no picture, label, or instruction

is required

Affordance: actual vs. perceived




The Principle of Feedback: It Should Be Obvious When a Control Has Been Used

Discussion

• Principles to support usability, for example,

– learnability

• simplicity

• predicability

• …



Other Principles

• Constraints

• Natural mapping


Constraints

• Boundary

• Some can be selected, some cannot

• physical vs. logical

– cannot move cursor outside the screen


Natural Mapping

• Mapping should match functionality

• direct is the best

• natural mapping does not have to be direct – light switch

– oven control

– turn signal


Poor Physical Natural Mapping


Good Physical Natural Mapping


Logical Mapping


8 Golden Rules

• Strive for consistency

• Enable frequent users to use shortcuts

• Offer informative feedback

• Design dialog to yield closure

• Offer simple error handling

• Permit easy reversal of actions

• Support internal locus of control

• Reduce short-term memory load


Documents

05-knowledge of user interface design · 2011-07-01 · 4 Psychological Principles It Is Easier to Recognize Something Than to Recall It C. Patanothai 2110646:04-Knowledge of User