HCI_principles

Lecture notes: Principles of HCI and UID

(based on Shneiderman chapter 2)

[ lecture notes | CSC 397 | Pete Sanderson | Computer Science | SMSU ]

Principle 1 : Recognize the Diversity
Characterizing and classifying users

Common designer's fallacy: "I know what the users need."

Understand and characterize (profile) users before designing system.

Some characteristics: age, gender, physical abilities, education, cultural background, training, motivation, goals, personality, skills

Typical user classification:

novice or first-time (latter may know domain)

knowledgeable intermittent

expert frequent

General UI Requirements for each type of user

NOVICE:

limited UI OA vocabulary (Ease mapping of task OA to UI OA)

consistency

guidance

verbose help

tutorials

feedback

INTERMITTENT:

consistency

help

more freedom to explore

recognition aids

FREQUENT:

"power user" acceleration techniques

ability to define macros

Consider take "level-structured" (layered, spiral) approach:

Level of expertise determines feature subset.

In-class exercise: Debate pros and cons of system adapting automatically based on initial profile and updating profile through monitoring. [example: after I typed previous sentence, I inserted a ":" between two words then "<enter>". An animated star popped up and stated that it looked like I was writing a letter and asked if I wanted help.]

Identifying and profiling tasks

Task analysis is difficult (appropriate decomposition).

Consider relative frequency of task in mapping task OA to UI OA

Frequencies can be determined for each user class (see table p 71).

More-frequent tasks should be easier to perform.

Selecting interaction styles

Five primary interaction styles, each has ADV/DIS (p 72):

form fill

command language

natural language

Designer considerations for selecting UI OA:

mapping to task

speed of use

error rate

mental burden

training

ease of learning

ease of use

Principle 2 : Use the Eight Golden Rules of User Interface Design

1. strive for consistency (there are many types)

2. enable frequent users to use shortcuts

3. offer informative feedback (feedback for every user action)

4. design dialogs to yield closure (organize actions into beginning, middle, end)

5. offer error prevention and simple error handling

6. permit easy reversal of actions (reduce anxiety, encourage experiment)

7. support internal locus of control (user is in control, no surprises)

8. reduce short-term memory load (7+-2 chunks)

Other views of UID golden rules:

"The golden rule of design: Don't do to others what others have done to you. Remember the things you don't like in software interfaces you use. Then make sure you don't do the same things to users of interfaces you design and develop." Tracy Leonard (1996)

The Golden Rules of User Interface Design: Place users in control, Reduce users' memory load, Make the interface consistent. (details) Theo Mandel, in The Elements of User Interface Design, 1997.

Principle 3 : Avoid Errors

User errors WILL occur.

Designer should:

Support prevention through interaction techniques (e.g. list selection)

Support repair through effective error messages (Text section 11.2)

[ lecture notes | CSC 397 | Pete Sanderson | Computer Science | SMSU ]

Last reviewed: 25 September 1998

Peter Sanderson ( pete@csc.smsu.edu )