User Interfaces 4

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User modelling• Types of user model• User models and evaluation• Interface evaluation methods

Types of user model1. Psychological theories as user models2. Task analysis for user models3. Cut-down psychological theories as

user models4. Simplistic psychological theories as

user models5. More: Search for

Norman’s (1988) modelNorman’s model (2004) for emotional design

1. Psychological theories as user

models• Complex• Requires expert knowledge• Simplified for HCI use

2. Task analysis for user models

• Analysis of core tasks lead to how users undertake these tasks

• Reinventing the wheel• Good theories already exist• Behaviouristic approach

3. Cut-down psychological theories as

user models• Model Human Processor

Short Term Memory

Long-Term Memory

Perception

Response

Cognitive Processing

4. Simplistic psychological theories

as user models• Combine Task analysis and Model

Human Processor• Provide powerful conceptual

framework to accommodate complex theories and research

• Ability to be repackage to be used as a guide

Initial version of Simplex One

Adams, R and Landon, P. 2003. Principles and Concepts for Information and Communication Technologies Design. Journal of Visual Impairment and Blindness, October.

5 Zones to consider

Input Output Zone• Input/ Output zone:

o Easy to perceive and understand?o Should input be changed to improve

perceptual resource use of the individual?o Picture -> Text?o Systems allows most suitable ways to

generate output?o When are traditional devices, keyboard

and mouse, not best option?

Memory Zones• Long term data warehouse (long term

memory)o Do users have to have learned large

amounts of tacit knowledge to navigate through the system?

• Abstract working memory (short term memory)o Is amount of information an individual is

required to hold to navigate the system too much?

o Does design increase memory problems for visually impaired?

Central Processor/Executive

functions• Learning the overall task,

organization and implementation• Transfer information between zones• Manageable tasks, or steep learning

curve required• Does design provide support?• Balance between what to remember

and what to do?

Advances Simplex Theory

Adams, R and Landon, P. 2003. Principles and Concepts for Information and Communication Technologies Design. Journal of Visual Impairment and Blindness, October

4 Extra zones• Feedback to the user: good quality

understandable feedback• Emotional response to the system: is

it fun to use?• Cognitive models: Mental models to

aid understanding• Complex and skilled response

sequences: dos the sign support the development of such sequences?

Principles for evaluation

• Guidelines, Rules and standards• Guidelines (principles): more general• Rules: specific are based on studies• Standards: International Standards

Organisation, standards for industrial software

ISO 9241-11• Defines usability as

“the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a special context of use”.

Well Known Design Principles

• Learnability• Predictability• Consistency• Flexibility• Recoverability• Responsiveness

User models assist design

• Use model to determine user requirements• Use models to determine profiles of target

users• Use models to evaluated proposed designs• Use to generate questions to either of the

above

Questions for perception

• What are the perceptual skills of the target users?• Do the symbols/icons make sense to the target

users?• Do the symbols/icons/colours convey the same

nuances/meanings to all the target users?• Examples:

• Perception relies on past experiences, motivation and development

Questions for Responses

• What are user responses likely to be?• How will the environment influence user

responses?• Should a variety of responses be accepted?

What is abstract working memory

Short-term memory (or "primary" or "active memory") is the capacity for holding a small amount of information in mind in an active, readily available state for a short period of time. The duration of short-term memory (when rehearsal or active maintenance is prevented) is believed to be in the order of seconds. A commonly cited capacity is 7 ± 2 elements. Short-term memory should be distinguished from working memory, which refers to structures and processes used for temporarily storing and manipulating information.Working memory refers to structures and processes used for temporarily storing and manipulating information

• What kind of memory capabilities do the targets users have?

• What other factors will impact on the capacity of the working memory?

• Examples: selection of pass words, user names

Questions for abstract working memory

Questions for Long-term memory

• Are the metaphors used intuitive?• Does the interface offer support to

remember things?• Does the interface offer different levels of

support for remembering?• Does the interface offer different ways of

retrieving knowledge?• Examples: Database construct search

without fields being visible, technical terms SSL, ports, etc

Questions for Executive Functions

• What steps are required to convert input into the intended output?

• Are the steps interchangeable?• How much user interaction is required for

data to be moved from one area to another?• Examples:

o Formula construction in spreadsheetso Database reports

Evaluation Methods• Usability testing involves

o a method to test the system, o a product or system to be tested and o somebody to test the system.

• 3 main groups of evaluating: inspection, testing and inquiry

• Inspection: experts evaluate interfaces, example heuristic walkthroughs, …

• Testing: keystrokes, eye tracking, calculations• Inquiry: contextual inquiry, ethnographic

study/field observation, interviews and focus groups, surveys and questionnaires, users evaluate the interface

Exercise• Construct 2 questions for each zone of your

cell phone to determine usability