COSC 3461: Module 1S04

Introduction to Interaction &Principles of Design I

What is the User Interface?The simple view:

The user interface is the junction between

the user and the computer

The Simple View: Discussion

• Pro: Consistent with perspectives of software

developers– understandable to those with a background in

computer science, software engineering– UI and “back- end” are often developed separately

– What makes this possible?• An application’s functionality can be abstracted away

from the user interface• “Back- end” often is more of a focus in development

• the user interface might even be viewed as an add- on!

• Con: Not consistent with perspectives of users

The User’s Perspective

The user:Sees application as a whole

Doesn’t see (nor care about) the distinction between the UI and other components

Has tasks to perform; doesn’t care about back- end components

Foreshadowing:What are the consequence of these two different

perspectives?

Characteristics of the User Population[Solloway et al, 1994, 1996]

1. The activity to be performed is alreadyestablished

– users understand their work domain– they want to complete their tasks easily and

effectively2. Work culture is shared

– can be considered homogeneous to some extent– tasks to be performed are often similar from user to

user– designer can rely on notion of “archetypical user”

Characteristics of the User Population[Solloway et al, 1994, 1996]

3. Motivation is intrinsic– by virtue of their involvement with the task in the

first place– tool does not need to supply any extra motivating

factors4. Users are not necessarily trying to learn

– Goal is to complete successfully the task at hand– Users certainly will learn new things, but the

applications will stay the same– Users who are trying to learn use applications to

facilitate learning , which are different from theapplications that are the focus of this course

In summary: Users see the application as a tool

Consequences

• What are the consequence of these two differentperspectives?

– A mismatch between designers and users:• “the interface is the application” vs.

“ the interface is one component of the application”• Goal for the designer should be: develop a tool to help users

complete their work easily and effectively• Goal for the designer might instead be: develop a back end that

has all of the required features

– If the UI is well designed and usable, then entire applicationis usable

– Corollary: if the UI is poor, then the entire application isunusable, even if the other components have all of the

required functionality

What is the User Interface?

• The user interface is considered to include:

– The users’ “conceptual model” (the model of how usersconceive of the viewable objects, how they correspond to

objectsin the real world)

– the metaphors used (such as the “desktop”)– all controls and their behaviour

– all techniques for navigation within a display– all techniques for establishing continuity between different

types of displays (e. g., “flow” between screens)– all elements of the display (e. g., visual design of screen,

acousticcues, haptic feedback)

Code, Cost, and Effort• The user interface:

– typically is about 60% of the total lines of codein an application

– typically uses, at a minimum, 29% of thesoftware development project budget

– typically takes as much as 40% of thedevelopment effort

Software Lifecycle

• Pre- release software development is but one phase of software lifecycle.

– Recall the phases of sw development: requirements analysis, design specification, implementation, testing

• 80% percent of software lifecycle costs occur after the product is released, in the maintenance phase

– Of that work, 80% is due to unmet or unseen user requirements

– Only 20% of this is due to bugs or reliability problems

Karat, C. Usability engineering in dollars and cents. IEEE Software , May 1993, p 89.

What you need to know beforedesign…

• The user population– What do they know? How well do they see, hear, move, react?

– How are the users the same? How do they differ?

• The task( s)– What is the task or tasks?

– What is the flow of these tasks? What strategies do usersemploy? Do these strategies differ?

– What is the interaction, if any, between multiple tasks?

• The environment in which the task is performed– Is it noisy or quiet? Is it dark or light? Is it full of dust or grease?

– How will it vary? Will this have any effect on the interaction?

Disciplines Relevant to HCIHuman aspects:

– Anthropometrics• The measurement of the human body with a view to

determine its average dimensions, and the proportion of its parts, at different ages and in different races or classes.

– Psychology• The science of the nature, functions, and phenomena of

the human mind (formerly also of the soul)• Specializations: Cognitive, Social, Developmental,

Organizational– Communication theory

• Socio- Psychology, Socio- Cultural, Cybernetics, Rhetorics–Graphic design

• The use of graphic elements and text to communicate an idea or concept.

Disciplines Relevant to HCI

Human aspects:– Industrial design

• The professional service of creating and developing concepts and specifications that optimize the function, value, and appearance of products and systems for the

mutual benefit of both user and manufacturer.

– Ergonomics and human factors• The scientific study of the efficiency of man in his working

environment

– Linguistics and pragmatics• The scientific study of language and language use

– Sociology• The science or study of the origin, history, and constitution

of human society

– Anthropology• The science of man, or of mankind, in the widest sense

Disciplines Relevant to HCI

Computational aspects:–Computer science

• The science of data structures and the algorithms that operate

upon them (just one of many possible definitions)• …, operating systems, programming languages,…

– Software engineering• The system of applying of an engineering discipline to the

design,implementation and maintenance of software systems.

• Software development environments and tools

– Computer graphics– Artificial intelligence

– Computational linguistics (discourse and dialog management)

Issues•The tool needs to make business sense

– In a customer service organization, training on the system took 6 months, but employees typically stayed only 18

months in that department.

• The tool needs to forgive human error– Extensive and expensive functionality in a Human

Resources system was not used because users forgot how to access it one week after training.

• Users might refuse to cooperate– A $3 million application for an insurance company to be

used by independent agents to support them in selling their company’s products. However, agents refused to use the application because the system was “un- learnable” and

“unusable”.

Example 1.1