human factors and professional issues

Arab Open University2nd Semester, 2006-2007

M301

Unit 5.5Human Factors and Professional

Issues

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Topic Road Map

Designing and implementing the user interface

Usability analysis and evaluationIntroducing human and professional

issuesPerson-related factorsTask- and environment-related factors

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What is HCI?

Human Computer Interaction. HCI is the study of interaction between people (users)

and computers. It is an interdisciplinary subject, relating computer

science with many other fields of study and research. Interaction between users and computers occurs at the

user interface, which includes both hardware (i.e. peripherals and other hardware) and software (for example determining which, and how, information is presented to the user on a screen).

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The disciplines that contribute to HCI

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Major Contributors

1. Computing2. Cognitive psychology: is primarily concerned with

understanding human behavior and the mental processes that underlie it.

3. Social and organizational psychology: is concerned with studying the nature and causes of human behavior in a social context.

4. Ergonomics and human factors: are concerned with maximizing the user’s safety, efficiency and reliability of performance, and with increasing the user’s feelings of comfort and satisfaction.

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Minor Contributors

1. Artificial intelligence.2. Linguistics.3. Philosophy.4. Sociology.5. Anthropology.6. Design.7. Engineering.

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What are the capabilities of humans?

Perception and representation.Attention and memory.Knowledge and learning.

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Perception and representation

The main area of HCI where work on perception and representation comes into play is in presenting information graphically at a user interface.

The main techniques used are: Three-dimensional representations. Graphical coding. Color coding. Icons.

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Attention and memory

How to guide the user’s attention to important parts of a display? Presenting neither too much information nor too little on

screen. Spatial and temporal cues may also be used, such as

consistently putting important information in the same place or sequencing the display of information in a predictable way.

Color can also guide attention.

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… Attention and memory

Kinds of memory storage: Sensory store, where each of the senses holds stimuli they

receive for a few tenths of a second; Short-term or working memory, which holds a limited amount

of information for about 15–30 seconds; Long-term memory, which holds information indefinitely.

A factor that influences how easily new material can be stored in long-term memory is meaningfulness. Familiarity and imagery influence meaningfulness.

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… Attention and memory

Factors that influence the meaningfulness of icons include: The context in which the icon is being used, The task for which it is being used, and The form of representation:

Resemblance. Exemplar. Symbolic. Arbitrary.

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Knowledge and learning One of the most important concepts in examining how a

user understands a system is that of a mental model.

A mental model is an explanation in someone's thought process for how something works in the real world. It is a kind of internal symbol or representation of external reality, hypothesized to play a major part in cognition.

Two basic types of mental model: Structural model describes how a system is built. Functional model describes how it works.

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… Knowledge and learning

Understanding a user’s mental model allows a designer to construct an interface that matches it most closely and hence reduces errors.

Errors categories: Mistakes, which are conscious decisions to take

actions which turn out to be incorrect; and Slips, which are unintentional errors such as

accidentally pressing the wrong key or selecting the wrong menu item by overshooting.

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Input devices

Keyboards.Joysticks.Mice.Trackballs. Speech recognition.

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Output devices

LCD's.3D virtual reality devices.

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Communication style

Command-line interface (CLI).Menus:

pull-down menus. pop-up menus.

Fill-in forms.Natural-language dialogue.Direct manipulation.

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Why some interfaces cause problems to their users?

Gulf of execution: user’s formulation of actions

actions allowed by the system

Gulf of evaluation: user’s expectation of changed system state

actual presentation of this state

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Widgets

Are user-interface components. Standard widget names for window control:

title bar, close box, maximize box, minimize box, scroll bar, resize button, resize button.

Widgets concerned with control within an application inclusive check box, exclusive check box or radio

button, slider or scroll bar, button, menu, submenu, text box, dialogue box.

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Topic Road Map




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Observation and monitoring

Direct observation: one simply watches the users using the interface and notes where they seem to have problems and the sequences they follow to perform actions.

Indirect observation: by means of a one-way mirror or video recording.

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Collecting users’ opinions

Interviews.Questionnaires.

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Interviews

Two main kinds of interviews: Structured interviews have a predetermined

set of questions and permit a relatively formal and balanced result.

Flexible interviews are generally based on some predetermined set of topics, but allow the interviewer and interviewee to explore opinions and ideas that the interviewer may not have considered at the outset.

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Questionnaires

Two types of question structure: Open questions are of the short-answer/essay

type. Closed questions are easier to analyze and

generate statistics from, and can take the form of multiple-choice answers or of asking the user to rate something on a multipoint scale.

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Usability The attribute that determines the effort required to learn,

operate, prepare input for, and interpret the output of a system.

This can be decomposed into four aspects: Learn ability — the time and effort to reach some particular

level of proficiency; Throughput — the speed at which experienced users can do

things; Flexibility — the extent to which changes can be

accommodated; Attitude to the tasks being carried out, measured by

questionnaires and interviews.

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Predictive evaluation

Uses modeling to predict user behavior and interface performance but does not involve any user testing.

Keystroke-level model: a predictive evaluation technique that takes no account of novice learning behavior, but instead relies on well-established metrics which measure a known time to complete a simple task.

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Keystroke-level model

It models a task in terms of the time taken on four physical activities, the response time of the system and the mental operation time of the user:

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Example

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Topic Road Map


Usability analysis and evaluation Introducing human and professional


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Human factors

Discipline that tries to enhance the relationship between people and technology, where the word ‘enhance’ means making the relationship safer or more productive.

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Process-related human factors

1. Person-related human factors1. The engineer’s experience of programming;2. The engineer’s understanding of the specification.

2. Task-related human factors3. The number of other tasks the engineer has to do;4. The similarity between this code module and others the engineer has

implemented.3. Environment-related human factor

5. The usability of the debugging tools;6. The length of time the engineer can expect to work without interruption;7. The layout and clutter of the engineer’s desk;8. The noise in the office.

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What does it mean to be ‘professional‘? Profession: a form of employment, especially one that is

possible only for an educated person and after training (such as law, medicine or teaching) and that is respected in society as honorable.

If you consult a professional, you expect any advice given to be accurate and appropriate, any work resulting from the consultation to be carried out in a competent way, and the professional to take responsibility for the advice given.

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Three cornerstones of professionalism

Being knowledgeable about the field.Being competent to practice (i.E. Being

able to apply knowledge of the domain in making technical and ethical decisions).

Taking responsibility for one’s actions.

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What does it mean to be a ‘software professional’?

Being a member of a professional body.Being clear in the use of language.Being honest.

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Individual factors

Competence in a software engineer is a mixture of knowledge and experience with respect to a particular task or activity, and the ability to apply that knowledge and experience to the task.

Motivation is what arouses the individual to action and directs the nature of the action over time.

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Social factors

The individual engineer must be able to: Work as part of a team. Communicate effectively with others.

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Task-related factors

Task complexity: Very complex tasks take a long time to complete and are likely to involve errors.

Task familiarity: The more familiar the task, the faster and less error-prone the performance of that task will be.

Task variability: For tasks that are highly repetitive, automation is likely to yield benefits.

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Environment-related factors

Physical workspace Privacy: Many software engineers work in open-plan offices. Outside awareness: well-designed, open plan environment,

which also caters for the needs of privacy. Personalization: the ability to arrange the workspace to suit

individual work practices and preferences. Methods and tools

Ease of learning. Ease of use. Availability of training and support.

TMA5 – Q5

Thank You!

human factors and professional issues

Education