Copyright 2006 John Wiley & Sons, Inc Chapter 4 – Physical Engineering HCI: Developing Effective...

Copyright 2006 John Wiley & Sons, Inc

Chapter 4 – Physical EngineeringHCI: Developing Effective Organizational Systems

Dov Te’eni

Jane Carey

Ping Zhang


Road Map

6

Affective

Engineering

9

Organizational

Tasks

4

Physical

Engineering

7

Evaluation

8

Principles &

Guidelines

11

Methodology

12

Relationship, Collaboration,

& Organization

10

Componential

Design

3

Interactive

Technologies

5

Cognitive

Engineering

Context Foundation Application

Additional Context

1

Introduction

2

Org &

Business

Context

13

Social &

Global Issues

14

Changing Needs of IT

Development & Use


Learning Objectives Define physical engineering. Understand and discuss human performance. Understand and discuss human limitations. Understand and discuss human perception through

the various sensors including: Vision Audition Touch

Explain Fitts’ law and how it pertains to HCI understanding and physical engineering.


Learning Objectives Understand and discuss possible health problems

associated with computer use including: Emissions Repetitive motion problems Vision problems Muscular problems

Understand, explain, and design technologies to support disabled users including those who are: Visually impaired Hearing-impaired Physically disabled


Introduction Ergonomics has been at the heart of human factors

engineering. The word was coined in 1949 from two Greek words, ergos, which means work, and nomos, which means natural laws.

It has come to mean "the fit between man and machine". The group that coined the word, ergonomics, was interdisciplinary and included psychologists, design engineers, work study engineers, industrial medical officers, and others with an interest in human performance.


Introduction Ergonomics: the physical fit between human

and machine. Ergonomic Engineering: the science of

human engineering which combines the study of human body mechanics and physical limitations with industrial psychology.


Human Performance and Limitations Ergonomic engineering is concerned with the physical

interfaces between the human user and the computer and has three main categories: analysis, design, and assessment (Bullinger, 1988). The analysis category focuses on human attributes and capabilities, the tasks to be performed, and the technology that is being used to aid in task performance. The performance-related goals of ergonomics are to improve: The human ability to handle physical load or demands of the work

situation, Performance (reduce errors, improve quality, reduce time required to

complete task), and End user acceptance of the system.


Human Performance and Limitations Human Performance: measured by reducing

errors, improving quality, and reducing time required to complete task.

Human

Task Computer

Fit PerformanceEnvironment

Work

Work Space

Figure 4.1: The expanded Fit between human, task and computer in the work context


Human Limitations Human Limitations: human limitations

which are physical in nature and include such aspects as levels of hearing, arm reach, muscular strength, visual distance and others. Sensory Limits

Human sight, hearing, smell, touch, and taste have thresholds and deficiencies.


Human Limitations Responder (motor) limits:

Humans have limited reach and strength. Keyboard layout designs and required mouse actions

often cause users to change body positions in order to execute them.

Often resulting in health problems.


Fitt’s Law Fitts’ Law: measures the time it takes for a

human to move a certain distance. Fitts’ Law provides much of the theory

underpinning our understanding of human performance and limitations. Fitts' law is a robust model of human psychomotor behavior developed in 1954. The model is based on time and distance. It enables the prediction of human movement and human motion based on rapid, aimed movement, not drawing or writing.


Fitt’s Law Mathematically, Fitts' law is stated as follows:

MT = a + b log2(2A/W) Where

MT = movement time a,b = regression coefficients A = distance of movement from start to target center W = width of the target

Sensory Perceptions and Implications for Design: Vision Vision: the human process of seeing and comprehending

objects seen. Guidelines for visual display

Characters in displays must be readable. Fonts should be as simple. Character definition should be as sharp. Characters should sufficiently contrast with the background. There should be adequate space surrounding each character. Highlighting should facilitate the task. Levels of intensity should not lead to fatigue. Underscoring used sparingly. Attention devices such as blinking, and reserve video should be used

sparingly. Displays should be relatively inert. Displays should read from left to right. Navigation should be consistent.

Sensory Perceptions and Implications for Design: Audition Audition: the human process of hearing and

comprehending sound. Guidelines for Physical Characteristics of Auditory

Messages: The message should be short. Useful when:

Response is time critical. Visual field is overburdened. User is already focusing visual attention.

Nature of auditory messages high enough frequency and intensity to be heard, but not annoying. Duration is important. Modulated sound will attract more attention than a continuous sound.

Use sparingly The user should be allowed to turn on or off keystroke clicks.


Audition

0 Threshold for hearing

Ear damage possiblePainful sound

Loud thunderSubway train

Truck or busAverage auto: loud radioNormal conversation

Quiet office, household sounds

Whisper

140130120110100908070605040302010

0 Threshold for hearing





Whisper

140130120110100908070605040302010

Threshold for hearing





Whisper

140130120110100908070605040302010

Figure 4.2 Decibel levels for typical sounds.


Sensory Perceptions and Implications for Design: Touch Touch: the human process of sensing

environment objects and conditions such as temperature through skin as a sensory organ.


Health Problems associated with HCI Emissions: electronic radiation waves

emitted by visual display terminals. Repetitive Motion Problems: Physical

discomfort and inflammation of tendons and tendon sheaths caused by frequent use of keyboards and other input devices.

Vision Problems: Blurred visions and degraded ability to see brought on by frequent use of computers.


Health Problems associated with HCI Muscular Problems: sore and damaged muscles brought on

by frequent use of computers. Constrained postures such as those required in prolonged

computer-based work result in static muscular work and such symptoms as: Inflammation of the joints (arthritis), Inflammation of the tendon sheaths (tendonitis or peri-tendonitis), Inflammation of the attachment points of the tendons, Chronic degeneration of the joints (arthroses), Painful hardening of the muscles, and Inter-vertebral disc problems.


Technical Support for the Disabled Technical support for the visually

impaired: software and hardware design that accommodates visually impaired users.

Technical support for the hearing impaired: software and hardware design that accommodates hearing impaired users.

Technical support for the physically disabled: software and hardware design that accommodates physically disabled users.


Summary Physical engineering combines the study of human

body mechanics and physical limitations with industrial psychology to achieve a fit between human and machine and thereby improve performance and the user’s well-being.

The ergonomics of information systems deals with topics such as the physical workstation and furniture design, lighting, noise, and keyboard height and arrangement. These are all physical aspects of human engineering within an information systems context.


Summary The performance-related goals of physical

engineering are to improve: (1) the human ability to handle load or demands

of the work situation, (2) performance (reduce errors, improve quality,

reduce time required to complete task), and (3) end user acceptance of the system.

Date post:	19-Dec-2015
Category:	Documents
View:	213 times
Download:	0 times

Copyright 2006 John Wiley & Sons, Inc Chapter 4 – Physical Engineering HCI: Developing Effective...

Documents