Introduction to human factos and ergonomics for engineers

INTRODUCTION

TO HUMAN FACTORS

AND ERGONOMICS

FOR ENGINEERS

ch00_FM_8129_Lehto_LEA 7/2/07 9:36 AM Page i

HUMAN FACTORS AND ERGONOMICS

Gavriel Salvendy, Series Editor

Aykin, N., (Ed.): Usability and Internationalization of Information Technology.

Bagnara, S. (Ed): Theories and Practice in Interaction Design

Carayon, P. (Ed): Handbook of Human Factors and Ergonomics in Health Care and Patient Safety

Hendrick, H., and Kleiner, B. (Eds.): Macroergonomics: Theory, Methods and Applications.

Hollnagel, E. (Ed.): Handbook of Cognitive Task Design.

Jacko, J.A., and Sears, A. (Eds.): The Human-Computer Interaction Handbook: Fundamentals, Evolving

Technologies and Emerging Applications. (See 2nd edition under Sears.)

Karwowski, W., (Ed.): Handbook of Standards and Guidelines in Ergonomics and Human Factors.

Keates, S., (Au): Designing for Accessibility: A Business Guide to Countering Design Exclusion

Lehto, M. R , and Buck, J.R., (Au): Introduction to Human Factors and Ergonomics for Engineers

Meister, D., (Au.): Conceptual Foundations of Human Factors Measurement.

Meister, D., and Enderwick, T. (Eds.): Human Factors in System Design, Development, and Testing.

Proctor, R., and Vu, K. (Eds.) Handbook of Human Factors in Web Design.

Sears, A. and Jacko, J. A. (Eds.): The Human-Computer Interaction Handbook: Fundamentals,

Evolving Technologies, and Emerging Applications, 2nd Edition.

Stanney, K. (Ed.): Handbook of Virtual Environments: Design, Implementation, and Applications.

Stephanidis, C. (Ed.): User Interfaces for All: Concepts, Methods, and Tools.

Wogalter, M. (Eds.): Handbook of Warnings.

Ye, N. (Ed.): The Handbook of Data Mining.

ALSO IN THIS SERIES

HCI International 1999 Proceedings 2 Volume Set

HCI International 2001 Proceedings 3 Volume Set

HCI International 2003 Proceedings 4 Volume Set

HCI International 2005 Proceedings 11 Volume CD Rom Set ISBN# 0-8058-5807-5

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INTRODUCTION

TO HUMAN FACTORS

AND ERGONOMICS

FOR ENGINEERS

Mark R. Lehto

James R. Buck

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Cover design by Tomai Maridou.

Lawrence Erlbaum Associates Lawrence Erlbaum Associates

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CONTENTS

Series Foreword xvii

Preface xix

Acknowledgments xxiii

CHAPTER 1 A Guided Tour

of Ergonomic Design 1

About this Chapter 2

Introduction 2

What Is Ergonomic Design? 4

Human-Centered Design 10

Military Equipment Design 14

Ergonomic Criteria 16

Models of Human Performance 17

Helson’s Hypotheses 18

Other Models 19

A Model of Software Design 24

Macroergonomics 25

Carrots and Sticks 29

Trends in Industry That Impact Ergonomic Design 30

Organizations and Additional Information on Ergonomic Design 34

Ergonomic Methods 34

Field Studies 35

Experimental Simulations 36

Laboratory Experiments 37

Computer Simulation 37

Differences in Ergonomic Methods 37

Final Remarks 38

Discussion Questions and Exercises 39

CHAPTER 2 The Human System 41

About this Chapter 42

Introduction 42

The Skeletal Subsystem 43

The Extremities 43

Joint-Related Disorders 46

The Spine 48

The Muscles 50

Muscle Contractions and Capabilities 50

The Role of Oxygen in Muscle Actions 52

Muscle Injuries and Disorders 53

Effects of Gender and Muscular Strength 53

Exercise as a Means of CTD Prevention 54

Anthropometry 54

Predicting the Stature of People 54

Estimating Body Dimensions 56

Predicting the Segment Mass of the Human Body 56

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Other Anthropometric Relationships 58

Body Movement 60

The Muscular-Skeletal System as Levers 60

The Sensory Subsystems 64

The Visual Sensory Subsystem 64

Human Perception of Sound 73

Position and Motion Sensing 77

Other Senses 80

Support Subsystems 81

Respiratory Operations and Mechanics 81

The Circulatory Subsystem 82

Metabolism 84

Indirect Calorimetry 87

Final Remarks 88

Discussion Questions and Exercises 89

CHAPTER 3 Design to Fit Tasks, Processes,

and People 93

About the Chapter 94

Introduction 94

Ergonomic Design Principles 95

Traditional Principles in Ergonomic Design 97

Visual Graphs of Operations 99

Operations Process Charts 100

Flow Process Charts 101

Flow Diagrams 103

Multiple Activity Charts 104

Precedence Diagrams and Matrices 105

Link Diagrams 106

Task Time-Line Analysis Graphs 108

Fault Trees 109

Failure Modes and Effects Tables 112

Cause-and-Effect Diagrams 112

Decision Flow Diagrams 114

Analysis of Tasks and Jobs 116

Describing the Task 117

Determining Task Requirements 120

Function Allocation 124

Final Remarks 126

Discussion Questions and Exercises 126

CHAPTER 4 Assessment and Design

of the Physical Environment 129

About the Chapter 130

Introduction 130

Cleanliness, Clutter, and Disorder 131

General Housekeeping and Maintenance 131

5S Programs 132

Air Quality and Ventilation 135

Temperature and Humidity 136

Thermal Regulation 136

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Heat Transfer 137

Control Strategies for Hot or Cold Environments 142

Assessing Thermal Conditions and Comfort 145

Effects of Thermal Conditions on Performance 154

Lighting and Illumination 154

The Luminous Environment and Its Measurement 156

Lighting Methods 160

Some Basic Principles and Lighting Requirements 163

Noise 172

Health Effects of Noise 173

Annoyance and Other Effects of Noise 175

Noise Control Strategies 176

Hearing Protection 177

Final Remarks 179

Discussion Questions and Exercises 179

CHAPTER 5 Design of Work Areas,

Tools, and Equipment 183

About the Chapter 184

Introduction 184

Applied Anthropometry 185

Drafting Templates 188

Computer Modeling Methods 189

Design of Work Areas and Stations 192

Traffic Areas 192

Workplace Dimensions and Layout Principles 195

Design of Seating 199

Office Design 205

Computer Workstations 205

Design of Tools and Equipment 214

Hands and Handedness: Some Initial Design Principles 214

Other Desired Properties of Grip Design 218

Other Features of Hand Tool Design 226

Techniques for Determining Hand Tool Adequacy 227

Power Tools 228

Power Transmission Hazards 230

Point of Operation Hazards 231

Protective Equipment for the Operator 234

Safety Shoes 234

Helmets 236

Protective Gloves 238

Eye Protection and Spectacles 239

Hearing Protection 240

Accommodating Handicapped People 240

Final Remarks 244

Discussion Questions and Exercises 244

CHAPTER 6 Methods Improvement and Motion

Analysis of Physical Tasks 247

About the Chapter 248

Contents vii

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Introduction 248

Methods Improvement 250

Principles of Motion Economy 251

Work-Physiology Related Principles 253

Motion and Micromotion Study 258

Biodynamics of Hand Motions 261

Speed-Accuracy Tradeoffs 262

Fitts’ Law 262

Eye-Hand Coordination 266

Some Principles of Manual Assembly 268

Manual Materials Handling 270

Principles of Lifting 274

Computer Tools for Analyzing Lifting Tasks 276

Ergonomic Support Belts 277

Grips and Grasps in Materials Handling 278

Handling Liquids and Powders 278

Carrying Methods 280

Equipment to Assist in Manual Materials Handling 281

Powered and Gravity Conveyors 283

Forklift Trucks 284

Wheelchairs 285

Final Remarks 285

Discussion Questions and Exercises 287

CHAPTER 7 Measurement of Human

Performance 289

About the Chapter 290

Introduction 290

Some Probabilistic Assumptions 292

Time Study 294

Performance Leveling 302

Determining Allowances 306

Machine Interference Allowances 309

Maintaining Standards 309

Indirect Performance Measurement 310

Criteria Other Than Time 311

Final Remarks 312

Discussion Questions and Exercises 312

CHAPTER 8 Predicting Human Performance 317

About the Chapter 318

Introduction 318

Synthetic Data Systems 319

Why Use a Synthetic Data System? 319

Motion-Time-Measurement (MTM) 320

Work-Factor System 329

Mento-Factor System 332

Standard Data Systems 335

Formula Development 336

Finding the Relationship among Predictive Variables

and Normal Performance 338

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Statistical Computer Packages for Regression 339

Cognitive Modeling 341

GOMS: Cognitive Work Measurement of a Skill-Based Task 349

NGOMSL 352

Final Remarks 356

Discussion Questions and Exercises 357

CHAPTER 9 Measurement of Learning

and Forgetting 361

About this Chapter 362

Introduction 362

Some Applications of Learning Curves 363

Modeling Human Learning 363

Why Use a Model of Learning? 364

Performance Criteria and Experience Units 364

Some Learning Curve Models 365

Powerform Learning Curve 366

Discrete Exponential Learning Curve 370

Fitting Learning Curves 373

The Powerform Model 373

The Discrete Exponential Model 374

Comparing Alternatives for Learnability 375

The Correct Learning Curve Model 376

Forgetting Curves 376

Final Comments 377

Discussion Questions and Exercises 378

CHAPTER 10 Sampling Methods in

Industrial Ergonomics 379

About this Chapter 380

Introduction 380

Activity Sampling 381

Sampling Procedures 382

Sampling Theory and Sample Size 384

Developing the Observation Schedule 387

Recording and Analyzing the Data 390

Checking for Stationarity 390

Using Work Sampling to Estimate Performance Standards 391

Using Work Sampling in Problem Solving 393

Sampling Strategies 394

Stratified Sampling 395

Sequential Bayesian Work Sampling 399

The Beta Distribution and Its Parameters 400

Bayesian Confidence Intervals 400

Finding Tabled Bayesian Confidence Intervals 401

Bayes’ Theorem and the Bayesian Concept 402

Managing a Bayesian Work Sampling Study 403

Poisson Activity Sampling 408

Final Comments 409

Discussion Questions and Exercises 409

Contents ix

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CHAPTER 11 Questionnaires and

Interviews 413

About the Chapter 414

Introduction 414

Questionnaire Design 415

Planning the Questionnaire 415

Sampling Procedure 416

Constructing the Questionnaire 417

Pilot Testing and Data Collection 423

Data Analysis 424

Interviews 430

Interviewing Methods 431

Interrater Consistency 434

Final Remarks 435

Discussion Questions and Exercises 436

CHAPTER 12 Simulation in Ergonomic

Design 439

About the Chapter 440

Introduction 440

Simulation Versus Other Methods in Ergonomics 441

Essential Elements of Computer Simulation 441

Higher-Level Computer Languages 442

Computer Simulation in Ergonomics 443

Verifying and Validating a Simulation Model 445

Cognitive Simulation 446

Production System Modeling of Cognitive Tasks 448

Temporal Simulation Using the Production System Model 448

Methods Analysis Using Production Systems 449

Operator-in-the-Loop Simulation 450

Training Simulators 452

Ground Vehicle Simulators 452

Simulation Fidelity 453

A Case Study in Operator-in-the-Loop Simulation 455

Other Operator-in-the-Loop Simulators 459

A Simulation Strategy 459

Design of Simulation Experiments 461

Analysis of Variance 461

General Experimental Designs and Their Features 462

Final Remarks 466

Discussion Questions and Exercises 466

CHAPTER 13 Design for Crew-Team

Operations 469

About the Chapter 470

Introduction 470

Sports Analogies and Work Teams 471

Crew-Team Design 471

A Model of Group Effectiveness 472

The Life Cycle of Teams and Crews 474

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Group Effects and Characteristics 474

Measuring Team-Crew Work Performance 475

Industrial Work Teams 476

Some Principles in Designing and Developing

Industrial-Service Teams or Crews 480

Simulating Industrial Crews 480

Research, Development, and Design Teams 482

Roles of Team-Crew Members and Productive Team Composition 483

Problems with the Serial Design Process 486

Communications Within Research, Development,

and Design Teams 487

Research, Development, and Design Team Effectiveness 488

Concurrent and Iterative Design 489

Some Observations from NASA 489

Final Remarks 490

Discussion Questions and Exercises 490

CHAPTER 14 Ergonomics in Maintenance

and Repair 493

About the Chapter 494

Introduction 494

System Reliability and Availability 495

Maintenance Programs 495

Assigning and Coordinating Maintenance Activities 496

Setting Maintenance Priorities and Standards 498

Maintenance Schedules 499

Storing and Delivering Technical Information as Needed 501

Tools, Component Parts, and Materials Delivery 502

Training for Maintenance and Repair 503

Record Keeping and Measurement of Maintenance

Program Effectiveness 504

Reducing Maintenance Effort 504

Fault Avoidance and Fault Tolerance 505

Detecting Faults or Malfunctions 507

Diagnostic Support 512

Verifying the Fault and the Correction 516

Design for Disassembly 517

Design of Fasteners and Tools 521

Work Envelopes 522

Final Remarks 525

Discussion Questions and Excercises 526

CHAPTER 15 Ergonomics of Product Quality

and Usability 529

About the Chapter 530

Introduction 530

Quality Management and Customer-Driven Design 532

QFD: A Framework for Quality Assessment and Improvement 534

Identifying Customer Requirements 539

Specifying Design Requirements 541

Rapid Prototyping and Testing 545

Contents xi

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Usability Analysis and Testing 547

Task Analytic Methods 547

Expert Evaluation 550

Customer Ratings and Preference Testing 552

Some Principles of Preference Testing 554

Typical Procedures in Usability Testing 556

Interviews and Post-Experimental Questionnaires 560

Designed Experiments 562

Independent Variables 562

Dependent Variables 563

Basic Experimental Designs 564

Final Remarks 566

Discussion Questions and Exercises 567

CHAPTER 16 Inspection and

Quality Control 569

About the Chapter 570

Introduction 570

Some Common Types of Inspection 572

Quality Assurance Inspections 572

Maintenance and Safety Inspections 573

Screening of People and Materials 573

Detection of Tampering 573

Human Inspection 574

Inspection Strategies 574

Viewing Time and Movement 575

Task Pacing and Time Pressure 576

Individual Differences 578

Illumination Levels 579

Visual Freedom and Other Issues 581

Signal Detection Theory (SDT) 582

Some Basic Elements of SDT 583

Application of SDT to Inspection 586

Nonparametric Extensions of SDT 588

Inspection Economics 591

Inspection Costs 591

Location of the Inspection Station 593

Learning and Quality Improvement 595

Improvement and Correction Strategies 595

Analysis and Improvement of Inspection Tasks 596

Deming’s Points for Continuous Improvement 597

Final Remarks 600

Discussion Questions and Exercises 600

CHAPTER 17 Macroergonomics of Occupational

Safety and Health 603

About this Chapter 604

Introduction 604

Some Historical Background 604

Safety and Health Achievements and Future Promises 606

Fundamental Concepts of Industrial Safety and Health 607

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Contemporary Occupational Health and Safety Management 608

Compliance with Standards and Codes 608

Accident Reporting and Statistics 609

Hazards and Control Measures 612

Fall and Impact Hazards 612

Hazards of Mechanical Injury 614

Vibration Hazards and Cumulative Trauma Disorders 615

Noise Hazards 616

Pressure Hazards 617

Electrical Hazards 618

Heat, Temperature, and Fire Hazards 620

Hazards of Toxic Materials 623

Warnings and Safety Programs 627

Final Remarks 628

Discussion Questions and Exercises 629

CHAPTER 18 Communication and

Display Design 631

About the Chapter 632

Introduction 632

Communication Theory 633

Information Transmission 634

The Rate of Information Transmission 637

Information Partitioning and Hypothesis Testing 640

Human Information Processing 643

Selective Attention 643

The Role of Working Memory 644

The Mode of Processing 647

Mappings and Population Stereotypes 649

Message Meaning and Comprehension 653

Decision Making 657

Display Design 658

Types of Displays 659

Principles of Display Design 660

Hazard Communication 673

Design Guidelines and Requirements 675

Developing Safety Information 679

Final Remarks 681

Discussion Questions and Excercises 682

CHAPTER 19 Ergonomics of Control 685

About this Chapter 686

Introduction 686

Control Systems 687

Manual Control 690

An Elementary Model of Manual Control 691

Tracking Tasks 691

The Human Controller 694

A Naive Theory of Adaptive Control 696

Positioning and Movement Time 702

Control Error Statistics 703

Contents xiii

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A More Ergonomic Way of Measuring Control Errors: Partial Means 705

Numerical Simulation of Control Activity 707

Design of Controls 709

Some General Design Principles for Controls 709

Principles for Better Control-Display Relationships 715

Fuzzy Control 718

Fuzzy Measurements 718

Fuzzy Logic 720

Examples of Fuzzy Control 721

Supervisory Control 724

Final Remarks 729

Discussion Questions and Exercises 730

CHAPTER 20 Decision Making

and Decision Support 733

About this Chapter 734

Introduction 734

Classical or Normative Decision Theory 736

Subjective Expected Utility (SEU) Theory 737

Multiattribute Utility Theory 740

Statistical (Bayesian) Inference 741

Behavioral Decision Theory 743

Human Judgment and Inference 748

Naturalistic Decision Theory 757

Levels of Task Performance 757

Recognition-Primed Decision Making 758

Shared Mental Models and Awareness 759

Models of Time Pressure and Stress 759

Group Decision Making 761

Ethics and Social Norms 761

Group Processes and Conflict 762

Group Conflict Resolution 763

Group Performance and Biases 764

Improving Group Decision Making 765

Decision Support 767

Debiasing or Aiding Human Judgment 768

Holistic Comparison 769

Decision Analysis 770

Preference Assessment 776

Computer-Based Decision Support 779

Group and Organizational Decision Support 783

Final Remarks 786

Discussion Questions and Exercises 787

CHAPTER 21 Personnel Selection, Placement,

and Training 789

About the Chapter 790

Introduction 790

Personnel Selection and Placement 792

Personnel Systems 794

Concepts of Ability Testing 796

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