Industrial Psychology and People Management
Section B: Ergonomics and Consumer Behaviour
Learning Unit 1: Introduction to Ergonomics and Human Factors (Chapter 21)
Asessment Criteria:
~ Define the concept Ergonomics.
~ Explain the purpose of Ergonomics and give examples of how systems can be improved.
~ Describe how Ergonomics can be implemented in system design.
~ Explain the purpose of Ergonomics.
~ Differentiate between human-machine systems and basic work system.
~ Describe the history of Ergonomics
~ Discuss the factors that influence the direction and growth of Ergonomics
• Define the Concept Ergonomics
What is Ergonomics?
- an applied scientific discipline that is concerned with how humans interact with the tools and equipment they use while performing tasks and other activities
- common focus: the interface between humans and equipment
* e.g controls, displays, other operating equipment >> interface: connection between entities; between a user and a machine
- primary interest: the activities that humans perform while working
- also concerned with:
* the physical and social environment in which the tasks and activities are performed
* how humans and machines interact with the environment
- originates from the Greek words “ergon” meaning work and “nomos” meaning rules or laws
* combined the words mean the study of work
- ergonomist: professional focusing on ergonomics
- the term human factors is synonymous with ergonomics
- figure: continuum of physical and cognitive demands on the human worker represented by a scale
>> continuum: a continuous series or whole; the ends/extremes of it are very differernt from each other
• Explain the purpose of Ergonomics
Ergonomists – What They Do
* Research on human capabilities and limitations
o discover the characteristics of human performance
o e.g. how much can an average worker lift?
* Design and engineering applications
o use the research findings to design better tools and work methods
• Identify the Key Historical Contributions to the Field of Ergonomics
Historical Overview
* As a field of study, it can be traced back to around 1945:
> role of Taylorism (scientific movement)
> emphasis on task planning, motion and time study, and worker efficiency
* Early 1900s:
> considerable effort was placed on selecting workers for a given job (FMJ) using psy-testing
* 1920s:
> Hawthorne studies drew attention to the importance of social factors in the workplace
> beginning of human relations research
* NB influence on growth in the use of machinery and mechanisation between 1900 and 1945:
> World War II forced nations to develop modern productions technologies to meet the demand for amunitions
> recognition of ergonomics as an emerging discipline crystallised around the end of World War II
* US (human factors):
> military as a catalyst in the growth of human factors/ergonomics in the US
> need to deal with the new problem of human-machine systems
* Europe (ergonomics):
> emphasis was on industrial work systems including equipment and workspace design
* Between 1980 to present:
> ergonomics/human factors continued to grow motivated by:
o advances in computer and automation technologies
o disasters highlighting critical importance of the human in human-machine systems
• Explain the Objectives and Applications of Ergonomics
- main objective: improve the performance of systems consisting of people and equipment
- referred to as human-machine systems
- ergonomics emphasizes human aspects such as comfort and safety and the interactions that occur between the human, equipment, and environment
Objectives
- better performace of human-machine systems in ergonomics means the following:
1 Greater ease of interaction between the user and the equipment
2 Avoidance of errors and mistakes by the user
3 Greater comfort and satisfaction in use of the equipment
4 Reduced stress and fatigue while using the equipment
5 Greater efficiency and productivity
6 Safer operation of the equipment
7 Avoid accidents and injuries
Application Areas
* Work system design
o the interaction between worker and the equipment used in the workplace
o objectives: safety, accident avoidance, related performace attributes >> attribute: a characteristic or quality of a thing
o includes: work environment factors such as lighting and noise levels
* Product design
o the design of products
o objectives: safety, comfort, user-friendly, mistake proof = greater customer satisfaction
o includes: avoidance of product liability lawsuits through ergonomics >> product liability lawsuit: involves injuries caused by a product that is defective in some way
• Explain the Purpose and Processes of Fitting the Job to the Person
Fitting the Person to the Job (FPJ)
* Considers worker’s physical and mental aptitudes in employment decisions >> aptitude: a natural ability to do something; suitability
o e.g. using worker size and strength as criteria for physical work
* Common philosophy prior to ergonomics
* FPJ is still important:
o physical endurance requirements for fire fighters
o educational requirements for technical positions
Fitting the Job to the Person (FJP)
* Opposite of FPJ
* Philosophy of ergonomics is FJP:
o designing the job so that any member of the work force can perform it
* Why the FJP philosophy has evolved:
o changes in worker skill requirements (e.g. are now higher and involves the operation of machinery and computers)
o demographic changes (e.g. more women in the workforce)
o social and political changes (e.g. equal opportunity laws)
• Explain the Basic Model in Ergonomics known as the Human-Machine System
Human-Machine System
- defined as the combination of humans and equipment interacting to achieve some desired result (purpose/function)
- can have multiple objectives:
> produce a product for profit and
> provide a safe and comfortable workplace
* System Categories
1 Manual systems - hand tool or nonpowered implement to perform an activity
2 Mechanical systems - powered equipment to accomplish some job
3 Automated systems - minimum human attention
* Block diagram model of the interactions in a human-machine system
- the human controls the machine operation
- the machine displays its actions
- the human senses the operation
processes the sensed info
performs actions on the machine controls that regulate its operation
- interactions occur between humans and machines
- interactions consist of a cycle of activities
- interactions occur in both a physical and social environment that may influence system performance
- boundaries define what components are included within the scope of the system
- for purposes of analysis and design
- separates the human-machine system from its environment
* System Components
1 the human
2 the equipment
3 the environment
Human Components
* Human senses
- to sense the operation
- vision, hearing, touch, taste, and smell
* Human brain
- for information processing
- thinking, planning, calculating, making decisions, solving problems
* Human effectors
- to take action
- fingers, hands, feet, and voice
Machine Components
* The Process
- function or operation performed by the human-machine system
- digging a hole, driving a car, writing a test, automatic chemical processes, searching the net
* Displays
- to observe the process
- direct observation for simple processes (e.g. digging a hole)
- artificial displays for complex processes (e.g. automatic chemical processes)
* Controls
- to actuate and regulate the process >> actuate: cause (a machine or device) to operate
- steering wheel, computer keyboard
Environmental Components
* Physical environment
- immediate area of the human-machine system separated from the system by a defined boundry
- location and surrounding lighting, noise, temperature, and humidity
* Social environment
- work serves a social function
- determined by co-workers and colleagues, immediate supervisors, organisational culture, work organisation
- work organisation: individual or team work, pace of work
Describe the Major Topic Areas in Ergonomics
Physical Ergonomics
* Physical exertion = manual labour
* How the human body functions during physical exertion
- physiology – vital processes carried out by living organisms and how their constituent tissues and cells function
* How physical dimensions of the body affect capabilities of worker
- anthropometry – physical dimensions of the human body such as height, reach, and weight
Cognitive Ergonomics
* Concerned with the capabilities of the human brain and sensory system while performing information processing activities
* Human cognitive processes include:
o sensory sytem - 5 senses activated by external stimuli (most input from sight and hearing)
o perception - aware of sensation and interpretation based on past experiences
o memory - working memory (tempory) & long-term memory (warehouse of knowledge and experiences)
o response selection and execution - what actions are needed
The Physical Work Environment
* Visual environment
- lighting levels and workplace design
* Auditory environment
- intensity and duration of noise
* Climate
- air temperature, humidity, air movement, and radiation
Occupational Safety and Health
* Occupational safety
- concerned with the avoidance of industrial accidents which are one-time events that cause injury or fatality
- understand how and why they occur and to take steps to prevent them
* Occupational health
- concerned with avoiding diseases and disorders caused by exposure to hazardous materials or conditions
- develop after prolonged periods of exposure
- may take years before symptoms reveal the onset of the malady >> malady: a disease or ailment
SUMMARY:
* OVERVIEW OF THE FIELD OF ERGONOMICS AND HUMAN FACTORS
INLCUDING ITS HISTORY
INCLUDING ITS MAIN TOPICAL AREAS
* OBJECTIVES AND APPLICATIONS OF ERGONOMICS
HOW THE FIELD HAS EVOLVED INTO AN NB AREA IN WORK DESIGN
THAT ATTEMPTS TO ADAPT THE TASK TO THE WORKER'S CAPABILITIES
* CONSIDER BASIC WORK SYSTEMS FROM AN ERGONOMICS VIEWPOINT
THE BASIC MODEL IN ERGONOMICS IS THE HUMAN-MACHINE SYSTEM
A COMBO OF HUMANS AND EQUIPMENT INTERACTING TO ACHIEVE SOME DESIRED RESULT
* TOPIC AREAS
PHYSICAL ERGONOMICS
COGNITIVE ERGONOMICS
THE PHYSICAL WORK ENVIRONMENT
OCCUPATIONAL HEALTH & SAFETY
,Learning Unit 2:
Cognitive Ergonomics: The Human Sensory System and Information Processing
(Chapter 23)
Asessment Criteria:
~ Demonstrate an understanding of Cognitive Ergonomics and the increased importance thereof
~ Describe the Human Sensory System and its components, in relation to Ergonomics and the design of work
~ Provide examples to illustrate the role of perception within human information processing
~ Distinguish between the different types of attention and explain the impact of each of these types on human work
~ Discuss human information processing in line with the memory systems an individual possesses
~ Illustrate the process of Response Selection and Execution as part of human information processing
~ Distinguish between the common cognitive task individuals encounter in cognitive work
~ Provide examples for work design by incorporating all underlying factors of human information processing
•Understand the Concept of Cognitive Ergonomics
The Block Diagram Model of the Interactions in a Human-Machine System (Fig 2 pg 346):
Cognitive Ergonomics: >> Sensory nervous system: part of the nervous system responsible for processing sensory
* Study of the capabilities and limitations information. A sensory system consists of sensory neurons, neural pathways, and parts of the
of the human brain and sensory system brain involved in sensory perception.
while performing activities
that have a significant information processing content.
* Examples: reading, writing, listening, speaking, thinking, learning, planning, designing, calculating, problem solving, diagnosing, decision making, computer interaction
* Why cognitive ergonomics is important?
>growth in the service industry sector in which work has high content of information processing and communication
>more use of mechanisation and automation
>increased use of technologically sophisticated equipment
•Understand and Describe each of the Components involved in the Human Sensory System
Human Information Processing Model:
Human Sensory System:
* Humans receive stimuli from sources of energy both external and internal to the body
* Receptors (the body’s sensory organs):
>Exteroceptors – sense external stimuli
- vision ~ 80% of human information input
- hearing ~ 15% to 19% of information input
- touch
- smell
- taste
>Proprioceptors – excited by internal stimuli >>Proprioceptor: a sensory receptor which receives stimuli from within the body, especially one that responds to position and
- muscles movement
- tendons
- joints
Vision:
* Most important of the five basic human senses
* Eye is stimulated by light
* Light: electromagnetic radiant energy that lies within the visible spectrum >> Electromagnetic energy: a form of energy that is reflected or emitted from
>Wavelengths between ~ 400 nm (blue-violet) and ~ 700 nm (red) objects in the form of electrical and magnetic waves that can travel through
space
* Human eye is stimulated by light:
>light passes through the cornea (the eyeball’s window) and is focused by the lens onto the retina at the back of the eyeball
>the retina consists of millions of light receptors
>the optic nerve transmits the image focused on the retina to the brain for interpretation
Visual Performance:
* Visual acuity >> Acuity: sharpness or keenness of thought, vision, or hearing
>capability to discriminate small objects or fine details >> Discriminate: recognize a distinction; differentiate
>depends on eye accommodation – capacity of the lens to make focusing adjustments >> Ophthalmologist: a specialist in the
>Snellen chart – test for visual acuity branch of medicine concerned with the
- used by ophthalmologists study and treatment of disorders and
- patient asked to identify letters as their sizes get smaller and smaller diseases of the eye
* Stereoscopic acuity
>capability to perceive depth in one’s field of vision
>enabled by the two eyes – each eye sees a slightly different view of the object
* Colour discrimination
>capability to distinguish colours
* Adaptation
>ability to adapt to changes in light levels
- dark adaptation - adapting from a bright environment to a dark one
- light adaptation - adapting from a dark environment to a light one (relatively quick)
Hearing:
* Process of perceiving sound >> Acoustic waves: is a longitudinal wave generated as a result of the
* The sensation that is stimulated by acoustic waves which are pressure oscillations in air vibration from any source (such as a machine).
* A simple sound-generating source produces a pure tone which is characterised by two physical attribut>> Sound waves: acoustic waves that can be heard by a normal
1 frequency (Hz) - perceived as the pitch of the sound human ear.
2 intensity (dB) - perceived as loudness >> A wave is something that propagates through a given medium.
>> An oscillation is anything that can be described as a repeating cycle.
dB Level of Various Sounds:
Threshold of hearing 0 dB
Soft whispering at 1 m (3 ft) 20 dB
Library environment 40 dB
Room air conditioner at 3 m (10 ft) 60 dB
Talking at 15 cm (6 in) 80 dB
Powered lawnmower at 1 m (3 ft) 100 dB
Jet engine at 60 m (200 ft) 120 dB
Jet engine at 30 m (100 ft) 140 dB
The Ear:
* It’s a transducer: a device that converts variations in a physical quantity, such as pressure or brightness, into an electrical signals or vice versa
* Basic function: transforms - the mechanical energy of sound waves - into electrical nerve signals - that are transmitted to the brain - for interpretation
* The ear consists of:
1 Outer ear = eardrum mechanically transmits sound vibration to middle ear
2 Middle ear = transmits and amplifies (20 times) vibrations to the inner ear
3 Inner ear = converts vibrations to neural impulses that are transmitted to brain
Auditory Performance:
* Humans with normal hearing can perceive sound frequencies (in the range 20 - 20 000 Hz)
* Low frequencies (below ~ 300 Hz) are not heard as well as high frequencies (in the range 1000 - 5000 Hz)
* The aging process takes its toll:
>perception of high frequencies decreases with age
>normal hearing loss due to aging is called presbycusis
Other Sensory Receptors:
* Tactile sense:
>sense of touch excited by receptors in the skin
>more general term is cutaneous sense which is stimulated by:
- pressure
- temperature
- pain
* Olfactory sense:
>sense of smell due to receptors in each nostril that are stimulated by vapor molecules in the air
* Sense of taste
•Sensation vs Perception
•Discuss the Essential Parts that are Underlying of Cognitive Ergonomics. These include: Perception, Attention, Memory, and Response Selection and Execution
Perception
* Human Information Processing Model:
* Stage of cognition in which the human becomes aware of the sensation caused by stimuli and interprets it in the light of his or her experience and knowledge
* Consists of two steps:
1 Detection - human becomes aware of the stimulus of interest which may be mixed with other stimuli
>Bottom-up processing
- stimulation of the senses by external sources
- human info processing responding to sight, sound, and other stimuli in the outside world
2 Recognition - human interprets the meaning of the stimulus and identifies it in the context of previous experience
>Top-down processing
- information processing activities of perception that are based on a human's knowledge, experiences, and expectations
- added dimension of our previous experience with similar or identical stimuli
* Perception is usually a combination of bottom up and top down processing
* Deficiencies in the actual stimulus during bottom up processing can often be compensated for during top down processing
Attention Resources
* Human Information Processing Model:
* Attention resources:
>Attention means keeping one’s mind on something
>Involves mental concentration and readiness for such concentration
>Types of attention:
1 selective attention
2 focused attention
3 divided attention
4 sustained attention
5 lack of attention, sometimes caused by boredom
* Selective attention:
>Refers to a situation in which a person needs to monitor multiple sources of information in order to perceive irregularities or opportunities
>Involves filtering out certain channels of information in order to focus on one channel that is deemed important
>Example: pilot checking gauges and looking for readings that might explain the airplane’s erratic behavior
>Person must select which channels to give attention to and which to ignore
>Factors that influence this selection process:
- expectancy - the person expects a certain channel to provide the information and pays more attention to it
- salience - stimulus that stands out among the other channels >> Salience: the salience of an item is the state or quality by which it
- value - if the channel is deemed important, more attention will be paid to it stands out from its neighbors.
* Focused attention:
>Refers to situations in which a person must cope with multiple input channels, but focus on only one channel for a sustained period of time
>Person pays attention to one stimulus and is not distracted by others ("noise")
>Examples:
- conversing with a friend in a crowded room full of people who are also talking
- reading a book in an airport lobby
- fighter pilot landing an airplane on the deck of an aircraft carrier during rough seas
>Factors affecting one’s ability to focus attention on one stimulus:
- proximity - distance of the stimulus source from the person trying to focus attention
- separation - refers to stimuli arriving from different directions
- easier to focus attention on a source directly in front of a person
- background noise (e.g. visual clutter, auditory noise) affects one’s ability to focus on a desired stimulus
* Divided attention:
>Refers to situations in which there are multiple stimuli, but multiple tasks must be performed together
>Examples:
- driving a car while talking on a cell phone with someone
- doing income tax return while watching television
- machine operator attending several machines in a machine cluster
* Sustained attention:
>Refers to situations in which a person must watch for a signal of interest over a relatively long period of time and it is important to avoid missing the signal
>Also known as vigilance
>Examples:
- inspector looking for defective products moving along a conveyor line
- radar operator monitoring a radar screen for incoming aircraft
* Lack of attention and boredom:
>Lack of attention - not concentrating on the task
>Usually caused by boredom - state of being weary and restless due to lack of interest
>Factors leading to boredom on the job:
- short cycle times
- low requirements for body movements
- warm environment
- lack of contact with other workers
- low motivation
- low lighting levels in workplace
Memory
* Human Information Processing Model:
* Three categories of memory in the model of human information processing:
* Sensory memory:
>Associated with the human sensory channels - mainly sight and hearing
>Operates autonomously >> Autonomously: with the freedom to act independently
- does not require attention resources
>Vision sensory memory called iconic storage
- only lasts ~ 1 second
>Hearing sensory memory called echoic storage
- lasts a few seconds
>Sensory memory data disappears unless encoded and processed in working memory
* Working memory:
>Attention resources are required to keep an information item active in working memory
>AKA short term memory
>Key performance factors in operation of working memory:
- Capacity = the number of images, sounds, and ideas that can be processed in working memory at one time is limited
- Time factor = the length of time that the information itemscan be kept active is also limited
- Attention resources = the amount of atten required depends of the amount of information chunks being processed
- Similarity = information chunks that are similar are more difficult to process and decay at a faster rate
* Long-term memory:
>Much of the information processed in working memory is transferred to and retrieved from long-term memory
>Information in long-term memory consists of semantic codes: >> Semantic: connected with the meanings of words
- individual items are given meaning and are organised into symbolic structures and associations
- the structures allow for new information to be added
>Model of Long-Term Memory:
>Types of long-term memory:
1 Semantic memory - used predominantly to store facts, figures, and other information related to
- general knowledge about the world
- specific knowledge about one’s work
2 Episodic memory - refers to memory of important events and episodes in one’s life
- example: memory of the death of a parent
Response Selection and Execution
* Human Information Processing Model:
* Response selection:
>Cognitive process of figuring out what actions to take in light of information:
- perceived through sensory channels (bottom-up processing) and
- information stored in long-term memory (top-down processing)
>Accomplished in working memory as a series of information-processing transformations:
- capability to perform these transformations is limited by the capacity of working memory as well as the time factor
* Response execution:
>Carrying out the actions determined in response selection
>Actions are usually executed by the human effectors (fingers, hands, feet, and voice)
>Actions can also be passive
- e.g. a person reading and the action is to continue reading
>Involves both cognitive and physical elements
- cognitive elements - coordinating the actions of the musculoskeletal system
- physical elements - expending the necessary strength and energy for the action
* Response selection and execution:
> Five factors that affect the difficulty and speed with which response selection and execution are carried out:
1 Decision Complexity
- the number of alternative responses that could be selected in response selection
- decision-making (deciding among several alternative courses of actions)
- as more choices become available, the complexity of the decision process increases and therefore the time to make the selection increases (reaction time)
2 Response Expectancy
- humans can process info they are expecting faster than info they are not expecting
- humans can select a response they expect to choose more quickly and accurately than one that is not expected
3 Compatibility
- compatibility and expectancy are closely related
- when a person must select a response, the possible actions must be consistent with ther person's expectations
- example: when flipping a switch on, we expect the light to be turned on
4 Speed-Accuracy Trade-off
- the faster a person selects a response, the more likely it is that an error will be made
- negative correlation between speed and accuracy
- need a proper balance between these two
5 Feedback
, - the feedback loop (in the model) allows a person to see/hear the effect of his/her actions
- provides verification and reinforcement of of the response action that was taken
- time delay between the response action and the feedback should be as small as possible to confirm if the response action had the desired affect
Make sure you understand each factor
* Skill-Rule-Knowledge (SRK) Model
>Identifies three types of behaviour in cognitive processing while performing various kinds of tasks:
1 Skill-based
- characteristic behaviour when a person has gained a high degree of familiarity and proficiency in a task
2 Rule-based
- characteristic behaviour when a person performs a task according to a set of rules or instructions
3 Knowledge-based
- characteristic behaviour when a person performs a task that requires a high degree of cognitive processing because the situation is unfamiliar
•Identify and Describe the Common Cognitive Tasks used to Carry Out Work
Common Cognitive Tasks:
* Decision making
>mental process in which a person makes a judgment to select one alternative over other possible alternatives in order to achieve some objective or satisfy some criteria
* Planning
>mental process of devising a detailed method for doing or making something
* Problem solving
>mental process in which a question or issue is considered and analysed to determine an appropriate answer or solution
Make sure you understand each task
•Provide Guidelines for Designing Systems Focused on Cognitive Work
Design Guidelines for Cognitive Work:
Make sure you understand these guidelines
* Guidelines for sensory reception and perception
* Guidelines for working memory
>Provide reminders for sequencial operations
- visual feedback to help operators remember which step they are working for work cycles with multiple steps
>Maintain congruence in written instructions
- instructions should be written in simple and easily understood sentences
- NB that the sequence of the instructions is the same as the order they must be carried out
* Guidelines for long-term memory
, Learning Unit 3:
The Physical Work Environment
(Chapter 24)
Asessment Criteria:
~ Discuss visibility as part of the visual environment and the factors affecting visibility and visual performance
~ Discuss the role of noise on human performance in the workplace
~ Provide examples of how noise can be controlled as a means to ensure optimal human performance
~ Describe the role of climate control in the work environment in relation to human performance
~ Distinguish between heat stress and cold stress and explain the impact it has on executing work
~ Provide guidelines for controlling both heat- and cold stress as part of climate control
The Block Diagram Model of the Interactions in a Human-Machine System (Fig 2 pg 346):
