262 Theme 1-5
Theme 1 - 3
Industrial psychology 262
Chapter 1: Introduction to
ergonomics
Theme 1: the difference between Ergonomics
and human factors
Definition
the scientific discipline concerned with the
understanding of the interactions among humans and
other elements of a system and the profession that
applies theory, principles, data, and methods to design
in order to optimise human well-being and overall
system performance.
Key words: it is a discipline concerned with the interaction of 3 main items
humans/ workers
machines / systems
the environment
Human factors:
Human factors refer to environmental, organisational and job factors, and
human and individual characteristics which influence behaviour at work in a
way which can affect health and safety.
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This definition is actually an aggregation of all 3 factors that potentially can affect health and
safety.
The difference between ergonomics and human factors
It is generally accepted that Ergonomics and Human Factors are synonymous and...the
historical difference was that ergonomics emphasised work physiology and anthropometry,
while human factors emphasised experimental psychology and systems engineering.
The two terms are usually used together as HFE to emphasize the broadest of the
discipline.
Sometimes referred to as engineering psychology. Problems come from human related
side of the entire system.
This helps us understand that:
→ The primary purpose of human factors and Ergonomics is design.
→this design refers to systems, systems components and products.
→ HFE, a systematic interdisciplinary approach is necessary for design and analysis systems
and products. { the products and systems are interlinked}
The Human factors and ergonomics field is multidisciplinary
Application
Socio-technical system design
·Optimise H. M.E interaction
·Avoid accidents, ensuring performance
· system reliability should increase
Product/systems components design
·Optimisation of H-M interactions
· User friendly
· comfortable
· Reliable/certainty
·safe l inbuild failure mode.
Fields include: Medicine, Aviation, Ships, Mining, Manufacturing, Automotive industry,
Education
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Examples of discipline domains:
A. MEDICINE
Cardiology
Neuroscience
Physical Medicine
B. PSYCHOLOGY
Organisational Psychology
Forensic Psychology
Health Psychology
HFE: a systems description
HFE problems requires scientific systems approach.
In HFE terms an organisation is technically referred to as a Human-MachineEnvironment (HME) System. (Book page 8-11)
The HME System has to achieve three fundamental goals:
Safety – It has become an outcome, especially in high risk industries like mining
Productivity
Satisfaction – e.g. health and safety, good social environment (Book of 4-5)
The HME goals are aligned with the ultimate goal of organizations- sustainability. Profit
has to be made in a sustainable way. They cannot be separated.
The HME goals are achieved through fitting the job to the person (FJP) – essentially the
objective of HFE (book of 5-6). The person needs to have the right qualifications to fit
the job.
You cannot fit a person into a job (scientific management).
Cannot fit a person to a job because jobs have become highly skilled, so highly skilled
individuals must be found.
Also need to be able to hire people from all sorts of diverse backgrounds because of moral
and legal requirements - keep in mind the labour relations act.
Historical scientific management approach – someone gets hurt in the workplace, they
have to be removed because you can't change the whole workplace to accommodate them.
People can be replaced the same way an equipment can be replaced.
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Fitting the job to the person is trying to move away from this e.g. if someone is injured at
work, we dismiss them and have to find a way to accommodate them from a moral point of
view. Can we create another job for them?
The basic human-machine-environment system
Human produces actions by using controls on a machine, the Machine Processing the input
information. Machine displays, Human Senses it and processes the information and the
process is repeated. So, it's an input output (e.g. work accomplished) process. This is the
system at a very basic level.
The HME System classification
1. Manual: involves a person using some effector tool (Hands, voice) or other nonpowered implement to perform an activity. Example Someone who is digging a trench.
Less Sophisticated. In terms of unit of analysis, we talking about 1 person 1 equipment
based.
2. Mechanical system:Refers to one or more humans using powered equipment to achieve
one or more system outcomes. The role of the human is “simply" to control for manage
the equipment. Example If you are operating a forklift, land movers or a loan mower.
3. Automated system: Involves a system performing (processing) and achieving one or
more system goals with minimum human (H) attention. The system is almost working on
its own, it’s also powered. Minimal human interaction (Programming the system,
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reloading the system, rebooting the system, the system needs to be installed and if it
fails, it needs human attention). Example Tesla was banned for including “full potential
autonomous driving" and “Autopilot inclusive" in its advertising materials.
The Huamn components
a. Human Senses: Basic gives human senses
b. Human Brain: As viewed/considered as a data and information processing unit (analogous
to the CPU of a computer)
c. Human effectors: a body part such as a muscle or group of muscles that actuates in
response to a stimuli.
Machine components
a. The Process: The function or the operation performed by the HME system
b.Displays: ranges form observing the process being preformed to artificial displays in
mechanised and/or automated processes in mechanized and/or automated processes.
c. Controls: Humans interact with the equipment using machine controls that can be operated
by human effectors. The complexity of the machine determines the relationship, including
distance, between controls and the HME process
Environmental components
Physical Environment: Includes the immediate area of the HME System, e.g. lighting,
noise, vibrations, air toxins. These environmental factors can affect the performance of the
human-machine system and are of interest to the ergonomist. For example, the workspace of
a fighter aircraft is its cockpit, which imposes severe limitations on the freedom of movement
of the pilot. The many controls of the aircraft must be located within easy reach of the pilot.
Social Environment: Primary Human to Human work interactions in a HME system are job
related but social interactions also occur. The social environment at work is overall shaped by
co-workers, superiors, organisational culture, the work (design) etc
During the scientific management era it was almost accepted that the more human interaction
that must happen in the work place must be for formal reasons, but now it has been accepted
that people are human beings first before they become employees so elements of social
interactions at informal levels must also be equally accepted in the organisation.
The broad human-machine-environment (HME) system
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7 elements : Harry Potter was somewhat helping Inform malfoy
H human characteristics
P physical environment
W work design
S socio-economic factors
H health and safety
I information presentation
M methods
A. HUMAN CHARACTERISTICS
- Psychological Aspects
- Physiological and anatomical
- Group factors
- Individual Differences
- Psychophysiological state variables
- Task-related factors
B. THE PHYSICAL ENVIRONMENT
- Illumination
- Noise
- Vibrations
- Climate
- Altitude, depth and Space
- Other environmental issues
C. WORK DESIGN AND ORGANISATION
Total system design
Hours of work
Job attitudes and satisfaction
Job design
Payment systems
Technological and ergonomic change
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D. SOCIO-ECONOMIC FACTORS
- Trade Unions
- Employment, job security and job sharing
- Productivity
- Women and work
- Organisational design
- Education
- Law
- Family and home life
- Quality of work life
- Politics and ethics
E. HEALTH AND SAFETY
- General health and safety
- Aetiology
- Injuries and illness
- Prevention
F. UNFORMATION PRESENTATION AND COMMUNICATION
Visual communication
Auditory and other communication modalities
Choice of media
Person-machine dialogue
System feedback
Error prevention and recovery
User control features
Language design
Software performance evaluation
G. METHODS AND TECHNIQUES
- Approaches and methods
- Techniques
- Measures
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The HME system summary
- An organisation (HME system) operates as an open system, I.e. it regularly exchanges
information with it’s external environment.
- An organisation is a complex system, I.e. there is high degree of systematic interdependence
among both the internal and external agents of the system.
-To provide effective HFE intervention (To improve the design and functioning of systems), a
scientific systems approach is required and all factors have to be interrogated.
HFE: Cost-benefit analysis of improvement in design
REMINDER: The HME system has to achieve three fundamental goals which are
aligned with the ultimate sustainability goal.
HFE interventions can be developed and applied to redesign systems to make them more
productive, safer and to ensure they promote human satisfaction.
Because improvements cost money, they have to be justified based on a scientific costbenefit analysis.
In a typical HFE system, the following improvements can be expected by following a
scientific approach:
Illumination level including special lighting for inspection
Job rotation and shift rotation (& overlap)
Sitting and standing (e.g. ergonomic chairs)
Communication systems
Material handling
Automation of routine and monotonous jobs
Metric to decimal conversion
Housekeeping
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Noise and vibration management
Ergonomics training
Production technique changes e.g. Continuous flow manufacturing
Specific Problems
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Chapter 2: Physical Ergonomics:
work Physiology and
anthropometry
Physical Ergonomics
• Many work activities require physical exertion/manual labor [to varying degrees].
This is quite common in the extracting industries, particularly in developed countries. E.g.
Agriculture, mining, oil industry, manufacturing.
Physical [Human-body-centered] ergonomics is [mostly] concerned with:
1. how the human body functions during physical exertion and;
2. how the physical dimensions of the body affect the capabilities of the worker
• The subfield is related [draws from] to the two sciences of human physiology and
anthropometry.
This theme is sub-divided into two parts:
1. Anthropometry and Work Posture
2. Muscular effort and Work Physiology
1) ANTHROPOMETRY AND WORK
POSTURE
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• Human variability
• Anthropometric variables and data
• Anthropometric design principles
• Procedure for Anthropometric Workstation Design
• Accommodation of Disability
• Sitting, Standing, and Sit-Standing (In terms of Posture)
• Work posture measurements
1.1 Anthropometry
Empirical science that is concerned with the physical measurement of the human
body such as height, range of joint movements, and weight The study of the
human body and how it is measured)
Anthropos = man; Metron = to measure.
Anthropometry→ Branch of anthropology that is concerned with the physical
dimensions and other data related to the human body, such as height, reach, and weight.
These two definitions both refer to the scientific study of the human body and how to
measure the different dimensions of the human body. To understand how human beings,
exert physical labour in terms of work or manual work.
1.1.1. Human Variability
Differences in body dimensions exist among people because of many different factors
including nationality, ethnicity, age, heredity, sex, living conditions, training...[Bk 35 -36]
Human variability is very critical in the design of systems and products in multinational
companies or cross-national businesses where different people from different countries have
to work the same machines in the same space, same uniform.
This represents a challenge because human variability needs to be accepted. When designing
something in the business, these factors need to be taken into consideration.
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Data is collected about different measurements for different genders, nationalities etc. This
data is then used by multiple organisations.
1.1.2 Anthropometric variables and data
Stature (height)
Standing height, vertical distance between
floor and highest part of head with subject
standing erect, feet together, and heels,
buttocks, shoulders, and back of head
against a vertical surface.
Eye height
Vertical distance between floor and inner
eye corner, with subject standing as in the
preceding.
Shoulder height
Elbow height
Vertical distance between floor and outer
upper point of the shoulder blade, with
subject standing as in the preceding.
Vertical distance between floor and lowest
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bony point of elbow, with upper arm
hanging freely and elbow flexed at 90
degrees, with subject standing as in the
preceding.
Sitting height
Sitting erect, vertical distance between
horizontal sitting surface and highest part of
head, with subject sitting against a vertical
Sitting eye height
Sitting shoulder height
surface, thighs fully supported and lower
legs hanging freely.
Vertical distance between horizontal sitting
surface and inner eye corner, with subject
sitting as in the preceding.
Shoulder breadth
Knee height
Vertical distance between horizontal sitting
surface and outer upper point of the
shoulder blade, with subject sitting as in the
preceding.
Horizontal distance between right and left
Hand length
Foot length
Head length
outer upper points of the shoulder blades.
Vertical distance between floor and upper
surface of thigh, with knees bent
90 degrees.
Distance between tip of middle finger and
most distal point of styloid process of radius
with hand outstretched.
Head breadth
Maximum distance between back of heel
Head circumference
and tip of longest toe.
~
Forward reach
Distance along a straight line between
glabella (smooth prominence on the
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forehead between the eyebrows) and
rearmost point of the skull.
Waist circumference
Body weight
Head breadth
Head circumference
Maximum breadth of head above ears.
Maximum circumference around head over
glabella (smooth prominence on the
forehead between the eyebrows) and
rearmost point of the skull.
Maximum distance between a vertical wall
Forward reach
against which subject presses shoulder
blades and grip axis of hand.
Waist circumference
Trunk circumference in region of navel.
Body weight
Subject standing still on weighing scale.
1.1.3 Anthropometric data characteristics
Anthropometric data are usually normally distributed within a homogeneous/ given
population with a known mean, percentile and standard deviation
Homogenous as in nationality, ethnicity etc.
Anthropometric measures are usually expressed as percentiles (Common ones are
5th, 50th and 95th percentiles)
1.1.4 Anthropometric design principles and applications
→ Design for Extreme individuals: developing a design that accommodates nearly all
individuals, either by designing for maximum or designing for minimum.
(You want to nearly cover everyone e.g. A door is designed to accommodate the tallest
person so it’s designed for maximum)
→ Design for Adjustability: design that accommodates a wide range of users’ anthropometric
variability. (The same equipment for everyone but the equipment should come with
adjustments e.g. Cars come with adjustable seats, there are
adjustable chairs in offices, computer monitors can be adjusted too)
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always
will
There some
↳2
people
no
2
in a
cartcomodated
→ Design for the Average User: when design for extremes and adjustability is inappropriate
and/or impossible. (e.g. Seats in football stadiums, checkout counters. 95 percentile
(extremes) will have to stoop low to reach the counter)
→Designing Different Sizes for Different Users: designing the same (usually product) in
different sizes. (e.g. shoes, clothing, chairs in elementary schools (Kindergarten))
1.1.5. Procedure for Anthropometric Workstation Design [not in
textbook]
If given a new workstation or you must redesign an existing one, what are the procedures that
have to be followed?
Step 1: Characterize the user population.
Whom are you accommodating?
What Anthropometric data is available?
Can existing Anthropometric data be used with the present population if there are no valid
data?
Consider creating a database by obtaining your own measures.
Step 2: Determine the percentile range to be accommodated in the workstation design.
Here it’s important to understand that you need to think about whether that particular
aspect for the system or workstation needs to accommodate the minimum or maximum or the
average user or everyone.
Its dominated by either men or women. It would make sense to design for the predominant
gender e.g. by using the 5th to 95th percentile male or 5th to 95th percentile female
measures.
On the other hand, it may also be an issue of gender equality. You have to design
accessibility to other genders even if it’s a minority. You cannot rule out. 5th percentile
female 95th percentile males.
Step 3: Determine reach (5th percentile) and clearance dimensions (95th percentile) for
the specific work situation.
Need to look at dynamic functions
Clearance is also important (under the table)
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Step 4: Find and/or develop the anthropometric measures that correspond to the
workstation measures.
Step 5: Simulate the redesigned workstation.
You need to simulate the workplace and see if it works.
Can operators reach for tools and parts.
Can they swing around?
Need to evaluate the dynamic aspects of the workplace appropriately
Basically, a mock workstation can be created based on the measurements and allow
people to simulate it to see if it works.
1.1.6. Accommodating the needs of disabled employees.
In most countries, the needs of the disabled (physically challenged) is recognized in and
regulated by the legislation (The Constitution, Employment Equity Act in SA).
The business case for a diverse workforce.
Corporate social responsibility (CSR) considerations.
Physical disabilities. Mental disabilities are something else.
The workplace has to fit the person, not the person fitting the job.
Someone who has a disability does not necessarily mean that they cannot do the job.
1.2. WORK POSTURE
1.2.1. Sitting, Standing and Sit-standing
→ Any workstation design should be related to the type of work to be done.
→ The type of work determines the work posture.
→There are three possible work postures (sitting, standing and sit-standing).
→It’s not about individual preferences.
→Depending on the task [not so much the employee preference], it is advantageous for an
operator to stand, sit, or sit-stand:
TASK
CHOICE 1
CHOICE 2
Handling and lifting of heavy projects
Standing
Sit-standing
Work below elbow height, e.g. packaging
Standing
Sit-standing
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Extended horizontal reaching
Standing
Sit-standing
Light assembly with repetitive movements
Sitting
Sit-standing
Fine manipulation and precision work
Sitting
Sit-standing
Visual inspection and monitoring
Sitting
Sit-standing
Frequent moving around
Sit-standing
Standing
1.2.2 The effect of work posture on employees
Poor body posture and forceful working methods can lead to permanent musculoskeletal
damage, and pain in various parts of the body.
Common complains are as follows:
Posture
Complaint
Standing
Feet, lower back
Sitting without lower back support
Lower back
Sitting without back support
Central back
Sitting without proper foot support
Knees,legs,lower back
Sitting with elbows on a high surface
Upper back, lower neck
Unsupported arms or arms reaching up
Shoulders, upper arms
Head bent back
Neck
Trunk bent forward
Lower back, central back
Cramped position
Muscles involved
Joint in extreme position
Joints involved
By knowing these aspects, you have a way of providing interventions.
e.g. if someone works by the nature of the job with elbows on a high surface and that
cannot be adjusted then you need to manage exposure time (The frequency at which they do
the job). You need to provide many breaks in between or vary the kind of work that they do.
So they cannot have a situation where for the greater part of the 8 hours of their day, they are
sitting with their elbows on a high surface. (Job rotation)
1.2.3 How to measure work posture
Subjective methods
These are reported by the employee through questionnaires or interviews. Might not be very
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accurate but that’s the method.
Body Part Discomfort Scale – Measuring of work posture and related discomfort as
reported by the employee which is usually related to the nature of the task and its duration
Questionnaires – Can be used to make before and after comparisons to demonstrate the
effectiveness of ergonomic improvements (the Swedish National Board of Occupational
Safety and Health Questionnaire)
OR to evaluate musculoskeletal problems (Nordic).
Questionnaire is normally used when you are planning on doing an improvement and you
want to know before the improvement what is the employees’ current level of comfort or
discomfort. Then we implement what we want to implement then evaluate after the
implementation by giving another questionnaire to see if there has been an improvement.
Objective methods
OWAS Method – OWAS is used to code work postures results of which can be used to
inform decisions on especially immediate workstation or task [re]design. This is when you
think there is a problem in the workstation, and you want to change it by deciding from an
objective point of view. You do the measurements around the employees yourself; you don’t
ask them personally.
RULA Method – The Rapid upper limb assessment (RULA) method evaluates postures
using numbers, the greater the number, the worse the posture. Values of force are then
estimated. Highly mathematical method. Used when you need more level of precision, but
particularly for the upper limb
The level of accuracy depends on whether you go for the subjective or objective method.
Objective methods are more expensive.
Objective methods are rarely used. They are used when you want to decide and there
is no room for error
General Assessment of work discomfort: Subjective method will be used.
2) HUMAN PHYSIOLOGY; MUSCULAR
EFFORT AND WORK PHYSIOLOGY
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Human Physiology:
Muscle activity and metabolism
Cardiovascular and respiratory system
Muscular efforts and Work Physiology (work capacity determinants)
Cardiovascular/respiratory Capacity and energy Expenditure
Muscle Strength and Endurance
Thermal Balance and Thermoregulation
MASCULAR EFFORTS AND WORK PHYSIOLOGY →
1.1. Background:
1. Heavy physical (manual) labor is very much part of the industrially developing countries
[IDCs] and no longer as common for developed countries (DCs).
2. Reasons:
a. low level of mechanization [including automation].
b. Developing countries do not have as much strength as developed countries
c. less structured work activities in developing countries - difficult to mechanize.
Therefore, manual labor stays central to how work is done.
d. Variability in common occupational health and safety (OHS) challenges experienced
by different regions (IDCs vs. DCs) based on the differences in work and work
activities. [On the bases of comparison between developed and developing
countries]
e. You do not often get serious injuries in developing countries, you’ll get them, but
they are more common.
Example: Working side by side with machines in Mining sector, oil rig sector or driving
trucks by transporting goods from one point to another, many accidents happen.
1.2. Human physiology: muscle activity and metabolism
[Page 17]
Body muscle contraction (Physiological condition of the muscle when it is activated by
movement or force that is applied) is enabled by the process of metabolism.
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Metabolism – The sum of the biochemical reactions that occur in the cells of a living
organism to (1) provide energy for the vital body processes and activities and,
(2) assimilate new organic material into the body.
TYPES OF METABOLISM:
a. Basalmetabolism:
• The minimal amount of energy the body requires when it is resting.
• Basically, the energy your body requires to sustain your circulatory and respiratory
system because they function while you are still sleeping.
“The body does not stop working even if you are sleeping.”
• We measure it in Basal metabolic rate – The rate at which the heart is given off
by an awake resting human in a warm location of at least 12 hours after eating.
Thus, it’s the rate at which chemical energy is converted into mechanical energy and
mechanical energy is measured by your heartbeat and all the other circulatory
activities with a bio/mechanical nature.
b. Activity metabolism - The energy associated with physical energy like working.
c. Digestive metabolism - Eating requires the process of digestion.
All three are involved in the conversion of chemical energy into mechanical energy, to
different degrees.
How we measure metabolism:
• Common HFE measure = kilocalories (kcal)
Metabolism rate (i.e. amount of energy per unit time (conversion rate) = kcal/min
• Alternative measure = Kilojoules (kj)
1 kcal = 4.2 Kj
• Energy producing value in food = kilocalories (or C)
• The rate depends on what you are doing.
• When you are sleeping Basal metabolic rate is very low. Digestive metabolism is quite low.
1.3. Human Physiology: Cardiovascular & respiratory
system
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The metabolic process is supported by two critical systems:
• The cardiovascular system – Heart, arteries, veins, and capillaries
• The respiratory system – Heart, lungs, nasal cavity, air passageway.
Respiratory system important for metabolism because it is the source of oxygen.
What we need to know: When the physical activity on the body increases due to
increased muscle contraction, the respiratory and the cardiovascular system must
work harder. [The 2 complement each other]
DETERMINANTS OF BODY ACTIVITY CAPACITY
Cardiovascular and respiratory systems’ capacity.
Rate of oxygen consumption/usage is proportionate to the heart rate, both of which
depend on the quantity of energy expended.
The amount of energy needed to convert chemical energy to mechanical energy depends
on the type of activity that you are doing which determines the amount of energy that
must be expected.
Different work activities (WA) require different expenditure rates [Book, Table 4 pg. 25]
The question becomes, what is your total daily energy requirements =??
Answer – It has to do with your daily basal metabolic rate, then the daily activity
metabolic rate, then daily digestive metabolic rate and they all differ.
Excess energy is stored as fat in your body. That is why you need to exercise. Cant go to
the gym without eating.
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Cardiovascular and respiratory systems’ capacity
NB: Understand the following:
Metabolic activity (oxygen uptake) does not increase immediately at the onset of work,
rather,
there is a gradual increase in oxygen uptake – for the first few minutes of work, the
muscles use energy that does not require oxygen – hence.
Oxygen debt - amount of oxygen required after the beginning of work, OVER and
ABOVE that which is supplied to the muscle by the circulatory system during the
activity. [You are borrowing oxygen from your body. The rate of depletion depends
on the rate that you’re borrowing]
[Book 26; Figure 3, pg.27]
Oxygen deficit is created at the beginning.
Graph does not start at the beginning because you are using oxygen at every moment,
even when you are not in action.
Heavy breathing starts where the graph is gradually increasing because of the high level
of oxygen.
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Blue section represents the amount of oxygen you need to repay to your body [EPOC].
Because the amount of oxygen consumption from outside through the respiratory system
is less than the usage very often, especially during activity.
Thus, you create another debt at the end of your activity and need to rest during the
EPOC period.
Oxygen debt must be repaid!
A worker cannot / must not work against maximum tempo and be in constant oxygen
debt state.
Excessive energy expenditure (& increased oxygen consumption) activates the anaerobic
process which results in the release of lactic acid in the body and consequently fatigue to
the muscles. It can lead to death if you do not rest.
Rest periods are required – regulated by the law (South African requirements?).
South African Law says: “A worker cannot work over 5 hours continuously without an
hour break per day”
2.2. Muscle Strength and Endurance
Apart from the energy expenditure in muscle operation, strength is also important in physical
work activities.
Strength – The maximum force that can be applied by the muscle or group of
muscles under specified conditions.
Two types:
2.2.1. Static strength – Measured by the human subject applying a high force against an
immovable object. Depends on strength of arms or legs.
2.2.2. Dynamic strength – Involves changes in joint angles and motion speed. It is affected by
the speed of the motion parting. Example: Those who play discus depend on dynamic
strength. [The motion capability of the body] How strong your body is in terms of lifting
objects.
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Factors affecting strength:
Age, gender, size, your physical condition (training is important here). Training improves
your strength.
Endurance – The capability to maintain an applied force over time. Unlike strength, this is
about how you can hold on to a force over a period of time.
Applies more to static force than dynamic force because dynamic force is more about speed.
Dynamic is quick.
2.3. Thermal balance and Thermoregulation
• Apart from the cardiovascular and respiratory systems as well as muscle strength and
endurance (& limitations), the capacity of the body to use energy and apply force also
depends on the ability of the body to maintain a proper thermal balance – [Book 32 - 34].
• Thermal balance – The ability of your body to maintain an equilibrium in terms of heat
exchange. Heat that you take in and which you lose. This is the thermoregulation system.
• The body maintains thermal balance through thermoregulation
• Thermoregulation is a complex system, that is involuntarily controlled by the central
nervous system, and that controls the body temperature within the narrow range of its core of
about 37 +/- 0.5 ̊C
• Central Nervous system controls your daily, minute by minute activities of your body. It is
linked to your brain, neurotransmitters.
• The body temperature does slightly deviate from the core within a given a day.
• Significant temperature deviation (increase or decrease) from the core causes
problems including death.
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To keep the body temperature within a narrow-regulated range (thermoregulation), the
amount of heat gained and lost by the body over the span of time must be equivalent
(thermal balance)
The thermal balance of the body can be expressed in the following thermal balance
equation:
Significant temperature deviation (increase or decrease) from the core causes problems
including death. [Risk Temperatures]
• Body temperatures above 38 ̊C tend to reduce physiological performance
• Temperatures above 40 ̊C tend to be disabling
• Temperatures above 42 ̊C are likely to cause death
• Below about 35 ̊C, central nervous system coordination is reduced (apathetic state)
• Below 32 ̊C, the muscles become rigid (loss of consciousness)
•Below 30 ̊C but over 27 ̊C, severe cardiovascular stress
• 27 ̊C and below, death! (The body seizes)
Heat Stress [hyperthermia]
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- Occurs when the body fails to cope with increases in ambient temperature (The
objective temperature from outside) through thermoregulation processes resulting in the body
core temperature rising to 39oC ≥
The body is designed to adapt when faced with high or too low ambient temperature. But
sometimes it can not cope.
• Symptoms of hyperthermia include weak pulse, pale skin, etc.
• Various prevention and treatment methods
There are two types of temperatures:
Experiential Temperature: How you feel the temperature as an individual.
Example: When you are in a room someone might say it’s cold, but another person is
saying its fine.
Ambient temperature: Objective one measured by different tools.
3. PHYSICAL ERGONOMICS: PHYSICAL
WORKLOAD AND
THERMOREGULATION
Thermal balance and thermoregulation
Cold Stress [hypothermia] occurs when the body fails to cope with decreases in ambient
temperature through thermoregulation resulting in the body core temperature falling to
≥36oC. [Opposite of heat stress]
If Ambient temperature continues to decrease the body tries to help you by shivering.
• Symptoms include droziness, confusion, passive, pale skin, weak pulse, nausea, etc.
• Various prevention and treatment methods
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Chapter 3: Cognitive ergonomics
Cognitive human factors and ergonomics
Apart from physical elements, most work activities also include cognitive elements –
Human activities with a high cognitive component include thinking, reading, speaking,
learning, problem solving and decision making...or interaction with a computer.
Cognitive ergonomics is concerned with the capabilities and limitations of the
human brain and sensory system while performing activities that include a
significant amount of information processing – it considers how the human brain
receives information from the environment, processes that information, and
determines appropriate responses and actions.
Emphasis on significant amount of information processing because any work anyway
requires some cognitive application to some degree example: If you are digging a trench you
still need to apply a bit of some planning thinking here, but we are mainly focusing on the
kind of work where there is a significant amount of that planning decision making.
Cognitive HFE has become increasingly important relative to physical HFE because of
several trends in industry and technology, including:
Growth in the service industry sector of the economy relative to the manufacturing sector.
[especially in developed counties]
Increased use of mechanization and automation in physical tasks previously performed
manually.
Increased use of technologically sophisticated equipment.
These are what has brought industry and the scientific world of cognitive factors closer
to
each other.
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1.1 Information theory
This is one of the foundational theories or the bases of the cognitive human factors and
ergonomics which has its basic argument on the complexity that we face on the daily basis in
the contemporary world in terms of the amount of information that we have to deal with on a
daily basis and that includes both at industry level or household level. We are basically
bombarded with computers, new technology, new appliances etc.
One major problem with the design of information processing-based systems such as
computers is that there is often too much information, either displayed or required to
perform the machine controls.
Generally, the amount of information in a stimulus depends on the probability that the
stimulus carries relevant information – Shannon and Weaver 1949 - Information theory.
1.2. HUMAN INFORMATION PROCESSING
The human cognitive processes include the following components:
• Sensory system (sensation) – consists of the five senses
• Perception – follows the sensing of the external stimuli
• Memory – consists of working and long-term memory
• Response selection and execution – involves figuring out relevant action based on
perception and memory.
A model of human information processing
The human sensory system ( sensation)
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The body receives external stimuli via sensory organs (exteroceptors) associated with the
five human senses.
The two most important exteroceptors are the eyes (80% of human information input) and
ears (15 -19% of human information input)
The human sensory system ( vision-light)
The eye is stimulated by light.
Light is the region in the electromagnetic spectrum that can be perceived by human
vision (the visible spectrum) which ranges from 380-780nm.
The entire electromagnetic spectrum consists of other waves of radiant energy, including
cosmic rays, gamma rays, and X-rays, ultraviolet rays, infrared rays, FM, TV and radio
broadcast rays.
Human beings see between violet to red on the electromagnetic radiation spectrum from
400 to 700 nanometres.
We see more compared to other animals. Example Bees see a lot more violet than
red and we see more red than violet. Dogs do not see red.
Visual performance is a function of various factors.
factors related to human visual physiology (& variability)
Visual acuity - capability to discriminate small objects or fine details.
Colour discrimination – colour sensitivity/ability to distinguish colours.
Monochromatism
Dichromatism
Adaption- ability to adapt to changes in light levels
Factors related to the light [theme 5].
Factors related to the environment [theme 5].
1.2.3 The human sensory system (hearing-sound)
Hearing is the process of receiving sound.
Sound waves typically originate from vibrating elements such as vibrating strings
(human vocal cords).
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The vibrating element creates disturbances by alternately compressing the surrounding
air on a forward movement and expanding it on a backward movement.
The disturbances then travel outward from the source as [sound] waves.
Auditory performance is a function of various factors:
Factors related to human hearing physiology (& variability):
• Presbycusis
• Sociocusis
• Nosocusis
Factors related to the sound [theme 5].
Factors related to the environment [theme 5]
1.2.4 Perception
Perception is that stage of the cognitive process where humans become aware of
sensation. They become aware of stimuli from the external environment and interprets it
within the context of their own experience or knowledge leading to variability amongst
different people.
“Variability” - We see the same thing but we make totally different interpretations of
what we are sensing.
Perception follows the sensing of some external stimuli by the human sensory system.
Perception refers to the stage of cognition in which the human becomes aware of the
sensation caused by the stimuli and interprets it in the light of his or her experience and
knowledge.
Perception has two components.
1. Detection (becoming aware). It comes immediately after sensation.
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2. Recognition (interpreting the meaning of the stimulus). Comes from experienced
knowledge (motivation)
1.2.5 Sensation and perception- holistic understanding
They cannot be separated
General basic concepts
Absolute Threshold
Differential threshold (Just noticeable difference)
Signal detection theory
Sensory Adaptation
Situational Awareness
Visual sensation and perception
• Perceiving forms, patterns, and objects
• Perceptual constancies in vision
• Misleading cues: optical illusions
1.2.6. Sensation and perception – General concepts
Absolute Threshold
This is based on the least amount of a stimuli. The least pint of a stimuli when it
becomes detectable. (The threshold when a stimulus begins to become detectable)
The first second/minute you detect a stimulus is your absolute threshold.
Sensation begins with a stimulus (i.e. any detectable input from the environment).
What counts as detectable depends on who is doing the detecting and what is being
detected.
A threshold is a dividing point between energy levels that do and do not have a
detectable effect.
Absolute threshold (for a specific stimulus) is the minimum amount of stimulation that
an organism can detect.
Example: A candle flame seen at 30 miles on dark clear night .
The Just noticeable difference (JND)
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Also known as differential threshold.
A just noticeable difference is the smallest difference in the amount of stimulation that a
specific sense can detect.
This is about when we change something the moment that point/threshold where the
change can be detected is basically the aspect of differential threshold.
Example: In consumer behaviour, a change in price will be set just bellow the JND
Signal detection theory (SDT)
Is related to sustained attention.
The theory proposes that detection of stimuli involves decision processes, which are
both influenced by a variety of factors besides the stimulus intensity. The SDT attempts
to account for the influence of decision-making processes on stimulus detection.
Example:
When monitoring a radar, looking for signs of possible enemy aircraft, there are four
possible outcomes: Hits, Misses, False alarms, Correct rejections.
If you are observing something and you miss it even if that something is there, what could
possibly explain this is the idea of signal detection theory
Sensory Adaptation
Sensory adaptation is the gradual decline in sensitivity to prolonged stimulation.
E.g. If you are in an environment which is very noisy, along the way you might not end
up picking up the noise (You get used to it/ you won’t notice it anymore)
Problem results in lack of sensory adaptation.
Situational Awarenes.
Refers to an individual’s ‘perception of the elements in the environment within the
volume of time and space, the comprehension of their meaning, and the projection of
their status in the near future’
Involves continuously monitoring what is happening in the task environment to
understand what is going on and what might happen in the next minutes or hours.
Example: When you are driving and approaching traffic lights the fact that you do not
proceed or rather proceed with caution is based on the fact that you are fully conscious. (You
are perceiving what could possibly happen).
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Situational awareness and concentration are diminished by fatigue and stress and can be
affected by interruptions and distractions.
1.2.7. Sensation and perception – Visual perception
a) Perceiving Forms, Patterns, and Objects
Reversible figure – A drawing with two different interpretations that can shift back and forth.
Such drawings that demonstrate that the same visual input can result in radically different
perceptions, reason why people’s interpretation of the world (& reaction) is subjective.
b) Perceiving Forms, Patterns, and Objects
Gestalt principles – A series of principles that helps to demonstrates that the whole can be
greater than the sum of its parts. The series of principles describe how the visual system
organises a scene into discrete forms. [You rely on your memory and experience to interpret
things no matter what order they are presented to you]
Some of the principles include:
Figure and ground – The tendency to perceive objects or figures as existing on a
background.
Proximity – The tendency to perceive objects that are close to one another as part of the
same grouping.
Similarity – The tendency to perceive things that look similar as being part of the same
group.
Continuity – The tendency to follow in whatever direction one has been led OR
perceive things as simple as possible with a continuous pattern rather than with a
complex, broken-up pattern.
Simplicity – The tendency to group elements that combine to form a ‘good’ figure (the
simplest possible figure)
Common fate - The tendency to group together things that move together.
Closure - The tendency to create a sense of closure or completeness, even when there
are notable gaps.
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Perceptual constancies
A perceptual constancy is a tendency to experience a stable perception in the face of
continually changing sensory input. It can be size or shape constancy [perceiving things as
stable even when they are changing]
Misleading cues: optical illusions
An optical illusion involves an apparently inexplicable discrepancy between the appearance
of a visual stimulus and its physical reality. It’s important since you tend to see things that
are not there. A trick of sensation and perception.
1.2.8 Attention resources
→ Attention resources occupy an important position in the human information processing
model
→Attention means keeping one’s mind on something. It involves mental concentration and
the readiness for such concentration
There are different types of attention in HFE:
→Selective attention - Refers to a situation in which a person is required to monitor multiple
sources of information to perceive irregularities or opportunities. It involves filtering out
certain channels of information that are at least temporarily extraneous to focus on the
important channel. E.g. Driving a car in general.
→ Focused attention – Similar to selective attention in that tasks force the individual to cope
with multiple input channels, but here the person must focus only on one channel for a
sustained period of time and exclude all the other stimuli. E.g. Driving
on a mountain pass with someone in the passenger seat.
→ Divided attention – Here there are again multiple stimuli present, but multiple tasks
must be performed together [not necessarily simultaneously]
Improving divided attention:
1. Minimise the number of input channels.
2. Reduce the level of difficulty of the tasks.
3. Reduce the similarity of the tasks in terms of demands on input channels, mental
processing, and output requirements.
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Sustained attention – Also known as vigilance. Involves a situation in which an
individual must watch for a signal of interest over a relatively long period of time, and it
is important not to miss the signal.
Improving performance in tasks requiring sustained attention:
1. Rotate workers.
2. Increase the intensity of the incoming signal.
3. Provide periodic feedback.
4. Emphasise the importance of the consequences of misses.
5. Provide the optimal environmental conditions.
Lack of attention – Means not concentrating on the task. Usually caused by boredom and
results in a diminished state of readiness to perform the task.
Possible causes of boredom:
1. Short cycle timed tasks.
2. Low requirements for body movement.
3. Warm environments.
4. Lack of social interaction.
5. Low motivation.
6. Power environmental conditions, especially poor lighting.
1.2.9 Memory
Sensory memory: It is associated with the human sensory channels mainly sight and hearing.
Represents a very short-term (1 sec to few seconds) storage unit that retains a representation
of the stimulus after the actual stimulus stops.
Working memory: Temporary storage that holds a limited amount of information from
sensory memory, while it is being processed (Equivalence of a CPU/phone RAM)
Has three components: Central executive (Controls the two), visuospatial sketchpad, and the
phonological loop (where you store your verbal and acoustic information).
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Aspects of Working memory:
1. Its Capacity. (Your working memory can only take a certain amount of information.
Can’t hold +/- 7 chunks)
2. The time factors.
3. The role of attention Resources.
4. Similarityofinformation.
Long term memory - Is the warehouse for all the retained knowledge and experiences that
have been accumulated over one’s lifetime (equivalence to internal CPU/phone storage).
Semantic [Where you store facts especially in work e.g. These concepts are arranged in
themes to make it easy to retain] (e.g. semantic network model) VS. Episodic memory
models [About life events, no need to arrange in any order. They are known immediately].
Determinants of information retrieval from long term memory depends on the strength of the
item, and association with other items in the same memory.
Strength depends on:
Frequency with which the item is used. [First time you meet someone, you forget their
name. Unless you interact with the person a lot, that’s how you will remember]
Attention
Recency.
1.2.10. Response selection and execution
Response selection:
Is the cognitive process of figuring out what actions to take, if any, in the light of
information perceived through the sensory channels and information stored in the longterm memory
Action, if deemed necessarily, may take several forms ranging from walking, talking,
moving hands or both and is usually executed by human effectors (fingers, feet or voice)
Response execution:
Carrying out the action. Involves both cognitive (action coordination) and physical
elements (expending energy & strength into an action).
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Factors affecting response selection and execution:
1. Decision complexity – The number of possible alternative responses.
2. Response expectancy – Expected information is processed faster than
unexpected information.
3. Compatibility–Therelationshipbetweenstimulusandtheexpectedconsequence
of a given response to that stimulus.
4. Speed-Accuracy Trade-Off – Propensity for error is mostly positively related to
speed.
5. Feedback – Allows a person to see and/or hear the effect of his/her actions.
2- CONGNITIVE HFE APPLICATIONS: CONTROLS
AND DISPLAYS
Focus of the rest of the theme [Part 2] will be on explaining the design related issues based
on the understanding of cognitive human factors and ergonomics theory. Specific focus will
mainly be on Controls and Displays.
2.1. DISPLAYS
Human, custom made presentation of information used when direct perception is not
possible/to communicate. Why? If direct perception is not possible/to communicate. Displays
aids in interpretation.
REASON FOR DISPLAYS
• Stimuli is at or below threshold values and needs to be amplified.
• Stimuli needs to be sensed with greater precision that people can discriminate.
• Information about events /circumstances by it’s nature require some display.
PRINCIPLES OF DISPLAY DESIGN
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1. Make displays legible
2. Avoid absolute. judgement limits
3. Top-down processing
4. Redundancy gain
5. Discriminability
6. Pictorialrealism
7. Moving part principle
8. Minimise information access cost
9. Proximity compatibility principle
10.Principle of multiple resources
11.Replace memory with visual
information
12.Principle of predictive aiding
13.Principle of consistency
1. Make displays legible – Relates to contrast, visual angle, illumination, noise, masking
etc. Displays must do what they are supposed to do.
2. Avoid absolute judgement limits – Operator should not be expected to make a precision
decision from too many possible levels (Colour, size, loudness)
3. Top down processing – A display should conform to expectations, based on mental
model or immediate context. Do not design something that doesn’t work according to
how people expected it to work.
4. Redundancy gain – Display message is more likely to be perceived correctly if expressed
more than once in alternative forms. Position matters too.
5. Discriminability – Similar appearing signals likely to be confused immediately [during
perception] or later [during retrieval]. E.g. Traffic light (good because it has three
completely different colours)
6. Pictorial realism – A display should look like the variable that it presents.
7. Moving part- Moving element(s) of dynamic information displays should be compatible
with the user’s mental model of how the represented element moves in
the physical system.
3
Only these 7 are applicapble
INFORMATION TYPES
1. Quantitative
Display presentations that reflect the quantitative value of some variable. This is used
when more precision is needed.
2. Qualitative
Display presentations that reflect the approximate...
a. value
b. trend
c. rate of change
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d. direction of change
e. Other aspect of changing variable
A warning sign is an example of a qualitative variable
3. Status
Display presentations that reflect the condition or status of a system. Stop and go signs.
4. Warning / signal
Display presentations used to indicate emergency or unsafe conditions.
5. Representational
Pictorial or graphic representations of objects, areas, or other configurations.
6. Alpha numerical and symbolic
Display presentations of verbal, numerical, and related coded information in many
forms.
E.g. music notes, excel formulas [you need knowledge and experience to interpret them
properly]
7. Identification
Display presentations used to identify some static condition, situation, or object.
8. Time-phased
Task, resource, or assignment information that is distributed over time. For example, a
Morse code [is a method of transmitting text information as a series of on-off tones,
lights, or clicks that can be directly understood by a skilled listener or observer without
special equipment]
The different types are not mutually exclusive [One display can only have 1 information
type]
2.2 Controls
Facilitates the transmission of user’s ideas or decisions to machines / mechanism / system.
TYPES OF CONTROLS
1. Activation: Activation of a certain status of a system / machine, example light switch.
2. Discretesettings:Separatepre-existingpositions,examplecarradiowithpre-set channels.
Speaker and TV channel remote (cannot create your own channel)
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3. Continuous settings: Finer, in between settings, radio volume tuner, water pressure from
tap.
4. Continuouscontrol:controlrequirescontinuouscontrol,examplesteeringwheel.
Predominant to manual systems e.g. a car.
5. Data entry: controls used to input data into system, example keyboard.
6. Tools: Examples hammer, drill, cutlery.
DESIGN (CODING) PRINCIPLES
1. Position/location: use a standard location and provide sufficient spacing, placed well
within reach
2. Shape: especially important where vision is unreliable, e.g. gear levers of a automobile
3. Size: especially important where vision is restricted. Size difference must allow
discrimination
4. Colour – it’s important to limit the categories of colours - 5 colours max. is
recommended
5. Labels-mustbevisibleandcomplementanothercoding.Operatormustbeliterate to them.
6. Grouping – controls that relate to same function should be grouped together
7. Controls – display proximity – Controls should be as close as possible to the
display/response they control. Complex machines are an exception – related to the
control-response compatibility theory [below].
8. Control movement stereotypes
People have expectations (trained stereotypes) of what to do with controls to activate them.
Control design should take these stereotypes into consideration.
9. Control-response compatibility
The problem with the design of most machines/systems, e.g. the electric stove, is that
there is usually no clear control-response compatibility, i.e. there is no one-to-one
relationship between the controls (knobs) and the responses (burners).
COMMON COGNITIVE TASKS
Overall (considering everything you have learned at this point), cognitive work and tasks
typically involves the following three information-processing tasks:
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It involves, planning, designing, problem solving, troubleshooting. You can’t disentangle the
three completely.
1. Decision making: The cognitive operation which involves making a judgment to select,
from several alternatives, one alternative to achieve some objective or satisfy some
criteria.
a. There are circumstances where decisions must be made. There has to be different
alternatives to choose from. The time frame which the decision has to be made is
relatively long, this is a distinction that needs to be made and this distinction is
important because it makes decision making slightly different from choice reaction
(This is where judgment has to be made very quickly in a spontaneous way)
b. We try to move from choice reaction.
c. To decide whether a decision is good, bad, optimal, sub-optimal, correct, or
incorrect, the decision needs to be made and implemented first. And then compare
the outcome to other outcomes of decisions that have not been made.
d. In human factors and Ergonomics, the main interest is to understand decision
making from a human information processing point of view. This will increase the
probability of people making good, correct, and optimal decisions
i. Decision is different to choose reaction
ii. Decision making Models
1. Rational Decision Making
a. Sometimes called a normative decision making because these are
decisions that are made in a way which takes consideration what ought
to be achieved.
b. They take a quantitative process to arrive at decisions.
c. They are rooted in economics, measurement, statistics.
d. “You take a conscious effort to play lotto or to invest in
something and that decision is then weighed against facts”
e. To people making rational decisions will arrive at the same
f. outcome.
2. Descriptive Decision Making
a. This is a situation where choices are made in a cognitive and
behavioural sense. You make decisions based on heuristics, you do not
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have to calculate everything to the detail or using statistical models.
(Simplifications)
b. Used when we are bombarded with a lot of information.
c. You need to open to being vulnerable by going for descriptive decision
making.
d. You’re making decisions on the rule of thumb. You do not have time to
make rational decisions.
e. Gut feelings.People make bad decisions because they have no
experience.
f. There is no way of knowing if two people making descriptive
decisions will arrive at the same outcome or conclusion.
There are several possible ways of making those decisions [heuristics that people use in
decision making]:
1. Satisfying heuristics
a. The decision maker considers a series of options until one is found that is
satisfactory.
b. That alternative is then selected because finding a better alternative is not worth the
additional effort.
c. The term satisfying is derived from “satisfactory decision,”.
d. Given the limitations of working memory, and perhaps the need to make a decision
within limited time frame, satisficing is a practical and reasonable way for people to
make decisions.
2. Anchoring heuristics
a. People tend to give more weight to information obtained early in the decisionmaking process.
b. This the final decision is influenced more by early information that anchors the
process than by information obtained subsequently.
3. Availability heuristics
a. People are more likely to retrieve from long-term memory a hypothesis that has
been used recently or frequently.
b. It is readily available and
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c. The first thing that comes to mind and is therefore assumed to be a
reasonable hypothesis for making a decision or solving a problem.
4. Representative heuristics
a. Here, a person makes a decision about a given entity because it appears to fit the
mind’s prototype of that entity.
b. The entity is representative of the prototype.
For example: If we are asked to decide if a certain individual (whom we do not know) is
a constructive worker or a librarian, our decision would be influenced by the person’s
appearance relative to how we perceive the appearance of a construction worker and a
librarian.
The two decision making models are equally plausible and equally used.
Planning: The mental process of devising a detailed method for doing or making something.
It is related to decision making, the two are related in a way. This is something that is
developed before a decision is made.
Planning is accomplished using two processes:
Script based – Where you develop something based on previous experience that is saved
in the long-term memory. Planning here is based on recalling. There can be different
aspects of the plan, but the outcome needs to remain the same as past experiences.
Mental simulation – Mentally developing steps in the method and imagining what the
possible outcome would be if you follow the steps.
The importance of planning aids:
Because both processes rely more on your working memory, it then makes sense that you
need additional aids or assistance to do mental planning or mental simulation. And
everything cannot be kept as a mental note, so things are then put on paper.
3. Problem solving involves the (or a combination of calculation, brainstorming, analysis,
diagnosis, evaluation of alternatives...in solving a problem. Depending on how sophisticated
the problem is.
There are two processes that are generally involved with problem solving:
Diagnosis – The identification of the cause of a problem, but not necessarily attempting
to resolve it. Which then naturally leads to troubleshooting.
Troubleshooting – Goes beyond identification of the cause of the problem by trying to
repair or correcting the problem.
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Problems take place in different context, this could be physical context, psychosocial context,
or technical context. Therefore, Diagnosis or troubleshooting is ought to be done within a
particular context.
The context are not mutually exclusive
These two are not necessarily done one after the other, they can overlap.
Relies on Skills, Rules and Knowledge (or a combination of) depending on the task
(S5.2; p.68).
Highlight: There are certain situations or problems which requires more skills, more than
applications of rules or knowledge. Hence, it is more about the nature of the work itself
and the person doing it.
The Skill-Rule-Knowledge Model was first proposed by Rasmussen in 1983 and is widely
cited in the ergonomics and human factors literature.
The three categories refer to types of cognitive processing that are performed in executing
various kinds of tasks and takes into account the level of experience possessed by the person
performing a given task.
Skill-based and rule-based behaviour tend to be routine. Knowledge-based behaviour tend to
be non-routine.
Skill-based behaviour – Occurs when a person has gained a high degree of familiarity and
proficiency in a task (or other activity), to the point where the task can be performed
automatically and subconsciously.
It uses significant manual content.
Attention resources required for activities are minimal because the motion pattern is
automatic.
Examples: walking, riding a bicycle, performing a repetitive one-minute work cycle on an
assembly line, and loading and unloading a production machine that operates on a
semiautomatic cycle and produces the same part over and over.
Rule-based behaviour - Occurs when a person performs a task according to a set of rules or
instruction.
Greater demands are made on attention resources because the rules or guidelines must be
consciously followed.
When a person is learning a new task but has not yet mastered it, his or her actions tend to
be guided by rule-based behaviour.
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Examples:
Following a check list when starting up a chemical process
setting up a fixture on a milling machine
performing blood tests in a medical clinic
following a recipe to prepare a dessert
and performing a new repetitive task according to the
recommended procedure.
Once the task has been fully learned, the behaviour transitions from rule-based to skill based.
Knowledge-based problem solving – This is the problem solving at the highest level of
difficulty which cannot be solved either by rules or a person cannot rely on a semi
autonomic system.
Tasks and activities require a high degree of cognitive processing because the
situations are unfamiliar and cannot be dealt with using rules or experience.
Here a person must define objectives, evaluate alternatives, and mentally analyse or
physically test the consequences of the alternatives.
Examples:
Senior doctors use this method. Demands a lot from the working memory, but
working memory is limited to its capacity.
Designing a mechanical component for a machine.
Diagnosing a medical patients’ symptoms.
Solving a complex mathematical problem
Analysing the results of a scientific experiment
Identifying the cause of a quality problem in a production operation.
A person can use more than one behaviour on the job.
Problems with/in in the problem-solving process:
Cognitive tunneling – Also called cognitive capture and inattentional blindness, is
the mental state in which the brain focuses on one thing. As a result, the brain does
not see other relevant data.
This is a bias associated with troubleshooting and diagnosis. It is when the
expert identifies one hypothesis to answer the question and stays focused on it
to the exclusion of other possible explanations. He or she seeks out evidence to
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confirm the chosen hypothesis but overlooks or ignores clues that might
disprove it.
Stuck in a loop – This is a repeating pattern where thoughts and beliefs produce
feelings that fuel our rightness about our feelings, and on and on. They burn energy
and get in the way of progress. The problem solver continues to repeat a sequence of
action that have no result except to lead back to the starting point of the problem.
One solution fixation – A situation related to a system called escalation of
commitment. Where you continue to solve a problem when its very clear that a
solution under the current path that you are on is not going to be found [stick to that
solution even though it may not be succeeding]. Will not be able to troubleshoot the
problem. The mind is blocked and cannot think of other solutions to solve a
problem. [Analogous to cognitive tunneling in troubleshooting and diagnosis].
Inability to think ahead – This problem occurs in situations that require multiple
solution steps or the consideration of multiple alternatives, which causes the
working memory of the problem solver to become overloaded. The person is unable
to think ahead more than a few steps.
Chapter 3: Cognitive ergonomics
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THEME 4: ORGANISATIONAL HUMAN FACTORS AND
ERGONOMICS A SYSTEMS APPROACH
REMEMBER:
• An organization operate as an open system, i.e. it regularly exchanges information with it’s external environment.
• An organization is a complex system, i.e. there is high degree of systematic interdependence amongst numerous factors
(agents) that make up the system
• To provide effective HFE intervention a systems approach is required and all factors [internal; external; personal;
situational; organisational] must be interrogated.
• A broad spectrum of factors affects the human-machine interaction in the organisation
ORGANISATIONAL HUMAN FACTORS AND ERGONOMICS
This is a discipline concerned with understanding the organization as a system involving individuals and groups; structures;
dynamics and how all these complexly interact to determine the relationship between humans and machines within the
work environment. With the ultimate objective of achieving the systems goals which is safety, productivity and employee
satisfaction.
THE HUMAN MACHINE SYSTEMS MODEL
Natural environment
Political enviroment
Input
Task
Human
Light
Noise
Space
Time
Smoke
Heat
Electricity
Economic environment
Output
E ↳
-
we
Output
Historical environment
Machine
Task
Built environment
Input
Ions
Gasses
Radiation
Chemicals
Vibration
Movement
Magnetism
Social environment
Reminder: Social Environment involves, humans, machines and the tasks that have to be done [inputs from human or
machine] outputs and displays [light, noise, heat, electricity]
HUMAN CHARACTERISTICS: STRESS AND FATIGUE
•
Stress is the adverse reaction people have to excessive pressure or other types of demand placed upon them – WHO/
•
HSE, 2005
Pressure and workload is a factor to an organizations outcomes be it productivity, employee satisfaction etc.
•
It is determined by the balance between perceptions of the demands being placed upon the person (e.g. workload)
against how she or he judges their available resources to cope with these demands (e.g. experience, skills,
personality).
•
Personality [two people given the same demands might react differently due to individual differences]
•
Stress is a perception
•
Conditions in the workplace and an individual’s reactions to these conditions over a period of time can cause stress
•
Stress at work can lead to health and safety problems
Model of stress and strain
•
Fatigue is the state of tiredness that is associated with long hours of work, prolonged periods without sleep, or
requirements to work at times that are “out of synch” with the body’s biological or circadian rhythm – WHO/HSE, 2005.
•
This is from a physical point of view where you are constantly put to work.
•
Fatigue can have consequences for both the safety, health and productivity of workers due to the following reasons:
Detrimental effects on cognitive performance (Your ability to sense and perceive a stimulus will be affected due to
tiredness)
Detrimental effects on the performance of psychomotor tasks (Your dynamic movement is affected)
Effects on communication and social skills (fatigue makes people irritable and they don’t want to communicate)
Work Design and organisation: Work scheduling and Shift
work
Several trends in industry and society have led to the growth of Shift work:
o Process industries - Many industries such as power plants and steel works cannot close at night. Some machines are
only closed at the end of the financial year e.g. mines. There is a lot of automation in industries.
o Economic pressures – Shared production machinery and growth in the use of overtime. Certain laws make workers
work overtime.
o Service sector demands: Many service sectors jobs such as nurses, policemen, emergency services are needed
around the clock.
Shifts are usually designated as morning, afternoon, and night shift as follows:
Shift
Typical time
Morning shift
6:00 am to 2:00 pm
Afternoon shift
2;00 pm - 10:00 pm
Night shift
10:00 pm - 06:00 am
1. THE CIRCADIAN RHYTHMS AND SHIFT WORK (impact of shift work on the body)
According to the circadian rhythm (cycle the body maintains) the body has a 24-hour rhythm (biological clock) which
regulates bodily activities as follows:
o Physiological variables – Alertness, heart rate, neurotrammiter activity o Body temperature – Rises during the day and
drops at night [rises within a range]
o Biochemical effects – in the evening, the clock releases into the brain of a chemical melatonin, which gives the body
the signal to fall asleep. Overnight, melatonin levels remain high, drop at daybreak, and remain low during the day.
o Urine production – increases at night and falls by day. o Appetite sensation – low during sleep time.
The circadian rhythm disturbance is usually a problem for night shift workers relative to morning and day shift workers
Night shift workers struggle because that system operates with everyone in the same way [respiratory system and
cardiovascular system]
A night shift worker struggles because of several reasons:
Requirement to sleep during the day in full day light (neurotomies is high when they are required to sleep)
Requirement to sleep under low melatonin levels
Easy to sleep at night due to low noise levels and low social activities
Health disorders with sleeping during the day: distorted appetite, poor digestive, poor hunger patterns, increased risk of
cardiovascular disease.
ILLUSTRATION OF THE CIRCADIAN RHYTHM WORKS:
2. IMPROVING SHIFT WORK: SOME IMPORTANT CONSIDERATIONS
The length of the shift should be related to the type of work
The scheduling of shift work is important
Direction: Forward (Morning-Afternoon-Evening-Night) with breaks in between is preferable over Backward (NightEvening-Afternoon-Morning) [NB]
Frequency – this refers to the rate of shift change [what is the structure of the shift, at what frequency are we taking
shifts?] (related to the type of work the individual will be doing)
Selection of individuals for shift work. Some individuals may never be able to adjust to shift work. Adjust shift scheduling
to people who are e.g.
People living alone
Morning-type people
Older employees
You need to understand your employees and accommodate them according to their preferences.
OCCUPATIONAL HEALTH AND SAFETY (Socio-economic
factor) Remember from Theme 1:
• The EHM system has to achieve three fundamental goals:
Occupational Health and Safety
Productivity and; Satisfaction
• These goals are aligned with the ultimate goal of business - sustainability (economic, social and environmental).
What is Occupational Health and Safety?
• Occupational Safety is concerned with the avoidance of industrial accidents and in particular accidents that cause injury
or fatality. The accidents are one-time events.
• Occupational Health is concerned with avoiding diseases and disorders that are induced by exposure, usually over a
period of time, to materials or hazardous conditions in the workplace.
The following will be covered under Occupational Health & Safety:
Occupational Safety, Accidents and Human Error
Occupational Health
Occupational Health and Safety Legislation
1. OCUPATIONAL SAFETY, ACCIDENTS & HUMAN ERROR
•
An industrial accident is an unexpected and unintentional event that disrupts and/or can potentially disrupt work
procedures and has the potential to cause damage to property and injury or death to workers [and/or other people]. It is
an unwanted outcome.
•
A hazard is a condition or a set of conditions that has the potential for causing an accident. You can’t talk of a hazard in
terms of a single item, it has to interact with other elements within a given set of time. E.g. an electrical cord laying on
the ground is harmless until you present a set of factors that can potentially make the electrical cord a hazard.
2. OCCUPATIONAL SAFETY AND ACCIDENTS – ETIOLOGY (causal factors)
•
The Systems approach assumes accidents occur because of the [complex] interaction between system components
•
Factors that cause or contribute to accidents can be classified into the following:
•
Employee characteristics – Smoking, alcohol consumption, inactivity, sleep disorders.
•
Job characteristics – Dissatisfaction at work, working hours, breaks.
•
Equipment and Tools – Are tools and equipment’s stable?
•
Physical environment – Noises, working conditions, lighting
•
Social environment – Conflict with colleagues?
•
Human Error – slips, lapses and mistakes. [These types of human error can happen to even the most experienced and
well-trained person.]
Natural factor
THE WORK SYSTEM
Management
or design error
Employee characteristics
Hazard
job characteristics
Equipment and tools
Physical environment
Social environment
Operator error
Accident
/injury
These systems are designed by management. Deficiency in the design of the system in terms of how employees are
selected, design of the job, the equipment’s that are used, failure to appreciate the possible physical environment or set
up the correct environment and of coarse social environment presents potential hazards in the system.
Natural factors such as the physical climate and operator error can result into accidents.
The Employee characteristics include:
•
Age
•
Job experience
•
Stress, fatigue, Drugs and Alcohol
The Job characteristics include:
•
Workload (physical and mental)
•
Work schedule
The Equipment and Tool factors include:
•
The nature of the tool or equipment itself
•
Controls and Displays
•
Electrical hazards
•
Mechanical hazards
•
Pressure and toxic substance hazards
The Psycho-social environment include:
•
Norms
•
Incentives and morale
•
Management practices
The Physical environment include:
•
Illumination
•
Noise and vibration
•
Temperature and Humidity
•
Fire
•
Radiation
•
Falls
•
Exits and Emergency Evacuation
•
HUMAN ERROR AND ACCIDENTS
Human error is a big contributor to problems in system safety. Human Error refers to inappropriate human behaviour that
lowers levels of system effectiveness (reliability) or safety) OR an action which fails to produce an expected result, and
which therefore lead to an unwanted consequence. An unwanted error that leads to an unwanted outcome. Involves
deviation from the goals of the system.
Important to classify errors because conditions that produce the different kinds of errors often have different remediations
(interventions).
ERROR CLASSIFICATION
Firstly, errors are different from violations (both human failures)
Human error is an unintentional action or decision.
Violations are intentional failures – deliberately doing the wrong thing.
1) Omission (resulting from failing to do something) vs. Commission (resulting from
doing something that you were not supposed to do).
The classification is too simplistic and limited as it only addresses the WHAT and
not the WHY. Leading to a discussion of intended and unintended actions.
2) Intended vs. Unintended. An intended inappropriate action is called a mistake (unintended action from the perspective of
the outcome) With a mistake, the action is intended, i.e. the error commission is unintended but intended action turns out to
be erroneous. In other words what you do during a mistake, Is the way you planned to do it, but that action is against the
system which is why it is inappropriate.
MISTAKES
• Mistakes, unlike lapses & slips, are decision making errors AKA thinking errors (You decided to do something which
turned out to be wrong).
• Mistakes can be:
Knowledge-based: Knowledge inadequate for a situation or just results from wrong conscious thought processing
based on learned principles and experience.
The reason why an individual can do something wrong or that is against the goals of the system is either because of
knowledge deficiency or a problem with rule application.
Wrong conscious thought processing.
Rule-based: Unaware of and/or misapplies a good rule governing appropriate
behaviour or application of a bad (wrong) rule.
LAPSES AND SLIPS
• Slips and Lapses, unlike mistakes, are skill-based errors AKA action errors.
These are errors that are obtained because of doing something that one ordinarily does autonomously. Something done so
many times that it becomes a routine resulting to a high possibility of slips and lapses.
o Slip – unlike a mistake, an incorrect act was not intended, but ‘slipped out’ through the selection of action. A slip is
therefore a commission error of non- intended action, i.e. a simple, frequently performed task goes wrong. It’s a responseselection (R-S) error.
When you have made a correct decision e.g. I have decided to press a red button, but end up pressing a green button as
an error.
o A-lapse–unlike a slip,this is a non-intentional error of omission.It is a‘lapse’ in short-term (working) memory. Involves
omitting to perform a known required action.
Failure to do something because of deficiency in short-term memory. Remember short-term memory and working memory
is limited in terms of capacity. Hence, lapses usually happen because you are over burdening your working memory to a
point where it cannot store or process everything that needs to be processed within a given time resulting in nonintentional
errors of omission.
E.g. when you gave been working very long on a project and forget to save your work
VIOLATIONS
• Violations: unlike errors, violations are intentional failures, i.e. intentionally doing something inappropriate AKA noncompliance. [Both the action and the outcome are intended. You already knew what you were doing]
Routine violations: normalization of non-compliance; unforced lack of meaningful attempt to follow rules, regulations. [by
nature, you just don’t want to follow rules e.g. you decide to go over the speed limit when driving and you’re not in a
rush to anywhere]
Situational violations: non-compliance dictated by situation-specific factors (e.g. time, workload, unsuitable tools etc.).
Non-compliance ‘seem to be’ the only solution. [The only thing that you could do e.g. waking up late for a meeting and
decide to break the speed limit to get to work on time]
Exceptional violations: attempting to solve a problem in highly unusual circumstances through an extraordinary ruletwisting solution. [Trying to solve a problem that is already obtaining in your situation by going for an extra ordinary
situation]
Slips of action
Skill-based error
1. Human error
Mistakes
Lapses of memory
Rule based mistakes
Knowledge based mistakes
2. Violations
Routine
Situational
Exceptional
Error
classification
HUMAN ERROR AND ACCIDENTS –
SUMMARY
• In an accident situation, the human operator
at the ‘sharp end’ is often [seen as] the
contributing factor.
• But often the sharp end human operator is
sometimes just the final ‘triggering’ event at
the end of series of earlier events (pre-existing
conditions)
• The pre-existing conditions (resident
pathogens) include any of the factors within
the Accident causation Model (Fig 4.1)
• The factors collectively form the safety
culture of the organisation
3.3. OCCUPATIONAL HEALTH HAS TWO CATEGORIES • Occupational health has two
categories:
Cumulative trauma disorders - Caused by repeated use of certain tendons and nerves, such as those in the fingers, wrist,
forearm, upper arm, and shoulder [Theme 2]. Health problems that come with the use of the body. E.g. Overuse of
computers resulting in painful wrists, overuse of the arms due to lifting heavy objects.
•
Occupational diseases usually result from exposure to chemical substances over an extended period. Examples:
•
Silicosis
•
Lung cancer
•
Asthma and chronic obstructive pulmonary disease
•
Asbestosis
•
Cole dust, mine dust
•
Gas
However, releases of gases can be the nature of the work. E.g. a refinery cannot operate without releasing any gases into
the atmosphere.
Occupational Health and safety legislation in South Africa
• Discuss general remarks regarding the relevant legislation
• Discuss the Occupational Health and Safety Act (OHSA) in terms of its objectives, definitions, general duties of employers
and employees, as well as other important stipulations that was discussed in class.
• Discuss the Basic Conditions of Employment Act in terms of general remarks as well as specific stipulations that were
discussed in class.
• Discuss Compensation for Occupational Injuries and Diseases Act (COIDA) in terms of the application and exclusion
areas, objectives as well as specific stipulations of the law.
S – Section
SS – Sub-section
Ch – Chapter in the Act [uploaded on sunlearn]
OCCUPATIONAL HEALTH AND SAFETY AMENDMENT ACT
(No 85/1993)
• Purpose of the Act
The aim of the OHS Act is to provide for the safety and health of persons at work and in connection with the use of plant
and machinery. It further provides for the protection of people other than people at work from hazards arising out of or in
connection with the activities from people at work.
DEFINITIONS
EMPLOYEE
Means, subject to the provisions of subsection (2), any person who is employed by or works for an employer and who
receives or is entitled to receive any remuneration or who works under the direction or supervision of an employer or any
other person.
EMPLOYER
Means, subject to the provisions of subsection (2), any person who is employed by or works for an employer and who
receives or is entitled to receive any remuneration or works under the direction or supervision of an employer or any other
person.
HAZARD
Mean a source of or exposure to danger
MACHINERY/ USER OF MACHINERY
Means any article or combination of articles assembled, arranged or connected and which is used or intended to be used
for conveying any form of energy to performing work, or which is used or intended to be used, whether incidental thereto or
not, for developing, receiving, storing, containing, confining, transforming, transmitting, transferring or controlling any form
of energy.
ACCIDENT
Means an accident arising out of and in the course of an employee’s employment and
resulting in a personal injury, illness or the death of the employee.
INCIDENT
Means an incident as contemplated in section 24 (1)
Reasonably practicable Means practicable having regard to:
a) The severity and scope of the hazard or risk concerned
b) The state of knowledge reasonably available concerning that hazard or risk and of any means of removing or mitigating
that hazard or risk
c) The availability and suitability of means to remove or mitigate that hazard or risk;
d) The cost of removing or mitigating that hazard or risk in relation to the benefits deriving therefrom
Risk
Means the probability that injury or damage will occur
Safe and healthy
Safe, means from any hazard. Healthy means, free from illness or injury attributable to occupational causes
Work
Means work as an employee or as self-employed person, and for such purpose an employee is deemed to be at work
during the time that he is in the course of his employment, and a self-employed person is deemed to be at work during
such time as he devotes to work as a self-employed person.
Workplace
Means any premises or place where a person performs work in the course of this employment.
Danger
Means anything which may cause injury or damage to persons or property.
GENERAL DUTIES OF EMPLOYER
Spatial orientation
16. Chief executive officer charged with certain duties
1) Every chief executive officer shall as far as be reasonably practicable ensure that the duties of his employer as
contemplated in this Act, are properly discharged
2) Without derogating from his/her responsibility or liability in terms of subsection (1), a chief executive officer may assign
any duty contemplated in the said subsection, to any person under his control, which person shall act subject to the control
and directions of the chief executive officer.
It does not matter how the person got injured, if there are health and safety measure. Example: Burglar – Fell off, but the
employer was charged for the faulty infrastructure.
Overall duties
Section 8, subsection (1): Every employer shall provide and maintain, as far is reasonably practicable, a working
environment that is safe and without risk to the health of his employees
Section 9, subsection (1): Every employer shall conduct his undertaking in such a manner as to ensure, as far as is
reasonably practicable, that persons other than those in his employment who may not directly affected by his activities are
not thereby exposed to hazards to their health or safety. ‘reasonably practicable’ means practicable having regard to• (a) The severity and scope of the hazard or risk concerned.
• (b) The state of knowledge reasonably available concerning that hazard or risk and of any means of removing or
mitigating that hazard or risk. E.g. a refinery is expected to have full knowledge of how to deal with a fire.
• (c) The availability and suitability of means to remove or mitigate that hazard or risk; ensure the resources to deal with the
hazard are available.
• (d) The cost of removing or mitigating that hazard or risk in relation to the benefits deriving there from [don’t put cost
considerations before risk considerations] e.g.Refinery cant say they cant have an adequate fire system because it
is too expensive.
Specific duties [S9 (2) (a; b...j)
• Provide and maintain safe systems; identify/determine hazards
• Provide information, instructions, supervision...
• As far as is reasonably practicable ensure health and safety of employees...
• Adaptation of disciplinary documents / procedures [Need to adapt them to suit your own circumstances]
• Make and manage tangible steps
• Avoid, Screen off, distance, only then personal protection
• Do not allow work in unsafe conditions
• Ensure that persons under his/her control comply with the act
GENERAL DUTIES OF EMPLOYEES AT WORK [S14]
• Take reasonable care for the health and safety of himself and of other persons who may be affected by his acts or
omissions.
• Co-operate with employer to enable that duty or requirement to be performed is complied with
• Obey rules/authority
• Report unsafe or unhealthy situations
• Involvement in any incident which may affect his health, or which has caused an injury to himself, report such incident
before end of shift
Application areas of the Act (inclusion & exclusion) All workers except:
• Mineworkers (Mines Health and Safety Act 1996)
• Shipping workers (Merchant Shipping Act & the Maritime Safety Code)
• Security force workers
• Charity workers [they are not employees and not entitled to compensation]
The Common law aspects of the Act.
• Spatial Orientation (Section 16)
• Reasonably practicable
BASIC CONDITIONS OF EMPLOYMENT ACT (No 75/1997)
• Flexible Act (the Act sets the minimum)
• Self-regulation (The government cannot police everything that happens in the workplace. Hence, as a good cooperation,
the organisation must take steps that comply with the Act) The law only descends noncompliance when there is a problem.
• Definitions [Section 1, PDF document on SUNLearn]
• Purpose of the Act (S2)
To give effect to the right to fair labour practices referred to in section 23 (1) of the Constitution by establishing and making
provision for the regulation of basic conditions of employment; and thereby to comply with the obligations of the Republic
as a member state of the International Labour Organisation (ILO); and to provide for matters connected therewith.
Application areas of the Act (inclusions & exclusion criteria).
This Act applies to all employees and employers including:
persons undergoing vocational training
This Act excludes:
•
National Defence Force, National Intelligence Agency; South African Secret Service.
•
unpaid volunteers working for an organisation serving a charitable purpose.
•
Workers who work less than 24 hours per month
•
Emergency workers (essential & maintenance services)
•
Travelling sales staff [some provisions e.g. hrs]
•
Senior managerial staff [some provisions. e.g. hrs]
•
Employees earning more than a certain amount.
•
Workers at sea (except S41)
Ministerial determinations (Section 50) (The minister can make exceptions to the rule, they have the power to change or to
make determinations to provide more clarity where the law does not provide clear clarity)
Sectorial agreements (Subject to S5: S39: S51) (Despite the law setting a minimum, it also provides sectorial agreements
within industries or sectors. For example, the mining sector can decide to alter working times for employees despite the law
setting the minimum or maximum hours)
• Regulation of working time (CH2)
Application of the Chapter (S19)
(1) This chapter does not apply to an employee who works less than 24 hours a month for an employer.
(2) Unless an agreement provides otherwise, tis chapter does not apply to leave granted to an employee more than the
employee’s entitlement under this Chapter.
Annual Leave(S20) (ss1;2;3)
(1) In this Chapter, “annual leave cycle” means the period of 12 months’ employment with the same employer immediately
following:
•
An employee’s commencement of employment; or
•
The completion of that employee’s prior leave cycle
•
(2) An employer must grant an employee at least:
•
21 consecutive days for each annual leave on full remuneration in respect of each annual leave cycle.
•
(by agreement) 1 day for every 17 days worked (entitled to be paid)/ 1 hour for every 17 days worked (entitled to be
paid).
•
By agreement, one hour of annual leave on full remuneration for every 17 hours on which the employee worked or was
entitled to be paid.
•
(3) An employee is entitled to take leave accumulated in an annual leave cycle in 20 terms of subsection (2) on consecutive
days.
Sick Leave (S22) (ss1; 2; 3; 4)
(1) In this chapter “sick leave cycle” means the period of 36 months’ 5 employment with the same employer immediately
following:
•
An employee’s commencement of employment or
•
The completion of that employee’s prior sick leave cycle.
•
(During every sick leave cycle, an employee is entitled to an amount of paid sick leave equal to the number of days the
employee would normally work during a period of six weeks
•
(3) Despite subsection (2), during the first six months of employment, an employee is entitled to one day’s paid sick
leave for every 26 days worked.
(4) During an employee’s first sick leave cycle, an employer may reduce the employee’s entitlement to sick leave in terms
of subsection (2) by the number of days’ sick leave taken in terms of subsection
(3) Maternity Leave (S25) (ss1;2;3;4)
(1) An employee is entitled to at least four consecutive months’ maternity leave.
(2) An employee may commence maternity leave:
•
At any time from four weeks before the expected date of birth, unless otherwise agreed: or
•
On a date from which a medical practitioner or a midwife certifies that it is necessary for the employee’s health or that
of her unborn child.
(3) No employee may work for six weeks after the birth of her child, unless a medical practitioner or midwife certifies that
she is fit to do so
(4) An employee who has a miscarriage during the third trimester of pregnancy or bears a stillborn child is entitled to
maternity leave for six weeks after the miscarriage or stillbirth, whether or not the employee had commenced maternity
leave at the time of the miscarriage or stillbirth.
•
Protection of employees during and after birth of a child (26) (ss 1;2)
(1) No employer may require or permit a pregnant employee or an employee who is nursing her child to perform work that
is hazardous to her health or the health of her child.
(2) During an employee’s pregnancy, and for a period of six months after the birth of her child, her employer must offer her
suitable, alternative employment on terms and conditions that are no less favourable than her ordinary terms and
conditions of employment, if:
•
The employee is required to perform night work, as defined in section 17 (1) or her work poses a danger to her health
or safety or that of her child; and
•
It is practicable for the employer to do so.
Working time (Ch3)
• Application of the Chapter
•
Ordinary hours of work (S9).
(1) Subject to this Chapter, an employer may not require or permit an employee to work more than:
•
Maximum 45 hours OR better
•
9 hours if 5-day work week; 8hours if 6-day work week
•
Can be 40/week (Schedule 1)
Day extension [15 min max/day by agreement; no more than 60min/week]
• Meal interval (S14) (1 hr. in every 5 hours) or 1⁄2 hr. (collective agreement).,
• Night work (S17) (relevant sections as covered in class) [Work performed after 18:00 and before 06:00 the next day.
• Rest time (S15) (12 hours; 10 hours by agreement under certain circumstances)
• Overtime (max 3 hours/day, 10 hours/week; at least 1.5 hourly wage)
• Sundays and Public holidays (general rest-related aspects)
COMPENSATION FOR OCCUPATIONAL INJURIES AND DISEASES ACT (no. 130 of
1993) (COIDA)
•
Purpose of the Act
The Compensation for Occupational Injuries and Diseases Act, No 130 of 1993 (COIDA) provides for compensation for
disablement caused by occupational injuries or diseases sustained or contracted by employees in the course of their
employment, or for death resulting from such injuries or diseases.
•
Definition
Application of the Act (CH4) (S22)
The Compensation for Occupational Injuries and Diseases Act (COIDA) applies to all employees including:
•
casual and full-time workers.
•
Emergency services (including during training)
•
Working for an employer outside the Republic of South Africa
•
Seamen and Airmen working for
Right to compensation and the role of the Director-General in terms of the Act:
(2) No periodical payments shall be made in respect of temporary total disablement or
temporary partial disablement which lasts for three days or less.
(3) If an accident is attributable to the serious and wilful misconduct of the employee, no compensation shall be payable in
terms of this Act, unless –
(4) For the purposes of this Act an accident shall be deemed to have arisen out of and in the course of the employment of
an employee not withstanding that the employee was at
✔
the time of the accident acting contrary to any law applicable to his employment or to any order by or on behalf of his
employer, or that he was acting without any order of his employer, if the employee was, in the opinion of the DirectorGeneral, so acting for the purposes of or in the interests of or in connection with the business of his employer.
[You can only be compensated if the nature of your injury occurred when you were working or in the process of carrying
out a task given out by the employer]
(5) For the purposes of this Act the conveyance of an employee free of charge to or from his place of employment for the
purposes of his employment by means of a vehicle driven by the employer himself or one of his employee’s for the
purpose of such conveyance, shall be deemed to take place in the course of such employee’s employment. [Conflict
arising between employer or employee]
The COIDA excludes:
1. workers who are totally or partially disabled for less than 3 days.
2. domestic workers.
3. the South African National Defence Force (including those receiving military training), or the South African Police
Service.
4. Mines covered only for certain accidents and diseases – otherwise own Act
ORGANISATIONAL HFE – a systems approach
METHODS AND TECHNIQUES: HUMAN FACTORS INVESTIGATION
•
Principles of Human Factors and Ergonomics (HFE) can be used to redesign a work system to make it more
productive, safer, and more satisfying to employees. Improvements range from very small adjustments to major
system redesign.
•
All improvements, small or large, should follow and/or be based on a sound scientific research process.
•
Research is often used to diagnose, evaluate, or explain various human factors that can potentially directly and/or
indirectly affect the Human-Machine-Environment (H-M- E) interaction.
For instance, research can be used to investigate musculoskeletal disorders in the workplace for either pro-active and/or
reactive reasons.
The three common types of HFE research are
Descriptive - The main purpose is to collect data with the purpose of understanding a pattern, trend, or characteristic,
e.g. anthropometric measurements of the South African population
Experimental - Usually designed to investigate specific issues and allows cause- effect conclusions to be drawn, e.g.
relationship between shift duration and human errors
Evaluative - The purpose is usually to investigate an intervention or new work design on, e.g. productivity or safety
before, during and after implementation
Every investigation should follow be informed by proper scientific principles which include:
Reliability – a measure must be consistent and stable over time
Validity – a measure should measure what it claims to measure and measure it accurately if it is to be valid.