Industrial Psychology 262 A2 Notes PDF

**INDUSTRIAL PSYCHOLOGY 262** **\ ** **THEME 1: INTRODUCTION TO HUMAN FACTORS AND ERGONOMICS** 1. **Theme Outcomes** - Understand and define the two terms Human Factors and Ergonomics and explain the difference. - Explain the interdisciplinary nature of Human Factors and Ergonomics...

**INDUSTRIAL PSYCHOLOGY 262** **\ ** **THEME 1: INTRODUCTION TO HUMAN FACTORS AND ERGONOMICS** 1. **Theme Outcomes** - Understand and define the two terms Human Factors and Ergonomics and explain the difference. - Explain the interdisciplinary nature of Human Factors and Ergonomics. - Appreciate the importance of a systems approach to understanding HFE and (i) the implications to the diagnosis of and (ii) interventions to HFE related organisational problems and challenges. - Comprehend and explain the practical's goals of the field of human factors and Ergonomics to organisational performance and sustainability. - Be able to apply the scientific knowledge of HFE to the understanding of industry problems and explain how this understanding can be used to improve the design of organisational systems to enhance the field's intended goals. - Understand the historical development of the field and appreciate the current trends and issues. 2. **Definition of Human Factors and Ergonomics** The International Ergonomics Society (IEA) defines **Ergonomics** (or human factors) as: a. The scientific discipline b. concerned with the understanding of the interactions c. among humans and other elements of a system d. and the profession that applies theory, principles, data, and methods to design e. to optimise human well-being and overall system performance. According to The Health and Safety Executive: UK industrial Safety Regulator **Human Factors** refer to: a. environmental, organisational and job factors, and b. human and individual characteristics c. which influence behaviour at work in a way d. which can affect health and safety. It is accepted that Ergonomics and Human Factors are synonymous, and the historical difference: i. **Ergonomics** emphasised work physiology and anthropometry ii. **Human factors** emphasised experimental psychology and systems engineering. **\ ** **Important Takeaway from Definitions** - The primary purpose of HFE is Design. - In HFE, a systematic, interdisciplinary approach is necessary for design and analysis. - The HFE field is multi-disciplinary. Examples of discipline domains: A. Medicine: Cardiology, Neuroscience, Physical medicine B. Psychology: Organisational Psychology, Forensic Psychology, Health Psychology 3. **HFE: A Systems Description** - HFE problems requires scientific **systems approach**. - Organisation is referred to as a Human-Machine-Environment (HME) System. - The HME goals are aligned with the goal of organisations: **Sustainability** and are achieved through fitting the job to the person (FJP) -- the objective of HFE. You cannot fit a person into a job (scientific management). - The HME system has to achieve three fundamental goals: 1. Safety - It has become an outcome, especially in high risk industries like mining. 2. Productivity 3. Satisfaction - e.g. health and safety, good social environment (Book of 4-5). 4. **The Basic Human-Machine-Environment (HME) System** There are three different components of the Basic Human-Machine-Environment System namely: 1. **Human** Components: human senses, brain, and effectors. 2. **Machine** Components: the process, displays and controls. 3. **Environmental** Components: the physical and social environment. +-----------------------+-----------------------+-----------------------+ | **COMPONENTS OF THE | | | | BASIC HME SYSTEM** | | | +=======================+=======================+=======================+ | **4.1** | Human Senses | The basic five human | | | | senses: touch, sight, | | **Human Components** | | hearing, smell and | | | | taste. The sensing | | | | organs associated | | | | with each sense send | | | | information to the | | | | brain to help us | | | | understand and | | | | perceive the world | | | | around us. | +-----------------------+-----------------------+-----------------------+ | | Human Brain | Viewed as a data and | | | | information | | | | processing unit | | | | (analogous to the CPU | | | | of a computer). | | | | Includes decision | | | | making. | +-----------------------+-----------------------+-----------------------+ | | Human Effectors | A body part such as a | | | | muscle or group of | | | | muscles that actuates | | | | in response to a | | | | stimulus. Principal | | | | effectors are | | | | fingers, hands, feet, | | | | and voice. They are | | | | supported by the | | | | musculoskeletal | | | | system of the body, | | | | and the stimulus | | | | provided by the | | | | information | | | | processing occurring | | | | in the brain. | +-----------------------+-----------------------+-----------------------+ | **4.2** | The Process | The function or | | | | operation performed | | **Machine | | by the HM system e.g. | | Components** | | digging a hole, | | | | driving a car, | | | | writing an exam, | | | | performing a chemical | | | | process automatically | +-----------------------+-----------------------+-----------------------+ | | Displays | Ranges from observing | | | | the process being | | | | performed to | | | | artificial displays | | | | in mechanised and/or | | | | automated processes. | +-----------------------+-----------------------+-----------------------+ | | Controls | Ranges from observing | | | | the process being | | | | performed (digging a | | | | hole), to artificial | | | | displays in | | | | mechanised and/or | | | | automated processes | | | | (driving a car, | | | | automated chemical | | | | process). | +-----------------------+-----------------------+-----------------------+ | **4.3** | Physical | Includes the | | | | immediate area of HME | | **Environmental | | System. Components | | Components** | | include the location, | | | | lighting, noise, | | | | temperature and air | | | | quality. | +-----------------------+-----------------------+-----------------------+ | | Social Environment | Work serves a social | | | | function for | | | | employees. Primary | | | | interactions are job | | | | related, but social | | | | interactions also | | | | occur. The social | | | | environment at work | | | | is determined by | | | | co-workers, immediate | | | | supervisors, | | | | organisational | | | | culture, the work | | | | organisation design. | +-----------------------+-----------------------+-----------------------+ 5. **The HME System Classification** 1. **Manual**: involves a person using some effector tool or other non-powered implement to perform an activity. Example: Someone who is digging a trench. Less Sophisticated. In terms of unit of analysis, we are 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, 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 Broad | | | | | Human-Machine-E | | | | | nvironment | | | | | (HME) System** | | | | +=================+=================+=================+=================+ | **Human | - Psychologic | **The Physical | - Illuminatio | | characteristics | al | Environment** | n | | ** | aspects | | | | | | | - Noise | | | - Physiologic | | | | | al | | - Vibration | | | and | | | | | anatomical | | - Climate | | | | | | | | - Group | | - Altitude, | | | factors | | depth and | | | | | Space | | | - Individual | | | | | Differences | | - Other | | | | | environment | | | - Psychophysi | | al | | | ological | | issues | | | state | | | | | variables | | | | | | | | | | - Task-relate | | | | | d | | | | | factors | | | +-----------------+-----------------+-----------------+-----------------+ +-----------------+-----------------+-----------------+-----------------+ | **Work Design | - Total | **Socio-Economi | - Trade | | and | system | c | Unions | | Organisation** | design | Factors** | | | | | | - Employment, | | | - Hours of | | job | | | work | | security | | | | | and job | | | - Job | | sharing | | | attitudes | | | | | and | | - Productivit | | | satisfactio | | y | | | n | | | | | | | - Women and | | | - Job design | | work | | | | | | | | - Payment | | - Organisatio | | | systems | | nal | | | | | design | | | - Technologic | | | | | al | | - Education | | | and | | | | | ergonomic | | - Law | | | change... | | | | | | | - Family and | | | | | home life | | | | | | | | | | - Quality of | | | | | work life | | | | | | | | | | - Politics | | | | | and ethics | +=================+=================+=================+=================+ | **Health and | - General | **Methods and | - Approaches | | Safety** | Health and | Techniques** | and methods | | | Safety | | | | | | | - Techniques | | | - Etiology | | | | | | | - Measures | | | - Injuries | | | | | and illness | | | | | | | | | | - Prevention | | | +-----------------+-----------------+-----------------+-----------------+ | **Information | - Visual | | | | Presentation | communicati | | | | and | on | | | | Communication** | | | | | | - Auditory | | | | | and other | | | | | communicati | | | | | on | | | | | modalities | | | | | | | | | | - Choice of | | | | | media | | | | | | | | | | - Person-mach | | | | | ine | | | | | dialogue | | | | | mode | | | | | | | | | | - System | | | | | feedback | | | | | | | | | | - Error | | | | | prevention | | | | | and | | | | | recovery | | | | | | | | | | - User | | | | | control | | | | | features | | | | | | | | | | - Language | | | | | design | | | | | | | | | | - Database | | | | | organisatio | | | | | n | | | | | and | | | | | retrieval | | | | | | | | | | - Programming | | | | | , | | | | | debugging, | | | | | editing and | | | | | programming | | | | | aids | | | | | | | | | | - Software | | | | | performance | | | | | and | | | | | evaluation | | | | | | | | | | - Software | | | | | design, | | | | | maintenance | | | | | and | | | | | reliability | | | +-----------------+-----------------+-----------------+-----------------+ 6. **A Brief Summary of HFE** An organisation (HME system) operate as an open system, i.e. it regularly exchanges information with its 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, a scientific systems approach is required, and all factors have to be interrogated. 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 promotes human satisfaction. Because improvements cost money, they have to be justified based on a scientific cost-benefit analysis. 7. **HFE: Cost-Benefit Analysis of Improvements in Design** In a typical HFE system, the following improvements can be expected: - Illumination level including special lighting for inspection - Job rotation and shift rotation \[& overlap\] - Sitting and standing \[e.g. ergonomic chairs\] - Communication systems - Materials handling - Automation of routine and monotonous jobs - Metric to decimal conversion - Housekeeping - Noise and vibration management - Ergonomics training - Production technique changes e.g. Continuous flow manufacturing - Specific problems 8. **HFE: Early Historical Development, Contemporary Trends and Issues** **1850** Industrial Revolution (& Mechanization) ----------- ------------------------------------------------------------------------------------------------------------------------ **1875** \"Scientific Management" **1900** Industrial Psychology, Work Study, WWI **1923** Hawthorne Studies (Human Relations) **1940** WW II (Complex Equipment, Training, Accidents), "Knobs and Dials" **1949** Ergonomics **1965** Human Rights (Work, Health, Quality of Life, Subgroups, Laws, Standards). **1975** Computers, Information technology, Automation **1990** Environmental Quality; /Diversity; Global Village; Work Changes (Right replaces workers; Temporary and contract work). **2000+** Rapid and radical Technology changes (more automated complex systems) **\ ** **THEME 2: PHYSICAL \[HUMAN-BODY-CENTRED\] HFE** 1. **Physical Ergonomics** Many work activities require physical exertion/manual labour \[to varying degrees\]. **Physical** \[Human-body-centered\] **ergonomics** is \[mostly\] concerned with: i. How the human body functions during physical exertion, ii. 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. 2. **Anthropometry and Work Posture** In this section we will be discussing Anthropometry, Human variability, Anthropometric variables and data, Anthropometric design principles, Procedure for Anthropometric Workstation Design, Accommodation of Disability, Sitting, Standing, and Sit-Standing and Work posture measurements. 1. **Anthropometry** Empirical science that is concerned with the physical measurement of the human body such as height, range of joint movements, and weight. It is a branch of anthropology that is concerned with the physical dimensions and other data related to the human body, such as height, reach, and weight. Anthropometry Anthropos Man. Metron to measure 2. **Human Variability:** Differences in body dimensions exist among people cause of many different factors including nationality. **Example with nationality:** "A piece of equipment was designed to fit 90% of the male US population, it would fit roughly 90% of Germans, 80% of Frenchmen, 65% of Italians, 45% of Japanese, 25% of Thais and 10% of Vietnamese" 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. Example: Survey Conducted in South Africa -------------------- -- -- --------- -------- --------- **Measurement** **95%** **5%** **95%** **Stature (mm)** 1865 1492 1722 **Body mass (kg)** 93 50 99 -------------------- -- -- --------- -------- --------- Male data: Stature: 5th percentile (5%) was 1579 (This actually means that 5% of South African males were below 1579mm in terms of stature). 95th percentile (95%) was 1865 (Same interpretation goes for Body mass). (5% of South African males were below 47kg of Body mass) Female data: (95% of females have at least a stature of 1722mm). This data is used by many organisations e.g. SANDF, Sports teams. **SANDF uniform allocation process example:** The process for the issuing of clothing items for the South African Army is presently as follows: The individual's personal detail is registered on the computer. Body measurements are taken on the semi-naked individual with the measurement instrument. This entails the measurements of: Body Height, Inside leg length, Foot Width, Foot length, Body mass, Head circumference, Chest circumference, Waist circumference, Hip circumference, Inside arm length and Palm circumference. The measurement values appear on the personal computer as they are entered on the measurement instrument. Clothing item sizes are allocated for the range of clothing items: shirts, jackets, trousers, underwear, footwear, headgear and hand wear. A size allocation sheet is then printed for the individual. The size allocation sheet is now used to collect the correct size clothing item from store. The duration of the process is less than 5 minutes. 3. **Anthropometric variables and data** Selected anthropometric measures. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 11. 12. 13. 14. 15. 16. 17. 18. 4. **Anthropometric Variables and Data**  5. **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)  6. **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) - 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)) 7. **Procedure for Anthropometric Workstation Design** Steps are: Characterise the user population, determine the percentile range to be accommodated in the workstation design, determine reach (5th percentile) and clearance dimensions (95th percentile) for the specific work situation, find and/or develop the anthropometric measures that correspond to the workstation measures and simulate the redesigned workstation. 1. **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. 2. **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 95^th^ 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. 5^th^ percentile female 95^th^ percentile males. 3. **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) 4. **Step 4: Find & develop the anthropometric measures 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. 8. **Accommodating the needs of Disabled employees** In most countries, the needs of the disabled (physically challenged) is recognised 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. 9. **Work Posture** 5. **Sitting, Standing and Sit-standing** **Preferred Work Posture** ------------------------------------------ ---------------- ---------------- **Type of Task** **1st Choice** **2nd Choice** Handling and lifting of heavy projects Standing Sit-standing Work below elbow height, e.g. packaging Standing Sit-standing 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 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, Sit-standing. Depending on the task \[not so much the employee preference\], it is advantageous for an operator to stand, sit, or sit-stand. 6. **Work Posture Effect 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: **Type of Posture** **Risk Area** --------------------------------------- -------------------------- 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 7. **Work Posture Measurements** **Methods** ------------------------ ---------------------------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- **SUBJECTIVE METHODS** Body Part Discomfort Scale 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). **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. 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. The level of accuracy depends on whether you go for the subjective or objective method. Objective methods are more expensive and 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. 3. **Muscular effort and Work** - Human Physiology: Muscle activity and Metabolism. - Cardiovascular & respiratory system' 10. **Background** Heavy physical (manual) labour is very much part of the industrially developing countries \[IDCs\] and no longer as common for developed countries (DCs). Reasons can be: - Low level of mechanisation \[including automation\] - Less structured work activities - difficult to mechanise. 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. 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. 11. **Human Physiology: Muscle activity and Metabolism** - Body muscle contraction is enabled by the process of metabolism. - **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:** i. Basal metabolism: 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. It is the rate at which chemical energy is converted to mechanical energy & mechanical energy is measured by your heartbeat & all other circulatory activities with a bio/mechanical nature. ii. Activity metabolism: The energy associated with physical energy like working. iii. Digestive metabolism: Eating requires the process of digestion. **Common HFE measure: Kilocalories (kcal)** **Metabolism rate**: - 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 12. **Human Physiology: Cardiovascular & Respiratory System** The metabolic process is supported by two critical systems: - The cardiovascular system. - The respiratory system. When the physical activity on the body increases due to increased muscle contraction, the respiratory and the cardiovascular system must work harder. 8. **Cardiovascular and respiratory systems' capacity.** Rate of oxygen consumption is proportionate to the heart rate, both of which depend on the quantity of energy expended. Different work activities (WA) requires different expenditure rates. 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. **Work Activity** **Kilocalories/day** -------------------- ---------------------- Seated Office 800 kcal/day Light Assembly 1680 kcal/day Ocean Fish Netting 4800 kcal/day Lumberjacking 6000 kcal/day Oxygen debt must be repaid! A worker cannot/must not work against maximum tempo and be in constant oxygen debt state. Excessive energy expenditure activates the anaerobic process which results in the release consequently fatigue to the muscles. Rest periods are required -- regulated by the law. 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. 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 -- South African Law says: "A worker cannot work over 5 hours continuously without an hour break per day"** 9. **Muscle Strength and Endurance** Apart from energy expenditure in muscle operation, strength is also important in physical work activities. **Strength**: The maximum force that can be applied by the muscle/ group of under specified conditions. **There are two types of strength:** \(1) **Static** strength: Measured by the human subject applying a high force against an immovable object. Depends on strength of arms or legs. \(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. **Factors affecting strength:** Age, gender, size, your physical condition (training is important here). Training improves your strength. **Endurance** is 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. Applies more to static force than dynamic force because dynamic force is more about speed. Dynamic is quick. 10. **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**. 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. 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. In order 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: Z M W R C K E ------------------------------------ ------------ ------ ----------- ------------ ------------ ------------- The store of the body temperature. Metabolism Work Radiation Convection Conduction Evaporation Significant temperature deviation (increase or decrease) from the core causes problems including death. Temperatures above 42˚C are likely to cause death Temperatures above 40˚C tend to be disabling. Body temperatures above 38˚C tend to reduce physiological performance. 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. **Heat Stress** \[hyperthermia\] occurs when the body fails to cope with increases in ambient temperature through thermoregulation processes resulting in the body core temperature rising to 39ºC ≥. Symptoms include weak pulse, pale skin, etc. There are various prevention and treatment methods. The body is designed to adapt when faced with high or too low ambient temperature, but sometimes it can not cope. Possible Treatments (just read): It\'s critical to move a person with hyperthermia to a cooler place and seek emergency care. Supportive care: IV fluids, Hydrotherapy, Exposure to air conditioning, Hyperthermia therapy, Ice packs and Rapid cooling of body. **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. Symptoms include weak pulse, nausea, etc. There are various prevention and treatment methods. Possible Treatments (just read): Removing wet clothing, wrapping the body in blankets, drinking warm beverages and taking a warm bath may help raise body temperature. **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. **THEME 3: COGNITIVE HUMAN FACTORS AND ERGONOMICS (HFE)\ COGNITIVE HFE THEORY PART 1** 1. **Cognitive HFE** Apart from physical elements, most work activities also include cognitive elements -- even manual labour! 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. Cognitive HFE has become increasingly important relative to physical HFE because of several trends in industry and technology, including: 1. Growth in the service industry sector of the economy relative to the manufacturing sector. 2. Increased use of mechanisation and automation in physical tasks previously performed manually. 3. Increased use of technologically sophisticated equipment. 2. **The 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. 3. **Human Information Processing** The human cognitive processes include the following components: - **Sensory system** -- 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.  **The Human Sensory System** 1. **Sensation** 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). 1. **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 among others. 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: - - - - - - - - 2. **Hearing (sound)** Hearing is the process of receiving sound. Sound waves typically originate from vibrating elements such as vibrating strings (human vocal cords). 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 \[theme 5\] sound 2. **Perception** 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. "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) and 2\. Recognition (interpreting the meaning of the stimulus). 3. **Sensation and Perception -- Holistic Understanding** **General Basic Concepts** 1. Absolute Threshold 2. Differential threshold (Just noticeable difference) 3. Signal detection theory 4. Sensory Adaptation 5. Situational Awareness **\ Visual Sensation And Perception** 6. Perceiving forms, patterns, and objects 7. Perceptual constancies in vision 8. Misleading cues: optical illusions 1. **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. 2. **The Just noticeable difference (JND)** - 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 JN. 3. **Signal detection theory (SDT)** - 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. It is related to sustained attention. - 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. 4. **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. 5. **Situational Awareness** - 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 in order 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). - Situational awareness and concentration are diminished by fatigue and stress and can be affected by interruptions and distractions. 6. **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. - **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, 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. 7. **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 \[perceiving things as stable even when they are changing\]. 8. **Misleading cues: optical illusions** - An optical illusion involves an apparently inexplicable discrepancy between the appearance of a visual stimulus and its physical reality. - 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, Focused Attention, Divided Attention, Sustained Attention And Lack of Attention. 9. **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. - **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. 10. 4. **Memory** 3. **Sensory memory** It is associated with the human sensory channels mainly sight and hearing. Represents a very short-term (1 sec to few seconds) storages unit that retains a representation of the stimulus after the actual stimulus stops. 4. **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). **Aspects of Working memory:** - It's capacity (your WM can only take a certain amount of information, can't hold +/- 7 chunks) - The time factors. - The role of attention Resources. - Similarity of information. 5. **Long term memory** It 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) - **Episodic** memory models \[About life events, no need to arrange in any order, known immediately\]. - 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. 5. **Response selection and execution** - **Response selection:** 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 long-term 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). Factors affecting response selection and execution: Decision complexity; Response expectancy; Compatibility; Speed-Accuracy Trade-Off; Feedback. Factors affecting response selection and execution: - - - - - **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. 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. 6. **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. 7. **Principles of Display Design** 1. Make displays legible 2. Avoid absolute judgement limits 3. Top-down processing 4. Redundancy gain 5. Discriminability 6. Pictorial realism 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. +-----------------------------------+-----------------------------------+ | **PRINCIPLES** | | +===================================+===================================+ | 1. **Make displays legible** | Relates to contrast, visual | | | angle, illumination, noise, | | | masking etc. | +-----------------------------------+-----------------------------------+ | 2. **Avoid absolute judgement | Operator should not be expected | | limits** | 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. | +-----------------------------------+-----------------------------------+ | 4. **Redundancy Gain** | Display message is more likely to | | | be perceived correctly if | | | expressed more than once in | | | alternative forms. | +-----------------------------------+-----------------------------------+ | 5. **Discriminability** | Similar appearing signals likely | | | to be confused immediately | | | \[during perception\] or later | | | \[during retrieval\]. | +-----------------------------------+-----------------------------------+ | 6. **Pictorial realism** | A display should look like the | | | variable that it represents. | +-----------------------------------+-----------------------------------+ | 7. **Moving part** | Moving element(s) of dynamic | | | information display should be | | | compatible with the user's mental | | | model of how the represented | | | element actually moves in the | | | physical system. | +-----------------------------------+-----------------------------------+ 8. **Auditory or Visual Display?** **Consideration** **Visual** **Audio** ----------------------------------------------------------------------------------------------- ------------ ----------- 1.Message complex vs. 2. simple? 1.Message short vs. 2. long? 1.Message not referred to later vs. 2.Message to be referred to later? 1.Message deals with events in time vs. 2. Location in space? 1.Message calls for immediate action vs. 2. Future action? 1.Audio system burdened vs. 2. Visual system burdened? 1.Recipient expected to be moving around vs. 2. Recipient expected to remain in one location? 2 1 9. **Information Types** 1. 2. **Quantitative** Display presentations that reflect the quantitative value of some variable. This is used when more precision is needed. 3. **Qualitative** Display presentations that reflect the approximate: value, trend, rate of change, direction of change, other aspect of changing variable. 4. **Status** Display presentations that reflect the condition or status of a system. Stop and go signs**.** 5. **Warning / signal** Display presentations used to indicate emergency or unsafe conditions. 6. **Representational** Pictorial or graphic representations of objects, areas, or other configurations. 7. **Alpha numerical and** **symbolic** Display presentations of verbal, numerical, and related coded information in many forms. E.g. music notes, excel formulas \[you need knowledge and experience to interpret them properly\] 8. **Identification** Display presentations used to identify some static condition, situation, or object. 9. **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 \[One display can only have 1 information type\]. +-----------------------------------+-----------------------------------+ | **INFORMATION TYPES** | | +===================================+===================================+ | 1. **Quantitative** | Display presentations that | | | reflect the quantitative value of | | | some variable. | +-----------------------------------+-----------------------------------+ | 2. **Qualitative** | Display presentations that | | | reflect the approximate... | | | | | | - value | | | | | | - trend | | | | | | - rate of change | | | | | | - direction of change | | | | | | - other aspect of changing | | | variable | +-----------------------------------+-----------------------------------+ | 3. **Status** | Display presentations that | | | reflect the condition or status | | | of a system. | +-----------------------------------+-----------------------------------+ | 4. **Warning and signal | Display presentations used to | | information** | indicate emergency or unsafe | | | conditions. | +-----------------------------------+-----------------------------------+ | 5. **Representational | Pictorial or graphic | | information** | representations of objects, | | | areas, or other configurations. | +-----------------------------------+-----------------------------------+ | 6. **Alphanumerical and symbolic | Display presentations of verbal, | | information** | numerical, and related coded | | | information in many forms. | +-----------------------------------+-----------------------------------+ | 7. **Identification | Display presentations used to | | information** | identify some static condition, | | | situation, or object. | +-----------------------------------+-----------------------------------+ | 8. **Time-phased information** | Task, resource, or assignment | | | information that is distributed | | | over time. For example, a Morse | | | code. | +-----------------------------------+-----------------------------------+ 2. **Controls** Facilitates the transmission of user's ideas or decisions to machines / mechanism / system. 10. **Types of controls** **Activation** Activation of a certain status of a system / machine, example light switch. ------------------------- ----------------------------------------------------------------------------- **Discrete settings** Separate pre-existing positions, example car radio with pre-set channels. **Continuous settings** Finer, in between settings, radio volume tuner. **Continuous control** control requires continuous control, example steering wheel. **Data entry** controls used to input data into system, example keyboard. **Tools** Examples hammer, drill, cutlery. 11. **Design (coding) principles** **Position/location** Use a standard location and provide sufficient spacing, placed well within reach ------------------------------------ ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- **Shape** Especially important where vision is unreliable, e.g. Gear levers of a automobile **Size** Especially important where vision is restricted. Size difference must allow discrimination **Colour** It's important to limit the categories of colours -5 colours max. Is recommended **Labels** Must be visible and complement another coding. Operator must be literate to them. **Grouping** Controls that relate to same function should be grouped together **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* \[below\]. **Control movement stereotypes** People have expectations (trained stereotypes) of what to do with controls in order to activate them. Control design should take these stereotypes into consideration. Examples of stereotypes: **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*). 12. **Common Cognitive Tasks** Overall (considering everything you have learned at this point), cognitive work typically involves the following three information-processing tasks: It involves, planning, designing, problem solving, troubleshooting. You can't disentangle the three completely. 6. **Decision making** The cognitive operation which involves making a judgment to select, from a number of alternatives, one alternative to achieve some objective or satisfy some criteria. - Decision is different to choice reaction - Decision making Models 1. **Rational Decision Making** Sometimes called a normative decision making because these are decisions that are made in a way which takes consideration what ought to be achieved. They take a quantitative process to arrive at decisions. They are rooted in economics, measurement, statistics. "You take a conscious effort to play lotto or to invest in something and that decision is then weighed against facts". To people making rational decisions will arrive at the same outcome. 2. **Descriptive Decision Making** This is a situation where choices are made in a cognitive and behavioural sense. You make decisions based on heuristics, you do not have to calculate everything to the detail or using statistical models. (Simplifications). Used when we are bombarded with a lot of information. You need to open to being vulnerable by going for descriptive decision making. You're making decisions on the rule of thumb. You do not have time to make rational decisions. Gut feelings. People make bad decisions because they have no experience. 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 - The decision maker considers a series of options until one is found that is satisfactory. - That alternative is then selected because finding a better alternative is not worth the additional effort. - The term satisfying is derived from "satisfactory decision,". - 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 - People tend to give more weight to information obtained early in the decision-making process. - This the final decision is influenced more by early information that anchors the process than by information obtained subsequently. 3. Availability heuristics - People are more likely to retrieve from long-term memory a hypothesis that has been used recently or frequently. - It is readily available. - 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 - Here, a person makes a decision about a given entity because it appears to fit the mind's prototype of that entity. - 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. 2. - **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. - **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. - 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. - 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. - 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. - 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. **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 confirm the chosen hypothesis but overlooks or ignores clues that might disprove it. - **Stuck in a loop**: This0 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. **\ ** **THEME 4: ORGANISATIONAL HUMAN FACTORS AND ERGONOMICS** **A SYSTEMS APPROACH** 1. **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 2. **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. **HUMAN-MACHINE SYSTEMS MODEL** It explains the working context of Human Machine interaction. Humans and machines interact and affect one another; however, compared to communication between humans, the media available are restricted only to the below mentioned displays and operating elements. In this context humans can only use physical input devices, such as buttons, touch-screens, keyboards, or mouse. For their part, machines can give information visually (e.g. as pictures and characters), acoustically (verbal or nonverbal) or physically (e.g. vibration). Complex interaction between humans and machines (like in aviation) is limited/challenged by the fact that whereas humans have natural intelligence, which enables us to interpret situations according to the context, this ability is absent in most machines and very restricted even in the most advanced Human Machine interaction happens through the media of Human-Machine Interface (HMI): the part of an electronic machine or device which serves for the information exchange between the operator/user (human)and the machine/device. The HMI therefore consists of three parts which are (1) operating elements, (2) displays,and (3) an inner structure. The inner structure compasses hardware and software (electronic circuits and computer programmes). Displays show and transfer information about the machine to the user (for instance by means of graphical displays) and operating elements transfer information from the operator to the machine via for instance push buttons,switches, adjusting knobs, etc. Reminder: Social Environment involves, humans, machines and the tasks that have to be done \[inputs from human or machine\] outputs and displays \[light, noise, heat, electricity\] **Outline of the Theme** - Human characteristics: Psychological aspects (Stress) - The physical environment: Theme 2 & 5 - Work design and organization: Hours of work (Shift work) - Socio-economic factors: Law (Occupational Health & Safety) - Health and Safety: Accidents, Human Errors and Safety - Information Presentation and Communication: Theme 3 - Methods and Techniques: Human Factors Investigation 3. **Human Characteristics:** 1. **Stress and Fatihue** 1. **Stress** - It is the adverse reaction people have to excessive pressure or other types of demand placed upon them. - **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. 2. **Fatigue** - 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. - 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) 2. **Work Design and Organisation: Work Scheduling and Shift-Work** - **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. - **Economic pressures:** Shared production machinery and growth in the use of overtime. Certain laws make workers work overtime. - **Service sector demands:** Many service sectors jobs such as nurses, policemen, emergency services are needed around the clock. -- -- -- -- 3. **The Circadian Rhythms and Shift Work (Impact of Shift Work on The Body)** - **Physiological variables**: Alertness, heart rate, neurotrammiter activity - **Body temperature**: Rises during the day and drops at night \[rises within a range\] - **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. - **Urine production**: increases at night and falls by day. - **Appetite sensation**: low during sleep time. - 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. 3. **Improving Shift Work: Some Important Considerations** - **Direction**: Forward (Morning-Afternoon-Evening-Night) with breaks in between is preferable over Backward (Night-Evening-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) - People living alone - Morning-type people - Older employees 4. **Occupational Health And Safety (Socio-Economic Factor)** - 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). - 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. \[Event related occurrence\] - 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. 1. ***\ *** A. Occupational Safety, Accidents and Human Error B. Occupational Health C. Occupational Health and Safety Legislation 4. **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. 5. **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. \[These types of human error can happen to even the most experienced and well-trained person.\] 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 1. **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 and to classify errors because conditions that produce the different kinds of errors often have different remediations (interventions). 1. **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. **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. **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. 2. **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. 3. **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. - **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 response-selection (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. - **A lapse**: unlike a slip, this is a nonintentional 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. you've been typing an assignment document for a very long time and forget to save it. 2. **Violations** Violations: unlike errors, violations are intentional failures, i.e. intentionally doing something inappropriate AKA non-compliance. \[Both the action and the outcome are intended. You already knew what you were doing\] - - - **Error Classification Summary** **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. +-----------+-----------+-----------+-----------+-----------+-----------+ | **Errors* | **Charact | **Failure | **Example | **Typical | | | * | eristics* | Types** | s** | Control | | | | * | | | Measures* | | | | | | | * | | +===========+===========+===========+===========+===========+===========+ | | | Associate | **Slip** | A simple, | - Human | | | | d | | frequentl | -centred | | | | with | (Commissi | y | desig | | | | familiar | on) | performed | n | | | | tasks | | physical | (cons | | | | that | | action | istency | | | | require | | goes | e.g. | | | | little | | wrong: | Up | | | | conscious | | | alway | | | | attention | | - flash | s | | | |. | | headl | means | | | | These | | ights | off; | | | | 'skill-ba | | inste | intui | | | | sed' | | ad | tive | | | | errors | | of | layou | | | | occur if | | opera | t | | | | attention | | ting | of | | | | is | | winds | contr | | | | diverted, | | creen | ols | | | | even | | wash/ | and | | | | momentari | | wipe | instr | | | | ly. | | funct | umentatio | | | | | | ion | n; | | | | Resulting | | | level | | | | action is | | - move | of | | | | not | | a | autom | | | | intended: | | switc | ation | | | | 'not | | h | etc.) | | | | doing | | up | | | | | what you | | rathe | - Check | | | | meant to | | r | lists | | | | do'. | | than | and | | | | | | down | remin | | | | Common | | (wron | ders; | | | | during | | g | proce | | | | maintenan | | actio | dures | | | | ce | | n | with | | | | and | | on | 'plac | | | | repair | | right | e | | | | activitie | | objec | marke | | | | s. | | t) | rs' | | | | | | | (tick | | | | | | - take | off | | | | | | readi | each | | | | | | ng | step) | | | | | | from | | |