HUMAN FACTORS
AND ERGONOMICS
IB DESIGN TECHNOLOGY
1
Edited by Jolan Martinez
HUMAN FACTORS AND ERGONOMICS
1.1
Anthropometrics
Featured Designer
Anthropometrics
“Design is human centred and, therefore, designers need to ensure that the products they design are the right size for the user and therefore comfortable to use. Designers have access to data and drawings, which state measurements of human beings of all ages and sizes. Designers need to consider how users will interact with the product or service. Use and misuse is an important consideration”.
1.1
Human Factors and Ergonomics
ERGONOMICS
As designers, many of the things we create will interact with human bodies. The user might wear them, hold them, swing them, look through them, or ride them. The products we make therefore have to fit the human body. This is called ERGONOMICS - The relationship between products and workplaces and the human body.
ANTHROPOMETRICS�Making sure a product or workplace fits the body is where anthropometrics come into play. Anthropometry is the measurement of the human body. Common measurements focus on length, girth, weight, angles and more, but the precise measurements required will depend on the product type.
Q: Look at the headphones pictured. What measurements might you need?
THE DIFFERENT TYPES OF DATA�When measuring the body, there are two main types of measurement we need to consider…
�STATIC (aka STRUCTURAL)
This type of measurement is taken from a body in a fixed position, such as a the height of a standing person, or the circumference of the head in the case of the headphones.
DYNAMIC (aka FUNCTIONAL)
This type shows the measurements while an action is taking place, for example, what is the angle change between hands as someone is steering, or the angle of the bend of a foot when running? For some wired headphones, it might be the angle and distance of head rotation.
Q: For headphones, what data would we need, and what type would it be?
1.1
Anthropometrics
Human Factors and Ergonomics
SOURCES OF DATA�
SECONDARY
Collecting data isn't easy or cheap. For good data, you need a large number of users measured, maybe spanning a variety of age and genders. A designer working on an internationally distributed product will need to know the data of people from different countries to know how they vary, For this reason, if that data is already available, it makes sense to buy it rather than generate it. Secondary data is data collected by someone other you as the designer/user. It might come from commercial or government surveys, such as this one by the CDC.
PRIMARY
Of course, there might be times when you need to generate this data yourself. Some products are bespoke for a single user, such as a prosthetic limb. Primary data is data collected personally for a specific purpose.
PERCENTILES and PERCENTILE RANGES
So you have all that data. The first thing you will notice is that there will be quite a range. This range is often presented in percentiles. A percentile shows the percent of people who meet or are below a certain condition. For example, if you are in the 20th percentile for height, 80 percent of the people out there are taller than you. If you are in the 50th percentile, you are average!
This data is used to decide what dimensions our product must adhere to in order to cater to our users measurements. A designer has to decide the range of measurements they want to cater for.
Buttons on a vending machine are placed for the 50th for height.
A cinema seat might consider the 95th for size.
A seat belt might consider 5th to 95th for size.
Buttons on remote might consider the 5th for finger length.
PERCENTILE | STATURE (HEIGHT) |
5 | 110cm |
10 | 116cm |
20 | 122cm |
30 | 128cm |
40 | 132cm |
50 | 137cm |
60 | 141cm |
70 | 144cm |
80 | 149cm |
90 | 152cm |
95 | 155cm |
Q: Think of a product that would fail without secondary data, and one that would fail with primary?
Q: What is your percentile for height? Check here.
LINKS
TBA
1.1
Anthropometrics
Human Factors and Ergonomics
RANGE OF SIZES vs ADJUSTABILITY
RANGE OF SIZES- A designer will create products in a range of sizes to best accommodate the range of user measurements. In the headphones pictured, a number of inner ear attachments are included, from S to XL size!
ADJUSTABILITY- It might be possible to create a product that physically adjust to the measurements of all users within a certain range. Think a baseball cap or car seat. The benefit of this is that with ranged sizes, some users might fall between the gaps (EG too small for XL but too big for L). The headstrap of over ear headphones adjusts in this way.
CLEARANCE, REACH and ADJUSTABILITY
CLEARANCE- The distance or space between points, such as a head and a door frame.
REACH- Distance/range that can be reached from a certain position, such as a car brake.
ADJUSTABILITY - How a product can adjust form to fit users of different measurements.
Q: Advantages/disadvantages of each?
Q: Name a product that could fail if this data was not used in the design, and why?
1.2
Psychological Factors
Featured Designer
Psychological Factors
1.2
Human Factors and Ergonomics
Human beings vary psychologically in complex ways. Any attempt by designers to classify people into groups merely results in a statement of broad principles that may or may not be relevant to the individual. Design permeates every aspect of human experience and data pertaining to what cannot be seen such as touch, taste, and smell are often expressions of opinion rather than checkable fact.
PSYCHOLOGICAL FACTOR DATA�We just spent time looking at anthropometric data. To make a product successful, we need to know more than just body measurements. We need to know what is going on in the mind. We need to know how to make our product fit with how people think and behave in the environment that they will use the product.
Psychological Data (or Human factor Data)
is data related to psychological interpretations caused by factors such as
�LIGHT - TEMPERATURE - TASTE - SMELL - SOUND - TEXTURE
Notice that these are all things that can be sensed.
The user will interpret information gained from these factors, which then influences their behaviour. It might make the user react in a certain way, for example feel the need to break if their vision is obscured. If the temperature is too hot, it might make them irritable and lose concentration.
We need to understand how our user will interpret and react to these factors.
Q: How might the rider experience these factors?
1.2
Psychological Factors
Human Factors and Ergonomics
ENVIRONMENTAL FACTORS
Some psychological interpretations are influenced by the environment. These affect things such as the users…
PERCEPTION - The way in which something is regarded, understood or interpreted.
ALERTNESS - The level of vigilance, readiness or caution of an individual.
Some of the environmental factors that affect perception and alertness are…�
VISIBILITY- On a dust filled track, it might be hard to perceive the track ahead.
ACOUSTICS - With a screaming crowd, it might be hard to perceive audio cues.
TEMPERATURE- Riding on a hot day might reduce your alertness levels
ALTITUDE- Riding high with lower oxygen levels will also reduce alertness.
Q: How might these factors influence this rider?
DATA TYPES�Collecting this kind of data is a little different to Anthropometric data, which as a data type falls under the category of ��QUANTITATIVE DATA- Measured by number or value (key is in the word - quantity).
�Psychological data cannot be measured with a ruler however. It doesn't present as a number. A feeling or thought presents as a description given by the user. For this reason, it is of the type QUALITATIVE DATA- Measurement of the quality, rather than the quantity.
An example of qualitative data might be how hot a user FEELS, rather than the actual temperature (which would be quantitative).
Q: Prepare for a rapid fire “Which is is test”.
1.2
Psychological Factors
Human Factors and Ergonomics
HUMAN INFORMATION PROCESSING SYSTEMS�So we now know some of the factors that might affect how users think. Now let's look a way to understand HOW the user will react to them. Think of this as Cognitive ergonomics
We are going to look at how humans process information. If you can understand how this works, we can design products that work with the process, not against it. Here is a simple example:�
You might have heard people say a product it counter intuitive. This could be because the way the designer intended the product to be used goes against the way the user will process while using.
Mud splashes over the riders visor
The eyes can no longer detect light
User has a choice. Stop or keep going. As the rider cant see, the brain says stop. Message is sent to arms.
The rider breaks with one hand, and moves the other up to clean the visor.
INPUT
-----
SENSORY PROCESS
CENTRAL PROCESS
MOTOR PROCESS
Rider can see again and speeds up.
OUTPUT
-----
Q: What would the process be for a burst tire?
BREAKDOWN OF HUMAN INFORMATION PROCESSING SYSTEMS�As a designer we might create products to work perfectly with the way people process information. We have to be aware however, that there can be a breakdown at any of the stages listed above. This needs to factor in our designs. Here are some examples.
SENSORY PROCESS- It is possible that the user does not, or cannot sense the input. For example, a fire alarm is missed by a person with hearing loss
CENTRAL PROCESS- The user may process slowly, or incorrectly. Maybe a drunk driver is too slow to react to seeing a person in the road.
MOTOR PROCESS - What happens if a user gets cramp, or has limited movement in one arm?
Q: Give an example of a product and process that can break in each way listed above.
1.2
Psychological Factors
Human Factors and Ergonomics
LINKS
TBA
COLLECTING PSYCHOLOGICAL DATA�There are a number of ways to collect this type of data. It could be
�OBSERVATION- Recording how a user behaves in a certain situation
SURVEY/INTERVIEW- Written or spoken questioning
CASE STUDY- A study over a period of time, on location, including the methods above.
QUESTIONING METHODS
Q: Imagine you are questioning someone on their breakfast habits. Create a question for each.
Which of the following bike safety products do you use? | How hot did it feel inside the helmet? | What day did you take part in the test ride? | Rate your experience running between 1 and 5… | ||||
HELMET VISOR GLOVES SHIN/WRIST GUARDS BACK PROTECTOR | X X |
| x | Mon Tue Wed Thur Fri Sat | x | 0 1 2 3 4 5 | x |
ORDINAL
Options in a hierarchical order. The difference between values is not objectively equal or measurable.
INTERVAL
Interval data are based on numeric scales in which we know the order and the exact difference between the values. Organised into even divisions or intervals, and intervals are of equal size.
RATIO
A ratio scale allows you to compare differences between numbers FROM ZERO. For example, use a rating scale of 0-10 to evaluate user responses.
NOMINAL
Selection of options by named class or
group
1.3
Physiological Factors
Featured Designer
Physiological Factors
1.3
Human Factors and Ergonomics
Designers study physical characteristics to optimize the user’s safety, health, comfort and performance.
PHYSIOLOGICAL FACTOR DATA�The final thing we will look at in unit 1 is PHYSIOLOGICAL data. This type of data concerns data related to physical characteristics used to optimise the user's safety, health, comfort and performance. The body is a complex system. We sweat when it is hot. Muscles cramp when strained. We blink when something gets in your eye. All these physiological processes combine to keep us functioning as a whole.
When designing a product, we need to consider how the body will function during use. Examples of physiological factors a designer might take into consideration are:��ENDURANCE- How long a certain action can be performed before exhaustion stops it.
�TOLERANCE- How much force can be withstood.
�COORDINATION- How different body systems interact to complete a task.
�STRENGTH- How much force can be applied during an particular action.
�STRESS- The physical type. What points on the body feel the most impact or strain?
A variety of methods can be used to generate this data, such as testing, observation and measurement. Let’s think about the example pictured...running shoes.
Q: What data can be used to make a shoe safer, more comfortable, and enhance performance?
Physiological Factors
1.3
Human Factors and Ergonomics
Q: For a running shoe, give an example of how this knowedge could improve a product.
BIOMECHANICS
Biomechanics is the study of how the components of the human body interact to perform movements. These components include muscle, bone, skin, ligaments, tendons, and blood. Think about our runner over there. There is a lot going on in order to propel them forward to create motion. Muscles will tighten and relax. Joints will rotate. Blood will rush to certain areas. Understanding this helps designers to be more successful in terms of creating an effective design. It could help shape designs in these four areas
INCREASED PERFORMANCE- by understanding how the body moves mechanically, we can increase the performance of the user at a given task. The running shoe is a great example. The designer will understand the point on the foot where pressure is exerted to propel the runner forward. They can then use a more springy material to help push off from that point.
REDUCTION OF INJURY/SAFETY- By understanding data related to strain, designers can reduce the chances or severity of injury. The Nike Zoom are a good example of this. They have a custom foam that absorbs much more of the impact on the heel when the runner brings down their foot. Biomechanical data from observation will have helped decide the location of this foam.
REDUCTION OF FATIGUE
The longer a person is engaged in physical or mental activity, the more fatigued they will become. Fatigue can take the form of a loss of physical energy, in the case of a runner at the back end of a race, and/or tiredness. Through understanding the physiological data, designers can work to reduce fatigue.
INCREASED COMFORT
Comfort can be defined as “A feeling of ease, and freedom from pain or discomfort”. Pretty important for a product, as a user will not want to use something that causes them to suffer. Understanding physiology is vital in making something comfortable.
1.3
Physiological Factors
Human Factors and Ergonomics
OTHER FACTORS
It is really important to understand that there is not one universal biomechanical system. Different people work in different ways. Examples being:
AGE- For example the ability to rotate the wrist to open a jar (TORQUE) is reduced.�GENDER- Slight variations in bone and muscle structure are what lead to male and female shoes.�DISABILITY- For example, partial paralysis.
WORKPLACE ENVIRONMENTAL FACTORS
The workplace is a physical place! If you want to maximise performance and reduce injuries…
• Management should have policies, and organise safety education
• Consider the physical environment (noise, temperature, pollutants, trip hazards, signage).
• Have safe equipment design (controls, visibility, hazards, warnings, safety guards).
• Consider the the nature of the job (repetitiveness, mental or physical workload, force, pressure).
• Understand the social or psychological environment (Social group, morale).
• Know your workers (personal ability, alertness, age, fatigue).
LINKS
TBA
Q: What other biomechanical processes change as we age?
1
GLOSSARY
TOPIC 1 GLOSSARY
TERM | DEFINITION |
Adjustability | The ability of a product to be changed in size, commonly used to increase the range of percentiles that a product is appropriate for. |
Alertness | The level of vigilance, readiness or caution of an individual. |
Anthropometrics | The aspect of ergonomics that deals with body measurements, particularly those of size, strength and physical capacity. |
Biomechanics | The research and analysis of the mechanics of living organisms. Biomechanics in Human factors includes the research and analysis of the mechanics (operation of our muscles, joints, tendons, etc.) of our human body. It also includes Force (impact on user’s joints), Repetition, Duration and Posture. |
Clearance | The physical space between two objects. |
Cognitive ergonomics | How mental processes, (memory, reasoning, motor response and perception), affect the interactions between users and other components of a system. |
Comfort | A person's sense of physical or psychological ease. |
Dynamic data | Human body measurements taken when the subject is in motion related to range and reach of various body movements. E.g. crawling height, overhead reach and the range of upper body movements. |
Environmental factors | A set of psychological factors that can affect the performance of an individual that come from the environment that the individual is situated. |
Ergonomics | The application of scientific information concerning the relationship between human beings and the design of products, systems and environments. |
Fatigue | A person's sense of physical or psychological tiredness. |
Functional data | Functional data includes dynamic data measurements while performing a required task e.g. reaching abilities, manoeuvring and aspects of space and equipment use. |
Human error | Mistakes made by users, some of which can result in catastrophic consequences for people, property and the environment, as they are considered key contributors to major accidents. |
Human factors | A scientific discipline concerned with understanding how humans interact with elements of a system. It can also be considered the practice of designing products, systems or processes to take account of the interaction between them and their users. It is also known as comfort design, functional design and user-friendly systems. |
Human information processing system | An automatic system that a person uses to interpret information and react. It is normally comprised of inputs, processes (which can be sensory, central and motor), and outputs. |
Interval data | Interval data are based on numeric scales in which we know the order and the exact difference between the values. Organised into even divisions or intervals, and intervals are of equal size. |
Nominal data scale | Nominal means 'by name' and used in classification or division of objects into discrete groups. Each of which is identified with a name e.g. category of cars, and the scale does not provide any measurement within or between categories. |
TOPIC 1 GLOSSARY
TERM | DEFINITION |
Ordinal data | A statistical data type that exists on an arbitrary numerical scale where the exact numerical value has no significance other than to rank a set of data points. Deals with the order or position of items such as words, letters, symbols or numbers arranged in a hierarchical order. Quantitative assessment cannot be made. |
Percentile range | That proportion of a population with a dimension at or less than a given value. For a given demographic (gender, race, age), the 50th percentile is the average. |
Perception | The way in which something is regarded, understood or interpreted. |
Physiological factor data | Human factor data related to physical characteristics used to optimise the user's safety, health, comfort and performance |
Primary data | Data collected by a user for a specific purpose. |
Psychological factor data | Human factor data related to psychological interpretations caused by light, smell, sound, taste, temperature and texture. |
Qualitative data | Typically descriptive data used to find out in depth the way people think or feel - their perception. Useful for research at the individual or small (focus) group level |
Quantitative data | Data that can be measured and recorded using numbers. Examples include height, shoe size, and fingernail length. |
Range of sizes | A selection of sizes a product is made in that caters for the majority of a market. |
Ratio data scale | A ratio scale allows you to compare differences between numbers. For example, use a rating scale of 1-10 to evaluate user responses. |
Reach | A range that a person can stretch to touch or grasp an object from a specified position. |
Secondary data | Data collected by someone other than the user. |
Static data | Human body measurements when the subject is still. |
Structural data | Refers to measurements taken while the subject is in a fixed or standard position, e.g. height, arm length. |
Workplace environmental factors | These factors can be considered to maximise performance of a user in a role and reduce the risk of accidents. They can be categorised as: • Management (policies, safety education) • Physical environment (noise, temperature, pollutants, trip hazards, signage) • Equipment design (controls, visibility, hazards, warnings, safety guards) • The nature of the job (repetitiveness, mental or physical workload, force, pressure) • Social or psychological environment (Social group, morale) • The worker (personal ability, alertness, age, fatigue) |