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CVEN 4405 Human Factors in Civil and Transport Engineering

Term 3 2020 Week 2 - Lectures 1a and 1b

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CVEN4405: Human Factors in Civil and Transport Engineering

Human Performance Limitations 3:

Memory and Decision Making Term 3, 2020

Week 2, Lecture 1a

3

Welcome Back!

4

Course Coordinator and Lecturer

Prof. Michael Regan, PhD Professor of Human Factors

Research Centre for Integrated Transport Innovation (rCITI) School of Civil and Environmental Engineering

University of NSW Sydney

T: +61 (0)2 9385 9504 E: [email protected]

Staff Webpage

5

The CVEN 4405 Teaching Team

Coordinator and Lecturer Prof. Michael Regan Professor of Human Factors Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Teaching Fellow Dr Prasannah Prabhakharan Research Fellow Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Demonstrator Mitch Cunningham E: [email protected]

6

Last Thursdays Tutorial

• How was it? (for those who went…) • Which of the following Civil Engineering functions do you

think Human Factors is most relevant to:

 Design?  Construct?  Manage?  Maintain?

7

Review of Last Lecture

• Perception • Perceptual Countermeasures • Attention • Types of Attention • Design guidelines for attention • Questions?

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Lecture 1a - Overview

• Human memory • Sensory Memory • Working Memory

– Design guidance for working memory • Long-Term Memory • Decision Making

– Biases and design guidance for decision making • Questions

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Learning Outcomes

CLO1: Explain the fundamental principles of HF that can be used by civil and transport engineers to facilitate user- centred design

CLO2: Apply HF principles, methods and data to the design of road and traffic management systems

CLO3: Plan for the integration of HF into the design lifecycle of the road and traffic management system

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Wickens’ Model of Human Information Processing - Memory

Source: Source: Adapted from Wickens (1992), p. 17

Human Memory

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3 Types of Memory

Psychologists have distinguished between 3 types of human memory:

1. Sensory Memory (short term sensory store; STSS) 2. Working Memory 3. Long-Term Memory

Source: Sanders & McCormick (1987), p. 60

Sensory Memory

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Sensory Memory

• Sensory memory - is a temporary storage mechanism that allows people to retain representations of sensory information for very short periods after the original stimulus has ceased

• Sensory memory enables us to sense a lot of information while the brain decides what is important to process further and what is not.

• There is evidence that there is sensory memory for each of the five major senses - touch, taste, sight, hearing, and smell.

Source: Sanders & McCormick (1987), p. 61

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Sensory Memory (2)

Most is known about 2 types of sensory memory: – echoic memory (auditory system) – iconic memory (visual system)

Iconic storage lasts for less than a second – look out the window then close your eyes

Echoic memory can last for a few seconds before fading – listen to the sound I make

Sensory information isn’t coded – it is stored in its original sensory representation

Source: Sanders & McCormick (1987), p. 61

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Sensory Memory (3)

It is not necessary for people to attend to sensory information in order for it to be stored in sensory memory; storage is automatic

Not much can be done to prolong the length of sensory representations; for the information to be retained for longer, it has to be transferred to working memory

Source: Sanders & McCormick (1987), p. 61

Working Memory

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Working Memory – Defined

Working memory is storage mechanism that allows you to keep information in your mind for a short period of time so that it is available for further processing.

The half time (HT) of working memory is 7 secs; after 7 secs, half the information in it has been forgotten.

In order to transfer information from sensory memory to working memory we have to code it and direct attention to the information.

Source: Sanders & McCormick (1987), p. 61; Hender, 2006, p.72

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Working Memory - Coding

It is thought that we code information so that it gets into working memory in 3 ways:

1. Visually • e.g. we remember a picture of a dog in our heads

2. Phonetically • e.g. we remember the sound of the word “dog” in our heads

3. Semantically • e.g. we remember a more abstract memory of a dog in our heads

Source: Sanders & McCormick (1987), p. 61

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Working Memory - Capacity (1)

To keep information in working memory, we have to rehearse it: to pay attention to it and code it in the ways just described.

If we don’t rehearse it, it is lost from working memory after 2-3 seconds or so and never reaches long-term memory.

Forgetting someone’s name after you just heard it is an example

• Unless you keep repeating it in your head, you forget it.

Source: Sanders & McCormick (1987), p. 62; Goldstein (2010)

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Working Memory - Capacity (2)

Exercise: When I say “GO”, start counting backward by 3s starting from the number 187.

While you are counting backwards, I’m going to flash 4 letters onto the screen while you count backwards

But keep counting backwards by 3s when you see them. When I say “STOP”, after 15 seconds, stop counting

backwards. OK start counting backwards by 3s from 187 and don’t stop

until I say stop – OK “GO”

Source: Sanders & McCormick (1987), p. 62

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Working Memory - Exercise: Letters (1)

T J N L

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Working Memory - Exercise: Letters (2)

• “STOP” - how many of you remembered: – 1 letter? – 2 letters? – 3 letters?

• What were the letters?

What is usually found, in laboratory settings, is that people often don’t remember any of the letters – because counting backwards prevents you from rehearsing the letters

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Working Memory - Capacity (3)

Even if people rehearse information in working memory, it can decay over time.

The more items of information you have in working memory, the more rapid is the decay – because rehearsing a long list of items delays the rehearsal of individual items.

Source: Sanders & McCormick (1987), p. 62

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Working Memory - Capacity (4)

• Discussion: What do you think is the maximum number of items you can hold in working memory? – e.g. the maximum number of letters you can hold in

working memory if you rehearse them?

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Working Memory - Capacity (5)

The answer is the “magical number 7 +/- 2” – in other words, between 5 and 9 items (e.g. 5 to nine letters or numbers)

BUT – people can “chunk” items of information.

Source: Sanders & McCormick (1987), p. 62

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Working Memory - Capacity (6)

I’m going to show you three items of information. I’ll give you 2 secs per item. Each time, write down what you see.

Ready?

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Working Memory - Capacity (7)

R F S

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Working Memory - Capacity (8)

N T O I A N M X E I A

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Working Memory - Capacity (9)

E X A M I N A T I O N

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Working Memory - Capacity (10)

R F S N T O I A N M X E I A E X A M I N A T I O N

• Which item of information was easiest to remember? Why?

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Working Memory - Capacity (11)

The last item “EXAMINATION” was easiest to remember because it contained only one “chunk” of information.

The second item “NTOIANMXEIA” was harder to hold in working memory because it contains 11 “chunks” of information (11 unrelated letters).

Working memory can only hold between 5 and 9 chunks of information at a time – so it is important, for example, not to present too much information at once to a driver of a car because much of it may not be remembered.

Source: Sanders & McCormick (1987), p. 62

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Working Memory - Capacity (12)

• What about the following letters. How many chunks of information do they contain?

C A T D O G R A T Are the number of chunks of information within the 7 +/- 2 limit

of working memory?

Source: Sanders & McCormick (1987), p. 62

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Working Memory - Capacity (13)

As design engineers, you can use chunking to advantage:

E.g. numbers can be recalled better if they are grouped into chunks of three or four items

Which phone number is easier to remember?

0437 737 214 vs

0437737214

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Working Memory - Capacity (14)

The more meaningful the chunks, the easier they will be to recall e.g.

IBM JFK TV vs

JB MJF KTV

Source: Sanders & McCormick (1987), p. 62

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Working Memory - Capacity (15)

Information in working memory fades or is replaced if another item of information arrives.

If a driver is trying to recall something in working memory, their ability to perceive other information along the road environment may be impaired, and they miss traffic and other signals.

Conversely, if a driver attends to a traffic or other signal in the road environment, the information that is in working memory may be lost

Source: Ogden (1992)

Design Guidance for Working Memory

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Design Guidelines for Working Memory (1)

1. Avoid presenting more than 5 to 9 chunks of information for people to remember

2. Present information in meaningful and distinct chunks 3. Provide training on how to better recall information by

chunking 4. Warnings should require an immediate response, so that

the warning information is not replaced or fades from working memory

5. Drivers should be frequently reminded of vehicle control information which varies along the road (e.g. speed limits)

Source: Sanders & McCormick (1987); Ogden (1992)

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Design Guidelines for Working Memory (3)

6. The rate of information gathering which is required should be limited to ensure that the driver has time to respond to one signal before the next signal is presented.

7. Drivers should be frequently reminded of vehicle control information which varies along the road (e.g. speed limits)

8. The rate of information gathering which is required should be limited to ensure that the driver has time to respond to one signal before the next signal is presented.

Source: Sanders & McCormick (1987); Ogden (1992)

Long Term Memory

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Long Term Memory

Whereas we maintain information in working memory for immediate use, we need a mechanism for storing information and retrieving it later.

This mechanism is Long-Term Memory.

We transfer information from short-term memory to long-term memory by coding it semantically – i.e. by attaching meaning to the information and relating it to information that has already been stored in long-term memory.

Source: Sanders & McCormick (1987), p. 62; Wickens et al., (2004)

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Long Term Memory – Mnemonics (1)

Mnemonics can be used to make it easier to store and retrieve information from long-term memory.

• Discussion: How, for example, do all of you remember the names of all the planets radiating, in order, away from the sun?

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Long Term Memory – Mnemonics (2)

I use the following mnemonic:

• My Very Eager Man Just Swept Up Nine Pins

• M = Mercury • V = Venus • E = Earth • etc

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Long Term Memory – Mnemonics (3)

• Discussion: How do you remember the colours of the light spectrum?

45

Long-Term Memory – Mnemonics (4)

I use the following mnemonic:

ROY G. BIV • colours of the spectrum (Red, Orange, Yellow, Green, Blue,

Indigo, Violet.)

Decision-Making

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Wickens’ Model - Decision Making

Source: Adapted from Wickens (1992), p. 17

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Decision Making (1)

Decision making is a critical point in the sequence of human information processing

Some decisions are careful and thoughtful, and take a long time (e.g. planning a holiday)

Others are rapid, and more automatic – e.g. when deciding to accelerate or decelerate when a traffic signal turns amber

Source: Wickens (1992), p. 19

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Decision Making (2)

When people make decisions, they “evaluate alternatives and select a course of action”.

Decision making involves 3 main processes: 1. Seeking information relevant to the situation at hand 2. Estimating the probabilities of various outcomes 3. Attaching values to the anticipated outcomes

Source: Sanders & McCormick (1987), p. 63

Decision Making – Biases and Design Guidance

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Decision Making – Biases

People – including road users – are not optimal decision makers and often do not act “rationally”

• they don’t act according to objective probabilities of gain and loss.

They are biased in the way they: 1. seek information 2. estimate probabilities and 3. attach values to this irrational behaviour.

See following slides Source: Sanders & McCormick (1987), p. 63-64; Wickens (1984)

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Decision Making – Biases and Design Guidance 1. People give an undue amount of weight to early evidence

or information. Subsequent information is considered less important.

2. Humans are generally conservative and do not extract as much information from sources as they optimally should.

3. The subjective odds in favour of one alternative or the other are not assessed to be extreme or given as much confidence as optimally they should.

Source: Sanders & McCormick (1987), p. 63-64

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Decision Making – Biases and Design Considerations (2) 4. As more information is gathered, people became more confident in

their decisions, but not necessarily more accurate. • E.g. people who engaged in troubleshooting a mechanical malfunction

are often unjustly confident that they entertained all possible diagnostic hypotheses

5. Human have a tendency to seek far more information than they can absorb adequately

6. People often treat all information as if it were equally reliable, even though it is not.

Source: Sanders & McCormick (1987), p. 63-64

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Decision Making – Biases and Design Considerations (3) 7. Humans appear to have a limited ability to entertain a maximum of

more than a few (three or four) hypotheses at a time.

8. People tend to focus on just a few critical attributes at a time and consider only about two or four possible choices that are ranked highest on those critical attributes

9. People tend to seek information that confirms the chosen course of action and to avoid information or tests whose outcome would disconfirm the choice.

Source: Sanders & McCormick (1987), p. 63-64

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Decision Making – Biases and Design Considerations (4) 10. A potential loss is viewed as having greater consequence

and therefore exerts a greater influence over decision making behaviour than does a gain of the same amount.

11. People believe that mildly positive outcomes are more likely than mildly negative outcomes , but that highly positive outcomes are less likely than mildly positive outcomes.

12. People tend to believe that highly negative outcomes are less likely than mildly negative outcomes.”

These biases explain why, in part, humans do not always make the best decisions based on the information available to them.

Source: Sanders & McCormick (1987), p. 63-64

56

Questions ?

Over to ….

CVEN4405: Human Factors in Civil and Transport Engineering

Human Performance Limitations 4: Response Execution and Responding –

Physiology, Biomechanics, Anthropometry and Feedback

Term 3, 2020

Week 2, Lecture 1b

58

Welcome Back!

59

Course Coordinator and Lecturer

Prof. Michael Regan, PhD Professor of Human Factors

Research Centre for Integrated Transport Innovation (rCITI) School of Civil and Environmental Engineering

University of NSW Sydney

T: +61 (0)2 9385 9504 E: [email protected]

Staff Webpage

60

The CVEN 4405 Teaching Team

Coordinator and Lecturer Prof. Michael Regan Professor of Human Factors Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Teaching Fellow Dr Prasannah Prabhakharan Research Fellow Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Demonstrator Mitch Cunningham E: [email protected]

61

Review of Last Lecture

• Human memory • Sensory Memory • Working Memory

» Design guidance for working memory • Long-Term Memory • Decision Making

» Biases and design guidance for decision making • Questions

62

Lecture 1b - Overview

• Response Execution • Body physiology – Bones, Joints and Muscles • Body movement – Biomechanics

» Manual work » locomotion

• Body size and shape – Anthropometry • Feedback • Questions

63

Learning Outcomes

CLO1: Explain the fundamental principles of HF that can be used by civil and transport engineers to facilitate user- centred design

CLO2: Apply HF principles, methods and data to the design of road and traffic management systems

CLO3: Plan for the integration of HF into the design lifecycle of the road and traffic management system

Response Execution

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Wickens’ Model - Response Execution

Source: Adapted from Wickens (1992), p. 17

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Response Execution (1)

Response execution – or responding – is the last step in Wickens’ chain of information processes that underlie human performance.

A factor that limits the ability of humans to execute a response is the ability to use our joints and muscles, which connect the limbs.

Which brings us to physiology…. (next slide)

Source: Wickens (1992), p. 20

Physiology: Bones, Joints and Muscles

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Physiology: Bones, Joints and Muscles

The human skeleton is made up of 206 bones

The skeleton as two lever systems: • The arms and legs • The spine

Bones are connected to each other at joints

Ligaments and muscles holds the joints tightly together to resist sideways movement; but limit movement when muscles are fully stretched

Source: Oborne (1987), p. 36

69

Muscles: 3 Types of Muscles

There are 3 types of muscles:

1. Skeletal muscles – which control the actions of the main working bones

2. Smooth muscles – which maintains functioning of vital organs not under voluntary control e.g. stomach; intestines

3. Cardiac muscle – which maintains heart function

Source: Oborne (1987), p. 36

Body Movement: Biomechanics

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Biomechanics

“Biomechanics uses laws of physics to describe motion undergone by the various body segments and the forces acting on these body parts during normal daily activities.”

These body movements and forces may enable workers to safely perform jobs

But if they over-stress the body, they may cause musculoskeletal disorders.

Source: Chaffin & Andersson, (1999)

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Biomechanics (2)

Understanding the bases of biomechanical demands when performing physical tasks allows us to design workplaces to minimise the potential for injury.

Two areas of concern in occupational biomechanics are: – Manual work – Locomotion

Biomechanics: Manual Work

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Biomechanics: Manual Work

Musculoskeletal injury as a result of manual tasks are responsible for nearly half of all workers’ compensation claims in Australia.

Manual tasks are defined as tasks “requiring the person to use force to lift, lower, push, pull, carry or otherwise move, hold or restrain any person, animal or thing.”.

Source: Safe Work Australia, (2010), p. 5

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Biomechanics: Manual Work

Biomechanical hazards creating body-stressing forces and movements are the major cause of such injuries.

Mechanisms cited for workers’ compensation claims for body stressing, 2006–07 (Safe Work Australia, 2006–07)

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Biomechanics: Injury

Injury occurs when the forces on a body tissue (e.g. muscle, tendon, ligament, bone) are greater than the tissue can withstand.

These injuries can be: • Acute (i.e., occur suddenly due to a single exposure to a high force) • Cumulative (i.e., occur gradually due to repeated or long-duration

exposure to lower levels of force); or • Combination (e.g., a tissue that has been weakened by cumulative

damage may then be vulnerable to sudden injury by lower forces)

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Biomechanics: Injury (2)

Body parts: Excessive biomechanical loads can damage any body parts involved in movement or force exertion:

• Muscle • Bone • Connective tissues (tendon, ligament, cartilage) • Nerves

Body regions: • Back • Lower limbs (knees, ankles) • Neck • Shoulder • Upper limbs (elbow, wrist, hand).

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Biomechanics: Injury (3)

Biomechanical risk factors: • Force (level of exertion) • Posture • Repetition • Duration • Vibration

Note: Psychosocial factors can exacerbate biomechanical injury risk (e.g., cognitive demands, time pressure, high perceived work demand, fear of consequences, personal workstyle).

79

Muscles: Strength and Endurance

Muscles are limited in their ability to execute actions in 2 main ways:

1. They are limited in strength 2. They are limited in their ability to maintain strength (i.e. muscular

endurance)

Muscle strength varies with many factors: • E.g. age, gender, body position, fitness, health, etc.

Muscle endurance depends on the strength being exerted • the smaller the force required, the longer it can be exerted.

Source: Oborne (1987), p. 40

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Muscles: Strength and Endurance (2)

The maximum force muscles can exert declines exponentially with time.

Maximum efforts can only be maintained for seconds, while a relatively low level of force can be maintained for considerably longer.

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Muscles: Levers and Load

To determine optimum body positions for force exertion or to design work layouts to minimise force demands, the body can be considered as a system of (bio)mechanical levers.

The amount of force necessary to move a load depends on both the mass (weight) of a load and the relative lengths of the load moment arm and muscle moment arm.

Muscle moment arms can’t be changed. Therefore, optimum work layouts aim to minimise load moment arms.

82

Muscles: Levers and Load (2)

Shoulder and lower back moment arms increase with distance of the load from joints.

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Muscles: Levers and Load (3)

Task-related factors that determine biomechanical exposure to loading:

• Size & weight of objects • Position in relation to person (moment arms) • Frequency and/or duration of handling • Weight distribution of object • Friction of surfaces (if pushing or pulling loads) • Environmental constraints (e.g. surrounding equipment, walls, ceilings,

etc.) • Handle design is important for grip (shape, size, position, texture)

84

Muscles: Controls for Biomechanical Risks

Design to control biomechanical risks: • Elimination (change material flows, change to bulk handling, reduce

double handling, outsourcing to specialists) • Work areas (height, space, reach distances, work flow, adjustability) • Loads (size, shape, weight, stability, location, height) • Tools (size, weight, handles, grips, trigger, vibration) • Mechanical aids (hoists, trolleys, conveyers, turntables, adjustable

height pallets, etc.)

85

Muscles: Controls for Biomechanical Risks (2)

Administrative controls to reduce biomechanical risks: • e.g., maintenance, job rotation, task variety, team lifting, training,

housekeeping, PPE • Are significantly less effective and reliable; depend on human behaviour,

supervision and other resources • Are more effective when used in combination with other (design)

controls • Some PPE (e.g., kneepads, protective aprons and gloves) help minimise

loading. • No evidence for ‘back belts’ or ‘abdominal belts’ as prevention.

Biomechanics: Locomotion

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Biomechanics: Slips, Trips and Falls

Inattention to design or maintenance of walking surfaces can lead to slips, trips and resultant falls.

These are a significant cause of musculoskeletal injuries and, occasionally, fatalities.

Injuries occur as a result of either impact forces or internal stresses from the rapid balance-recovery movements necessary.

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Biomechanics: Slips

Safe locomotion requires sufficient friction between the surface and footwear.

This relationship is expressed as the coefficient of friction (CoF):

CoF = F/N Where: • F is the horizontal force required to slide on the surface • N is the normal (i.e., vertical) force exerted on surface.

Australian Standards recommend a minimum CoF of 0.40 for pedestrian safety on level surfaces.

Sloping surfaces require higher levels of slip resistance.

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Biomechanics: Slips (2)

Slip at heel strike

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Biomechanics: Trips

Trips occur when the movement of the foot is unexpectedly impeded by contact with an obstruction in the path of travel.

Obstructions as little as 6 mm above the surface may be potential trip hazards.

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Biomechanics: Trips (2)

Risk factors for slips and trips: – Slippery surfaces – Areas where lubricating contaminants are routinely present (e.g.

water, dust, other spills) – Sudden change in floor surfaces material, level or gradient – Fine growth (e.g. moss on a pavement) – Excessive speed of movement for a given situation (e.g. running, or

turning sharply) – Footwear that is inadequately slip resistant.

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Biomechanics: Trip (2)

Trip on low obstruction

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Slips, Trips and Falls: Prevention

Preventing slips and trips • Ensure design, installation and maintenance of walking

surfaces produces CoF of min. 0.40. • Higher CoF values (e.g., >0.6) may be necessary where

slopes or slippery contaminants might be present. • Ensure good housekeeping • Provide sufficient lighting

Body size and shape: Anthropometry

95

Anthropometry: Overview

• The term “anthropometry” is derived from two Greek words – Anthropo(s) - human – Metricos - pertaining to measurement

• Anthropometry is concerned with the measurement of the dimensions and some other physical characteristics of the body, which are relevant to the design of things that humans use.

Source: Oborne (1987), p. 36; Sanders & McCormick (1987), p. 331

96

Anthropometry: Overview (2)

• Anthropometric measurements and data are used to ensure that the built environment fits the person

• e.g. – Using height data to design door heights – Using pelvis width to design escape hatches – Using hand size to design control dimensions – Using arm reach to design distance to controls

Source: Oborne (1987), p. 36

97

Anthropometry: Overview (3)

Anthropometric data used to come from measurement of people in military populations.

• Discussion: Why do you think that was?

• There are two kinds of anthropometric data that can be used for design:

– Static data – e.g. weight, height, circumference – Dynamic data – e.g. reach; angular ranges of different joints

Source: Oborne (1987), p. 36

98

Anthropometry: Overview (4)

Various databases of anthropometric data now exist for civilian populations e.g.

• (Next slide)

Source: Oborne (1987), p. 36

99

Anthropometric Estimates of British Adults (19- 65 years)

Source: Pheasant (2003), p. 30-45; All dimensions in mm, except for body weight (kg)

100

Anthropometric Estimates of British Adults (19- 65 years)

Source: Pheasant (2003), p. 30-45; All dimensions in mm, except for body weight (kg)

101

Body Dimension Diagrams

Source: Pheasant (2003), p. 30-45

102

Anthropometry: Populations

Most anthropometric measures of populations are normally distributed.

• E.g. Frequency distribution of the stature of adult British men

Source: Pheasant (2003), p. 16

103

Anthropometry: Percentile

Since the curve is symmetrical, it follows that 50% of the population are shorter than average and 50% are taller

In the distribution on the previous slide, the mean is equal to the 50th percentile (50th %ile).

In general, n% of people are shorter that the nth %ile

Source: Pheasant (2003), p. 17

104

Anthropometry: Variability in Size & Shape

People vary in size and shape depending on a range of factors e.g. age, gender, culture, occupation, time.

• E.g. door heights in old castles

Because of this, anthropometric data are reported as average figures and as percentiles

• E.g. average height of males • E.g. 95th percentile height of males (i.e. 95% of males are

this height or less; only 5% are taller

Source: Oborne (1987), p. 47

105

Anthropometry: Application of Data

There are 3 principles for applying anthropometric data to design problems:

1. Design for Extreme Individuals 2. Designing for Adjustable Range 3. Designing for the Average

Source: Sanders & McCormick (1992), p. 336

106

Application: Designing for Extreme Individuals

Where a specific design dimension or feature is a limiting factor restricting use for some people, and we want to design to accommodate virtually all people.

The limiting factor can dictate that we use either a maximum or a minimum anthropometric value for a population to guide design.

• E.g. designing for maximum - door height; escape hatch; others? • E.g. designing for minimum - distance of control from operator; force

required to operate a control; others?

Source: Sanders & McCormick (1992), p. 336

107

Application: Designing for Adjustable Range

Where we want equipment or facilities to be adjusted to the individuals who use them.

Here, usually design to cover the range from the 5th to the 95th percentile for the population characteristic:

• E.g. for adjustable seat height • E.g. adjustable work table height • E.g. adjustable vehicle seats (distance from steering control)

Overcomes problems in designing for extreme ranges

Source: Sanders & McCormick (1992), p. 336

108

Application: Designing for the Average

There is no such thing as the average person – we come in all shapes and sizes.

However, using average anthropometric measures is appropriate in some circumstances – when designing for extreme values or extreme individuals is not appropriate

• E.g. checkout counter at supermarket: height of counter is designed for average height of customers; same with kitchen bench heights

Collectively, causes less inconvenience to customers than catering for the very tall or the very short

Source: Sanders & McCormick (1992), p. 336

109

Wickens’ Model - Feedback

Source: Adapted from Wickens (1992), p. 17

110

Feedback

• We monitor the consequences of our actions as a basis for modifying and improving performance.

• This is depicted as the closed-loop feedback loop in Wickens’ model.

111

Feedback (2)

We receive feedback through not only the visual and auditory receptors, but also through the tactile and proprioceptive receptors.

• eg auditory click we get when pressing a button • eg vibration we get when steer over a rumble strip • eg the visual looming cues we get when get too close

to a vehicle in front

112

Questions ?

Over to ….

Prof. Michael Regan, PhD Research Centre for Integrated Transport Innovation

(rCITI) Room 112, Civil Engineering Building (H20)

E: [email protected]

CVEN4405: Human Factors in Civil and Transport Engineering

Human Performance Limitations 5:

Reaction Time and Human Error Term 3, 2020

Week 2, Lecture 2

115

CVEN 4405 Human Factors in Civil and Transport Engineering

Term 3 2020 Week 2 - Lecture 2

PRESS RECORD BUTTON

+

SHARE SCREEN

+

PRESS AUDIO BUTTON

116

Lecture Recordings

PLEASE NOTE.

This lecture is being recorded.

Participation in this meeting indicates your consent to be included in the meeting recording.

117

Welcome Back!

118

Course Coordinator and Lecturer

Prof. Michael Regan, PhD Professor of Human Factors

Research Centre for Integrated Transport Innovation (rCITI) School of Civil and Environmental Engineering

University of NSW Sydney

T: +61 (0)2 9385 9504 E: [email protected]

Staff Webpage

119

The CVEN 4405 Teaching Team

Coordinator and Lecturer Prof. Michael Regan Professor of Human Factors Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Teaching Fellow Dr Prasannah Prabhakharan Research Fellow Research Centre for Integrated Transport, UNSW Sydney E: [email protected]

Demonstrator Mitch Cunningham E: [email protected]

120

Review of Last Lecture

• Response Execution • Body physiology – Bones, Joints and Muscles • Body movement – Biomechanics

» Manual work » locomotion

• Body size and shape – Anthropometry • Feedback • Questions

121

Lecture 2 - Overview

• Reaction Time (RT) • Movement Time • Human Error • Error Management

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Learning Outcomes

CLO1: Explain the fundamental principles of HF that can be used by civil and transport engineers to facilitate user- centred design

CLO2: Apply HF principles, methods and data to the design of road and traffic management systems

CLO3: Plan for the integration of HF into the design lifecycle of the road and traffic management system

Reaction Time

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Reaction Time: Why Important?

When driving, or when working, people have to make physical responses to stimuli they receive from their environment - from visual displays, auditory events, etc

Sometimes it is safety-critical to respond as quickly as possible:

• E.g. for example, to brake (the response) when a lead vehicle slams its brakes on unexpectedly (the stimulus) in order to avoid a crash.

In situations where time is critical, the work or driving situation can be designed to take advantage of the response capabilities of humans.

Source: Sanders & McCormick (1987), p. 218

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Reaction Time & Movement Time

Reaction time is… “the time to initiate a response following the presentation of a stimulus”

It is the time taken to complete the various processes in Wickens’ model up to Response Execution.

Movement time is the time to make the response after it has been initiated.

Source: Sanders & McCormick (1987), p. 218

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Wickens’ Model – Reaction Time

Source: Adapted from Wickens (1992), p. 17

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Neurological Components of RT

Source: Sanders & McCormick (1987, p. 218-219)

Neurological Process Time Required

Receptor (sense organ) delays 1 to 38 ms

Neural transmission to the cortex 2 to 100 ms

Central processing delays (i.e. boxes in Wickens’ model) 70 to 300 ms

Neural transmission to muscle 10 to 20 ms

Muscle latency and activation time 30 to 70 ms

Total time to react 113 to 528 ms

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Simple and Choice Reaction Time

Psychologists have distinguished between “simple” and “choice” reaction time.

Simple RT is … “the interval of time that elapses between the presentation of one stimulus and the beginning of its associated response”.

Choice RT is … “the interval of time that elapses between the presentation of several possible stimuli and the beginning of one of several possible responses”.

Source: https://www.youtube.com/watch?v=lKADFIml6xM

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Simple and Choice RT – Examples

Simple RT: • If I blow a whistle once (stimulus) and you jump in the air (response)

Choice RT (2 choice): • If I blow a whistle once (stimulus) and you jump in the air (response) • If I blow whistle twice (stimulus), you pat your head

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Simple and Choice RT – Examples

Choice RT (3 choice):

– If I blow a whistle once (stimulus) and you jump in the air (response) – If I blow whistle twice (stimulus), you pat your head – If I blow the whistle three times (stimulus), you rub your tummy

LET’S TRY IT !

I’M GOING TO BLOW THE WHISTLE ONCE, TWICE OR THREE TIMES, AND YOU HAVE TO RESPOND THE RIGHT WAY.

START WHISTLING

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Simple and Choice RT – Findings

• Reaction time is shorter when there is one stimulus and one response.

• Reaction time is longer, the more stimuli and the more responses there are

• (See next slide...)

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Choice Reaction Time: No. of Choices

The influence on RT of the number of choices is shown below:

Source: Damon et al (1966); in Sanders & McCormick (1987), p. 219

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

1 2 3 4 5 6 7 8 9 10

No. of Choice x RT (secs)

RT (secs)

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Choice Reaction Time: Other Factors

The number of response choices is only one factor that influence RT.

(Next slides...)

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Choice Reaction Time: Other Factors (2)

The number of response choices is only one factor that influence RT. There are other factors that can also be influenced by design:

Expectancy – when a stimulus/signal that needs to be responded to is unexpected, or occurs infrequently, RT increases.

• E.g. drivers who were told to brake in response to an auditory signal that would occur in next 10 km took on average 0.54 secs to hit the brake

• E.g. drivers in the “surprise” group, with no warning, took on average 0.73 secs to respond.

Source: Damon et al (1966); in Sanders & McCormick (1987), p. 219

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Choice Reaction Time: Other Factors (3)

Response Modality – e.g. simple RT to auditory stimuli (around 100-120 ms) is faster than to visual stimuli (around 130-170 ms)

Stimulus Intensity – e.g. as intensity increases, RT decreases up to a certain point, then levels off

Temporal Uncertainty – if there is a warning in advance of the stimulus, RT will increase if there is any uncertainty about the advanced warning. So advanced warning needs to be clear and unambiguous.

Source: Sanders & McCormick (1987), p. 220

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Choice Reaction Time: Other Factors (4)

Compatibility – the more compatible are the stimulus and the response, the shorter is the RT

• e.g. if you press a light switch downwards, does the light go on or off?

• e.g. if you turn a circular radio control clockwise, does the volume increase or decrease?

• e.g. if you driver your car faster, does the speedo needle move right or left?

• e.g. what about the controls for your hotplates? A,B,C,D

Source: Sanders & McCormick (1987), p. 220

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Choice Reaction Time: Other Factors (5)

Repetition – learning that accompanies repetition generally reduces RT

• e.g. the time it takes to solve a Rubrik’s cube.

Accuracy required – if the task to be performed is a choice reaction time task, and a high degree of accuracy is required to make the correct response, RT generally increases.

Source: Sanders & McCormick (1987), p. 220

Movement Time

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Movement Time (1)

Movement time is the time to make the response after it has been initiated.

• A minimum of around 300msec is expected to complete most simple control actions

• Movement time depends on two main factors (NEXT SLIDES)

Source: Sanders & McCormick (1987), p. 221

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Movement Time (1)

1. Direction of movement – we can move our body members more rapidly in some directions than others because of our physical body structure

• e.g. reaching with the right hand lower left and upper right takes less time than reaching lower right or upper left

Source: Sanders & McCormick (1987), p. 221

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Movement Time (3)

2. Distance of movement: » Movement time is related to distance, but not

proportional to distance.

» Movement time is fast initially, then slows down as corrective movements are made to bring body member to stopping point

Source: Sanders & McCormick, 1987, 222

Human Error

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Human Error: Defined

In transport, and many other domains areas, Human Factors is about designing things that people use to enhance performance and reduce error.

Human error is “an inappropriate or undesirable human decision or behaviour that reduces, or has the potential for reducing, effectiveness, safety, or system performance”

Source: Sanders & McCormick (1987), p. 606

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Human Error: Defined (2)

There used to be a tendency to blame the operator for errors e.g. the vehicle operator.

A useful distinction here is between: • “faulty” design (where an error has been made by the designers or

builders and the device doesn’t work as intended) and • “bad” design (it works as the designers intended, but it’s not sufficiently

compatible with users’ capabilities – i.e., it’s “workable” but not “usable”.

The former is the province of Engineering; the latter is the province of Human Factors

Source: Dr Max Hely (2020; personal communication)

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Human Error and Violations

A distinction can be made between errors and violations: • Errors are unintentional actions or decisions.

• Violations are intentional deviations from rules or procedures (e.g. where person may be deviating from rules and procedures because of commercial imperatives or rules and procedures are not good ones).

Source: Health and Safety Executive, UK

Slips of action

Lapse of memory

Rule-based mistakes

Knowledge-based mistakes

Routine

Situational

Exceptional

Skill-based errors

Mistakes

1. Error

2. Violations

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Human Error: Classification

Several different frameworks for defining and classifying errors have been developed.

We will touch on 3 of these schemes: 1. Discrete-Action Classification Schemes 2. Information Processing Classification Schemes 3. Planning & Action Classification Schemes

Ultimately, with all of these simple classifications schemes, they can help us to understand how errors occur and how to mitigate them – but they do not fully capture the complexity of human error.

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1) Discrete-Action Classification Schemes

This classification framework classifies the errors that people make when they perform individual, discrete, actions:

Errors of Omission involve a failure to do something • e.g. a pilot forgets to lower the landing gear • e.g. a train driver forgetting to stop train at a specific station

Errors of Commission involve performing an act incorrectly • e.g. a driver putting their foot on the accelerator instead of the brake in

order to stop • e.g. Entering incorrect data into a spreadsheet

Source: Swain & Guttmann (1983), cited in Sanders & McCormick (1987), p. 607

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1) Discrete-Action Classification Schemes (2)

Sequence errors – when a person performs a task, or step in a task, out of sequence

• e.g. a driver who tries to change gear before depressing the clutch

Timing errors – when a person fails to perform an act within the allotted time (too quickly or slowly)

• e.g. a person takes too long removing their hand from under a drill press, and drills a hole in their hand

Source: Swain & Guttmann (1983), cited in Sanders & McCormick (1987), p. 607

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2) Information Processing Classification Schemes These use information processing models, like Wickens’

model (1984) to classify human errors based on where in the flow of information the error occurred.

Errors are classified as Input, Decision or Output errors

Source: DeGreen, (1972), cited in Sanders & McCormick (1987), p. 608

Stage of Information Processing

Types of errors

Input (Perception) sensing, detecting, identifying, coding, classifying

Decision (Cognition) estimating, logical manipulation, problem solving

Outputs (Action) omissions, insertions, mis-ordering

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3) Planning & Action Classification Schemes

Human action usually has 3 components: 1. a plan (a goal and means of achieving it), 2. a sequence of actions initiated by the plan and 3. an outcome (success or failure)

This class of model describes failures that can occur in both of the first 2 components:

• Skill-Based Errors and • Mistakes

Source: Reason, (1997); cited in Fuller & Santos (2002), p. 93

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Human Error: Skill-Based (Slips & Lapses)

Skill-based errors occur where the plan is adequate, but actions fail to proceed as planned and include:

• Slips of Action – carrying out part of a sequence of actions incorrectly, perhaps due to inattention – e.g. turning on a loud machine before affixing ear protectors

• Lapses of Memory – omitting part of a sequence of actions, perhaps due to working memory limitations – e.g. forgetting to put a hard-hat back on after removing it for some

reason.

Source: Fuller & Santos (2002), p. 93

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Human Error: Skill-Based (Slips & Lapses) (2)

Slips and lapses occur when: • “the task is very familiar and requires little thought”

– E.g. driving through your suburb, on familiar roads

• “people confuse two similar tasks” – E.g. making an English breakfast tea and a green tea at the same

time

• “tasks are too complicated and long-winded” – E.g. building flatpack furniture without instructions

Source: Health and Safety Executive, UK

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Human Error: Skill-Based (Slips & Lapses) (3)

Slips and lapses occur when: • “the main part is done but the finer details are missed”

– E.g. not giving someone the right cutlery when you give them a meal

• “steps in a procedure don’t follow naturally” – E.g. remembering to put a mask on before you leave the house

(during a pandemic)

• “there are distractions and interruptions” – E.g. getting interrupted by a colleague when you’re running through a

checklist

Source: Health and Safety Executive, UK

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Human Error: Mistakes

Mistakes – occur when the plan is inadequate, but the person selects the wrong sequence of actions:

• Rule-Based Mistakes – involve the application of the wrong rule for a given situation – e.g. switching on the windscreen wipers instead of the turn indicator

when driving a left-hand drive vehicle

• Knowledge-Based Mistakes – involves doing the wrong thing, believing it is right, for a given situation – e.g. thinking that you are leaving enough room for oncoming traffic

when overtaking, when in fact you haven’t

Source: Health and Safety Executive, UK

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Human Error: Mistakes (2)

Mistakes occur when: • “Doing too many things at the same time”

– E.g. trying to placate young children in the back seat while navigating in an unfamiliar location

• “Doing too many complex tasks at once” – E.g. trying to drive through an intersection and send a lengthy text

message

• “When there are time pressures” – E.g. rushing to get to an appointment or meeting

Source: Health and Safety Executive, UK

Error Management

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Error Management: Slips and Lapses

“How to reduce slips and lapses: • Use constraints to inadvertently limit what can be done

– e.g., plug/socket designs that only permit a plug to fit into correct socket, or the correct way around.

• use checklists to help confirm that all actions have been completed – E.g. shopping list

• include in your procedures the setting out of equipment, site layout and methods of work to ensure there is a logical sequence” – E.g. building flatpack furniture with instructions

Source: Health and Safety Executive, UK

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Error Management: Slips and Lapses (2)

How to reduce slips and lapses: • make sure checks are in place for complicated tasks

– E.g. Nurses double verifying dosage of medication before administering them

• try to ensure distractions and interruptions are minimised” – E.g. not talking to colleagues during when tasks need to completed.

– Remember: simply adding more training will not eliminate slips and lapses. Effective procedures and appropriate design are required.

Source: Health and Safety Executive, UK

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Error Management: Mistakes

“To avoid rule-based mistakes: • increase worker awareness of high-risk tasks”

– E.g. appropriate training and education

• “provide procedures for predictable non-routine, high-risk tasks”. – E.g. manuals and guides

Source: Health and Safety Executive, UK

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Error Management: Mistakes (2)

“To avoid knowledge-based mistakes: • ensure proper supervision for inexperienced workers”

• “provide job aids” – E.g. instruction cards

• “diagrams to explain procedures”

Source: Health and Safety Executive, UK

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Required Reading

There are two readings this week:

1. Read the following short (3-page) document which provides a nice overview of Reason’s (1997) Planning & Action Classification Scheme in an industrial workplace context, with some examples and practical advice on how to reduce slips, lapses and mistakes.

• http://www.hse.gov.uk/construction/lwit/assets/download s/human-failure.pdf

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Required Reading (2)

2. Go to Chapter 9 of the e-copy of one of your recommended texts:

Wickens, Gordon, Liu, Lee (2014). Introduction to Human Factors Engineering

• Read the section called “GENERAL PRINICPLES FOR WORKSPACE DESIGN” which starts on page 238 and finishes on page 248 (i.e. 10 pages)

This reading will build on our discussion of Anthropometry and Biomechanics and explain in more detail how the principles of Anthropometry and Biomechanics can be used to design workspaces.

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Thursday Tutorial

• Everyone is required to attend their allotted tutorial class.

• Remember – the material covered in all Tutorials is assessable.

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Questions ?

Over to ….

Prof. Michael Regan, PhD Research Centre for Integrated Transport Innovation

(rCITI) Room 112, Civil Engineering Building (H20)

E: [email protected]