Military Psychology

Gerhard Ohrband – ULIM University, Moldova

9th lecture

Human factor engineering

Course structure

1. Introduction: Historical Overview, main applications2. Environmental Stressors3. Leadership4. Team Effectiveness5. Individual and Group Behaviour6. Clinical Psychology7. Selection and Classification8. Training 9. Human Factor Engineering10. Psychotherapy and Counseling11. Terrorism12. Trauma Therapy13. Psychological Warfare14. Ethical Issues for a Psychologist in the Armed Forces15. Review: Preparation for the exams

Outline:

1. What is workload?

2. Why assess workload?

3. Requirements for effective workload assessment

4. Workload assessment techniques

5. The application of workload assessment techniques

6. Automation and task allocation

1. What is workload?

performance problems associated with tasks high in explicit demand (i.e., the overload or cognitive strain scenario)

exploring/modelling errors at lower levels of the task demand spectrum

Physical vs. mental workload Focus on mental workload Examples: air traffic controllers, pilots, process control

operators and medical staff Primary tasks: cognitive processes which require

memory, attention, perception and communication skills rather than extensive physical demands

Definition (Kramer, 1991): Mental workload can be conceptualized as the costs that human operators incur in performing tasks

Industries traditionally defined ashigh risk Defence Road transportation Railways Aerospace Process control Power generation

Workload and error

The complexity of the relationship between workload, task performance and task load can be illustrated with reference to the debate in which a number ofinvestigators have aimed to provide an answer to the question “How much workload is too much?” (e.g., de Waard, 1996; Meijman and O’Hanlon, 1984;Teigen, 1994).

To answer this question, investigators have found it useful todivide the Yerkes-Dodson inverted U function into 6 task performance-related regions as shown in Figure 8.

Task performance and workload as a function of demand

Single resource models

Kahneman’s capacity of attention

Performance Resource Function (PRF)

Multiple resource models

the human information processing system is a multiple channel processor(e.g., it has multiple structures)

each processor, or group of processors, has its own internal capacity. In MRT approaches, mental resources are often seen as analogous to

fuel that is consumed by various activities, or as a tank of liquid to be divided among several competing tasks (Wickens, 1984).

In stressful conditions, or multitasking situations, the amount of resource may become depleted and give rise to interference effects. One important feature of this view is the idea that the impact ofchanges in task demand on mental resources may not be purely quantitative, but may also be qualitative as well, (i.e., structural).

Sources of mental resource relative to information processing stage

Diagrammatic representation of Wickens Multiple Resource Theory

Composite models

relatively new type of cognitive modelling activity that aims to use elements of the single channel hypothesis and resource theory to account for workload effects in human performance.

These composite models are usually represented in the form of computer programs that are applied to tasks and used to predict various aspects of human performance.

The ability of these models to reproduce workload effects has frequently been mentioned as a justification for their development – although the extent to which they have managed to do this has been a matter of some debate.

Perhaps the most frequently mentioned composite model in the workload literature has been the Executive-Process Interactive Control (EPIC) model developed by Kieras and Meyer, 1997

2. Why assess workload?

Solve practical problems in the workplace Effects of workload on performance, well-being, health and

safety Design complex task environments that do not place

disproportionate demands on the human operator 1. Safety critical systems such as air traffic control and aircraft

cockpit design 2. Aid evaluation of the effects of automation or the introduction

of new technology and other changes in the nature of work on individual well-being and health

3. Assessment of individual operators (selection or training) Acute vs. chronic effects of workload

3. Requirements for effective workload assessment Sensitivity Diagnosticity Intrusiveness Validity Reliability Acceptability Applicability Generality

4. Workload assessment techniques Subjective/self-report measures: Cooper-Harper scale (Cooper and Harper, 1969) NASA task load index (TLX) (Hart and Staveland, 1988) Subjective workload assessment technique (SWAT)

(Reid and Nygren, 1988) Instantaneous self-assessment technique (ISA) Situation awareness rating scale (SART) (Taylor, 1989) Situation awareness global assessment technique

(SAGAT) (Endsley, 1995)

NASA Task Load Index (TLX)

NASA-TLX Scoring example

Subjective Workload Assessment Technique - SWAT

Time Based Task Loading Models

Performance measures

Primary task measures Secondary task measures

Primary task: the task or system function whose workload is to be measured

Secondary task: one task that is performed concurrently with a primary task to investigate the workload associated with the latter

Physiological Measures

cardiac function brain function respiration eyeblinks pupil dilation urine blood saliva (hormonal and immunological changes)

5. The application of workload assessment techniquesSummary of the capability of different broad categories of workload assessment techniques to satisfy different requirements for use

Intrusiveness Sensitivity Diagnosticity Applicability Acceptability

Subjective Measures

Post-task measures Generally not intrusive

Good but may depend on length of task

Generally difficult to use diagnostically

Minimal equipment requirements

Very good

Instantaneous measures

Potentially intrusive Good Provides only a global measure

Some equipment required

good

Performance measures

Primary task Not intrusive Reasonable but difficulties in interpreting variation

Poor Depends on task complexity and variability

Should be acceptable to operator

Secondary task Potential for intrusion Good Very good May require training and extra equipment

Additional demands may be distracting

Intrusiveness Sensitivity Diagnosticity Applicability Acceptability

Physiological measures

EEG measures Not usually a problem

Good Varies according to specific measure but reasonably good

Extensive equipment and analysis requirements

Some potential problems

ECG measures Not intrusive Good Not fully established

Extensive equipment and analysis requirements

Not generally found to be problematical

6. Automation and task allocation advancements in computer technology

Wickens (1992): three reasons for automation

1. Situations which may be hazardous or dangerous to humans or which humans cannot perform (diving operations, handling of toxic materials)

2. Tasks with high levels of workload for the human operator (autopilots)

3. Overcome human limitations, e.g. in memory or attention (radar advance warning systems)

Dangers of automation

Thoughtless design which may simply require the operator to perform those functions or tasks that have been unable to be automated

Difficulties:1. Automation may induce feelings of loss of control and situation

awareness when the human is operating “out of the loop”2. Risk of deskilling the operator in highly automated systems3. Automation does not always lead to improved performance and

levels of operator workload

Unscheduled manual interventions (Hockey and Maule, 1995) operators overriding automated systems in order to

assume control of production or other processes at times when the system is scheduled to be under automatic control

Why?1. desire for control2. motivation to improve the speed and quality of

production3. low trust in the automated system

Selection of the appropriate type and degree of automation Goal: achieving desirable levels of safety and

effectiveness Question: Which tasks should be allocated to the

operator and which to be automated part of the system?

Task allocation/function allocation Traditional approaches: Fitt’s list (1951, Kantowitz

and Sorkin, 1987) Think about it: Where are machines and where are

humans more effective?

Answer: Machines: performing mathematical and

computational operations, integrating information and dealing with predictable events reliably

Human operators: making decisions, inductive reasoning, more flexible, particularly when unexpected events occur and possess experience of previous events

Dynamic task allocation (DTA) Def.: flexible allocation of tasks or functions

between the operator and the system in human-machine systems; sometimes referred to as adaptive control

some or all of the task elements have the potential to be carried out by either the operator or the system itself

control of task allocation: explicit and implicit allocation

explicit: operator control, implicit: computer control of task allocation

Advantages of DTA

1. Workload of operators will be maintained at a relatively constant level

2. Resources of the systems (both human and computer) will be used more fully

3. More acceptances by the operators than static automation4. Enhancement of situation awareness and prevention of decay of

manual control and problem-solving skills which may be required in breakdown or emergency situations

5. Enhancement of the operator’s ability to diagnose failures and errors made by the computer

Discussion Points

1. What are the different workload assessment techniques?

2. Explain the hazards of automation.

3. Discuss the objectives of workload assessment.

Literature

Hockey, G.R.J. and Maule, A.J. (1995). Unscheduled manual interventions in automated process control. Ergonomics, 38, 2504-24.

Kramer, A.F. (1991). Physiological metrics of mental workload: a review of recent progress. In D.L. Damos (ed.), Multiple-Task Performance. London: Taylor and Francis

Outline:

1. The growth of technology in the workplace

2. Approaches to the study of work technology

1. The growth of technology in the workplaceComputer type Approximate growth era Main users Users issues

Purpose-built research machines

1950s Mathematicians and scientists Machine reliability; users must learn programming

Mainframe computers 1960s/1970s Data processing, professionals supplying a service

Users of the output (e.g. managers); system response and flexibility

Minicomputers 1970s Engineering and other non-computer professionals

Users still do much of the programming; usability starts to be recognized as a problem

Microcomputers 1980s Almost everyone Usability most pressing problem

Laptops, notebooks, PDAs (Personal digital assistants), the Internet

1990s Almost everyone Usability

Information appliance 2000 - Everyone? Usability? Security and privacy?

Examples of manufacturing technologies and their primary domain of application

Type of manufacturing technology Primary domain of application

Computer-aided design and engineering, e.g. computer-aided design (CAD) and computer-aided software engineering (CASE) tools

Design and production

Electronic data exchange systems (EDI), e.g. on-line computerized links to customer stock levels to enable planning and distribution

Inventory and stock control

Computer-supported collaborative work (CSCW), e.g. the use of computers to aid communication and cooperation between different manufacturing departments

Work organization

Manufacturing resource planning (MRP), e.g. computer-based systems which control the planning and allocation of work among employees

Work organization

2. Approaches to the study of work technology –different types of interfaces with technology and example issues which are studied

Technology interface Example issue

Human-technology interface Physical characteristics of the user

Workload issues

Display design

Health and safety

User-technology interface Job and workspace design

User satisfaction

Usability

Allocation of tasks

Organization-technology interface Communication and coordination

Distribution of power and responsibility

Knowledge sharing

Participation in design

Management of change

Stages and activities in the system development cycle

Stage Activities

Requirements Where the design problem is initially defined, often in an explicit requirements document

Design Where the design is shaped and which culminates in the detailed specification of the artefact

Building Where the system is implemented, constructed or manufactured

Deployment Where the system is marketed sold and put into user settings

Maintenance Where the system is serviced for repairs and enhanced as needed

Redesign (optional) Where the system is used as the basis of a design effort to produce a new system

Socio-technical systems approaches (STS) Trist and Bamforth, 1951; Emery, 1959 Recognition that organizations should consider the joint optimization

and parallel design of both social and technical systems when designing new technology

Guidelines when introducing new technology:1. methods of working should be minimally specified2. variances in the work processes (e.g., production breakdowns,

changes in product) should be handled at source (i.e. as near as possible to location of breakdown or change-over)

3. those who need resources should have access to and authority over them

4. roles should be multifunctional and multi-skilled5. redesign should be continuous, not ‘one and for all’ change

Human factors (ergonomics) and human-computer interaction HF: wider range of issues (e.g. anatomical and

anthropometric characteristics of the user) HCI: design of the user interface and overall functionality1. Cognitive models of the user:

Formalization of the types of knowledge that an individual needs to make use of when operating a machine or system (e.g. a word processor or a graphics package); examples of cognitive models: TAG (task-action grammar; Payne and Green, 1986), GOMS (goals, operators, methods and selection rules; Card et. al., 1983)

Ergonomics

2. Task allocation: assigning functions to human and machine agents. Which to tasks to be automated or manually operated.

3. Usability: formative vs. summative evaluation of the usability of a system. Methods: qualitative (e.g. user questionnaires, interviews and focus groups) and quantitative (e.g., lab-based experiments)

Organizational approaches

Perspective Central issues

Rationalist Employment (job loss, levels of hierarchy)

Centralization/decentralization

Formalization

Information processing Patterns of communication

Social context cues

Motivational Individual motivations (skill variety, autonomy)

Interpersonal motivations

Political Power (vertical, horizontal distribution)

Kitchen timer

This is a nice little kitchen timer unless you want to set a time less than 15 minutes. To do so you must first turn the indicator to a time greater than 15 minutes and then turn it back to the time you actually want! There is no indication of this on the front of the timer. What ends up happening is that you set times less than 15 minutes without first turning the indicator past 15 minutes. Then the timer doesn't go off.

Design suggestion This design violates your expectations by having one rule for setting

times greater than 15 minutes (turn the indicator to the desired time) and a different rule for setting times less than 15 minutes (turn the indicator to a time greater than 15 minutes and then to the desired time). A device like this should follow a consistent rule. There is nothing in the appearance of the timer that would lead you to believe that it works like this.

Mop sink

This picture is from a restaurant in Santa Barbara. There is no urinal in the men's restroom. The fixture in the corner affords a certain activity. To try to discourage this activity someone taped a small sign to the wall above the fixture. The sign says "This is a mop sink."

That's not a handle!

The lids on oatmeal containers were recently redesigned. The new-style lid fits down into the top of the oatmeal container. There's a lip all the way around the inside of the lid (arrow). The lip, which looks like it could work as a handle, affords sliding one's fingers underneath to pick up the oatmeal container. The other day I reached into the pantry to grab the oatmeal. I put my fingers under the lip of the lid using my thumb to hold the side of the container. I got just a few steps from the pantry before the lid came off dumping oatmeal all over the floor! The problem is that it looks like you can pick up the container by the lid, but you can't. Maybe the purpose of this new lid is to get people to buy more oatmeal, since half of it ends up on the floor!

The old-style lid doesn't look like you could use it as a handle to pick up the oatmeal container, so people probably aren't inclined try it. People are probably more apt to use two hands to pick up containers with these old-style lids.

Design suggestion The lid on the new-style container should not look like it could work as a "handle" to pick up the

container. This might be done by: Not making the center of the lid set down in the top of the container so deeply. Removing the "handle" from the inside of the lid by curving the lip outward rather than inward

How do you open the toothpaste? I recently took a vacation that involved flying across the ocean. Since it was a long overnight flight, passengers

were provided with little "kits" including a toothbrush and a tiny tube of toothpaste, slippers and so on. I tried to get some sleep on the flight, and when I awoke, I went to the lavatory to freshen up. When I unscrewed the cap from the tiny tube of toothpaste, I discovered the tube was sealed. Since I didn't have anything with me to pierce the seal, I tried to pop out the seal by squeezing the tube. This resulted in the side of the tube splitting open and sending toothpaste all over my trousers!

When I got back to my seat, I told my wife about my experience. She showed me how the seal could be broken by using the small piercing tool in the top of the toothpaste cap. (See arrow.) Many people might blame themselves for not knowing how to open the toothpaste tube, but I opt to blame the designers of this tube for not making it more obvious how to open it. After all, I am no different than many people who have never seen a tiny toothpaste tube that opens in this way. And perhaps they, like me, will have to figure out how to open the tube while still half asleep.

Design suggestion

A more obvious design might be to provide the type of sealed cap used on many soft-drink bottles, where unscrewing the cap breaks the seal. At the very least it would be helpful to include directions on the tube for piercing the seal. The directions should be illustrated graphically so they could be understood by speakers of any

language.

Trapped between the doors!

This picture shows a short walkway connecting two buildings. There are a set of doors at each end of the walkway. A friend told me a funny story about the first time she used this walkway. She was walking from one building to the other with a co-worker. They pulled the handles that opened the doors and went down the walkway. Upon reaching the other end they again pulled the handles, but the doors wouldn't budge. Assuming the doors were locked, they returned to the doors they originally opened to enter the walkway. But when they tried to pull open these doors, they wouldn't open either. They were trapped in the walkway between the two buildings!

My friend and her co-worker spent the next few minutes trying to signal to people though the windows in the buildings, but the people they signaled seemed strangely reluctant to come to the rescue. Finally, after trying the doors again, they discovered they needed to push the doors rather than pull them.

There are two problems with these doors. The first problem is that the handles are designed for pulling rather than pushing. Doors designed for pushing usually have handles with flat surfaces that look easy to push and hard to pull.

The second problem is that the two sets of doors work in opposite ways. To pass through the walkway you must first PULL open one set of doors and then PUSH open the second set of doors.

My friend has observed many other people getting "trapped" in this walkway. While it makes for a funny story, imagine if people unfamiliar with these doors had to cross from one building to the other in an emergency, like a fire. Then it could turn from a comedy to a tragedy.

Design suggestion One way to solve this problem would be to install (swinging) doors that can be opened by both pushing and pulling. Another

solution would be to install appropriate door handles. Flat push-bar handles would be installed on the sides of the doors to be pushed; the pull-type handles like those shown here would be installed on the sides of the doors to be pulled.

Finally, PUSH and PULL labels could be added to the doors, but this would not be an ideal solution. Labels would only work for people who could read the language. They would only work under adequate lighting conditions. In practice, many people do not read such labels.

Out of order?

We were late for the recital. We quickly parked the car in the college parking lot, and then saw a sign saying we had to buy a parking permit. Dashing over to the parking permit machine, I took a dollar from my wallet and tried to insert it into the bill reader (See white arrow). It would not go into the bill reader! I turned the dollar one way and then the other way, trying to get the bill reader to respond, but it would not respond at all. It was getting late. "It's out of order!", I told my friend, "Let's just skip the parking permit and go to the recital!" As we started walking to the recital hall, we saw a man walk up to the same parking permit machine. I told him, "It doesn't work!", but he just walked up anyway and proceeded to buy a permit! He was a student at the college. Seeing that the machine was not out of order, we returned, and after reading the instructions, bought our permit.

What was the problem? As it turned out, to buy a permit, you first have to push a button (any button) on the parking permit machine. This activates the bill reader. It clearly says this on the machine in large print. Why didn't I initially read it? I believe there were two reasons: First, I was in a hurry. Second, vending machines usually don't work this way. Typically, you first insert money and then you make a choice. If you try to insert money and the machine doesn't respond to it, the most likely reason is that the machine is out of order.

I told another friend at the recital about this problem, and she said she couldn't figure out how to use it either. Design suggestion The parking permit machine should be designed to accept bills prior to making a ticket selection. People expect vending machines to work

that way. Printed instructions, even obvious ones, aren't going to be read by some people, especially people in a hurry. People skip reading operating instructions for devices they believe they already know how to use. After all, what's the point? They already know how to use the device.

Literature

Caroll, J.M. (1997). Human-computer interaction: psychology as a science of design. International Journal of Human-Computer Studies, 46, 501-22.

Norman, D.A. (1998). The Invisible Computer. Cambridge, MA: MIT Press.

Parker, S.K. and Wall, T.D. (1998). Job and Work Design. London: Sage.

Wilson, J.R. and Corlett, E.N. (eds) (1995). Evaluation of Human Work, 2nd edn. London: Taylor and Francis.