Cognitive ergonomics

A Study On
COGNITIVE
ERGONOMICS
Guided by:
Prof. D. A. Jolhe
Assistant Professor,
Dept. of Mechanical Engineering,
VNIT, Nagpur.
Submitted By:
NAMITA DUBEY
M.Tech 2015-16
Industrial Engg,
Roll no. MT15IND0110

CONTENTS
1. Definition
2. History
3. How does our brain work
4. Perception
5. How we remember things
6. How memories are stored
7. How we forget things
8. Areas of application
9. Attention and assessment of workload
10. Problem solving
11. Expert and expert system
12. Hand eye coordination
13. Response time
14. References
19 October 2015 COGNITIVE ERGONOMICS 2

DEFINITION
Cognitive ergonomics, defined by the International Ergonomics Association "is concerned with mental processes, such as
perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a
system”. The relevant topics include:
mental workload
decision-making
skilled performance
human-computer interaction,
human reliability
work stress
training
as these may relate to human-system design.
Cognitive ergonomics studies cognition in work and operational settings, in order to optimize human well-being and
system performance. It is a subset of the larger field of human factors and ergonomics.

History
•The field of cognitive ergonomics emerged predominantly in the 70's with the advent of the
personal computer and new developments in the fields of cognitive psychology and artificial
intelligence.
•"cognitive ergonomics is the application of psychology to work ,to achieve the optimization
between people and their work.”
• it is an applied science, and has rapidly developed over the last 27 year.
• According to van der Veer, Enid Mumford was one of the pioneers of interactive systems
engineering, and advocated the notion of user-centered design
• criteria for developing user centered design:
1. task analysis ( the evaluation of cognitive task demands)
2. analyzing motor control cognition during visual tasks (operating machinery, or the evaluation of
attention)

Neuroergonomics
Neuro-ergonomics, a subfield of cognitive ergonomics, aims to enhance human-computer
interaction by using neural correlates to better understand situational task demands. Neuro-
ergonomic research at the university of Iowa has been involved with assessing safe-driving
protocol, enhancing elderly mobility, and analyzing cognitive abilities involved with the navigation
of abstract virtual environments.

Simplifying the definition
Cognitive ergonomics is a division of ergonomics (human factors), a discipline and practice that
aims to ensure appropriate interaction between work, product and environment, and human
needs capabilities and limitations.

APPLICATION OF COGNITIVE ERGONOMICS
Designing a software interface to be "easy to use“
Designing a icons and visual cues so that the majority of people will understand and act in the
intended manner
Designing an airplane cockpit or nuclear power plant control system so that the operators will
not make catastrophic errors

Need of cognitive ergonomics
The way people perceive and act has direct implications on the design of the
objects and environment that they use
Mind is as comfortable at work as the body
If physical surroundings reflect and support their natural cognitive tendencies,
 Less errors
 performance & productivity -positive boost

How does our brain work ?
Going to early history, phrenologist Franz Joseph Gall was spending lots of time moving his
fingers across the skull of the humans to claim he can tell by the shape, size and feel of the head
the person’s personality. He advocated the skull morphology as an aspect for recognition of
person’s abilities and character.
Phrenology :
The detailed study of the shape and size of cranium as a supposed indication of mental abilities
and character
Of late it was dismissed as pseudoscience as the cranial contours tell nothing about what’s
happening inside. Yet we can turn Gall into a personality of importance as he brought out the
consensus that it is our brain and not the soul or heart the controls our body. His lasting
preposition was that he figured out that different parts of brain controls differ parts of body.

Brain function (cont.)
Localized parts of brain have specific functions. This turns out a strong result as psychology and
biology are strongly associated. If we can stimulate any part of our brain we wanted to, we can
actually have control on our brain, something that Gall found out. Now the stimulation part of
brain is done by neurotransmitter and hormones alleviating the part we want to function on.
Brain we can call the physical part of our body while mind is our consciousness, our decisions
our personality and so on. Thus we may say what the mind is same as what our brain does.

Basics of CNS
Central nervous system (CNS)- it is the main command center that defines our decisions.
Peripheral nervous system – consists of sensory neurons that collect information and report it
back to the central nervous system.
We may have heard that we use only 10% of our brain. However the brain scan shows that
nearly every portion of the brain lights up even when doing simple tasks as walking and talking.
Also brain requires about 20% of our whole body’s energy.
Obviously our brain as evolved over the ages from simple to complex system.

Ancestral structure of brain
Brain stem : most ancient and central core of brain where spinal cord enters the
skull. Here all brain functions take place without conscious effort such breathing
of lungs, beating of heart etc.
Pons : helps coordinate automatic functions
Thalamus : pair of egg shaped structure that takes in sensory information
related to hearing, sensing, tasting , smelling, touching, seeing etc.
Reticular formation : finger shaped nerve network inside brain that’s essential
for arousal that refers to sleeping, walking, pain perception and other important
functions.
Cerebellum ( little brain) : base ball like structure swelling out from brain stem is
responsible for non-verbal learning, memory, perception of tie, modulating
emotions and other voluntary movements. But it also gets impaired easily under
the influence of alcohol.

Limbic system
This was all about the old brain that performs sort of elementary or basic function which any
living organism may require. From here brain for reptiles stops. We will discuss some complex or
higher order parts.
Limbic system : this includes amygdala, hippocampus and hypothalamus.
◦ Amygdala: two-lima-bean sized cluster of neurons involved memory consolidation and emotions both
our greatest fear and aggression.
◦ Hippocampus : center to learning and memory
◦ Hypothalamus: regulates body temperature, rhythm, hunger and helps govern the endocrine system. It
helps us feeling pleasure of rewards.

New structure of brain
Two hemisphere of brain makes up 85% of our brain weight and helps us oversee the ability to think ,
perceive and speak
Left and right hemisphere govern and regulate different functions giving us split brain connected by
corpus callosum.
For instance language production are affected by our left brain while certain creative functions are
handled by right brain. This however has nothing to do with the handedness of the person.
Covering of the hemispheres is called cerebral cortex which is a thin layer of interconnected 20
million neurons.
Glial cells are the non neuron cells that provide a spider wed surrounding, supporting, insulating and
nourishing neuron cells.

Cerebral cortex is divided into four lobes :
1. Temporal
2. Parietal
3. Frontal
4. Occipital
Each lobe coordinates the opposite side

Specialized function
Motor cortex : controls voluntary movements and sends messages from brain out of the body.
Sensory cortex : processes incoming sensation
Rest of gray matter is made up of association areas that are related to higher mental functions
like remembering, thinking , learning and speaking

Perception
Perception :
The top down way our brain organizes and interprets that information and puts it into context.
Perceptual set :
The psychological factor that determines how you perceive your environment.
Factors affecting perception:
1. Context
2. Culture
3. Emotions or moods
4. Position
10/13/2015 COGNITIVE ERGONOMICS 20

Figure ground relationship

Rules of grouping
Form perception:
1. Proximity: grouping common objects nearby
2. Continuity : perceive smooth, continuous pattern rather than broken
3. Closure : fill in gaps to create whole object
Depth perception : ability to see object in three dimension although images that strike retina
are two dimensional
Binocular cues : depth cues, such as retinal disparity, depends on use of both eyes. Since eyes are
only2.5 inches apart not distinct images are produced by the senses. Therefore our brain uses the two
images to define distance, i.e. if objects are closure finer distinction can be obtained. This is what we
call retinal disparity
Monocular cues : depth cues, such as inter-positional and linear perspective, available to one eye only

The monocular cues are:
1. Relative size, height
2. Perspective
3. Texture gradient
4. Interposition
Motion perception: infers speed and direction of moving object
“Shrinking objects are retreating and enlarging objects are approaching”
Large objects appear to move slowly as compared to small objects moving with same speed
Constancy: tendency to recognize objects irrespective of its distance, viewing angle, motion or
illumination

How do we remember things?
Memory :
◦ Technically is defined as the learning that has persisted over time, information that can be stored and in
most cases recalled
◦ Chain connecting past and present
◦ Helps us recognize our loved ones, recall joyful moments, define basic functions as how to talk, walk,
eat etc.
◦ If it breaks we cant live the present moment nor can we assimilate future

Memory
◦ Memory is built and retrieved in three different ways:
◦ Recall
◦ Recognition
◦ Relearning

Memory (cont.)
Recall: a measure of memory in which the person must retrieve
information learned earlier.
Recognition: a measure of memory in which the person has to only
identify the previously learned information.
Relearning : a measure of memory that assess the time saved
while learning material again.
Richard Atkinson and Richard Shiffrin, the American psychologists
in 1960s, figured out that memory can be broken into three stages.

External stimuli sensory
memory
short-term memory
( working memory)
long term memory
encoding
encoding
encoding
retrieval

◦ We initially record the things we want to remember as immediate fleeting sensory memory.
◦ Short-term memory is the one where we keep the memories encoded by rehearsal. This is how we
remember briefly the short memories like passwords, phone nos. etc. without any rehearsal any
stimuli can be recalled within 30 seconds.
◦ This is because mind can only hold and retrieve 4-7 bits of information at a time.
◦ This also points that it either gets decayed or transferred to long term memory.
◦ Long term memory is spacious durable unit that holds all the knowledge, experience and we have.
◦ Depends on both time we take to learn it and process we use to retain
◦ Shapes reshapes brain and eventually identity

Working memory :
Conscious, active processing of incoming auditory and visual-spatial information and of
information retrieved from long term memory
Classically conditioned association:
represent association with some incidences
Automatic processing :
non-conscious encoding of incidental information , such as time, space and frequency and well-
learned information

Auditory
rehearsal
central
executive
short-term memory
( working memory)
long term memory
encoding
retrieval

long term memory
Different kinds of long-term memory:
1. Procedural memory: how we remember to do things
2. Episodic: connected with some episode of life

Leonidas

How our memories are stored ?
We all have been constantly retrieving the memories where we parked the vehicle, did we lock
the room, have we turned the lights off, dates, day, birthdays, names, events and so on.
Implicit memory
Retention independent of conscious recollection
i.e. how we ride our bikes, how to talk, eat dress are dealt in on a mostly automatic non-
conscious level
Explicit memory
Memory of fact and experiences that one can consciously know or “declare”
i.e. the chronicles of our personal experience and general knowledge often requiring conscious
and effortful work

Memory retrieval cycle

Retrieval cues and priming
Our memories are not like books neatly kept on the shelf that we often take off to read, retrieve,
relate and reproduce. It, however is more like a cobweb in the dark catacomb of our mind that is
closely interrelated in series of association that builds all sorts of diverse links as bits of source of
information.
For ex : if we try to remember a person seen in the dull lights or vague darkness we may remember
certain features of the place as the color of his jacket, his hair, complexion and so on but we cannot
explicitly identify the person with certainty. Here the darkness, jacket, color, complexion etc. acts as
retrieval cues.
“Memories are built in our mind as bits of pieces lying in the cobweb which is retrieved by the
retrieval cues”
The more we have retrieval cues the better we can remember things.
Priming :
The act of activating associations unconsciously. Sometimes it’s called the “memory-less” memory in
which we have some invisible images captured that we may awaken for associations

Context and mood dependence
• context-dependent memory
• state-dependent memory
• mood congruent memory
Serial position effect : memory is dependent on the order in which we receive information so it’s a
tendency to recall first and last items on the list
1. Primacy effect
2. Recency effect

How information are forgotten ?
We forget in three ways :
1. We forget to encode it
2. We fail to retrieve it
3. Memory suffers storage decay

Tricks to build healthy memory
Mnemonics :
Memory aids especially those techniques that uses vivid imagery and organizational devices
Chunking:
Organizing information into familiar, manageable unit; often occurs automatically.
These techniques help you to encode explicit memory but how we retain depends on how deeply
the information has penetrated through different levels of processing
Shallow processing: encoding information on basic auditory or visual levels, based on sound,
structure or appearance of word.
Deep processing : encodes semantically based on actual meaning associated with word
Connection to something meaningful such as some personal or emotional experience.

AREAS OF APPLICATION
Industrial Areas
1. Human computer interaction
2. Transportation
3. Control processes
Intervention Areas
1. Design
2. Technological Innovation
3. Safety and accident Investigations

Human Computer Interaction(HCI)
HCI involves the study, planning, and design of the interaction between human (users) and
computers.
Supporting knowledge on both the computer and the human
Computer side - techniques in computer graphics operating systems, programming languages and
development environments - relevant
Human side - communication theory, graphic and industrial design disciplines, linguistics, social
sciences, cognitive psychology and human factors such as computer user satisfaction - relevant
Interaction occurs at the user interface which includes both hardware and software

Transportation
Some of the most important artefacts of our lives are used to support human
mobility. Cars, buses, trains, boats, planes, etc. have to be designed to enable their users
an effective, efficient and safe transportation. Although some of these artefacts are used
by only one person, an analysis of dynamic transportation situations indicates that
cognitive ergonomists must take a more global viewpoint that includes considering
many persons who interact with each other through a large number of artefacts under
conditions of severe time constrains and deadly hazards. Therefore, although
ergonomics has been involved of the design of the cockpit of airplanes and cars (for
example, being recently involved in designing assistant systems for helping car drivers
to drive safely), experts in this profession have started also to be interested in the development
of the whole socio-technical system that have to be considered in air traffic or railway
transportation.

Control Process

Control Process
The term "process" refers here to the industry known as "processing industry". A processing
industry is one where energy and matter interact and transform one into another (Woods,
O’Brien and Hanes, 1987).
A typical example of such industries is nuclear power plants. But the industries of paper
production and the pasteurization of milk also belong to this category.
There is one ergonomically relevant characteristic that distinguishes among the examples of
processing industries. One can say that the various process industries differ in the degree of
dependence on the artefacts that play a mediating role between the operators and the physical
processes that they control.

Design
There are two aspects of interest in system design:
Human Beings who design the system
Human Beings who interact with system
In the early times of human factor engineering, they were called to explain why the particular
design had not worked. Later on, they were called to intervene directly in the design process
(Wickens and Hollands, 2000). Today, the processes of innovation requires that ergonomists
"proactively" supply ideas and empirical data for the design of future artefacts improving human
performance and public acceptance of new technologies (Akoumianakis and Stephanidis, 2003;
Kohler, Pannasch and Velichkovsky, 2008).

Technological Innovation
New concept of design is “user centered “ designing
It bases its development on the fact describing the human being who interacts with the system
from the viewpoint of cognitive science.
Based on those characteristics cognitive ergonomists provided engineers with a set of principles
to be considered in the design.
Paradigm has let to the establishment of usability research that has contributed greatly to the
effectiveness, efficiency and satisfaction of users in their interaction with the technologies and
to a better interaction between users through technology (Holzinger, 2005)

Safety and accident investigation
“Human reliability analysis” (HRA) : These techniques are based on the assumption that the actions
of a person in a workplace can be considered from the same point of view as operations of a machine. The
objective is to predict the likelihood of human error and evaluate how the entire work system is degraded as a
result of this error alone or in connection with the operation of the machines, the characteristics of the task, the
system design and characteristics of individuals (Swain and Guttmann, 1983). This approach has let to a
considerable progress in the efforts to predict the occurrence of human error. However, it has have been criticized
as insufficient. Reason (1992) particularly notes that the main difficulty is the estimation of error probability. In
designing new systems, there are no prior data on the error probabilities. One can count on data from simple
components, such as errors that are committed to read a data into a dial or enter them into a keyboard, but not
the errors that may be committed by interacting with the system.

“Cognitive psychology”: ergonomics seek to know the mental processes responsible for
committing an error (Norman 1981; Reason, 1992). They assume that errors are not caused by
irresponsible behaviour or defective mental functioning. They may be rather the consequence of
not having taken into account how a person perceives, attends, remember, makes decisions,
communicates and acts in a particularly designed work system. This standpoint suggests
investigating the causes of human errors by analyzing the characteristics of human information
processing. The three types of errors can be largely attributed to the familiarity that the person
has with the system:
• Errors based on skills: When a person is very familiar with the task, actions are overlearned as
a low-level pre-programmed sequence of operations that do not require and often are not
under conscious control. If one of these actions is poorly performed or the sequence is applied
in an unusual order, a skill-based error occurs.

• Errors based on rules: The selection of actions in a situation often depends on the
implementation of a set of rules of the type IF(condition) THEN (action). The activation of the
right rules depends on the interpretation of the situational conditions. If a situation is
misinterpreted the retrieved rule will be inappropriate as well. In other words, an error based on
rules will occur.
• Errors based on knowledge. When we encounter a new problem situation, so that existing
skills and learned rules are of little help, it is necessary to plan a novel action sequence to its
resolution. This is a higher-order cognitive activity demanding a lot of conscious control. If it
actions are not planned correctly, a knowledge-based error will occur.

Attention and assessment of workload
Driving involves various subtasks :
Tracking
Decision making
Navigation
Adherence to warnings and signals
Tending environment and mechanical system(music system, AC)
Communicating
Observing inside and outside events
Points that can be noted :
Our ability to attend stimuli is limited
Direction of attention determines how well we perceive, remember and act on information
We may therefore conclude:
Observation that fall outside our awareness region has little influence in the performance. So an information on
display panel becomes irrelevant if not attended by the operator

It may also be noted that when a single overlearned response has been executed to a stimuli
many times in past, attention is not needed. In such situations, however, familiar or irrelevant
stimuli may interfere and affect the operator’s level of performance.

Types of attention
1. Selective attention
2. Divided attention
3. Demanding attention

Models of attention
Bottleneck model : it specifies a particular stage in the information-processing sequence at
which the amount of information to which we can attend is limited.
Resource model : in this, attention is viewed as limited capacity resource that can be allocated
to one or more tasks.
further classification can be done here by dividing the bottleneck model into : early selection
and late selection model while resource model as single resource and multi-resource model.

Bottleneck model
(Filter Theory)
•Proposed by Broadbent(1958)
According to the theory, the stimuli enters the central processing channel one at a time to be identified.
Thus the filtering of unwanted message takes place prior to identification.
•Filtering can be done according to gross physical characteristics.
•References of the theory is based on the studies of Cherry’s “cocktail-party phenomenon”.
•This exemplifies the study based on selective attention
highlights of the study:
Physically distinct words can be easily repeated
If distinct messages are passed simultaneously little attention was shown to unattended message even if
repeated many times
Change in language was also rarely noticed for unselected receptor
If rapidly spoken words on one ear are blocked till selected receptor processes the information

ATTENUATION AND LATE SELECTION
THEORY
Given by TREISMAN 1964
“She proposed filter attenuation model in which an early filter served only to attenuate the
segment of and un attended message rather than to block it entirely”
It proposes the leak
An attenuated message would not be identified under normal conditions but the message could
be identified if familiarity or context sufficiently lowered the identification threshold

LATE SELECTION
Deutsch and Norman 1968
They argued that all messages are identified but decay rapidly if not selected or attended
Both attenuation and Late selection theory presumed that bottleneck may not be fixed but vary
as function of specific task requirement
They suggested that as the information processing system shifts from early selection to late
selection mode more information is gathered from irrelevant sources requiring a greater
amount of effort to focus on relevant source

RESOURCE MODELS
Resource model views attentional limitation as arising from a limited capacity of resource for
mental activity
Performance suffers when resource demand exceeds the supply
There are two models
1. Unitary resource model
2. Multiple resource model

UNITARY RESOURCE MODEL
Proposed by Kahneman 1973
He proposed attention as a limited capacity resource that can be applied to a variety of
processes and tasks
The execution of multiple tasks is not difficult unless the available capacity of attentional
resources is exceeding
Allocation policy depends on momentary intentions and evaluation of demands being placed
from these resources
Dual Task Procedure proposed by Posner and Boies 1971

Unitary resource model
According to this a person is required to perform two tasks at once namely primary and
secondary with instruction to perform primary as well as secondary
According to resource model therefore all attentional pool should be devoted to primary task
and any spare should be devoted to secondary task

MULTIPLE RESOURCES
Proposed by Navon and Gopher 1979
According to this there is no single attentional resource rather several distinct sub systems each
have their own limited pool of resource
The model assumes that two tasks can be performed together more effectively to the extent
that they require separate pool of resources
This model was developed because the amount of performance decrement for multiple tasks
often depends on the stimulus and modalities and the response required for each task

MENTAL WORKLOAD ASSESMENT
Workload refers to total amount of work that a person or group of persons is to perform over a
given period of time therefore mental workload is the total amount of mental work or effort
necessary to perform a task
It can be viewed as difference between the capacities of information processing system that are
required for task performance to satisfy expectations and the capacity available at any given
time
Performance may suffer if the mental load is too high or too low
Workload is a function of several factors such as required accuracy level, time demand, number
of task to be performed simultaneously etc.

TECHNIQUES TO MEASURE WORKLOAD
EMPIRICAL TECHNIQUE :
1. Primary task measure
2. Secondary task measure
3. Psychophysiological measure
4. Subjective measure
ANALYTICAL TECHNIQUES :
1. Comparison and Expert opinion
2. Mathematical model
3. Task Analysis
4. Simulation Model

Primary-task Measures-
mental work required of a task by directly examining the performance
of the operator or the overall system. As the task becomes difficult,
additional processing resources would be required.
Secondary-task Measure-
based on the logic of dual-task performance. The operator is required to
perform a task in addition to the primary task of interest. Workload is
assessed by the degree to which performance deteriorates in dual-task in
comparison to tasks performed alone

Physiological measure-
Measures used are pupillometry, heart rate, breathing rate, event-
related potential etc.
Subjective measure-
Operators are asked to rate such things as perceived like mental
workload, time load and stress load.
These includes Cooper-Harper scale, SWAT, NASA-TLX etc

Comparison
in this previous data of study carried on for work load is compared for its load
levels and analyzed
Expert opinion
user or developer of same system are asked to predict workload after giving
description of proposed system
Mathematical model- these include:
◦ manual control models
◦ Information theory models
◦ Queuing theory models
◦ Simulation models

Problem solving
Solutions depend on the type of responses we require i.e. quick or accurate
Trial and error
Algorithms
◦ Logical, methodical, step by step procedure that eventually guarantees a solution but may be slow to
work with
Heuristics :
◦ Simple strategy that allows us to solve problem faster, although more error-prone than algorithms

Pic of tower of hanoi

A production system framework
Problem solving is proposed within an abstract mental problem space. This would need
following aspects to be clearly defined:
1. Declarative knowledge: Representation of the problem space, about facts relation we are
able to verbalize.
2. Procedural knowledge: allowable action as defined by the problem
3. Control knowledge: strategies used to coordinate the overall problem solving process
4. Production system : includes a global database, production rules that operate on database
and a control system that has rules to apply.
◦ Heart of production system is its “if-then “ statements.

5. Task environment : characterized by a set of states and a set of operators that bring allowable
change
Newell and Simon’s (1972) helped determine performance parameter i.e. “how to represent the
problem mentally, which is based on the task environment and other knowledge”.
Limitations of problem solving:
◦ Inaccurate and incomplete problem statement
◦ Limited capacity of short term memory

LOGIC AND REASONING
Two types of reasoning are usually distinguished
1. Deduction
2. Induction
DEDUCTION : It refers to reasoning in which the conclusion about particular condition follows
necessarily from general premises about the problem. Formal logic involves arguments in the
form of a list of premises and a conclusion which are called syllogism.
There are two inferences rules that are modus ponens and modus tollens
Modus Pollens states that given major premises that A implies B and minor premises that A is
true then it can be inferred that B is true

Modus Tollens states that that given major premises that A implies B and minor premises that B is
false then it can be inferred that A is false
Conditional Reasoning: deductive reasoning with conditional statements of an “if then” form is called
conditional reasoning
Example : If the system was shutdown then there was a system failure
Categorical Reasoning : These are the statements that include quantifiers some all no and some not
Example : All A’s are B’s and All B’s are C’s therefore all A’s are C’s.

INDUCTION
Induction is a reasoning in which a generalized conclusion is drawn from a particular condition .
It involves inferential processes that expand knowledge under uncertainty
Two types of knowledge are modified
1. Procedural
2. Conceptual
Adaptive Heuristics : Human inductions are constrained by adaptive Heuristics that favors
certain classes of hypotheses over others and by cognitive limitations. One such heuristic is
availability

DECISION MAKING
Normative Theory and Descriptive Theory
Normative Theory : Concerns how we should chose possible action under ideal conditions
It relies on notion of utility i.e. how much particular outcome is worth to the decision maker
Descriptive theory: decision makers pay attention to a single dominant attribute and are less
willing to make trade-offs in other dimension
It is a stressing situation and prone to performance reversal.

IMPROVING DECISIONS
Training and task environment : Research and reasoning proposes that people with formal training make same type
of error as those without training. The deficiency in decision making that seems amenable to instructional training is
the judgment of probability
The way in which information is presented should not be underestimated due to the factor called framing.
Information should usually be framed in such a way that its attributes are encoded positively rather than negatively
Decision aids: following the cognitive limitations decision maker should be provided with decision aids such as
decision analysis and decision support system.
◦ Decision analysis: it is a set of techniques for structuring a set of problems and decomposing them into similar components
◦ Decision Support System(DSS):It is a computer based tool used to guide operator through the decision making process . It
provides them with information that may involve retrieval of data filtering and simulation .Example – MAUD (Multi Attribute
Utility Decomposition)

EXPERT AND EXPERT SYSTEMS
Acquisition of cognitive skill
Power law of practice
T= 𝐵𝑁−∝
Where T= Time to perform task
N= Number of times task has been performed
B,α= Positive Constants

Phases of Skill Acquisition: phases are
◦ Cognitive: it is for novice learning to understand the task environment and must attend to cues and
events that do not require under later phase.
◦ Associative: It is an intermediate phase where skill acquired through cognitive approach are linked
together.
◦ Autonomous : It is characterized by the procedure becoming more automatic and less subject to
cognitive control
Automatic process is characterized by :
mandatory without intention
do not interfere with other mental activities
occur without awareness

Characteristics of expert performance

Human factor issues
Human factor concerns to be addressed during construction of an expert system are:
Selection of task or problem :
◦ deductive problems are easily framed
◦ Task should be easily structured
◦ Focus should be relied on area of knowledge
◦ Human expert should conform to the task
Representation of knowledge
◦ Object in the base must reflect experts’ knowledge structure
◦ Different objects should be discriminable
◦ knowledge engineer and subject matter expert maintain a common frame of reference
◦ Procedures should be compatible with experts’ mental model
◦ Biases and exaggeration should be detected and compensated for
◦ End user expectation to be kept in mind

Design of interface:
◦ Poor design of interface leads to user aversion and operator errors
◦ Human factor specialist should determine the information to be presented to optimize efficiency
◦ Use of natural language and direct graphical representation
Performance of expert system:
◦ Potential error in knowledge base should be tested
◦ Prototype testing
Successful expert system:
◦ Minimum acceptance problem
◦ Training programs to focus on various parts of integration of expert and expert system
◦ Maintenance of system ensures long term reliability
◦ Possible areas of intervention which was not initially dealt

Eye-hand Coordination
Eye–hand coordination (also known as hand–eye coordination) is the coordinated control of
eye movement with hand movement, and the processing of visual input to guide reaching and
grasping along with the use of proprioception of the hands to guide the eyes. Eye–hand
coordination has been studied in activities as diverse as the movement of solid objects such as
wooden blocks, archery, sporting performance, computer gaming, copy-typing, and even tea-
making.
It is part of the mechanisms of performing everyday tasks; in its absence most people would be
unable to carry out even the simplest of actions such as picking up a book from a table or
playing a video game.

Neural Mechanism
The neural control of eye–hand coordination is complex because it involves every part of the central nervous
system involved in vision: eye movements, touch, and hand control. This includes the eyes themselves, the
cerebral cortex, subcortical structures (such as the cerebellum, basal ganglia, and brain stem), the spinal cord, and
the peripheral nervous system. Other areas involved in eye–hand coordination that have been studied most
intensely are the frontal and parietal cortex areas for the control of eye saccades and hand-reach. Both of these
areas are believed to play a key role in eye–hand coordination and the planning of movements during tasks
A more specific area, the parieto occipital junction, is believed to be involved in the transformation of peripheral
visual input for reaching with the hands, as found via MRI. This region in particular has subdivisions for reach,
grasp, and saccades. In additional to the parieto–occipital junction, the posterior parietal cortex is believed to
play an important role in relating proprioception and the transformation of motor sensory input to plan and
control movement with regards to visual input.
Many of these areas, in addition to controlling saccades or reach, also show eye position signals that are required
for transforming visual signals into motor commands. In addition, some of the areas involved in reach, like the
medial intraparietal cortex, show a gaze-centered remapping of responses during eye movements in both
monkeys and humans. However, when single neurons are recorded in these areas, the reach areas often show
some saccade-related responses and the saccade areas often show some reach related responses. This may aid in
eye–hand coordination or hint at the ability of cells to wire together as they're used more frequently.

Eye-guided hand movement
When eyes and hands are used for core exercises, the eyes generally direct the movement of the
hands to targets. Furthermore, the eyes provide initial information of the object, including its size,
shape, and possibly grasping sites that are used to determine the force the fingertips need to exert to
engage in a task. For shorter tasks, the eyes often shift onto another task to provide additional input
for planning further input is used to adjust for errors in movement and to create more precise
movement.
For sequential tasks, eye-gaze movement occurs during important kinematic events like changing the
direction of a movement or when passing perceived landmarks. This is related to the task-search-
oriented nature of the eyes and their relation to the movement planning of the hands, and the errors
between motor signal output and consequences perceived by the eyes and other senses that can be
used for corrective movement. The eyes have a tendency to "refixate" on a target to refresh the
memory of its shape, or to update for changes in its shape or geometry in drawing tasks that involve
the relating of visual input and hand movement to produce a copy of what was perceived. In high
accuracy tasks, when acting on greater amounts of visual stimuli, the time it takes to plan and execute
movement increases linearly as per Fitts's Law.

Response time
Response time is the sum reaction time plus movement time. Reaction time is the elapsed time
between the presentation of a sensory stimulus and the subsequent behavioral response. It
indicates how fast the thinker can execute the mental operations needed by the task at hand. In
turn, speed of processing is considered an index of processing efficiency.
The behavioral response is typically a button press but can also be
an eye movement, a vocal response, or some other observable behavior.

Types of response time
Simple reaction time is the motion required for an observer to respond to the presence of a stimulus.
Recognition or Go/No-Go reaction time tasks require that the subject press a button when one stimulus type
appears and withhold a response when another stimulus type appears. For example, the subject may have to press
the button when a green light appears and not respond when a blue light appears.
Choice reaction time (CRT) tasks require distinct responses for each possible class of stimulus. For example, the
subject might be asked to press one button if a red light appears and a different button if a yellow light appears.
The Jensen box is an example of an instrument designed to measure choice reaction time.
Discrimination reaction time involves comparing pairs of simultaneously presented visual displays and then
pressing one of two buttons according to which display appears brighter, longer, heavier, or greater in magnitude
on some dimension of interest.
Due to momentary attentional lapses, there is a considerable amount of variability in an individual's response
time, which does not tend to follow a normal (Gaussian) distribution. To control for this, researchers typically
require a subject to perform multiple trials, from which a measure of the 'typical' response time can be
calculated. Taking the mean of the raw response time is rarely an effective method of characterizing the typical
response time, and alternative approaches (such as modeling the entire response time distribution) are often
more appropriate.

References
Proctor R., Zandt T. V., Human Factors in simple and complex systems. Allyn & Bacon
Murrell H., Ergonomics: Man in his working environment. Chapman & Hall
LEE J. D., Emerging challenges in cognitive ergonomics: managing swarms of self-organizing agent-
based automation. Issues in ergonomics. VOL. 2, NO. 3. 238,250.
Gerrit C. van der Veer., Cognitive Ergonomics in Interface Design : Discussion of a Moving Science .
Journal of Universal Computer Science, vol. 14, no. 16 (2008), 2614-2629
Sumner T, Bonnardel N., Kallak H.B., The Cognitive Ergonomics of Knowledge Based Design Support
Systems
Goebel R., Siekmann J., &Wahlster W. Engineering psychology and Cognitive Ergonomics. Springer
Cañas J.J., Velichkovsky B.B. & Velichkovsky B.M. Human Factors and Ergonomics
Franklin S, Baars Bernard J., Ramamurthy Uma, Ventura M. The role of consciousness in memory

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