Human Factors Engineering- Final Exam

Yerkes-Dodson Law

-Hancock and warm, coping function

Fault tree (Risk models)

A fault tree analyzes one or more chain of events and determines NODES where something may or may not happen

Synthesizer controls

Grouped by function primarily

Risk Models- Cusp Catastrophe Model

Includes psychosocial and hazard variables

Risk Models- Resiliences

Latter 2 are less analytic than the others and are considered here as part of safety climate and culture constructs

Chain of events

Multiple chain of events

Risk Models- Single Cause model

Multiple single causes

Explanations for Altereffects

Persistent coping, adpative cost

Risk Models- Petri nets

Simulations

Stress and Human Performance

Stress- Stress is the response of the organism any environmental demand. Includes positive or favorable outcomes as well as negative ones.

Human Computer Interaction

The interface is changing • Graphic user interfaces (displays) evolved • Point and click: The display is the control • Virtual reality- Operator surrounded again by both display and control functions • Handheld or pocket devices, prosthetics, nanotech • John von Neumann envisioned the computer as a flexible...

Ashby's Law of Requisite Variety

o A controller must be at least as complex as the system it is meant to control

Cumulative Fatigue Results: Compensatory Abilities

o Arithmetic o ....

More conventional person-interface system

o Control dominated Inherited old keyboard technology

Group workload Ratings (Helton et al., 2014)

o Coordination demand o Communication demand o Time-sharing demand o Team efficacy o Team support Team dissatisfaction

Results from first 6 projects on cusp model for fatigue

o Episodic memory o Verbally cued pictorial memory o .....

Accidents and Prevention- Top causes of death- US and Global (DISEASE)

o Heart disease o Cancer o Stroke o Accidents ♣ These 4 are partially stress-related o Respiratory illnesses o Alzheimer's disease

For multiple submovements, Fitts' law generalizes to

o MT= a + b(D/W) 1/n o N= number of submovements

Subjective workload- NASA TLX Ratings, Individual (Hart and Staveland, 1988)

o Mental demand o Physical demand o Temporal demand o Performance required o Effort required o Frustration

Degrees of freedom for fatigue

o Observe increased variability in performance when fatigued o Observed in task switching o Redistribution principle o Loss of total entropy

Sources of Stress

o Physical environment o Social environment o Speed and load -dysregulation due to irregular work schedules

Degrees of freedom principle for workload

o Reorganize tasks for minimum entropy o Automaticity with practice and learning o Within tasks DF between tasks during task switching

AI- Picked up more cognitive functions

o Smart displays first appeared on conventional machines Better error correction systems

ENIAC

o The operator was surrounded by control panels o Clumsy o Display technology minimal

Feedback and Control

• -Open loop • -Closed loop • -Feedback and be positive or negative

Animation and Hypermedia

• ..... • Channel capacity and information overload with irrelevant material. Same point applies to audio • Hypermedia could have an..

Cusp model for fatigue

• 7 different work curves... o Performance drops gradually o Performance drops suddenly o Maintains stable, high performance o Maintain stable, low performance o Stable before or after a performance drop o Highly unstable o Performance increases suddenly o Bifurcation- amount of work done o Asymmetry- compensatory ability

Recursion

• A recursive program can call itself as a subroutine and alter its own programming • Need to have some rules to launch capability

Donder's RT

• A: 1 stimulus, 1 possible response • B: 2+ stimuli, 2+ possible responses • C: 2+ stimuli, 1 stim maps to a response • Stimulus identification time= C- A • Response selection time= B - C

Circadian Rhythm and Alertness

• Alertness levels from noon to noon determined by the time....

Levels of Sophistication

• Algorithmic o Rules executed in an unvarying order • Rule-based o Uses metarules to vary the execution of the rules • Frame-based o Template and classification manipulation • Recursive o Can call itself a subroutine and alter its own programming

Life-style, Spillover

• Another attempt at individual accident proneness o However: o Life-style correlations with occupational accidents are very low; poor prognosis for personnel selection o Work-home spillover—more often in the direction of work spilling over to home or traffic, rather than the other way around When a system is properly engineered for ergonomics, individual difference sin personality should disappear

Batch Fugues

• Another example of recurions

Chaotic Controllers (Types)

• Anticipation requires knowledge of nonlinear functions • Adding instability forces the system to maximum variability, to which one applies an appropriate filter • Periodic entrainment- Force the system to sync to an oscillator • Use of control parameters requires knowledge of what they are

Cusp Catastrophe Models

• Anxiety and performance • Load and buckling stress • Diathesis stress model • Fatigue

Synthetic Vision

• Application areas: Airplane windshield, remote controlled vehicle (drones) • Instead of looking directly, cameras feed video • Software integrates and enhances • Could place automation in tasks that still require human and adaptation

Physiological Indicators of WL

• Autonomic • Electrodermal • Heart rate • Heart rate variability • CNS • EEGs • Near infrared • Different methods do not always respond to the same stimuli • Event-related EEG/ED vs streaming time series

Limitations of Synthetic Vision

• Because simultaneity is lost, the user can no longer be guaranteed to see new events on screen as they occur • Situation awareness not so high

Programming Languages- Levels

• Binary • Fortran, cobol, basic • Shell programs • Symbolic programs, LISP, C++, other object-oriented strategies

Simon

• Bounded rationality • Satisficing • Forrester's system dynamics for system simulations

Peripheral Nervous System

• Central- Brain and spinal column • Peripheral- all else o Somatic or voluntary o Autonomic or involuntary ♣ Sympathetic- activation ♣ Parasympathetic- Relaxation • Flight or flight are equivalent • Freezing, standing still

Gestural Interface

• Computer reads motions of hand inside glove • Problems with stereotypic motions • Virtual reality applications • Smart phones use combo of gesture and touchscreen • Midas touch in larger systems • Gaze control

Accident Proneness

• Concept of accident proneness: "90% of the accidents are incurred by 10% of the people" • Such distributions can occur by chance, however, with a poisson distribution • Psychologists tried using personality and life-stress variables. Low correlations with individual behavior

Voice Controllers

• Considered, e.g., military aircraft, when the eyes and hands are overly busy • Current systems can distinguish a small vocabulary • Uses the WORD, not the phoneme as the unit of analysis • Simply systems can be at least as accurate as deaf manual controls

Entangled Problems

• Coping and resilience o Fatigue conditions slow down work pace reduces speed stress maintain performance o Low demand, monotonous tasks could be fatiguing for different reasons compared to high demand tasks o Switching tasks can alleviate fatigue increases demand on working memory o Situational and trait variables for elasticity versus rigidity o Role of compensatory abilities

Parts of an Expert System

• Data base • Inference engine • Interface

Rule search strategies

• Depth first • Breadth first • Forward chaining • Backward chaining • Classification schemes are thought to be fundamental to all knowledge and expert data bases and inference strategies

Shift Work and Jet Lag

• Discoordination between the body's neurotransmitter secretion patterns, alertness, body temperature • Cognitve and psychomotor impairment, leading to errors and accidents • Eating and sleeping disroders • Anxiety and depression if disruption is prolonged

Some Types of Controls

• Discrete vs. Continuous • Pushbutton vs discrete • If the 2 deimensions of control are depicted as two 1-D displays, then two 1-D controls should be used instead • Hierarchical controls can reduce the number of dims operating at once, but they add chances for mode error

Challenges to voice controllers

• Discriminate users in a security-based system • Generalize users for mulit-user systems • Overcome intrusions from noise

Immersion and Interaction

• Dismounted Infantry Virtual Environment (DIVE) technology o Minimum encumbrance o Deep sensory and functional immersion o Body-centered interaction • Military applications

Displays

• Error messages • Screen organization • Graphic user interfaces • Use of color • Pop up and wait • Visual icons • Auditory icons • Speech interfaces • Animation and hypermedia • Pop-up windows prevent operator from having to open and close files repeatedly while working with several display-control modules • GUI screens controlling a power plant with ancillary..

Sometimes operations are better, faster with more keystrokes and greater meaning, vs.

• Fewer keystrokes, vague comments • Hysteris during performance improvement

Assets of Synthetic Vision

• Find more targets than direct feed • Fewer false positive • Lower cog workload ratings

Origins of Programming Languages

• First conceptualized computer programming • Vision of artificial life • Started with Artificial intelligence • Economic theory of games with Oscar Morganstern

Minimum Entropy Principle

• Get the job done with the path of least resistance • Explore possible pathways in early learning • Lock ontol something more efficient later • Ashby's law: A controller needs to be as complex as the system it tries to control • Some variability is necessary to support an adaptive response

Shape

• Helps recognition without complete visual attention • Standard joysticks on airplanes • Navy underwater series of knobs • Beer taps on power plant controls

Population stereotypes

• How people expect a control to work based on past experience • Which way do you turn the screw? • 2 aircraft approaching head-on, which way do they turn?

Size of Controls

• In old days, large size meant that large physical forces were being moved

Emotions in human-computer interaction

• Interfaces that detect stress and workload and adjust amount and type of information displayed • In VR, realism of emotional reactions and levels of intensity (sense of presence) As information to communicate with robots via vocal inflections or facial expressions

Locus of control

• Internals think that everything that happens to them is a result of something they did, good or bad • Externals think that everything that happens, good or bad, is a result of luck, chance or external forces

Types of rules

• Interpretations of measurements • Diagnosis • Monitoring • Planning • Design

A rule is perfect if

• It has a single clear purpose • Clear and concise with little room for doubt • No side effects • Purpose is constant • Perfect is a matter of degree

Fitts' Law

• MT= A + b (2D/W) • MT= Movement time • D= Distance to the target • W = Width of the target • A and b are regression constants Fitts' Law assumes a single movement

Other input methods

• Mouse • Trackball o An upside-down mouse. Essentially the same mouse function on laptop computers • Joystick • Touchscreen • Stylus o 2D examples in a graphics design program and terminal display allowed the user to draw on the screen o Screen became a control as well as a display ♣ 3d examples for encoding objects for a virtual reality program

Our understanding of accident deaths

• Much of our understanding of accident analysis and prevention can be drawn from occupational accidents • Although there are differences in situations, there is generalizability to the other settings Occupational environments are easier to study for some types of questions

Voice annotation guidelines

• Must be properly heard to start, so that user will have to use pause and repeat as little as possible • Beware of common tendency to be more wordy than necessary u • Voice annotations of whole sentences are processed more slowly than typewritten sentences • Provide ways of easily editing voice annotation • Long annotations may require, pause, stop, rewind, features • Use "quite different voices" for differentiated voice...

Designing Web Pages

• Navigation and strategic location of link s • Features of page design o Gestalt laws of form o Color o Orientation to other objects on a page o Texture s o Position

Associated characteristics of cusp model for fatigue

• Organize research design to capture both workload and fatigue at the same time • Sometimes the workload effect is stronger than the fatigue effect • Sometimes vice-versa

Implications of Stress

• Performance • Contributes to work-related accidents • Cumulative stress disorders • Occupational & other stress contribute to the major health disorders Circadian Rhythm and Alertness

What Rules do

• Permissions • Obligations • Prohibitions • Causal: If you do this, then x happens

Learning and Skill acquisition

• Practice lowers RT • Inverse learning curve for skill acquisition

Keyboards

• QWERT • Dvorak keyboard • Electric typewriter • Chord keyboards (court stenographers) • Numeric Keypads • Membrane—tactile feedback • Phone company needed a human factors study to determine the best arrangement for the touch-tone phone • Key punch machine and punch cards • Membrane keyboard o Not a QWERTY format

Small Integrated Displays

• Represent several pieces of information about a system in an iconic configuration • View system changes over time • Image design assumes a triadic PMS: Display<- Operator > System of meaning

Motor Control

• Robotic therapy device assists stroke survivors to re-establish neuromotor pathways • Comparison of mathematical models for emulating reach-grasp trajectories

Persistent Questions when designing window systems

• Should a wind message always appear in a fixed or variable position? (FIXED) • What distance should there be between the window message and the events that instigate it? • How should menu options be combined to form categories? • What title should be given to menu options? • How can the structure of menus be made transparent to the operator?

Adaptive Cost

• Some mental capacity was used to scan stressors for threatening stimuli or to adapt in other ways. This capacity remains depleted after stressors have been removed

Neural Networks, Cognitive

• Start with an open-textured classification system/concept • During training, expose the system to exemplars that either correspond to a member of a set, member of a different set, or not a member of known sets • System is then presented with new examples, which It classifies • Neural networks are subject to speed-accuracy trade-offs too • Low-noise training data is learned faster, but less robust for dealing with real data containing noise • Training on noisy data produces a more robust network in the long run • More sophisticated: Neural nets would be stocked with rules for developing new classification strategies o Variety of recursion

Resistance

• Static resistance- initial counterforce then free operation • Elastic (spring loaded)- • Viscous (dampens velocity) - proportional to speed of motion • Inertial (dampens acceleration or "jack-rabbit starts)

Too Much Stress Produces

• Strain (psychological or medical disorders) • Anxiety o A temporary state o A longer-term trait o Fatigue ♣ Too much time on task ♣ Too long since operator slept last ♣ An emotional escape response o Burnout ♣ A loss of emotional engagement after too much stress over too many years ♣ More often associated with emotionally demanding jobs

Auditory icons

• Symbolic-arbitrary association between sound and referent • Metaphorical icons- Some literal, but incomplete similarity • Nomic- as literal as possible • Earcons- symbolic-type auditory icons, often accompanying visual signs of system operation • Spearcons- spoken words at very high speed to accompany menu items. Facilitate navigation through redundancy

Turing

• Test to determine whether an intelligence is real or artificial • Universal computational machine- there is no difference between the "data" and the "program" • UCM allows for "recursion"- see later

Effects of control on stress

• The negative effects of stress on performance and health are greater to the extent that the worker perceives no control over the sources of stress • Learned helplessness- Also a premier explanation for the experience of depression

Godel

• Theorem- For any rigorous set of logical statements, there is always at least one statement that cannot be rationalized from the others • The "back door" on programs

Three main motivations for Using visualization technologies

• To present information with known complex, relationships; • Make comparisons from data sources

Space of Controls

• Total amount of action, or range of action resulting from the control motion

Types of Accident Deaths (USA)

• Traffic—43% • Home - 20% • Public situations—20% • Occupational (incl. transport work) 16%

Training Programs

• Transfer of training: learning new material or tasks is facilitated to the extent that new and old material is similar with respect to o Stimuli o Responses o Reinforcement structure

Determinants in Donder's RT

• Type of stimuli • Cluttered displays

Design Issues for Multimedia Systems

• UNDO command • Make different levels of detail available • Accommodate different user groups • Support with good navigation system...

Taxonomy of Pyschomotor Skills

• US military project to establish recruits abilities and training goals • Factor analysis study • 11 Psychomotor skill factors o Control precision—Involving tasks requiring finely controlled muscular adjustments, such as moving a lever to a precise setting

Frame-Based Systems

• Use search strategies for frame-based systems too • Frame= set of data containing several pieces of specific data for each itme, e.g., type of wine, that is in the data base • Frame- based system=.. • An open-textured rule is defined by the examples

Possible Uses of Virtual Reality

• Visualize real physical spaces remotely • Hold meetings with anyone, anywhere...

Graphic Help visualization

• Weather map • Geographic information systems and geographic locator systems...

Neural Networks

• Where expert systems pertain to cognitive activities, neural networks were initially built to emulate real neural process • Programs for psychomotor skill • Robotics and elsewhere • Cognitive applications also • Neural networks must be "trained" • Expose system to examples of correct actions or decisions • System acquires prototypic perception-action sequences • Training must usually be "supervised,"...

Stimulus compatibility

• Which way do you turn the knob to make the indicator move to the right?

Memory enhancements

• Word processing- typewriter and compositor • Desktop computer- hard drive and capabilities • Concept of user- friendly • Menu structures- Semantic memory and the magical number 7 +/- 2 • Latest- the tablet that has no hard drive or local storage. Files are stored in a "cloud" where other people can read them all

Theremin

• amuscial instrument that used the first gestural interface o Introduced in the 1930s o SciFi soundtracks in the 1950s o Evolved into the Moog Sythenthesizer in the late 1960s

Persistent Coping

• we adopt a strategy to cope with the stress, but the strategy remains in place even though the stressors have been removed

Virtual Reality

•Immerse yourself in a 4D world instead of just looking at it • Your new world operates according..