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..
