IE 5770 Midterm Exam | Verified with 100% Correct Answers

IE 5770 Midterm Exam | Verified with 100% Correct Answers Why are humans complex systems Flexible & Capable | Composed of cognitive, physical, and sensory systems Goals of HF Improve Safety, reliability, job/user satisfaction/comfort, production, reduce errors, enhance human capabilities Basic Principles of HF 1. Know the User (creating requires targeting towards users) 2. Recognition of individual differences What's involved with HF Design of tasks/tech/workplaces, analysis of humans, things design with user in mind, recognition of individual differences Factors that affect HF practices 1. technology changes over time 2. training HF professionals 3. Professional organizations 4. Government/Oversight organizations 5. Funding of research 6. HF/E industrial components / inputs Where does HF fit in the System Engineering Life Requirements Analysis (Beginning) Safety/Design Most HF start off with understanding who their customers are TOME Task | Operator | Machine | Environment (consider all at once) Task What people are doing | Ex: driving Operator Human psychological/physiological condition and factors Ex: motor/sensory/experience capabilities Machine Technologies and Work Objects used in task | Ex: button size/error recovery/ issues of display design Environment Physical (light/heat) & Social (work organization) Ex: lighting, placement of equipment, communication issues Sensory Processing STSS | Model of Human Information Processing short-term memory/ working memory Perception | Model of Human Information Processing pattern recognition - often doesn't require a lot of thinking Attention Resources | Model of Human Information Processing Resource distributed over system / often requires a lot of mental demand Estimating benefits for HF tends to be _________ more difficult Examples of estimating benefits increased sales, decreased user errors/costs/litigation costs, decreased # of accidents, etc Stage 1: Front End Analysis | System Development Life Cycle of HF Activities User/Function/Preliminary/ Environment Analysis, providing input for system specification Stage 2: Conceptual Design | System Development Life Cycle of HF Activities Functional allocation, support the conceptual design process Stage 3: Iterative Design and Testing | System Development Life Cycle of HF Activities Task Analysis, Interface Design, Develop prototypes, heuristic evaluation, additional evaluative studies Stage 4: Design of Support Materials | System Development Life Cycle of HF Activities Develop or provide input for support materials such as manuals Stage 5: System Production | System Development Life Cycle of HF Activities System in production Stage 6: Implementation and Evaluation | System Development Life Cycle of HF Activities Evaluate fielded system Stage 7: System Operation and Maintenance | System Development Life Cycle of HF Activities system in operation Stage 8: System Disposal | System Development Life Cycle of HF Activities Monitor system performance over time 1st Approach | Usability Engineering Early focus on user and tasks 2nd Approach | Usability Engineering Empirical measurement using questionnaires usability studies & usage studies focusing on quantitative performance data 3rd Approach | Usability Engineering Iterative design using prototypes / rapid changes are made to interface design 4th Approach | Usability Engineering Participatory design where users are directly involved as part of the design team Learnability System should be easy to learn so that the user can rapidly start getting some work done Efficiency System should be efficient to use so that a high level of productivity is possible once the user has learned the system Memorability The system should be easy to remember so that the casual user is able to return to the system after some period of not having used it, without having to learn everything all over again Errors System should have a low error rate Satisfaction System should be pleasant to use - users are satisfied Evaluation Sense & Recognize state of world / are the perceptions meaningful/ how do they relate to goals | Do I know how I can accomplish and execute my goals Gulf of Evaluation When you can't tell the system state (questions for evaluation) | Know what you want to do, but not how to do it "Bridging the Gulfs" • Have the system provide information about itself and its functions in a perceptible, meaningful way • Make sure that desired actions are clear and supported • Take Note of where the work is being done • Things change by perspective Affordance | Normans Affordance perceived properties that may or may not exists, suggestions or clues about properties | Can be dependent on experience, knowledge, culture of the actor | Example: opening a door - going in with speed to make it easier Examples of Affordance Button affords pushing Handle affords pulling/griping Chair affords sitting Knob affords turning (user should know how to use object by looking) Design Principles to bridge the gulfs • Help understand the relationship between controls/ goals • Make things visible (Example: cruise control in a car) • Give feedback (immediate reactions) • Mapping (relationships between 2 things/related to affordances/ adjust to feedback) • Good Mapping (Control - Displays/Functions - which controls/functions and displays are related) • Types of Mapping (grouping of functions) Types of Mapping • Inherent Constraints - Hardwires • Cultural Constraints - Learned • Natural Mapping - spatial - keep in mind distractions - why mistakes are made Examples of Natural Mapping • Controls on a stove • Controls on a car Transfer Effects People transfer their expectations from familiar objects to similar new ones • Positive Transfer: previous experience applies to a new situation • Negative Transfer: previous experience conflicts with the new situation EX: Typing on a keyboard Mental Mode (MM) individual's internal representation of a target system | Allows people to make predictions about how things work How are mental modes build? • Affordances • Constraints • Mappings • Positive Transfer • Cultural Associations/Standards • Instructions • Interactions Note: Mental modes are often wrong/incomplete (people find ways to explain things) Why are psychophysical models important? To detect the difference or the existence of 2 stimuli Psychophysical Models Crossover between physical and sensation Ex: Virtual display deign using tactile feedback (how much change in vibration is necessary before change is detectable) Just Noticable Difference (JND) - Psychophysical Small noticeable change in sensation (brain's ability to sense) Difference Threshold (DT) - Psychophysical Amount of change in the stimuli which causes the JND Note: Amount of change to cause brains ability to sense Absolute Threshold -Psychophysical the smallest amount of stimuli that can be detected Weber's Law DT is proportional to the stimulus intensity (phi) Note: For louder sounds it takes more of a change to be noticed (Ex: it starts to hurt) Measurement of Absolute Threshold When stimulus value i perceptible 50% of the time Note: The ____________ is the lowest intensity (or smallest amount) of a stimulus that a person can detect at least half the time. Measurement of DT (Difference Threshold) Method of Constraints • Compare to constant values • Respond greater or less • Plot p (say greater) Note: eye doctor - narrowing down range in test Absolute Threshold Example Examining sensitivity of inspectors for feeling crack - comparing ______ across probe sizes Note: Showed an increase with increased prope tip (less sensitive) Stimuli At the beginning of information processing chart (right before Sensory processing STSS) Ex: • light - led • sound - alarms • chemical - bitterness • tactile - degrees of rise and fall Note: like the senses (some system in your body Characteristic of a coding system • detectability of codes (thresholds) - see/read/feel/understand • discriminability of codes (JNDs) • meaningfulness of codes • standardization of codes • code redundancy All languages use these coding systems Modal Theory Sensory memory - holds sensory input (like sights and sounds) for a fraction of a second. Short-term memory (STM) - temporary storage for information currently being used. Long-term memory (LTM) - stores information more permanently. NOTE: Learn to ignore certain elements Sensory Memory • Iconic (visual) • Echoic (auditory) Limits • Detection thresholds • Discrimination thresholds • Pain Perception process of attaining awareness of sensory information • pattern recognition • preparation for further processing Examples: recognizing a friends face Processes for perception • feature analysis • unitization • top down processing (vs bottom up) - memory/experiences Sensory signal detection • stimulus • signal • noise • task Example: how much background noise can you allow before it becomes unsafe at power plant Signal Detection Theory • model of how humans separate noise from signal - relevant/important information • Collect observation - enough evidence to become a signal? • Normally distributed • Why was something seen Information Theory • What did you do • not that important for design • How much space is this taking up in your mind? Processes in Signal Detection Random variations lead to higher-than-normal X Note: smaller differences in intensity between signal and noise can cause greater likelihood in error (harder to find) Performance parameters for signal detection theory 1. Response Bias - prone to say "signal" 2. Sensitivity (increase DT/ training/practice) Countermeasures for signal detection - absolute judgement failures • training and experience • anchors •memory aids • redundant coding Sensory Processing • Senses have capabilities and limitations • filtering environment information (stimuli) Sensory Registry • Prolonged stimuli after it's no longer physically present Ex: sparkler and see a "trail" of light — that's your visual sensory memory keeping the image alive for a moment • Fades very quickly!! Rapid • Must use attention to perceive or recognize stimulus Electromagnetic (stimulus) Vision (sense) Mechanical (stimulus) • Hearing • Touch • Pain (nerve bending) • Balance (know when you're upside down) • Kinesthetic (body position and movement) Thermal (stimulus) • Cold • Warm Note: a lot of things can cause these feelings Chemical • Taste • Smell Note: trade secrets - prevent a lot of studies!! Sensory Receptor Delays • Delays in neural transmissions (brains & muscles) /cognitive processing Note: not as fast as what we think we are! Vision • Primary sensory system • Stimulus property (wavelength - color & amplitude - brightness) Sensory Organ: The eye The eye detects light and focuses images, but vision quality varies with lens shape, flexibility, and age-related or genetic differences. Contrast sensitivity Ability to see the difference between lighter and darker areas - implication of design of text, signs, computer screens etc. Loudness Loudness - what you perceive - related to dB (stimulus value) Note: "equal loudness" -concept means a high-frequency sound at a lower dB can seem as loud as a low-frequency sound at higher dB Temporary Threshold Shifts (TTS) Loss in ability to hear after exposure to loud noise -- declines over time * Repeat in TTS can cause PTS Permanent Threshold Shifts (PTS) Permanent loss * dif limits based on exposure Haptic (Touch) System • Pressure • Vibration Ex: Tactile feedback from equipment (steering wheel, brake, engine vibration) Olfactory (Smell) System - can be sensitive to some substances Example: drop of perfume UNKNOWN TOLERANCE Gustatory (Taste) System Measure and range fully the subsystem Ex: teaspoon of sugar in a gallon of water - can you detect it?? UNKNOWN TOLERANCE Proprioceptive & Kinesthesis where are all the parts of your body and how are they moving Vestibular • Inner ear, measures acceleration • Motion sickness Relative judgment - issue in recognition Compare to something else in the world Absolute judgement - issue in recognition Compare to something in memory * Note: feature analysis - recognize and analyze parts stored in memory Top Down Perception is shaped by expectations, goals, and context (e.g., recognizing a degraded photocopy because you know what to expect) • expected size • relative motion NOTE: Our perceptions can be tricked by context or expectations, leading to errors (like rear-ending small cars) or useful illusions (like pavement markings that slow traffic). Bottom Up Recognition starts with raw sensory input, building perception from the details upward • How many times have eyes rotated Post Sensory Registry Attention as information passes into perceived/recognized Modes of Attention • Selective (direction) • Focused (breath) • Divided (breath) Selective Attention A successful application is necessary for achieving perception Focused Attention ability to concentrate on one source of information Divided Attention Concurrent processing of different sources of information Note: sometimes describes our liited ability to time share two or more tasks SAF Selection of inappropriate aspects of the environment FAF Inability to concentrate on one source of information DAF Inability to divide attention among stimuli or task Salience - Selection of channels Quality of the stimulus Note: when salience is high - bottom up processing predmiate Example: High _______- loud/bright / grabs attention!! Effort - Selection of channels Required __ needed to sense a stimulus * Humans naturally want to conserve energy Expectancy and Value - Selection of channels The act of projecting on and assessing stimuli based on stored knowledge * Associated more with top-down processing * How can we be manipulated * Adds value to the goal state or not Average UFOV (Useful Field of View) Spec Attention