Human Factors
one last bais
we are influences by social pressure
naturalistic decision making
when faced with uncertainty decision makers use experience, pattern matching, analogy, and mental simulation to diagnose and solve problems
What do you mean by cognition?
-communicating -identifying problems -diagnosing problems -solving problems -forecasting/ planning -coordination -decision making -error management
compatibility
-conceptual: use of red cross to signify hospital -movement: relationships between displays and controls -spatial: physical arrangement of displays and controls
long term memory 3
-decay occurs exponentially with time, such that the first few days it is very rapid -decay a recall quicker than of recognition because signals in the recognition task prime the activation of a memory in LTM storage -decay happens because of : weakened strength, weakened associations, interfering associations
decision making recap
-decision making theories 1. normative decision making theory 2. bounded rationality 3. naturalistic decision making theory 4. heuristics and biases theory
HF design for LTM
-designers, who have complete and accurate mental models of a system need to design for users who do not -infrequently performed tasks will be forgotten -encourage regular use of information to increase frequency and recency
Learned Intuition
-difficult to remember not knowing something -worse, you can't believe other don't know it or can't grasp it
Expert decision making
-does not tend to look like the normative model, whish is very deliberative -in dynamic situations, experts perceive a set of cues and then react fairly automatically- this is a skill based behavior
long term memory
-ease of retrieval of information from long-term memory depends on: Strength of memory= frequency and recency Mnemonics rely on associations between easy-to-remember constructs
HF design for LTM 2
-encourage active verbalization (task analysis: think-aloud protocol) -use memory aids for infrequent tasks or high-risk tasks in which forgetting has bad consequences -create knowledge in the world to maximize bottom-up processing so as not to rely on knowledge in the head -design to support correct mental models by alternative for action -standardize
performance and stress
-evidence shows that there is a large flat area to the curve where people can adapt, even at high and low levels of stress -operators cannot sustain high stress levels very long, but they can cope for a short time
Principles conts
-flexibility and efficiency: design to support a range of user capability -minimalist design: KISS keep it simple stupid -help and documentation: should follow the same priciples
HF design and SA
-help people perceive what is happening -help people understand a situation -help people predict what will be happening next -important in highly automated systems
Sensitivity d'
-high d' = signal far separated from the noise -high d' = high probability of hits with few errors -sensitivity is influenced by: properties of the receptor (retina, cochlea, etc.) skill of observer (rapid instrument scan) signal to noise ratio (strength of the signal relative to the strength of the noise) d' = I z(H) - z(FA) I
Working Memory 3
-holds verbal and spatial information -transient, temporary store: My words are temporarily stored in your working memory as you make sense of what I am saying You learn as you file away my lessons into long-term memory for recall in Lab, on Exam 1 and in your future career
vision
-images that pass through the cornea and lens are distorted much like camera images
Long-term memory
-is always active during perception, regardless of whether or not working memory is active when following a car too closely, the process of see break light slam on brakes involves LTM
supporting mental models
-make process visible -provide feedback-immediate and obvious -standardize -good mapping
Design to Aid Perception
-maximize bottom-up processing -maximize standardization -maximize discrimination -use redundancy (visual and auditory signal)
labeling
-messages meaningful -aid sequential task performance -aid seldom-performance tasks -exploit codes and learned associations
design for working memory
-minimize working memory load -provide visual placeholders for sequential tasks to ease recovery from interruptions -exploit chucking 3 to 4 words or letters per chunk superiority of letters over numbers for chunking because of higher likelihood of meaningfulness -avoid unnecessary zeroes
learned intuition 1
-not remembering what is was like before automaticity
Contraints
-physical: constrain possible actions -semantic: rely on the context to control action -cutltural constraints: learned from culture
design for cognitive work
-redesign the system for feedback, error identification, error management, visibility and situation awareness -design support systems: cognitive tools and automated decision
knowledge in the world vs the head
-reduce reliance on LTM through good design
heuristics and biases 2
-salience bias: people tend to focus on those cues that are physically salient -"as if" heuristic: most cues are treated "as if" they were of equal reliability -confirmation bias: cue-seeking is guided by what we already believe to be true -availability heuristic: hypothesis that come to mind quickly are believed to have a higher probability of being correct -anchoring heuristic: undue importance assigned to early evidence or information -representative heuristic: humans try to understand a situation by matching in working memory the pattern of cues seen in the environment with a mental representation of the typical "representative" pattern -framing bias: the way we consider or "frame" an outcome will affect our decision
decision making
-select one option from a number of alternatives -there is some information available about the choice options, but uncertainity prevails -Theories of decision making: normative theory, bounded rationally, heuristics and baises, naturalistic decision making
Implications of Design for LTM
-semantic networks: networks of meanings of things -schemas: mental structures that represent some aspect of the world -scripts: a schema for sequential activities
Signal Detection Theory
-signal detection tasks include: detecting a tumor in a radiology graph detecting a flaw (crack, pit) in an engine block detecting an alarm in a noisy factory -signal detection theory is binary: signal is either present or absent -operator must discriminate signal from noise
multiple resource theory
-some research that dual task performance can be improved if the tasks put demands on different resources -performance on an auditory and visual task will likely be better than performing two auditory tasks
Working Memory
-sometimes perception is not intuitive and doesn't lead directly to action because we must analyse what is perceived before making a decision -analytic thoughts are stored in working memory
expert decision making (SRK)
-still biased decision making: occurs when performance is more or less automatic, due to experience with the some task -rule-based decision making: occurs when something cues the decision-maker to look up an existing rule in order to make a decision -knowledge based: occurs in novel situations that do not trigger an automatic response or a search for rules, or when there are no rules to rely on
Results
-stressors lead to reductions in attentional capacity if the demands imposed by the stressors begin to reach the resource capacity of individual or team -operators reduce their information intake and focus on a narrower set of cues perceived important
Working Memory 2
-temporary and cognitively demanding -sometimes feeds long-term memory (learning) -used during...rehearsing, planning, understanding, visualizing, decision making, problem solving
Attention resources
-the resources you have to perceive, think and execute -they are limited -you must select which sensory channels to attend (selective attention)
Take Home Messages
-the way we process information and our cognitive strategies influence the way we design tools and technologies -the way that tools and technologies are designed influences our cognition and performance -cognition happens jointly with tools and technologies we use
Response Bias (BETA)
-this is the response bias of the operator to respond "signal" versus "no signal" -also called criterion -affected by Operator's expectancy that a signal will be seen Value (cost/ benefit) of the four kinds of events BETA = z(False Alarm Rate)
Key usability concepts
-use affordances -support mental models -Norman's 4 prinicples: visibility, feedback, standardization, mapping -neilson's usability principles
HFE is NOT
-using oneself as a model for design -common sense
Selective Attention
-you may or may not perceive important information gathered by your senses -because of selective attention, you may have problems choosing the correct response or executing the response
Ergonomic Knowledge Base
Engineering anatomy orthopedics physiology medicine psychology sociology physics math statistics programming politics
Human Factors: What is it really
Practice: Designing the fit between people and products, equipment, facilities, procedures and environments
The goal of Human Factors and Engineering Psychology is to improve:
Productivity safety comfort all of the above
Preception: Bottom-Up Processing
Stimulus in the word/Design--> senses--> perception
Working Memory 5
Storage Capacity Magic number 7 +/- 2 for numbers only Recall more effective for letters (6) words (5) Temporal Degradation (time) Decay occurs without rehearsal Even with rehearsal, longer strings of information take longer to encode and are more likely to decay Interference New information "bumps" off information
heuristics and biases
cognitive heuristics: a "rule of thumb" that helps us make quick and accurate decision most of the time bias: favoritism that compromises objectivity
Performance and stress 2
cognitive load shedding: rejection of perceived irrelevant or unwanted tasks -since heuristics and biases can be detrimental to performance, we must address this through better design and displays
heuristics and biases 3
cognitive tunneling: is the tendency to stay fixated on one hypothesis of what is going on, look for cues to confirm it, interpret ambiguous evidence as supporting your hypothesis -availability heuristics: is that we retrieve hypothesis used frequently and recently
Physical Ergonomics
concerned with human anatomical, anthropometric, physiological and biomedical characteristics as they relate to physical activity. -Relevant topics include working postures, materials handling, repetitive movements, work-related musculoskeletal disorders, workplace layout, safety and health
information storage in LTM
mental models: schema of dynamic systems-components; how they work; how to use them cognitive maps: mental representations of spatial information
Goal of human factors
as making the human interaction with systems one that enhances performance, increases safety, increases user satisfaction.
When designing systems to support a user's mental model, the designer should not:
assume that the user's mental model is the same as their own
Human factors engineering research has demonstrated that the way information is visually displayed to users will affect how they view the problem, their accuracy in processing the information, and even their response time. This demonstrates that:
cognition occurs with the tools we use, not just in our heads
bounded rationality
in decision making, rationality is limited by: 1. Information available 2.cognitive limitations of the decision maker 3. time constraints
Performance
is an all-encompassing term that may involve the reduction of errors or an increase in productivity.
visible light
is electromagnetic radiation that is visible to the human eye, wavelength ranges from 380 nanometers (violet) to 740 nanometers (red)
What are the objectives?
-Reduce errors, fatigue, stress, and injuries at work, while at the same time -Improving productivity, ease of use, safety, comfort, acceptance, job satisfaction and quality of life
HFE landmarks in history machine
-1940: work started to become less physical and more cognitive -1980: personal computers changed the nature of work forever -new communities of practice evolved within HFE: Cognitive engineering, work analysis, naturalistic decision making, expertise studies, human-centered computing
History of Light Theory
-Al-hazen: light bounces off of objects , we see because there are rays traveling towards our eyes -Roger Bacon: studied the effect of glass on light rays, curved glass could change the shape and size of visible objects -Rene Descartes: considered that everything was a machine, discovered the inverted image on the retina -isaac newton: studied refraction of light and worked to prove wave theory of light, coined spectrum
Perception2
-Clear perception large text in a well-lit room -degraded perception traffic light in fog or alarm in noisy factory -top-down processing aids perception in degraded situations using long term memory
Perception and Attention
-Context: patterns shading distracters
What is Human Factors and Ergonomics?
-Fit between people and products, equipment, facilities, procedures, and environments
Person approach
-Focus on individuals -Blaming individuals for forgetfulness, inattention or carelessness, poor production -Methods: poster campaigns, writing another procedure, disciplinary measures, restraining -Target: individuals
System approach
-Focus on the conditions under which individuals work -Building defenses to avert errors/ poor productivity or mitigate their effects -Methods: creating better systems -Target: system (team, tasks, workplace, organization)
What is Human Factors and ergonomics
-How work design affects people -Matching design to people's capabilities, limitations, needs -Changing the organization, task, technology and environment to better fit the person
How does HFE meet its objectives?
-Identification of performance problems (safety or efficiency) -Analysis of performance problems (how much time/money/pain does it cost the organization or individual?) -Design of systems to improve performance and eliminate/reduce performance obstacles/risks -Evaluation of redesigns to calculate improvement and ensure error wasn't merely redistributed
Where did HFE come from?
-Late 1800 and early 1900 European and American traditions in psychology -ergonomics coined in 1857
Working Memory 4
-Limitations: storage capacity, temporal degradation (time)
Neilsen's usability prinicples
-Match the system or representation to the real world -consistency -visible system status -fluid user control and freedom
How are the goals achieved?
-Person approach -System approach
Selective Attention 2
-Selectively attending to one thing over another texting on your cell phone while driving -you need to selectively attend to sources of information from which you want perception focusing your vision on a part of the visual field listening to one conversation filters out others
Design implications of d' and BETA
-Shifting BETA What happens if you tell your inspectors to pay more attention and not miss any affects? Hit rate increases and false alarm rate increases -Increasing d' training on signal recognition, increase arousal of operator (rest breaks), increase the signal to noise ratio, sensors
HFE Thinking
-Systems need to be designed for and to work with people -Systems must be designed to accommodate a wide range of users with varying cognitive capabilities and physical capabilities and dimensions -The way in which systems are designed will influence human behavior and system performance -Design needs to be evidence-based, not "common sense" or designer driver -All design must take into account the system of use
HFE landmarks in history
-WWII engineering psychology labs established US Army Air Corps and US Navy changing from "fit the man to the job" to "fit the job to the man" -1957 Human Factors and Ergonomics Society estbalished
fundamental attribution error
-actor-observer bais: we attribute our own failures, successes, failures to others for internal causes, successes of others to external causes
Affordance: norm
-affordance -provide a good conceptual model -make things visible -use natural mapping
automaticity
-automated task are highly rehearsed -automated tasks are executed with little conscious thought (intuitive) -automated tasks are require few mental resources -automated tasks are support multi-tasking
Perception
-awareness and interpretation of sensations -influenced by prior knowledge and experience (expectancy) -influenced by context such as noise (salience) -influenced by goals and tasks (value and effort)
situation awareness
-awareness of dynamic environment -3 stages: 1. Perception: depends on selective attention 2. Understanding: WM and LTM 3. Prediction WM and LTM -importance for performance during unexpected events and uncertainty
Hindsight Bias
-believing, after the fact, that the outcome was foreseeable or predictible
take home message 2
-blaming the operator absolves others from fixing safety hazards beyond human control -blaming is also much cheaper than redesign -designers are not typical users, but they tend to think of themselves that way -designers' clients may not be the users
design for working memory
-building working memory considerations in to instructions Do A. Then do X and Y
which of the following controls (bottom) leads to better performance controlling the display (top)?
A up, up
Perception: Top-Down Processing
Experiences --> Knowledge/long term memory/ expectations --> perception
All together
Human Factors Engineering is the scientific discipline concerned with designing systems for the people who work in them to promote performance, safety, comfort, and satisfaction
Selective Attention 3
SEEV Model (wickens): Attention influenced by... -Salience Cues that are perceptually load Inattentional blindness to non-salient cues -Effort If attention requires effort, may be less likely -Expectancy we attend to where we expect to find information -Value we attend to things we believe have value
why we standardize
Safety and efficiency: eliminate ambiguity
Human Factors: What is it really?
Science: discovers and applies information about human behavior, limitations and other characteristics to the design of tools, machines, systems, tasks, jobs and environments for productive, safe, comfortable and effective human use
Senses
Senses gather information -Vision (seeing) -Audition (hearing) -Gustation (tasting) -Olfaction (smelling) -Tactition (feeling) -Thermoception (temp) -Nociception (neural encoding: tissue damage) -proprioception (spatial orientation)
Signal Detection Theory Formula Graph
Signal-noise detection theory. There are two distribution curves of noise intensity. The horizontal axis is the signal strength and other operator will decide on a cut-off point at a location BETA. Values to the right represent a signal, and values to the left represent noise. The sensitivity d' measures the distance between the two curves. [Hit, False Alarm, Miss, Correct Rejection]
Working Memory 6
Similarity confusion Retaining items with similar features is more difficult than keeping distinct items Attention Capacity Working memory is resource-limited so if you are trying to remember something while doing a secondary task, it will likely decay less unless you stop multitasking and focus
Perception Processing
Top-down processing: experiences-->knowledge/long term memory/expectations-->perception Bottom-up processing: stimulus in the word/design-->senses-->perception
Cognitive Ergonomics
concerned with mental processes such as perception, memory, reasoning and motor response, as they affect interactions among human and other elements of the system. Relevant topics include mental workload, decision-making, skilled performance, human-computer interaction, human reliability, work stress and training as these may relate to human-system design.
Organizational (Macro) Ergonomics
concerned with the optimization of sociotechnical systems, including their organizational structures, policies and processes
empedocles
first theory of light and vision: we objects because light streams out of our eye and touches them
Prior to WWII, the general principle for improving human performance was
fit the human to the job
blinded by experience
normalized deviance, learned helplessness, taught helplessness
Feedback
response execution leads to new information to be sensed and perceived
Ergonomics
the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data, and methods to design in order to optimize human well-being and overall system performance
