question

Slip

answer

failure occurs at execution ex. taking wrong medication

question

Mistake

answer

error in planning ex. substituting butter for vegetable oil

question

Lapse

answer

intended action forgotten and not carried out ex. forget attachment in email

question

Violation

answer

purposely ignore rule or procedure ex. ignore hand-washing at job

question

Mode Error

answer

action is appropriate in one system mode, but is carried out in a different mode ex. forgetting to put car in drive after reverse

question

ergonomics

answer

The study of designing equipment and devices that fit the human body, its movements, and its cognitive abilities.

question

Error of Commission

answer

perform inappropriate action ex. timing, sequence, selection

question

Human Factors

answer

The science of understanding the properties of human capability and applying this understanding to the design, development, and deployment of systems and services.

question

What is a human factor

answer

A human factor is a physical or cognitive property of an individual that influences functioning of technological systems as well as human-environment equilibriums.

question

Error of Omission

answer

fail to perform action

question

Input Error

answer

information from the sensory and perceptual processes

question

Output Error

answer

due to the selection and execution of physical responses

question

Mediation Error

answer

cognitive processes that translate between perception and action

question

Recoverable Failure

answer

can be corrected and consequences minimized

question

Non-Recoverable Failure

answer

system failure is inevitable

question

Economic Ergonomics

answer

By preventing health problems such as work-related musculoskeletal disorders, ergonomists not only improve well-being but reduce costs to companies and individuals Can also improve quality of products

question

Successful HFE

answer

Enhances performance Reduce error Increase productivity Increases safety Improves user satisfaction

question

Difficulty for human factors design:

answer

Systems should be designed in a way that they are suited to every user...

question

Affordances

answer

Relationship between the properties of a physical object and the capabilities of the human that determine how the object could possible be used

question

Solutions to the difficultys of human factors

answer

System design Task design Environmental design Selection Training

question

Foundations of Science

answer

Based on empiricism: Knowledge by observation Self-correcting: Continually test scientific statements with observations Revise scientific statements Systematically apply the scientific method

question

Scientific Method

answer

Logical approach to obtaining answers to questions Often equated with hypothesis generating and testing

question

1.Goals of Science. 2. How is it obtained?

answer

1.Description Prediction Explanation/Understanding 2.This is achieved by collecting data (gathering facts) to build a theory The theory provides the best explanation for the findings in the research

question

Four Benefits of theory

answer

1.Enables sensible interpolation to a specific real-world problem when there are no data 2.Provides quantitative predictions of the type demanded by engineers and designers 3.Allows the practitioner to recognize relations between problems that seem unrelated on the surface 4.Can be used cheaply and effectively to aid system design

question

How do we understand the problem and how do we know what to measure?

answer

1.Defines a domain of interest -In HFE, this is usually human performance within a system 2.Defines the conditions under which we can make useful measurements -If we are interested in the effects of cell phone use while driving, then we need to see people using cell phones while driving

question

1.What is an operational definition of a variable? 2.Why define them this way?

answer

1.A definition of the variable in terms of the operations or techniques the researcher uses in order to measure or manipulate it 2.Forces us to describe abstract concepts in concrete terms

question

Independent variables

answer

The variables that are manipulated or chosen by the researcher

question

Dependent variables

answer

The variables that are measured by the researcher (in other words, the variables you want to know). They "depend" on the independent variable because you set up your experiment with the prediction that the dependent variable(s) will change based on the independent variable(s)

question

Subject

answer

Human characteristics AKA individual differences

question

Reliability

answer

The consistency of measurements

question

Any measure has 2 parts:

answer

True effects Random error

question

Operating Error

answer

a system is not used according to correct procedure

question

Stressor

answer

anything which - Is not an inherent characteristic of the human/machine system - Is not inherent in the information to be processed - Is (usually) expected to degrade system performance

question

Arousal

answer

general energy level of the operator (more stress --> more arousal)

question

Psychological Stressors

answer

anxiety, frustration, fatigue, fear of failure, threat, incentive

question

Environmental Stressors

answer

noise, temperature, vibration etc.

question

Design Error

answer

system designer creates an error-likely situation by failing to consider human tendencies or limitations

question

Stress on arousal/alertness

answer

- increase attentional selectivity - under low stress, attention can be too non-selective - under high stress, attention can be too narrow

question

Stress on working memory

answer

- complex tasks rely more on working memory

question

Stress on decision making

answer

- less deliberative, more intuitive/fast - more OR less risk averse

question

Perseveration

answer

- a tendency to repeat the response to an experience in later situations where it is not appropriate - increased by stress

question

Reduce negative effects of stress

answer

- strategies to cope with stressors - minimize working memory demands

question

Hindsight bias

answer

errors look obvious in retrospect

question

Stress on speed and accuracy

answer

Under high stress people are more likely to emphasize speed at the expense of accuracy

question

The Goal of human factors

answer

Use knowledge about human cognitive, physical, and social characteristics to design machines, tools, and systems that are easy and safe to use

question

Stress and Performance

answer

For best performance, the optimal level of arousal depends on task complexity (high arousal on simple task, low arousal on difficult tasks)

question

Data-Limited Processing

answer

The information input to a stage is degraded or imperfect ex. visual stimulus only briefly flashed

question

Resource-Limited Processing

answer

The system is not powerful enough to perform the operations required for a task efficiently ex. system used to remember phone number before dialing

question

Perceptual Stage

answer

what is perceived by sensory organs, depends on quality of input

question

Model of Working Memory

answer

phonological loop: articulatory loop and acoustic store

question

Working Memory

answer

Second in cognitive stage: from attended sensory memory - maintained with rehearsal - unrehearsed information is quickly lost - can retrieve from long-term Components: - phonological loop (sound of language) - Visuo-spatial sketchpad (visual and spatial info)

question

Cognitive Stage

answer

classifies stimulus, may include: retrieval of information from memory, comparison of displayed items, comparison of items and memory, arithmetic operations, and decision-making

question

Sensory Memory

answer

first in cognitive stage: from sensory input - unattended information is lost iconic: visual echoic: auditory haptic: touch

question

Long-Term Memory

answer

third in cognitive stage: from encoded working memory - some info lost over time

question

Action Stage

answer

overt response is selected, programmed through neuromuscular commands, and executed

question

Why is human factors important?

answer

Daily occurrences such as accidents at work, in traffic, and at home, as well as disasters involving cranes, airplanes, and nuclear power stations can often be attributed to human error Analysis of these failures shows the cause is often a poor and misunderstood relationship between operators and their task

question

Three Stage Model

answer

Stimulus -> Perception -> Cognition -> Action -> Response

question

Human Information Processing

answer

human as a communication system that receives input from the environment, acts on that input, and then outputs a response back to the environment

question

Structurally Limited Processing

answer

Inability of one system to perform several operations at once ex. two competing movements performed simultaneously with the same limb

question

Detectability

answer

the absolute limits of the sensory systems to provide information that a stimulus is present

question

Discriminability

answer

the ability to determine that two stimuli differ from each other

question

Psychophysical Scaling

answer

discovering the relation between perceived magnitude and physical magnitude

question

Absolute threshold

answer

Smallest amount of intensity needed for a person to notice a stimulus, Developed by Fechner

question

Validity

answer

The degree to which an experiment, a procedure, or a measurement represents what it is supposed to represent

question

Construct validity

answer

does the measure that is employed actually measure the construct it is intended to measure?

question

Internal validity

answer

can the relations observed can be attributed with a high degree of confidence to the variables of interest? i.e., the ability to draw conclusions about causal relationships from our data.

question

Classical Methods

answer

absolute and difference thresholds pros: learn what is within range of perception cons: measures are subjective and vary between people, response bias

question

Signal Detection

answer

Observer is required to discriminate trials on which the stimulus is present from trials on which it is not yes response and signal = hit yes response and noise = false alarm no response and signal = miss no response and noise = correct rejection

question

Direct Scaling Procedure

answer

Ask the perceiver to rate the perceived intensity of the stimuli

question

Indirect Scaling Procedure

answer

Derive the quantitative scale indirectly from a perceiver's performance at discriminating stimuli, i.e. choosing which is louder

question

descriptive research method cont:Naturalistic observations and ethnographic methods

answer

-Great ecological validity -Used to characterize how people interact with a system in the "real world" -Measurement issues: Observations can be recorded at the time they are made or later Content and amount of detail in observations vary Length of time during which observations are made can be short or long Observations can vary in terms of the amount of inference, or degree of interpretation, that is required to classify events into measurement categories

question

descriptive research cont:Surveys and Questionnaires

answer

-The best way to begin addressing a problem by asking people in the natural environment -Steps to a good survey/questionnaire 1.Decide on the information you want the questionnaire to provide 2.Decide what type of questionnaire should be used If you decide to write your own questionnaire, the third 3.step is to write a first draft 4.Revise questionnaire 5.Pretest the questionnaire 6.Finalize the questionnaire

question

Simple reaction time (SRT)

answer

fastest, single response is made after the action occurs ex. press button when you hear sound

question

descriptive research cont:Interviews and Focus Groups

answer

-Structured and unstructured interviews with users at any phase of the research process and for a variety of purposes -Do not work well for discovering specific usability problems in a system

question

Descriptive research cont....again: Correlational and Differential Research

answer

-Must decide ahead of time which behavioral variables we will measure -Measure the degree of relationship between the variables -This can be used with any data obtained from Descriptive Methods -Valuable because they enable prediction based on the previously observed relationships

question

Correlational research

answer

measure the strength of a relationship between two or more variables

question

Experimental research

answer

-Test a hypothesis that makes a causal statement about the relation among variables -Compare a dependent measure at at least two levels of an independent variable -Randomly assign people to experimental conditions to make sure that the effects of many potentially confounding factors are distributed equally across conditions

question

Recognition reaction time (RRT)

answer

single response is made after some stimuli (the "memory set"), but not after others (the "distractor set") i.e. only press button for high pitch, not low pitch

question

Choice reaction time (CRT)

answer

more than one response can be made and the correct response depends on the stimulus that occurs i.e. press left arrow key for left, right arrow key for right

question

Stevens' Law

answer

The relationship between physical intensity and psychological magnitude (perceived magnitude) S = aI^n S reported sensory experience a constant I physical intensity n exponent that varies between senses

question

Reaction Time

answer

amount of time between event and person's response

question

Differential research

answer

observe two or more groups that are differentiated on the basis of some preexisting variable

question

types of research methods:

answer

1.Descriptive 2.Correlational and Differential 3.Experimental

question

Descriptive research method

answer

When you want to examine a situation that cannot be replicated You are unable to exercise any control over the events under the investigation Control can lead to a loss of ecological and external validity Using sources like Archival Data to obtain information about a system Archival data is data obtained from preexisting data collections like the census

question

External validity

answer

can the results or the principles derived from the results can be generalized to a variety of other settings?

question

Ecological validity

answer

do the behaviors observed in the study reflect the behaviors that actually occur in a natural setting?

question

Method of Limits

answer

different stimuli intensities in sequential order

question

Difference threshold

answer

Smallest amount of difference needed for a person to perceive two stimuli as different, Developed by Fechner

question

Method of Constant Stimuli

answer

different stimuli intensities in random order

question

Color Perception

answer

determined by wavelength (and other psychological factors), white/purple largest and red smallest

question

Within Subjects experiments

answer

-Use the same participants in each condition -Increases sensitivity of the design (more likely to find significant effects) -Reduces the number of participants needed -Major drawbacks: Carryover effect: previously received treatment conditions influence a subject's performance on subsequent conditions Practice/Fatigue effects: increase/decrease in performance due to experience

question

Spectral Colors

answer

comprised of single wavelength: ROYGBIV

question

Non-Spectral Colors

answer

color comprised of more than one wavelength

question

Whenever possible, use experimental designs

answer

Optimizes internal validity With the right setting, can be excellent external validity

question

Descriptive methods can provide info about real-world systems that cannot be obtained from controlled experiments

answer

Good for obtaining quick info about user characteristics and usability

question

Learnability

answer

- how easy is it to learn?

question

Design involves:

answer

Designing new products Modifying existing products Designing environments Safety Develop training programs or instruction manuals Organizational development and restructuring

question

Lightness

answer

Physically measured in Luminosity, perceived as "brightness"

question

Efficiency

answer

how quickly and accurately can you do it?

question

Memorability

answer

how easy is it to remember?

question

Satisfaction

answer

increase the user's satisfaction with the system

question

Low Error Rate

answer

reduce the number of possible errors

question

Defined 7 principles for transforming difficult tasks into simple ones (aka achieving usability):

answer

1.Knowledge in the World + Head 2.Simplify the Structure of Tasks 3.Make Things Visible 4.Get the Mapping Right 5.Exploit the Power of Constraints 6.Design for Error 7.Standardize

question

Knowledge in the World

answer

Sources of information outside of the individual Ex. Maps, signposts, labels, recipes, speedometer in a car

question

Knowledge in the Head

answer

Information from the world that has been internalized Ex. Affordances

question

Make things visible: Gulf of execution ; evaluation

answer

Gulf of Execution: The gap between the user's goal of action and the means to execute that goal Gulf of Evaluation: The degree to which the system provides representations that can be directly perceived and interpreted in terms of the expectations and intentions of the user BRIDGE THESE GAPS YO

question

Get the Mapping Right- Make sure that the user can determine the relationships:

answer

Between intentions and possible actions Between actions and the effects on the system Between actual system state and what is perceivable by sight, sound, or feel Between the perceived system state and the needs, intentions, and expectations of the user Described as "Response Compatibility"- Movement of control should match outcome goal When you turn the steering wheel left, the car should turn left

question

Simplify the Structure of Tasks

answer

-Provide simple mental aids Ex. Warning labels -Manage visible information Ex. Provide speedometers to drivers -Change the nature of the task Ex. Cashiers scan barcodes instead of typing in numbers -Making a task too simple can cause the user to lose some control of the system Ex. Preprogrammed radio buttons inhibit finding new stations

question

Make Things Visible: Feedback

answer

Feedback: When a user interacts with a system, the system should provide information that the interaction was successful or an error was made

question

Standardize

answer

When you can't exploit the previous principles... make everything the same Creates Knowledge in the Head Ex. Driving on the right side of the road Without conforming to standards, you can confuse people which causes errors Ex. Walking on the left side of a two-way door

question

Exploit the Power of Constraints

answer

Constraints can be used to prevent error: -Affordances -Only one option -Forcing function

question

Design for Error

answer

People will make errors Make it easy to recover from them! Design around them when possible

question

When Difficulty is Good

answer

Sometimes we want things to be difficult Ex. Fences block dangerous areas Ex. Child-proofing medications Use the same principles.. only opposite

question

Evaluating:Front End Analysis

answer

Before any design solutions are generated, answer the following: Who are the system users? What are the major functions of the system? What are the environmental conditions? What are user preferences and requirements?

question

Evaluating:User Analysis

answer

Who are your users? -Characteristics of users -Include all types of current users -Anticipate for potential users Develop personas -Hypothetical person derived from real user statistics

question

Evaluating:Function Analysis

answer

What functions should be performed by the system? Functions represent a general goal, not the actual tasks Ex. Function: Record a TV show Tasks: Turn on the TV and cable box, select the channel to record, select the time period to record, set recording settings

question

Evaluating:Task Analysis

answer

What are the specific activities performed by the human when interacting with the system? Should include: -Functions of system -More specific tasks to be performed -Concurrent activities Complexity will vary

question

Evaluating:Task Analysis cont.

answer

Define the Purpose -How will the data be used? -How are processes related? (e.g., Information flow, Task sequence) -What type of data should we collect? Collect Task Data -Under what conditions will this be performed? -Collection methods: observation, think-aloud, task performance with questions, interviews, and focus groups Summarize Data -Identify the task process by using an outline, flow chart, timeline, or map Analyze Data -Determine the quality of a task by conducting a workload analysis, simulation and modeling, safety/hazard analysis, or scenario specification

question

Evaluating:Environment Analysis

answer

Where will the tasks be completed and under what conditions?

question

Evaluating:User Preferences ; Requirements

answer

When different design options are available, you should determine the preferences and requirements of the intended users to guide design Examples include: Methods of collecting user preferences may include focus groups, questionnaires, etc

question

Final Test and Evaluation

answer

Based on what you found... Repeat the process in a more directed manner Reach an evaluation decision

question

Heuristic Evaluation

answer

Judge the compliance with HFE principles -should be done by several people to compare results -Not very scientific -Good to get started

question

Usability Testing

answer

-Have users interact with a system to identify flaws -Typically a functional product Conducted by: Giving the user a scenario and a task to complete Videotape Think aloud protocol Answer questions Debrief/ questionnaire Data Collected: Time to complete task Errors Comments

question

Additive mixing

answer

combinations that increase the amount of light reflected (E.g. computer monitors)

question

Subtractive mixing

answer

combinations that reduce the amount of light reflected (E.g. paint)

question

Perceptual Organization

answer

- perceive distinct objects - blind spot filled with spatial information - how brain determines what pieces in the visual field go together

question

Figure

answer

Object of focus

question

Ground

answer

Surrounding area

question

Contrast Sensitivity

answer

- distinguish bright and dim components of a static image - function of both the contrast and the spatial frequency of what is being viewed

question

Opponent Process Theory

answer

- theory of color vision, color perception is controlled by the activity of two opponent systems: blue-yellow and red-green - process of excitatory and inhibitory responses

question

Visual Acuity

answer

- clearness or sharpness of vision - Snellen Eye Chart

question

Tritanope

answer

the short wavelength (blue) cones do not contain cyanolabe

question

Protanopia

answer

the long wavelength (red) cones do not contain the erythrolabe

question

Deutanopia

answer

the medium wavelength (green) cones do not contain chlorolabe

question

Color Blindness

answer

- 1 in 12 men - dichromatic (missing one photopigment)

question

CIE Color Space

answer

Commission Internationale de l'Eclairage, describes colors based on three primaries

question

Color Circle

answer

Gradient developed by Isaac Newton, all dimensions of hue and saturation in rainbow (add luminance makes ALL COLORS)

question

Eye Cones

answer

Blue: Short wavelength receptors Photopigment: cyanolabe Green: Medium wavelength Photopigment: chlorolabe Red: Long wavelength Photopigment: erythrolabe

question

Trichromatic Theory

answer

- In humans, any hue can be matched with a combination of three primary colors - 3 types of cones are 3 different photoreceptors: red, blue, green

question

Hue

answer

property of color, variation described by names

question

Saturation

answer

purity, vividness, richness of color

question

Experimental research cont.

answer

Due to the restricted nature of laboratory experiments, we-designed experiments have high internal validity But.... strict control results in low ecological validity

question

Between subjects experiments

answer

-Two or more groups of people are tested and each group received only one of the treatment conditions of the independent variable -Typically random assignment -Matched designs are better

question

Similarity

answer

similar elements (in terms of color, form, or orientation) are perceived together

question

Common region

answer

artificially induce grouping with an explicit boundary

question

Continuity

answer

points connected in straight or smoothly curving lines are perceived together

question

Depth Perception

answer

Used to translate physiology and a 2D image on the retina into 3D spatial information Depth information: occulomotor and visual

question

Connectedness

answer

artificially induce grouping with explicit lines

question

Occulomotor cues

answer

proprioceptive: accommodation and convergence

question

Common fate

answer

elements moving in the same direction at the same speed are perceived as together

question

Accommodation

answer

automatic adjustments of the lens that maintain a focused image on the retina, good for stimuli between 20cm and 3m

question

Interposition

answer

nearer objects will block the view of more distant objects if they are in the same line of vision MONOCULAR

question

Size

answer

the "bigness" of an object MONOCULAR

question

Perspective

answer

angles such as when you know something is rectangular but it appears trapezoidal MONOCULAR

question

Motion Parallax

answer

apparent displacement or difference in position of an object viewed along two different lines of sight MONOCULAR

question

Binocular Depth Cues

answer

can only be perceived with two eyes

question

Object motion

answer

- external object is moving - with a single stimulus moving in a stationary background, we can detect movement as slow as 0.5mm per second

question

Perception of sound

answer

- Longer sounds are perceived as louder than shorter sounds, diminishes when constant -audible pitch and range decreases throughout lifetime

question

critical bandwidth

answer

If intensity is constant, loudness is not affected by an increase in range of frequencies until CRITICAL BANDWIDTH

question

mask

answer

If a sound is audible by itself but not in the presence of other sounds

question

Sound localization

answer

- the ability to locate sounds in space - need 2 ears, interaural - horizontal (not vertical) sound location - intensity differences from sound shadow of head ex. Doppler Effect

question

Vestibular System

answer

inner ear, provides information on the direction gravity is pulling and your own acceleration, works with vision and proprioception to control movements

question

Somesthetic System

answer

sense of touch, pressure, vibration, temperature, pain, and proprioception

question

Sensory system

answer

receptors in skin, muscles, joints

question

Somatosensory cortex

answer

- Adjacent areas in the skin are adjacent in the cortex - More sensitive areas have larger areas in the cortex

question

Absolute threshold for touch

answer

- smallest amount of touch that is detected, vary across the body - Lowest absolute threshold is on the face

question

Two-point thresholds

answer

- obtained by asking participants if they can determine the distance between two stimuli on their skin, when they are perceived as one stimuli then they are below the two-point threshold - Lowest two-point threshold is in the fingers

question

Passive touch

answer

the skin is stationary and an external pressure stimulus is applied to it

question

punctate touch

answer

poke

question

Active touch

answer

person contacts the stimulus by moving the skin

question

Temperature perception

answer

- Temperature sensitivity has an almost perfect temporal and spatial summation over large areas - If you press a heated flat surface on your skin, it will feel hotter than if you just press the edge - A hot object will feel hotter if it touches you longer until you experience adaptation

question

olfactory epithelium

answer

Receptor cells in the nasal cavity

question

Summary of the Senses

answer

- Audition is much like vision - Constructed around cues provided by many sensory sources - Vestibular sense is related to audition and provides us with information about our orientation and spatial relations in an environment - Skin senses provide touch, temperature, and pain perception - Chemical senses allow us to perceive different tastes and smells - Errors in our perceptions can come from false or misleading stimuli, lack of context, and discrepancy from expectancies - Need to minimize ambiguity and conform to expectancies

question

Sone

answer

unit for measuring sound based on Stevens' Law

question

Auditory Sensory System

answer

An auditory stimulus initiates a complex sequence of events that lead to the perception of sound: - Physical vibrations of the eardrum, ossicles, and oval window produce a wave motion in the fluid of the inner ear - This wave motion causes neural signals through the bending of hair cells in the basilar membrane - The auditory information is transmitted along pathways in which the neurons respond to different frequencies and other acoustic features - The processing of the sensory signal performed by the auditory system provides the basis for auditory perception

question

Size and shape constancy

answer

- We tend to see objects as the same size despite how large the image on our retina (close not giant) - We tend to perceive objects as the same shape even the image on the retina may be a different shape

question

Apparent motion

answer

discrete jumps of retinal images can produce the appearance of smooth motion

question

Induced motion

answer

- a stationary background causes movement to be attributed to the wrong part of a scene - after staring at a waterfall, other objects appear to be moving up

question

Binocular disparity

answer

each eye receives a slightly different image of the world because of the eye's location ex. stereogram

question

Monocular depth cues

answer

Convey impressions of depth in a still image: interposition, size, perspective, motion parallax,

question

Convergence

answer

degree to which the eyes are turned inward to maintain fixation on an object, good up to 6m

question

Closure

answer

open curves are perceived as complete forms

question

Proximity

answer

elements close together are perceived as a group

question

Use visual presentation if the...

answer

Message is complex Message is long Message will be referred to later Message deals with location in space Message does not call for immediate action Auditory system of the person is overburdened Receiving location is too noisy Person's job allows remaining in one position

question

Some people have impaired vision or hearing sooooo....

answer

Good to use more than one display modality when possible Ex. Fire trucks and other emergency vehicles

question

Static displays

answer

are fixed and do not change Ex. Road signs

question

Character size influences legibility

answer

Size necessary depends on the contrast ratio, viewing distance, environmental factors like ambient lighting, etc. Some fonts will be more legible than others

question

The font "Clearview" was developed specifically for improving road signs

answer

Increases the ability to differentiate between words People recognize words at a 16% greater distance When traveling 55 mph this is an additional 2 seconds

question

Alphanumeric Displays When used in variable settings they need to be

answer

flexible

question

Symbolic displays

answer

are used to convey information by using an image Typically concrete objects that can easily be drawn More complex or abstract concepts are not so easy to represent symbolically Good for overcoming a language barrier Best if standardized Must be identifiable and understandable Even when people can recognize the object or concept, they may not be able to comprehend the message

question

The speed and accuracy with which people can identify symbolic displays are influenced by :

answer

Gestalt organizational principles Clear figure-ground distinction helps eliminate ambiguity about the important elements of the display Simple and symmetric symbols will enhance readability Closed, solid figures are easier to interpret than more complex, open figures Figure contours should be smooth and continuous, unless discontinuity contributes to the information

question

Alphanumeric or Symbolic?

answer

Reading is a highly over-learned process for literate people fluent in the language Pro: No new relationships between symbols and concepts need to be learned Con: Interpreting the message takes more cognitive resources Symbolic displays can depict the intended information directly Pro: People can interpret symbolic signs faster than alphanumeric signs Pro: Requires less cognitive resources Con: More susceptible to misinterpretation In degraded viewing conditions people are much faster with symbolic displays Legibility and readability are not critical for symbolic displays Some situations require a combination of symbols and words When combined, people pay more attention as long as they follow proper design principles

question

Coding dimensions

answer

-Arbitrary features can be coded to objects or concepts -Can be based on alphanumeric forms, non-alphanumeric forms, colors, sizes, flash rates, etc Ex. Road signs are categorized by colors: green for road information, brown for sites of historic or recreational interest, blue for availability of services like food and gas, yellow for warnings, white signs are regulatory, and red are for stops or forbidden areas -Appropriateness of coding dimension depends on the task or situation

question

Absolute judgment

answer

refers to the classification of a stimulus when several options are available Ex. Deciding that a signal is "high" when the options are high, medium, or low If the stimulus varies on a single dimension, people can discriminate between 5 and 7 stimuli

question

relative judgments

answer

directly compare one to another

question

Color Coding

answer

is a method that can be very effective: Especially when the color is unique Ex. Searching for Washington apples in a basket of oranges vs. searching for tangerines in a basket of oranges -Can be used to distinguish between different levels and kinds of information Ex. Reading a map, roads are black and rivers are blue Allows people to focus on one thing because they can ignore the other colors

question

Shape coding

answer

is a useful method because people can distinguish between a very large number of geometric shapes E.g. road signs:

question

Combination codes

answer

are used to maximize discrimination ability between displays; using more than one type of coding in a display

question

If you want to know the best coding to use, then it depends on your situation:

answer

Numeral and color codes are best for people who are new to the display Experienced people are not affected by the type of coding

question

Dynamic Displays

answer

All of the principles from static displays apply Information is conveyed by movement within the display The user must perceive changes in the state of the system as the display changes

question

two types of dynamic displays:

answer

Analog: have a continuous scale and a pointer Digital: present information in alphanumeric form

question

analog displays

answer

Analog displays can be designed in 2 ways Moving pointer and a fixed scale Ex. Speedometer Fixed pointer and a moving scale Ex. Compass

question

digital displays

answer

Digital displays only present the current value to the measure Ex. Odometer

question

Analog or Digital?

answer

Best type will not be the same in all situations Digital display pro: Convey exact numerical values well Digital display cons: Difficult to read when measurements are changing rapidly Harder to see trends in the measurements (like if you are accelerating) Analog display pro: Convey spatial information and trends efficiently Analog display con: Do not provide precise values As a general rule, digital displays are more appropriate for devices in which the measurements are not changing rapidly Ex. Clocks or thermometers

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Analog Displays

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-Moving pointer with a fixed scale displays are very common and will usually be easiest for people to use -Best for depicting changes from user input -Need to consider whether to use labels or symbols to mark the scales Scale units How to mark them What type of pointer to use -All depend on the range of values and type of information

question

To make signs more efficient, ???????? words, symbols, colors, and locations should be used when available

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standardized

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Alphanumeric displays

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are any display that uses words, letters, or numbers to convey information Very common Drawbacks: Some letters and digits share many features and are easily confused with each other The person viewing the display is assumed literate Must keep in mind legibility and readability

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For practical purposes, a display should have ????????? or be constructed of appropriate material for the environment

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maintainability

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There should be ????? on important words

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emphasis

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Dynamic displays

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change over time Ex. Speedometer

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Legibility is also affected by the contrast between figures and their background

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Contrast is determined by the amount of light reflected by the figures on the display Dark print on a white background or light print on a dark background are best

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Intelligibility

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describes how the message in the display should be unambiguous and include information about consequences if ignored

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Readability

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concerns larger groups of characters (e.g. words, sentences) in which comprehension of the material is a consideration Readability is distinct from legibility! In simple terms: legibility concerns the way text looks, while readability concerns its content or meaning

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Legibility distance

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is the distance at which a person can read the display Good contrast increases legibility distance Ex. Fluorescent street signs are more legible than non-fluorescent street signs of the same color in both daylight and night time conditions

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Conspicuity

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how well the display attracts attention

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Legibility

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-the ease with which the symbols and letters present in the display can be discerned, i.e. how easy it is to distinguish individual letters/symbols so that they can be recognized -Influenced by factors like size of the letters, stroke width of the lines comprising letters, font -Legibility for images on computer displays are affected by the pixel density

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Visibility

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how well the display can be seen

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Use auditory presentation if the...

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Message is simple Message is short Message will not be referred to later Message deals with events in time Message calls for immediate action Visual system of the person is overburdened Receiving location is too bright or dark Person's job requires continual motion

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most displays are:

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visual or auditory

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Designing Displays

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-Well-designed displays insure the safe and effective operation of the system -Design considerations are important in both complex and simple situations Especially when lives are at stake like in a power plant or a plane cockpit -Designs should be related to principles from human perception

Human Factors Psychology #1 – Flashcards

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