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Unit 1 Foundation of Human Computer Interaction - Coggle Diagram
Unit 1 Foundation of Human Computer Interaction
1.1 Principles of good design of interface for user interaction
Human-centered development
process
of interface development that starts with users and their needs
requires developers to
understand people & tasks
they wish to achieve
to design a
good interface
for user's interaction
Visual
Size and depth
visual angle
indicates how much of view object occupies (relates to size and distance form eye)
visual acuity
is ability to perceive detail (limited)
familiar objects perceived as constant size (in spite of changes in visual angle when far away)
cues like overlapping help perception of size and depth
Brightness
subjective reaction to levels of light
affected by the luminance of the object
measured by just noticeable difference
visual acuity increases with luminance as does flicker
Colour
made up of hue, intensity, saturation
cones sensitive to colour wavelengths
blue acuity is lowest
8% males and 1% females colour blind
Reading
visual pattern perceived
decoded using internal representation of languages
interpreted using knowledge of syntax, semantics, pragmatics
Reading involves saccades and fixations
Perception occurs during fixations
Word shape is important to recognition
Negative contrast improves reading from computer screen
Hearing
Provides information about environment:
distance
directions
objects
Humans can hear frequencies from 20Hz to 15kHz
less accurate distinguishing high frequencies than low
Auditory system filters sounds
can attend to sounds over background noise.
example: the cocktail party phenomenon.
Movement
Time taken to respond to stimulus:
reaction time + movement time
Movement time dependent on age, fitness etc.
Reaction time - dependent on stimulus type:
visual ~200ms
Auditory ~150ms
pain ~700ms
Increasing reaction time decreases accuracy in the unskilled operator but not in the skilled operator
Touch
Provides important feedback about environment
May be key sense for someone who is visually impaired
Stimulus received via receptors in the skin:
thermoreceptors
heat and cold
nociceptors
pain
mechanoreceptors
pressure
Some areas more sensitive than others
e.g. fingers.
Kinethesis - awareness of body position
affects comfort and performance.
Cognitive process
how we acquire and store experience in our long term memory
help in decision making or coming up with creative ideas
increase the efficiency of the interface design
memory functions
sensory memory
short-term memory
long term memory
Short-term memory
working memory / temporary memory
properties(
rapidly accessed, recalled, decays and limited capacity
)
Example:
Facebook Chat, OTP
Long-term memory
memory that we had with us for a period
can stored more information
capacity immeasurable large, slower accessed, created and decays
Example:
login ID and password
how to reply messages to people using WhatsApp
Human impairment
Visual
Hearing
Physical
Speech
Usability heuristics
Visibility of system status
Match between system and the real world
User control and freedom
Consistency and standards
Error Prevention
Recognition or Recall
Flexibility and Efficiency of Use
Aesthetic and Minimalist Design
Help Users Recognize, Diagnose and Recover from Errors
Help and Documentation
1.2 Usability of interactive systems
Usability requirement
Learnability
= new users can begin effective interaction and achieve maximal performance
Flexibility
= many ways for user to exchange information with the system
Robustness
= level of supported provided the user in determining successful achievement and assessment of goal-directed behaviour
Learnability requirement
Predictability
可预测性 = determine effect of future actions based on past interaction history
Synthesizability
综合性 = assessing the effect of past actions
Familiarity
熟识性 = how prior knowledge applies to new system
Generalizability
概刮性 = extending specific interaction knowledge to new situation
Consistency
一致性 = likeness in input/output behaviour arising from similar situation or task objectives
Usability measures
Total performance time
Recording the usability problems
Counting the input form the user
Questionnaire
Flexibility requirement
Dialogue initiative
= freedom form system imposed constrains on input dialogue
Multi-threading
= ability of system to support user interaction for more than one task at a time
Substitution
= allowing equivalent values of input and output to be substituted for each other
Customizability
= modifiability of the user interface by user or system
Robustness requirement
Observability
= ability of user to evaluate the internal state of the system from its perceivable representation
Recoverability
= ability of user to take correction action once an error has been recognized
Responsiveness
= how user perceives the rate of communication with the system
Task conformance
= degree to which system services support all the user's tasks
1.3 Usability testing procedures
Testing and Evaluation
tests usability and functionality of system
occurs in laboratory, field and /or in collaboration with users
evaluate both design and implementation
should be considered at all stages in the design life cycle
Objective
to access the system functionality
to access users' experiences
to rectify any problems within the system
Principles of usability
repeatable design for usability relies on maximizing benefits of good design by abstracting out the general properties which can direct purposeful design
success of designing for usability requires both creative insight and purposeful principled practice
Evaluation through user participants
1. Empirical methods: experimental evaluation
controlled evaluation of specific aspects of interactive behavior
evaluator chooses hypothesis to be tested
a number of experimental conditions are considered which differ only in the value of some controlled variable
changes in behavioural measure are attributed to different conditions
2. Query Techniques(Interview)
Analyst questions user on one-to -one basis usually based on prepared questions
Informal, subjective and relatively cheap
Advantages
can be varied to suit context
issues can be explored more fully
can elicit user views and identify unanticipated problems
Disadvantages
time consuming
very subjective
3. Questionnaires
set of fixed questions given to users
Advantages
quick and reaches large user group
can be analyzed more rigorously
Disadvantages
less flexible
less probing
4. Think aloud and co-operative evaluation
user observed performing task
User asked to describe what he is doing and why, what he thinks is happening etc.
variation on think aloud
user collaborates in evaluation
both user and evaluator can ask each other questionsthroughout
Advantages
Simplicity = requires little expertise
can provide useful insight
can show how system is actually use
Disadvantages
Subjective
Selective
Act of describing may alter task performance
Less constrained and easier to use
user is encouraged to criticize system
Clarification possible