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Usability Techniques for Web-based Services. Diversity and Technology. Universal Accessibility. Design for All. General Principles Vanderheiden (1997). Use: equitable, flexible, simple and intuitive. Perceptible information and error tolerance. - PowerPoint PPT Presentation
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CHI2000 1 Lindenberg, NeerincxPemberton, Van Dijk
Usability Techniques for Web-based Services
Diversity and Technology
CHI2000 2 Lindenberg, NeerincxPemberton, Van Dijk
Universal Accessibility
Design for All
CHI2000 3 Lindenberg, NeerincxPemberton, Van Dijk
General PrinciplesVanderheiden (1997)
• Use: equitable, flexible, simple and intuitive.
• Perceptible information and error tolerance.
• Low physical effort and appropriate size and space for approach.
CHI2000 4 Lindenberg, NeerincxPemberton, Van Dijk
Guidelines for ElderlyCzaja (1997)
• Contrast, screen glare, object size
• Minimal info, consistent location, group
• Highlight, color discrimination, key label
• Clear icons, practice
• Minimal demands on memory
• Consistency, simplicity (e.g. online help)
CHI2000 5 Lindenberg, NeerincxPemberton, Van Dijk
Web Content Guidelines (W3C)http://www.w3.org/TR/WAI-WEBCONTENT
• Auditory/visual alternatives/not color alone
• Markup and style sheets
• Natural language, tables, pages
• User control, access of embedded UIs
• Device independence, interim solutions
• W3C technologies, context information
• Clear navigation and simple documents
CHI2000 6 Lindenberg, NeerincxPemberton, Van Dijk
Conclusions
• Guidelines are available
• A coherent, complete, well-founded and practical set is lacking
• Techniques for application of the guidelines are scarce
=> Cognitive engineering framework
CHI2000 7 Lindenberg, NeerincxPemberton, Van Dijk
Cognitive Engineering (1)
empiricalsummative
analysis
designempiricalformative
analyticalformative
AssessmentSpecification
implemen-tation
flow of spec/assess task/processflow of iteration
CHI2000 8 Lindenberg, NeerincxPemberton, Van Dijk
practicaltheory
effectiveness,efficiency and
satisfaction
objectivesWeb-service
users, goals,info/ supportneeds and use context
specification
Cognitive Engineering (2)
assessment
data/info
task or process
CHI2000 9 Lindenberg, NeerincxPemberton, Van Dijk
Practical Cognitive Theory
Factors that affect Web-navigation:
• Spatial ability for mental modeling
• Memory capacity for task-set switching
• Situation awareness during interaction
CHI2000 10 Lindenberg, NeerincxPemberton, Van Dijk
Theoretical and Empirical BasedUser Requirements
for Elderly
CHI2000 11 Lindenberg, NeerincxPemberton, Van Dijk
Web-Navigation Performance
0
20
40
60
80
100
young elderly
% c
orre
ct in
fo a
cqui
sitio
n
CHI2000 12 Lindenberg, NeerincxPemberton, Van Dijk
Spatial Ability
0
5
10
15
20
25
30
35
young elderly
# co
rrec
t ch
oice
sMentalrotation
task
=> spatial representation
CHI2000 13 Lindenberg, NeerincxPemberton, Van Dijk
Memory Capacity
=> scheduler and goal creation
memorytask
0
10
20
30
40
50
60
70
young elderly
task
com
ple
tion
tim
e (s
)
CHI2000 14 Lindenberg, NeerincxPemberton, Van Dijk
News
ProductsIntroduction
FacilitiesDepartments
PeopleProjects
Request for information
Situation Awareness
=> multi-media, context and goal refinement
0
1
2
3
4
5
6
young elderly
corr
ect c
ateg
oris
atio
ns
categorisetask
CHI2000 15 Lindenberg, NeerincxPemberton, Van Dijk
Transform User Requirements into Navigation Support
for Elderly
CHI2000 16 Lindenberg, NeerincxPemberton, Van Dijk
Analysis
• Map user requirements on current support functions
• Prioritize according to “Web-service objectives”
• Estimate implementation costs
=> synthesize support concepts
CHI2000 17 Lindenberg, NeerincxPemberton, Van Dijk
Design and Implementation
Three support functions:
• categorizing landmarks
• history map
• navigation assistant
CHI2000 18 Lindenberg, NeerincxPemberton, Van Dijk
Evaluation
Three usability measures:
• effectiveness
• efficiency
• satisfaction
CHI2000 19 Lindenberg, NeerincxPemberton, Van Dijk
Example Satisfaction Results
1
2
3
4
5
None Landmarks Hist. map Assistant Combined
subj
ectiv
e us
abili
ty r
atin
g
youngelderly
CHI2000 20 Lindenberg, NeerincxPemberton, Van Dijk
Conclusions
• Individualization of Web-interfaces is needed to realize “Universal Accessibility”
• Design for all results in adaptive interfaces (no “boring uniformity”)
• Elderly users need more navigation support
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