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The User
Universidade de Aveiro
Departamento de Electrónica,
Telecomunicações e Informática
Human-Computer Interaction Beatriz Sousa Santos, 2017/2018
www.id-book.com
3
Users profile
- Human Information Processing System (HIPS)
- Knowledge and experience
- Work and task
- Physical characteristics
- Environment
- Tools
More variable among users
There are many user models to be used in the design of Interactive systems
4
i
n
t
e
r
f
a
c
e computer
user
think
think
read-scan respond
respond read-scan
Dialog in an interactive system
Cognitive sub-system
Motor sub-system
Perceptual sub-system
5
Human Information Processing System (HIPS):
main aspects relevant to UI design
Perceptual sub-system memory – perceptual buffer (iconic, echoic, …)
process – pattern recognition
short term/working memory (STM)
memory -
long term memory (LTM)
Cognitive sub-system
selective attention
processes - problem resolution learning
…
Motor sub-system
HIPS
bottleneck
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Pattern Recognition
Process that matches information from
a stimulus with information retrieved
from memory
- It is a very powerful process
- It is subconscious
- It does not use only current data
- It solves ambiguities
(Kaniza illusion, Wikepedia)
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Visual Illusions illustrate that what we see does not depend only of the
stimulus
Kanizsa illusion
Necker cube
Pennrose triangle:
Impossible object?
Ponzo illusion
- bring out particular good adaptations of
our visual system to standard viewing
situations
- under some artificial manipulations can
cause inappropriate interpretations of
the visual scene
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Kanizsa illusion:
Necker cube:
Although there are no actual triangles a sort
of pattern recognition phenomenon is
triggered and the image is interpreted as two
overlapping triangles (simple explanation)
https://en.wikipedia.org/wiki/Necker_cube
Cube with no visual cues as to its
orientation; it can be interpreted to have
either the lower-left or the upper-right
square as its front side
https://en.wikipedia.org/wiki/Illusory_contours
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http://www.youtube.com/watch?v=2XqPOJLUM1s
http://www.youtube.com/watch?v=URLRdcnU6Hk&NR=1
http://www.michaelbach.de/ot/
https://www.youtube.com/watch?v=-
IWk5NkxQF8&ebc=ANyPxKoRFxfOSCgdPavBoMpgPrXjRRVqZmhiAvIBDgThnPfndq-gheNYZ-
6cNRv2yYwN5SqX52DQGDWjvBnzUQQ-_N6iCVgMdQ
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Memory
The Atkinson–Shiffrin model (1968) (a.k.a. multi-store model or modal model)
asserts that human memory has three components:
• Sensory memory
• Short-term memory / working memory
• Long-term memory
https://en.wikipedia.org/wiki/Atkinson%E2%80%93Shiffrin_memory_model
LTM STM Sensory
memory
Attention Transfer
Retrieval Rehearsal
14 https://www.youtube.com/watch?v=bSycdIx-C48
How We Make Memories - Crash Course Psychology #13
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Short Term Memory (STM) / Working memory
a few characteristics:
- Short duration: a few seconds (<30s)
- Limited capacity: 7+2 elements
what is an element?
example: try to memorize the following numbers 649325401741
111122223333
which is easier?
and this one: 351234370517
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Short Term Memory (STM)
649325401741 12 digits
111122223333 3 digits and a rule
234370200 351 234 370 517
Portugal Aveiro University area IEETA building
These numbers correspond to different “chunks”
Chunk: the largest meaningful unit that a person recognizes; depends
on the person knowledge
• Chunking refers to an approach for making more efficient use of
short-term memory by grouping information
• Resulting chunks are easier to commit to memory than a longer
uninterrupted string of information.
• Can be used for making more efficient use of short-term memory by
grouping information
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http://study.com/academy/lesson/george-
miller-psychologist-theories-on-short-term-
memory-lesson-quiz.html
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Long Term Memory
Stage of the dual memory model (Atkinson-Shiffrin memory model)
informative knowledge can be stored for long periods of time
Main characteristics:
- “Infinite” capacity and duration
- non reliable access
http://study.com/academy/lesson/long-term-
memory-definition-types-examples.html
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Selective attention
It may be:
- Voluntary
- Involuntary
Both can be (and are) exploited in UIs
Occurs when we block out certain
features of our environment
and focus on one particular feature
http://study.com/academy/lesson/selective-attention-definition-examples-quiz.html
Calling your attention to an application
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HIPS Strengths and weaknesses (versus computer)
Strengths Weakesses
LTM infinite capacity STM limited capacity
LTM duration and complexity STM limited duration
Capacity to learn Error prone processing
Powerful selective attention Non reliable access to LTM
Powerful pattern recognition process Slow processing
Recommendation:
Assign tasks between user and computer according to the capacities of each
Example: minimize the users STM load
do not ask the user to perform computations
• Emotional design is a critical part of design
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http://www.youtube.com/watch?v=_PM3uqPNrWY
• Other Donald Norman videos:
http://www.youtube.com/watch?v=Wl2LkzIkacM
Not only the cognitive system is important
But also the emotional system
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User Profile- other characteristics
- Experience and knowledge - education and reading level
experience with the system and task
mother language
computer literacy …
- Work and task - usage frequency
training
usage type (mandatory, optional)
usage of other systems …
- Physical Characteristics – color vision deficiencies
physical deficiencies
handedness
age …
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Color blindness
Ishihara test for red-green blindness (daltonism or deuteranopia)
(Shinobu Ishihara,1917)
- The test includes 38 figures
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How do these characteristics influence UI design?
• Much system experience, but low task experience -> more semantic help
• Much task experience but low system experience -> more syntactic help
• High usage frequency -> easy to use
• Low usage frequency -> easy to learn and remember
• Mandatory -> easy to use
• Optional -> easy to learn and remember
• Color (particularly red and green) should not be used as only cue to convey information
– Etc., …
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- Users are much different from UI designers
- Users vary a lot among thenselves
- Users change along time (evolve, forget...)
Final recommendation:
We should consider the user as an unknown
species and study it scientifically
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Mental and conceptual models
Universidade de Aveiro
Departamento de Electrónica,
Telecomunicações e Informática
(wikipedia.org; Windows 10)
32
• What are mental models?
• How do we construct them?
• What is known about them?
• What are they used for?
• What are conceptual models?
• Guidelines to obtain good conceptual models
Relevant issues:
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• The conceptual model is the UI highest level
• The conceptual model is the conceptual framework in which the functionality
is provided to the user
• To understand how to design a good conceptual model it is necessary to
understand mental models
• A mental model (in a simple way) is the user’s internal representation of the
current conceptualization and understanding of the system
• A conceptual model is the designer’s atempt to foster good mental models
through UI aspects
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How do we create a mental model?
• Using the system
• Observing others using the system
• Reading documentation
• …
and thus all these are important ways to train the user to use a system
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Mental models allow:
• Make predictions
• Determine causes of observed events
• Determine adequate actions to produce the wanted changes
• Understand analogous devices
• …
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Mental models:
• Are incomplete
• Are unstable
• Are not scientific
• don´t have specific limits
• …
37
“We must give up finding elegant mental models, and instead learn how to
understand the incomplete and confuse structures people have”
Donald Norman
39
Main guidelines to obtain a good conceptual model
• Make visible invisible parts and processes
• Give feedback
• Use coherence (colors names, command sintax, dialog styles, information
location on the screen, etc., etc.)
• Use a metaphor (optional)
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Metaphors
- Exploit existing mental models of the real
world
The Desktop metaphor:
Metaphors can be misleading since the “the
essence of metaphor is understanding and
experiencing one kind of thing in terms of
another” (Lakoff and Johnson 1983)
- Which, by definition, makes a metaphor
different from what it represents or points to
https://www.interaction-design.org/literature/book/the-
encyclopedia-of-human-computer-interaction-2nd-
ed/human-computer-interaction-brief-intro
42
Potential problems in using metaphors
• Incomplete metaphors may confound the user
• Risk of under-utilization of the system’s capacities
• Less experienced users (e.g. children) seem to expect more literal metaphors
• Sophisticated users seem to expect more “magical” metaphors
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Main bibliography
• Alan Dix, Janet Finlay, Gregory Abowd, Russell Beale, Human-Computer Interaction, 3rd edition, Prentice Hall, 2004
• Jenny Preece and Helen Sharp, Interaction Design – Beyond Human-Computer Interaction, 4th edition, John Wiley, 2015
(http://www.id-book.com/chapter3_teaching.php)
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