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CS365 - HCI. Prof. Ahmed Sameh. Week 2. Reflections. How long should it take to learn a new web development tool i.e. Dreamweaver or Microsoft’s’ new Expression Studio? 20-30 mins to become productive - What is meant by “usability?” Effective to use Efficient to use Safe to use

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cs365 hci

CS365 - HCI

Prof. Ahmed Sameh

Week 2

  • How long should it take to learn a new web development tool i.e. Dreamweaver or Microsoft’s’ new Expression Studio?
  • 20-30 mins to become productive -
  • What is meant by “usability?”
    • Effective to use
    • Efficient to use
    • Safe to use
    • Having good utility
    • Easy to learn
    • Easy to remember
  • Can you decide what people “experience” when they are satisfied with the interface?
problem solving
Problem solving
  • Process of finding solution to unfamiliar task using knowledge.
  • Several theories.
  • Gestalt
    • problem solving both productive and reproductive
    • productive draws on insight and restructuring of problem
    • attractive but not enough evidence to explain `insight\' etc.
    • move away from behaviourism and led towards information processing theories
problem solving cont
Problem solving (cont.)

Problem space theory

  • problem space comprises problem states
  • problem solving involves generating states using legal operators
  • heuristics may be employed to select operators e.g. means-ends analysis
  • operates within human information processing system e.g. STM limits etc.
  • largely applied to problem solving in well-defined areas e.g. puzzles rather than knowledge intensive areas
problem solving cont1
Problem solving (cont.)
  • Analogy
    • analogical mapping:
      • novel problems in new domain?
      • use knowledge of similar problem from similar domain
    • analogical mapping difficult if domains are semantically different
  • Skill acquisition
    • skilled activity characterized by chunking
      • lot of information is chunked to optimize STM
    • conceptual rather than superficial grouping of problems
    • information is structured more effectively
errors and mental models
Errors and mental models

Types of error

  • slips
    • right intention, but failed to do it right
    • causes: poor physical skill, inattention etc.
    • change to aspect of skilled behaviour can cause slip
  • mistakes
    • wrong intention
    • cause: incorrect understanding

humans create mental models to explain behaviour.

if wrong (different from actual system) errors can occur

  • Various theories of how emotion works
    • James-Lange: emotion is our interpretation of a physiological response to a stimuli
    • Cannon: emotion is a psychological response to a stimuli
    • Schacter-Singer: emotion is the result of our evaluation of our physiological responses, in the light of the whole situation we are in
  • Emotion clearly involves both cognitive and physical responses to stimuli
emotion cont
Emotion (cont.)
  • The biological response to physical stimuli is called affect
  • Affect influences how we respond to situations
    • positive  creative problem solving
    • negative  narrow thinking

“Negative affect can make it harder to do even easy tasks; positive affect can make it easier to do difficult tasks”

(Donald Norman)

emotion cont1
Emotion (cont.)
  • Implications for interface design
    • stress will increase the difficulty of problem solving
    • relaxed users will be more forgiving of shortcomings in design
    • aesthetically pleasing and rewarding interfaces will increase positive affect
individual differences
Individual differences
  • long term – sex, physical and intellectual abilities
  • short term – effect of stress or fatigue
  • changing – age

Ask yourself:will design decision exclude section of user population?

psychology and the design of interactive system
Psychology and the Design of Interactive System
  • Some direct applications
    • e.g. blue acuity is poor blue should not be used for important detail
  • However, correct application generally requires understanding of context in psychology, and an understanding of particular experimental conditions
  • A lot of knowledge has been distilled in
    • guidelines
    • cognitive models
    • experimental and analytic evaluation techniques
user experience goals
User experience goals

• satisfying • aesthetically pleasing

• enjoyable • supportive of creativity

• engaging • supportive of creativity

• pleasurable • rewarding

• exciting • fun

• entertaining • provocative

• helpful • surprising

• motivating • enhancing sociability

• emotionally fulfilling • challenging

• boring • annoying

• frustrating • cutsey

usability and user experience goals
Usability and user experience goals
  • Selecting terms to convey a person’s feelings, emotions, etc., can help designers understand the multifaceted nature of the user experience
  • How do usability goals differ from user experience goals?
  • Are there trade-offs between the two kinds of goals?
    • e.g. can a product be both fun and safe?
  • How easy is it to measure usability versus user experience goals?
design principles
Design principles
  • Generalizable abstractions for thinking about different aspects of design
  • The do’s and don’ts of interaction design
  • What to provide and what not to provide at the interface
  • Derived from a mix of theory-based knowledge, experience and common-sense

• This is a control panel for an elevator

• How does it work?

• Push a button for the floor you want?

• Nothing happens. Push any other button? Still nothing. What do you need to do?

It is not visible as to what to do!

From: www.baddesigns.com


…you need to insert your room card in the slot by the buttons to get the elevator to work!

How would you make this action more visible?

• make the card reader more obvious

• provide an auditory message, that says what to do (which language?)

• provide a big label next to the card reader that flashes when someone enters

• make relevant parts visible

• make what has to be done obvious

what do i do if i am wearing black
What do I do if I am wearing black?
  • Invisible automaticcontrols can make it more difficult to use
  • Sending information back to the user about what has been done
  • Includes sound, highlighting, animation and combinations of these
    • e.g. when screen button clicked on provides sound or red highlight feedback:


  • Restricting the possible actions that can be performed
  • Helps prevent user from selecting incorrect options
  • Physical objects can be designed to constrain things
    • e.g. only one way you can insert a key into a lock
logical or ambiguous design
Logical or ambiguous design?
  • Where do you plug the mouse?
  • Where do you plug the keyboard?
  • top or bottom connector?
  • Do the color coded icons help?

From: www.baddesigns.com

how to design them more logically
How to design them more logically

(i) A provides direct adjacent mapping between icon and connector

(ii) B provides color coding to associate the connectors with the labels

From: www.baddesigns.com

  • Design interfaces to have similar operations and use similar elements for similar tasks
  • For example:
    • always use ctrl key plus first initial of the command for an operation – ctrl+C, ctrl+S, ctrl+O
  • Main benefit is consistent interfaces are easier to learn and use
when consistency breaks down
When consistency breaks down
  • What happens if there is more than one command starting with the same letter?
    • e.g. save, spelling, select, style
  • Have to find other initials or combinations of keys, thereby breaking the consistency rule
    • e.g. ctrl+S, ctrl+Sp, ctrl+shift+L
  • Increases learning burden on user, making them more prone to errors
internal and external consistency
Internal and external consistency
  • Internal consistency refers to designing operations to behave the same within an application
    • Difficult to achieve with complex interfaces
  • External consistency refers to designing operations, interfaces, etc., to be the same across applications and devices
    • Very rarely the case, based on different designer’s preference
keypad numbers layout
Keypad numbers layout
  • A case of external inconsistency

(a) phones, remote controls

(b) calculators, computer keypads





















affordances to give a clue
Affordances: to give a clue
  • Refers to an attribute of an object that allows people to know how to use it
    • e.g. a mouse button invites pushing, a door handle affords pulling
  • Norman (1988) used the term to discuss the design of everyday objects
  • Since has been much popularised in interaction design to discuss how to design interface objects
    • e.g. scrollbars to afford moving up and down, icons to afford clicking on
what does affordance have to offer interaction design
What does ‘affordance’ have to offer interaction design?
  • Interfaces are virtual and do not have affordances like physical objects
  • Norman argues it does not make sense to talk about interfaces in terms of ‘real’ affordances
  • Instead interfaces are better conceptualized as ‘perceived’ affordances
    • Learned conventions of arbitrary mappings between action and effect at the interface
    • Some mappings are better than others
  • Physical affordances:

How do the following physical objects afford? Are they obvious?

  • Virtual affordances

How do the following screen objects afford?

What if you were a novice user?

Would you know what to do with them?

usability principles
Usability principles
  • Similar to design principles, except more prescriptive
  • Used mainly as the basis for evaluating systems
  • Provide a framework for heuristic evaluation
usability principles nielsen 2001
Usability principles (Nielsen 2001)
  • Visibility of system status
  • Match between system and the real world
  • User control and freedom
  • Consistency and standards
  • Help users recognize, diagnose and recover from errors
  • Error prevention
  • Recognition rather than recall
  • Flexibility and efficiency of use
  • Aesthetic and minimalist design
  • Help and documentation
key points
Key points
  • Interaction design is concerned with designing interactive products to support the way people communicate and interact in their everyday and working lives
  • It is concerned with how to create quality user experiences
  • It requires taking into account a number of interdependent factors, including context of use, type of activities, cultural differences, and user groups
  • It is multidisciplinary, involving many inputs from wide-reaching disciplines and fields