HCI Notes - PowerPoint PPT Presentation

Loading...

PPT – HCI Notes PowerPoint presentation | free to view - id: 8df17-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

HCI Notes

Description:

Understanding the Designer's Intent. Software designers should try to pick ... But, people want to touch clothes, see how they feel, judge the quality, ... – PowerPoint PPT presentation

Number of Views:141
Avg rating:3.0/5.0
Slides: 54
Provided by: evans9
Category:
Tags: hci | notes

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: HCI Notes


1
HCI Notes
  • Evans Adams
  • November 2006

2
The Desktop
  • Image displayed on the monitor when a PC starts
    up
  • Colored or patterned background
  • Information displayed on top, bottom, or side
  • Three types of icons
  • Applications (programs)
  • Folders (directories)
  • Files (documents)

3
The Desktop (cont'd)
  • "Desktop" is a metaphor
  • An analogy for computation
  • Working at PC is analogous to working at a desk
  • Work goes in files
  • Files go in folders
  • Tools (a program or a calculator) are used to
    perform tasks

4
Playing Recorded Music
  • Example of metaphoric user interface
  • Software that plays CDs on computer has graphical
    user interface (GUI)
  • This GUI resembles a familiar music player
  • Buttons resemble an ordinary CD player
  • User can apply knowledge of CD player to learn to
    use this GUI without special instruction because
    the metaphor is familiar

5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
Understanding the Designer's Intent
  • Software designers should try to pick
    easy-to-understand user interfaces
  • We can expect good software to be well crafted
    so we can "brain out" how it works
  • We use this idea every time we use new software

12
Consistent Interfaces
  • Designers use metaphors similarly
  • When we see an icon or metaphor we have seen
    before, we know how it works
  • There are standard metaphors found in all GUIs

13
Command Buttons
  • May look like a 3D rectangle or circle, with an
    icon or text centered on the button
  • We click mouse to "press" the button and the
    command is invoked
  • Tells the software to perform the operation
  • We receive feedback to confirm the button has
    been clicked
  • Color change, shadow, highlight, or audible click

14
Slider Control
  • Sets a value from a "continuous" range, like
    volume
  • Move slider by placing mouse pointer on it and
    dragging in the direction of change
  • Scroll bars are a type of slider control

15
(No Transcript)
16
Triangle Pointers
  • Indicates presence of hidden or alternative
    information
  • Clicking on triangle reveals the information
  • Triangles at the ends of slide bars shift the
    contents of the window
  • Experienced users look for familiar metaphors and
    learn new ones when they are encountered

17
Anatomy of an Interface
  • Menu
  • List of operations the software can perform
  • Grouped by similarity of operations
  • Listed in menu bar
  • All operations performed by the software are
    listed in the menu

18
(No Transcript)
19
(No Transcript)
20
Expecting Feedback
  • Feedback is any indication that the computer is
    still working, or has completed task
  • For editing change, proof of completion is that
    the revision is visible
  • For button click, software provides an indication
    like highlighting, shading, graying, underlining,
    changing color, or audible click

21
Expecting Feedback (cont'd)
  • Most common feedback Indication that computer
    is working on time-consuming task
  • Cursor is replaced with icon like hourglass
    (Windows) or rainbow spinner (Mac)
  • Other forms of feedback busy spinner, running
    dog (Fetch), time-estimating "fills", completion
    count

22
Human Computer Interaction
  • HCI involves
  • the design, implementation and evaluation of
    interactive systems
  • in the context of the user's task and work.
  • HCI is both an art and a science.

23
Computer Systems must be usable
  • Interfaces should
  • be suitable for task
  • easy to use - adapts to user's knowledge and
    experience
  • provides feedback on performance
  • displays info in a format and pace adapted to the
    user
  • conforms to principles of software ergonomics

24
We want systems to be
  • useful - accomplish a task
  • usable - do it easily and naturally without
    danger of error
  • used - make people want to use it, be attractive,
    engaging, fun

25
Interacting with a machine
  • Can use five senses site, hearing, touch, smell,
    taste
  • With a computer we use site, hearing and touch

26
Human Vision
  • Peripheral vision can perceive movement but is
    poor at perceiving patterns
  • the Fovea (center of retina (back part of the
    eye)) has a high concentration of X-cells which
    are used to see patterns
  • retina has two types of photo-receptors rods and
    cones
  • rods are very sensitive to light - good for
    seeing in low light
  • mainly found on the edge of the retina
  • poor for seeing detail
  • cones - concentrated in fovea - good for color
    detection
  • (see http//thalamus.wustl.edu/course/eyeret.html)

27
IMPLICATIONS
  • Error messages, away from the main focus of the
    page (at the bottom) should move in some way
    (blink?)

28
Design Issues
  • Our perception does not always match reality
  • We tend to perceive horizontal lines longer than
    they are and reduce vertical
  • Horizontal lines also appear thicker
  • For a rectangle to appear square it has to be
    higher than it is wide
  • We also tend to see the center of a page a little
    above the actual center - called the optical
    center

29
Reading
  • First, the visual pattern of word is perceived
  • Next, the pattern is decoded with reference to an
    internal representation of the language
  • During reading the eyes' motion is jerky (called
    saccades) then fixated.
  • Perception occurs during fixation (fixation is
    94 of the time)
  • There are times of regression too (backward eye
    movement)

30
Reading
  • adults read 250 words a minute
  • words are not read character by character
  • a word can be recognized as quickly as a
    character
  • probably recognized by shape
  • weird fonts and capitalization can hamper this
    shape recognition

31
Reading
  • Aoccdrnig to a rsecheearr at an Elingsh
    uinervtisy, it deosn't mttaer in waht oredr the
    ltteers in a wrod are, the olny iprmoetnt tihng
    is that frist and lsat ltteer is at the rghit
    pclae. The rset can be a toatl mses and you can
    sitll raed it wouthit a porbelm. Tihs is bcuseae
    we do not raed ervey lteter by itslef but the
    wrod as a wlohe.
  • Source http//www.microsoft.com/typography/ctfon
    ts/WordRecognition.aspx

32
Reading
  • font size and line length can affect reading
    speed
  • fonts 9 - 12 are equally legible.
  • line lengths between 2.3 and 5.2 inches are best
  • reading from a monitor is slower than reading
    from a book.
  • line length? fewer words/page? orientation?
    familiarity with medium?
  • negative contrast (dark character, light
    background) provides higher luminance and
    increase acuity (though can lead to flicker)
  • negative contrast is preferred by most

33
Hearing
  • processing sound
  • people can hear sounds from 20HZ to 15kHz
  • frequency changes of less than 1.5Hz can be
    detected (for low frequencies)
  • we filter sounds (conversation in a noisy
    restaurant) but have trouble if they are too
    similar
  • sound's potential not fully taken advantage of in
    user interfaces

34
Touch (haptic perception)
  • Feedback
  • It helps users when buttons provide haptic
    feedback
  • virtual reality users often have trouble picking
    things up because feedback is missing

35
(No Transcript)
36
Ecommerce Implications
  • People buy CDs and computers via the Web
  • But, people want to touch clothes, see how they
    feel, judge the quality, ...
  • see http//www.novint.com/

37
Human Memory
  • Three types of components
  • sensory buffers
  • short-term memory
  • long-term memory

38
Sensory buffers
  • buffers for stimuli - one for each sense
  • iconic memory for vision (move finger in front of
    eye - see in gt 1 place?)
  • stays in buffer for 0.5 seconds
  • echoic memory for sound
  • allows two ears to be coordinated as sound hits
    them at different times
  • can ascertain direction of sound based on the
    delay
  • haptic memory for touch

39
Sensory buffers
  • info passed from sensory buffers to short-term
    memory by attention
  • attention is the mind's concentration on a
    specific stimulus
  • if not attended to, info is lost

40
Short-term memory
  • acts as a scratch pad for temporary recall of
    info
  • can be accessed in 70ms
  • decays quickly (in about 200ms)
  • capacity limit 7 2
  • can be raw info or chunks of info

41
Implications
  • only expect users to remember about 7 chunks of
    information
  • as in unix command-line command arguments
  • when all are shown can have gt 7 (as in menus)

42
Long-term Memory
  • slow access time (100 ms)
  • huge (unlimited?) capacity
  • forgetting is minimal (if it happens at all)
  • information placed there through rehearsal amount
    learned is directly proportional to time spent
    learning
  • most effective if distributed over time
  • learning is improved if information is meaningful
  • sentences easier to learn than a series of
    unrelated words or nonsense words

43
Information Retrieval
  • Recall and Recognition
  • recall
  • information reproduced from memory
  • can be assisted by use of categories
  • recognition
  • the information provides the knowledge it has
    been seen before

44
Errors and Mental Models
  • Why do we make mistakes
  • behavior has become automatic and some aspect
    changes
  • old behavior might break through
  • EX decide to stop on the way to work
  • incorrect model (mental model) for current
    situation
  • might be partial
  • might be internally inconsistent
  • unstable and subject to change
  • may not understand workings of full system
  • might be unscientific
  • might be based on an incorrect interpretation of
    evidence

45
Errors and Mental Models
  • errors occur when mental model differs from
    reality
  • Implications for HCI
  • try to match user's mental model
  • stick to convention (or supply support when
    convention is violated)

46
Techniques for Learning New Software
  • Clicking Around
  • Exploring a user interface
  • Noting basic GUI features
  • Checking each menu to see what operations are
    available
  • Helps user figure out what operations are
    available without being taught
  • Clicking around works because consistent
    metaphors and interfaces make new software
    predictable

47
"Blazing Away"
  • The next step after clicking around
  • Assertively exploring features even without a
    clear idea of their functions
  • Nothing will break
  • Only risk is losing time spent and having to
    re-start or reboot
  • Concentrate on operations related to whatever
    task needs to be done

48
Watching Others
  • Complicated software systems usually have
    features that are not obvious, too advanced, or
    too specialized to learn by clicking around
  • Shift-Select Operation
  • Allows you to select non-adjacent pieces
  • Many obscure features, tricks, and shortcuts can
    be learned by watching others

49
A Basic Principle Form Follows Function
  • Fundamental operations of a software system and
    the way they work are determined by the task
    being solved
  • GUIs may look different, but two software systems
    for the same task will have same basic operations
    and will work similarly

50
Similar Operations Have Similar Features
  • Text processing applications all
  • Use a cursor to mark your place
  • Have operations for typing, deleting, selecting,
    copying, searching, replacing, etc.
  • These operations work similarly
  • e.g., backspace key removes character to the left
    of the cursor
  • So how do vendors compete?
  • Add non-fundamental features
  • Make systems more convenient, friendlier, faster,
    less error-prone, etc.

51
Learning About Technology
  • People do not have any innate technological
    abilities
  • Our experience using (related) devices, including
    software, shows us what to expect
  • Designers who create devices, including software,
    know about this experience and design products to
    match what we already know
  • Reference - Donald A. Norman, The Design of
    Everyday Things, MIT Press

52
Technology Take IT Personally
  • We have learned we can expect intuitive
    interfaces
  • To learn to use new software, we should ask
    ourselves
  • What do I have to learn about this software to do
    my task?
  • What does the designer of this software expect me
    to know?
  • What does the designer expect me to do?
  • What metaphor is the software showing me?
  • What additional information does the software
    need to do its task?

53
(No Transcript)
About PowerShow.com