Post on 26-Dec-2015
Gary Marsden Slide 1University of Cape Town
Human-Computer Interaction - 10
Mobile Interaction
Gary Marsden(gaz@cs.uct.ac.za)
July 2002
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Next big thing
Mobile computing is about more than making computers smaller (not Pocket PC)
Completely new applications and interactions become possible
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A Little Philosophy
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What are we talking about
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Devices
First thing to note is that these are consumer devices– they must work– they must be useful (not for their own sake)– think watches more than PC
Dancing bears will not cut it– Death of WAP– All cell-phone companies now reporting loss
and/or zero growth
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Physical considerations
Mobile devices have smaller screens and keyboards– Computing power is less of an issue
However,– never left behind– can ‘know’ things
• location• heart rate• Officially called “context” – research team in UK
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No mouse, no keyboard, no hope?
New innovations– Voice
recognition– Invisible
keyboard
All very well, but technology based Can we do any better with the
technology we have?
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HCI knowledge
All current cellphone interaction is based on menus
Can you recite your menu structure?
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Actual structure - I
Phone Book
Search
Add Entry
Erase
Edit
Send Entry
Options
Type of View
Memory Status
Speed dials
Messages Inbox Outbox Write Message Settings Message centre number Message sent as Message validity Common Delivery report Reply via same centre Info Service Off Topics index Topics Select Add Edit Erase Language On Voice mailbox number
Call Register Missed Calls Received calls Dialled numbers Erase recent call lists Show call duration Last call All calls Received calls Dialled Clear Timer Show call costs Last call All calls Clear Counter Call cost settings Call cost limit Show costs in
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Actual structure - II
Settings
Call Settings
Auto redial
Speed dialling
Call waiting option
Own number sending
Phone Settings
Language
Cell info display
Welcome note
Network selection
Security settings
PIN code request
Fixed dialling
Closed user group
Security level
Change access codes
Change PIN code
Change PIN2 code
Change security code
Restore factory settings
Call Divert Divert all Divert when busy Divert when not answered Divert when phone off Cancel all diverts
Games Memory Snake Logic
Calculator
Clock Alarm Settings Hide Set time Time format
Tones Incoming alert Ring tone Volume Message alert Keypad tones Warning and game tones
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Rules of menu design
Classifications typically achieve only 50% success
Alphabetic arrangements support “identity mapping” – expert behaviour
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Current designs
Typical handset – Nokia 5110 – uses classification
Is it good?– Avg: 8.2– Max: 14– Total: 110
Number of key presses
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Is this a problem?
Yes!Orange CSP in UK contacted us because
– Couldn’t market vertical services– Spending a fortune on customer support lines
Stories echoed by others such as US-West– big problem with elderly– (surprise success for WAP)
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How to improve
Depth vs breadth– Breadth works better– Actually concave is the best (don’t waste time
with branch nodes)– Most handsets follow this
All research conducted on large screen– a single line display is disastrous (3 times
slower than a 3 line display)– 10 options: Short term memory of 7 +/- 2
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Alternative design
Menus are not optimal for small screensCould use other data structuresE.g. linear list
– Total: 74 – Average: 37 – Max: 74
E.g. Binary tree– Total: 148 – Average: 5.4 – Max: 7
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Lower level - input
It is more likely that mobile devices will be used for data access than intensive data entry– there are exceptions, but these are vertical
market (e.g. Psion)
Input solutions include– voice (limited)– handwriting (graffiti)– predictive (T9) – “portable” keyboard
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Output – screen size
There is not much we can do about keyboard size – Fitt’s law and ergonomics dictate
How does screen size affect usability?
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Is height important
Yes, but width is more soFull width screen (640) read 25% more
quickly than 210– not happy with horizontal scroll
Optimal height is 4 lines – increasing to 20 only gives 9% speed increase in reading
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Comprehension rates
Study conducted by Dillon using a 3500 word text on 20 line displays and 60 line displays– no difference in comprehension (summary of
main points)– small screen users, however, perceived that
they were worse off
This was for linear textThings more interesting with hyper-text
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Web studies
Previous work carried out on terminals in the 80’s which had small screens– Seems to say the short, wide screens should
work
We were set problem by Reuters for accessing Web information
Conducted experiment on real Web site– used standard PC’s, one dropped to 640x480
• 15x75 compared to 11x65 on Psion and WinCE
– set tasks to find information
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Screen shots
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Experiment results
Small screen (640x480) experiment showed– ss users twice as likely to make mistakes in
comprehension– both groups followed same amount of links– 80% of ss users started by using the search feature:
twice as likely to search as ls users– ls users had longer path lengths – more exploratory– ss users did a lot more scrolling, but only down and to
the right
Design lessons– ??
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New interfaces to m-applications
Given those design criteria, what should mobile web applications look like?
WebTwig– 35% quicker– Greater
satisfaction
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Technologies
WebTwig is only one approachTechnologies change all the timeE.g. could use handheld to find pages for
off-line reading– then use BlueTooth to beam them to TV or
printer
Do not be technology focused, however– Learn from WAP!
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Summary
Don’t get locked in to new technology for its own sake
Use evaluation– Expert– User models– Actual humans