gary marsdenslide 1university of cape town human-computer interaction - 10 mobile interaction gary...

Gary Marsden Slide 1University of Cape Town

Human-Computer Interaction - 10

Mobile Interaction

Gary Marsden([email protected])

July 2002


Next big thing

Mobile computing is about more than making computers smaller (not Pocket PC)

Completely new applications and interactions become possible


A Little Philosophy


What are we talking about


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


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


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?


HCI knowledge

All current cellphone interaction is based on menus

Can you recite your menu structure?


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


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


Rules of menu design

Classifications typically achieve only 50% success

Alphabetic arrangements support “identity mapping” – expert behaviour


Current designs

Typical handset – Nokia 5110 – uses classification

Is it good?– Avg: 8.2– Max: 14– Total: 110

Number of key presses


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)


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


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


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


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?


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


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


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


Screen shots


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– ??


New interfaces to m-applications

Given those design criteria, what should mobile web applications look like?

WebTwig– 35% quicker– Greater

satisfaction


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!


Summary

Don’t get locked in to new technology for its own sake

Use evaluation– Expert– User models– Actual humans

gary marsdenslide 1university of cape town human-computer interaction - 10 mobile interaction gary...

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