Usability Study
The Effect of
Mouse Scroll-wheel Configuration
on Virtual Globe Navigation
Amenity Applewhite
Yikalo Hayelom
Jia Wang

Outline
• Introduction
• Motivation
• Hypothesis
• Study Methodology
• Results & Discussion
• Conclusion
• Recommendation
2

Introduction: Mouse Zoom
Available in many applications:
Microsoft Office, AutoCAD, ArcMap, Photoshop...
Default setting:
• “Push” forward
• “Pull” back
3

Introduction: Virtual Globes
• Streaming satellite imagery in 3D
• Zoomable User Interface ZUI
information navigation best supported by
natural and geographic ways of thinking*
*Perlin & Fox 1993 4

Introduction: Virtual Globes
Four ways to zoom:
• Double-click
• Mouse scroll-wheel 5

Introduction: Virtual Globes
Four ways to zoom:
• Double-click
• Mouse scroll-wheel 5

Introduction: Virtual Globes
Four ways to zoom:
• Double-click
• Mouse scroll-wheel 5

Motivation
• Increasing popularity of virtual globes
• Main ZUI navigation problem: users may
get “lost” while zooming*
• Need to provide intuitive tools for a
usable interface
Compare the usability of two zoom
configurations.
*Buring, et al 2006 6

Methodology
Hypothesis
Despite the fact that most software shares
the same default setting for mouse
zooming, users will be able to adjust to
the default configuration without a
marked decrease in usability.
7

Methodology
Usability (adapted from Nielsen)
Learnability
ease of accomplishing task the first time
Errors
number of errors and ease of recovery
Satisfaction
pleasant to use design?
8

Methodology
Test design
Participants
6 classmates: 4 males, 2 females; 23-29
Simple task instrucions
• 4 screenshots in Google Earth,
pasted into Word
• Instructed only to use mouse wheel
for movement
9

Methodology
10

Methodology
Test design
Two sessions
First with default zoom, second reverse
Recorded with CamStudio
Facial expressions and speech noted
Post study interview, scale 1-5
• Difficulty
• Enjoyment
10

Methodology
Test design
Errors & Learnability
• number of errors counted in second
half of tasks in both sessions
• compared results individually
Enjoyment
• observed during session
• reported during interview
11

Methodology
Test design
Criteria to accept hypothesis
• an increase of errors with reverse
configuration no greater than 10%
• no significant decrease in enjoyment
- observed or reported
12

Results
1
• Difference in errors
with reverse setting
2
greater than 10%
3
for 4 users
User
4
5
6
0 0.075
7.5% 0.150
15% 0.225
22.5% 0.300
Increase in zoom errors with reverse setting
13

Results
1
• Difference in errors
with reverse setting
2 12.38%
greater than 10%
3
for 4 users
User
4 20%
5 20.55%
6 13.18%
0 0.075
7.5% 0.150
15% 0.225
22.5% 0.300
Increase in zoom errors with reverse setting
13

Results
Total Number of Zooms • All users performed
1 more zooms with
2 reverse setting
3
User
4
5
6
0 20 40 60 80
Test 1 default zoom
Test 2 reverse zoom
14

Results
• Two users noticed the change immediately
• One vocalized frustration throughout task
with reverse setting
• One user reported that the reverse setting
was more difficult
• No one reported the reverse setting was
less enjoyable
15

Conclusion
Must reject hypothesis:
• Increase in errors was greater than 10%
for the majority of users; not learnable!
• Reported and observed decrease in
enjoyment; not enjoyable!
• Questions raised about efficiency, more
zooms
Ultimately, the reverse setting seems to have
lower usability. 16

Recommendation
• Some users not affected by reverse setting
• Using the scroll wheel instead of double-
click was very difficult for some users
• We recommend that virtual globe
interfaces offer a range of zooming
methods and allow users to adjust the
configurations
17

References
Büring, T., Gerken, J., and Reiterer, H. 2006. Usability of
overview-supported zooming on small screens with regard
to individual differences in spatial ability. In Proceedings of
the Working Conference on Advanced Visual interfaces
(Venezia, Italy, May 23 - 26, 2006). AVI '06. ACM, New York,
NY, 233-240.
Perlin, K. and Fox, D. 1993. Pad: an alternative approach to
the computer interface. In Proceedings of the 20th Annual
Conference on Computer Graphics and interactive
Techniques SIGGRAPH '93. ACM, New York, NY, 57-64.
18

Questions?
19