towards accessible touch interfaces
Post on 04-Jul-2015
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Towards Accessible Touch Interfaces
Tiago Guerreiro Hugo Nicolau
Joaquim Jorge Daniel Gonçalves
Mobile evolution …
Touch Interfaces
Leading to …
pleasant
Tactile feedback
loss of tactile feedback
Loss of physical stability
hard to select targets
it occurs to everyone
… and motor impaired
require less strength
Adapt to users’ needs
Provide the knowledge to build better touch interfaces
We performed …
Tested several …
Interaction Techniques
Screen areas …
… corners
Screen areas …
… edges
7 mm
… and target sizes
12 mm 17 mm
Tapping
Crossing
Exiting
Gesturing
15 participants 28-64 years old
C4-C7 lesion level 6 left-handed
never used touchscreens
Results
Error Rate
X
Precision
Movement Error
Movement Time
t0 tn
Tapping
Target Size
0%
10%
20%
30%
40%
50%
7mm 12mm 17mm
Erro
r R
ate
(%
)
Target sizes (milimeters)
Corners and Edges precision
7mm
Vertical error rate
45% 28% 27%
39% 28% 24%
43% 19% 12%
12mm 17mm
Distance error rate
28%
28%
20%
20%
12%
12%
11%
11% 6%
17mm
Crossing
Target Size
0%
10%
20%
30%
40%
50%
7mm 12mm 17mm
Erro
r R
ate
(%
)
Target size (milimeters)
Exiting
Target Size
0%
10%
20%
30%
40%
50%
60%
70%
80%
7mm 12mm 17mm
Erro
r R
ate
(%
)
Target size (milimeters)
Gesturing
Edges
0
10
20
30
40
50
60
Center Edge
Mo
vem
en
t E
rro
r (p
ixels
)
Gesture
Directions
0
50
100
150
200
250 N
W
NE
SW
SE
SLef
t N
WU
pp
er S E W
SRig
ht
NR
igh
t
EUp
per
NLe
ft
WB
ott
om
EBo
tto
m
Mo
vem
en
t Er
ror
(pix
els
)
Gesture Direction
Mixing All Techniques
0%
10%
20%
30%
40%
50%
60%
70%
80%
7mm 12mm 17mm
Erro
r R
ate
(%
)
Target Size (milimeters)
Exiting Gestures Tapping Crossing
All Techniques
Interact with edge support
Interact with edge support
22%
36%
Acquiring edge targets
Acquiring edge targets
Edge or Middle
Edge or Middle
Interacting mid-screen
Interacting mid-screen
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
7mm 12mm 17mm
Crossing GesturesM4Way Tapping Middle
Interacting mid-screen
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
7mm 12mm 17mm
Crossing GesturesM4Way Tapping Middle
0
1
2
3
4
5
Exiting Tapping Crossing Gesturing
Conclusions
What is the best size for each interaction technique?
12 mm
However, error rates are still …
High
What is the best screen area for each interaction technique?
Regarding target position …
Support
What is the best interaction technique for motor-impaired people?
What is the best interaction technique for each screen area?
What is the best technique-size-area combination?
Explore target size for the target population Differences between able-bodied and tetraplegics
Future Work
The End Tiago Guerreiro tjvg@vimmi.inesc-id.pt
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