A long term study was conducted with 5 blind users over 16 weeks to evaluate the usability and learnability of NavTap, a non-visual text entry and navigation method. Results showed improvements in key metrics like words per minute and keystrokes per character for most users. Usage logs also demonstrated that NavTap allowed independent texting and calling. The study highlights NavTap's potential for social inclusion and the need for long term analysis of alternative access methods.

1. A Long Term Study with
Excluded Blind Users
Tiago Guerreiro
Hugo Nicolau
Joaquim Jorge
Daniel Gonçalves
tjvg@vimmi.inesc-id.pt

2. ‘‘
Never doubt that a small group of committed
people can change the world.
’’
Indeed it is the only thing that ever has.
— Margaret Mead

3. We have the whole world in our hands.

4. SMS and Mail have had an
enormous growth in the last few years.

5. Mobile devices can do anything.

6. A common image for me.

7. What about the
Others ?

8. Some can only see this.

10. They are too heavy.

11. They are too big.

12. They are too expensive...

13. And definitely not mobile.

15. Can speech synthesis replace
visual feedback ?

17. Early and
adventitious
Blind

19. Variety of
Causes

20. Collateral Damages

26. Keep it Simple.

27. ABCDEFGHIJLMNOPQRSTUVXZ

28. A BCD
E FGH
I JLMN
O PQRST
U VXZ

29. A BCD
E FGH
I JLMN
O PQRST
U VXZ

30. A BCD
E FGH
I JLMN
O PQRST
U VXZ

31. A BCD
E FGH
I JLMN
O PQRST
U VXZ
A BCD E FGH I JLMN O PQRST U VXZ

32. We can navigate in any direction.

33. A BCDEFGHIJLMNOPQRSTUVX Z

34. ABCD
EFGH
I JLMN
OPQRST
UVXZ

36. ABCD
EFGH
I JLMN
OPQRST
UVXZ

38. ABCD
EFGH
I JLMN
OPQRST
UVXZ

40. No wrong choices.
Just shorter paths.

41. No memorization required.

43. Short term Evaluation
Guerreiro et al., NavTap and BrailleTap: Non-Visual
input interfaces, In RESNA 2008

44. Error Rate
Rate
80%
70%
60%
50%
40%
30%
20%
10%
0%
1 2 3
MultiTap NavTap
Session

45. Words Per Minute
WPM
1.6
1.4 1.37
1.32
1.2
1.07
1.0
0.8 0.88
0.80 0.68
0.6
0.4
0.2
0.0
1 2 3
MultiTap NavTap
Session

46. Ease first contact

47. And still leaves
room for
improvement

49. How does it
behave on a long
term basis?

50. In real life...

51. How it affects the
users and their
habits?

52. Understand the limits

55. The user sample

57. 49 to 64
years

59. Reduced to
performing and
taking calls

61. Calls
Info
Dial
Accept
Reject

62. SMS
Write
Read
Send
Receive

63. Agenda
Notebook

65. Study stages
Iterative (Re-)design
Learning the basics (users)
Improving the prototype (us)
Evaluation
Weekly laboratorial evaluation
Daily usage logging

66. 3
weeks

67. 3
sessions per week

68. 30
minutes per session

69. Navigation
Text-Entry
Events

70. Navigation
Text-Entry
Events

71. Navigation
Text-Entry
Events

72. Fine Tuning
the prototype

75. Weekly Controlled Results

76. 5
users

77. 16
weeks

78. Words per Minute
WPM
9
8
7
6
5
4
3
2
1
0
P01 P02 P03 P04 P05
Participant
First session Last session

79. Keystrokes per Character
KSPC
8
7
6
2way - 4.88
5
4
3
4way - 2.85
2
1
0
P01 P02 P03 P04 P05
Participant
First Session Last Session

80. Improvement in Interaction Times
Preparation Time Navigation Time (same direction)
Navigation Time (direction shift)
80% 0.58 1.08
70% 0.30 0.58 1.22
0.45 0.62 1.22
60% 0.45 1.1
1.25
1.25
50% 0.8 0.8 1.16
0.8
40%
1.24 1.0 1.93
30%
20% 0.83
10%
0%
P01 P02 P03 P04 P05

81. MSD Error Rate
9%
8%
7%
6%
5%
4%
3%
2%
1%
0%
P01 P02 P03 P04 P05
Participant

82. Participants’ Opinion
Rate
5
4
3
2
1
0

83. Daily Usage

84. Communication Method
Participant Calls SMS
P05
P04
P03
P02
P01
0% 20% 40% 60% 80% 100%

85. Overall Results
1200 received
1825 sent

86. Most Used Tasks
Date Hour
Send SMS
Battery
Calculator
Make Call Alarm
Add Contact
Delete
Contact
Search
Contact

87. Usage Influence

88. WPM vs. Sent SMSs
WPM
6
5
450
4
300
3 200
100
2 40
1 10
0
P01 P02 P03 P04 P05

89. KSPC vs. Sent SMSs
10 40 100 200 300 450
60%
50%
40%
30%
20%
10%
0%
P01 P02 P03 P04

90. Observing each
Participant

91. Participant 1
High Literacy Level
Used a 4-way approach
Near theoretical limit

92. Participant 2
Learning difficulties
Able to use NavTap
Enormous social inclusion

93. Participant 5
Low usage of text-messages
Social factors
Maintained his
navigation skills

94. Conclusions
Accessible for a wider user group
Impact on Social Interactions
Still Using NavTap
Long Term Analysis is IMPORTANT

95. The Future
Individual Differences
MultiTap learnability
MultiTap vs NavTap
(experienced )

96. Kevin Clarkson Martin Rotovnik

97. NavTap
A Long Term Study with Excluded
Blind Users
Tiago Guerreiro
tjvg@immi.inesc.pt