B# :: Chord-based Correction for Multitouch Braille InputHUGO NICOLAUKYLE MONTAGUETIAGO GUERREIROJOÃO GUERREIROVICKI L. HANSON

motivation :: non-visual input

motivation :: braille input

[Southern et al. 2012]

[Oliveira et al. 2011] [Azenkot et al. 2012]

motivation :: fast typing (4x)

problem :: error prone

50%

challenge :: accurate input

approach :: spellchecker

? ? ? ? ? ? ? ? ? ?

> e d k l o w u h k d _

approach :: character-level

e x i l e d u n k s

> e d k l o w u h k d _

B# :: chord-level spellchecker

h e l l o w o r l d

> e d k l o w u h k d _

B# :: data collection

B# :: data collection

11 blind participants :: ages 22 – 62 ::

3 females :: grade 1 braille ::

no touchscreen experience

major results :: substitutions

Insertions Substitutions Omissions

23%

72%

5%

Overall Error Rate: 18%

major results :: 43% single-dot error

omission

insertion

transposition

q g

i f

b k

major results :: invalid characters

! t

B# :: braille distance

[100010]

[100010]

= ?

-

distance :: damerau-levenshtein

[100] – [110] + [010] – [010]

= 1 + 0 = 1

B# :: scoring function

scoreword = wMSD(Chtyped, Chword) + ƒword

evaluation :: B#, AOSP

evaluation :: dataset

751 words :: 49% incorrect entries ::

word list with 213,133 entries

results :: B# is more accurate

1 2 3 4 5 6 7 8 9 1025%

35%

45%

55%

65%

75%

56%

75%

28%39%

Acc

ura

cy

B#

Android

results :: word correction

204 of 364

100 of 364

results :: no gain beyond 5

1 2 3 4 5 6 7 8 9 1025%

35%

45%

55%

65%

75%A

ccura

cy

B#

Android

6%

9%

results :: incorrectly corrected

Android B#

1.4%1.7%

conclusion :: B#

conclusion :: higher accuracy

2X

future :: non-visual interface

The End.HUGO NICOLAUhugonicolau@computing.dundee.ac.ukpaper, slides, and video @ http://web.ist.utl.pt/hugo.nicolau

non-visual correction :: challenges

Automatic correction?

Word-completion?

How to provide corrections?

When to provide them?

How to users explore suggestions?

B#: future improvements

Bi-grams, Tri-grams, N-grams

“Machine Learned” Distance Function

Personalized spellchecker

Leverage touch information

B#: android’s proximity matrix

Fairly complex spellchecker

Dozen of features

Worthwhile doing