touch typing using thumbs: understanding the effect of mobility and hand posture

Touch Typing using Thumbs: Understanding the Effect ofMobility and Hand Posture

Hugo Nicolauhman@vimmi.inesc-id.pt

Joaquim Jorge

SIIDSituationally-Induced Impairments and Disabilities

Hand oscillation hinder performance[Bergstrom-Lehtovirta et al., 2011]

Especially with small virtual targets[Mizobuchi et al., 2005; Lin et al., 2007]

Thumb interaction

Text-entry whilst walking

Effects of walking and hand posture on touch typing

22 participants19 males, 3 females

23 to 40 years old

Right-handed

Only 15used mobile touchscreens

regularly

3 mobility conditions

Seated Walking 65% of human pace[Barnard et al., 2005]

WalkingAverage human pace2 steps / second

Indoor test track and Pacesetter

Fixed pace [Kane et al., 2008]

Comparable level of walking demand

Vibrotactile feedback to pacesetter

Hand Postures

One-handportrait

Two-handlandscape

Two-handportrait

Copy task

2 practice sentences / condition

5 test sentences / condition

Portuguese language representative corpus

Error correction was not available

Apparatus

HTC Desire

7x10 mm – portrait mode

10x10 mm – landscape mode

Neither word prediction nor correction was used

Experiment Design

22 participants x 3 mobility settings x 3 hand postures

990 sentences overall

Two-way repeated measures analysis

Results

Two-hand input is faster

19.9

23.928.1

20.5

25.029.1

20.0

24.428.9

0

5

10

15

20

25

30

35

One-hand portrait Two-hand portrait Two-hand landscape

Words per Minute

Seated Walking (65%) Walking (100%)

Two-hand posture does not provide additional stability

0%

2%

4%

6%

8%

10%

12%

14%

16%

0.0 g 0.5 g 1.0 g 1.5 g 2.0 g

MSD Error Rate by Hand Oscillation

One-Hand Portrait Two-Hand Portrait Two-Hand Landscape

seated walking (65%) walking (100%)

Substitutions are the most common type of error

4.3% 3.8%1.7%

1.1%1.1%

0.7%

0.6% 1.1%

1.0%4.8% 5.2%

1.8%

0.9% 1.2%

0.8%

0.8%0.9%

0.8%7.0% 5.5%3.0%

1.0%1.4%

1.0%

0.6% 1.8%

1.2%

0%

2%

4%

6%

8%

Del Ins Subs

Hand oscillation causes poor aiming nor finger slips

88% 84%87%92% 87% 93%93%

81%

96%

0%

20%

40%

60%

80%

100%

120%

One-hand portrait Two-hand portrait Two-hand landscape

Substitutions: incorrect land-on

Seated Walking (65%) Walking (100%)

Substitution pattern

Same-row errors

Distance of one key

Typically at the right

Pattern was consistent across mobility demands

Most users prefer larger keys

0

2

4

6

8

10

12

14

16

18

One-hand portrait Two-hand portrait Two-hand landscape

Participants Preference

Preferred hand posture Less preferred hand posture

Design Implications(For all those sleeping/bored … WAKE UP!)

!Do not over rely on two-hand interaction for physical stability

~

!Take advantage of typing behaviors

T Ytranscribed > payyernintended > pattern

!Design for poor aiming, especially whilst mobile

Touch

Accelerometer data

+ Intended key

Conclusion

Negative effect of walking on touchtyping using thumbs

Consistent substitution pattern

Two-hand interaction does not improve text-entry accuracy; Increasing target size is an effective solution

Design implications

The End.

Hugo Nicolauhman@vimmi.inesc-id.pthttp://web.ist.utl.pt/hugo.nicolau/