elderly text-entry performance on touchscreens
DESCRIPTION
My presentation at ACM ASSETS 2012. Abstract:TRANSCRIPT
Mobile evolution
… led us to touchscreens
Direct Manipulation
Engaging
Adaptable[Findlater et al., 2012]
Hard to select targets[Jin et al., 2007]
Occurs to everyone[Nicolau, 2012]
Elderly
Hand tremor[Strickland and Bertoni, 2004]
Small targets[Jin et al., 2007]
Text-Entry is a challenge
Transversal task
Communication
Managing contacts
Document editing
Web browsing
Note taking
Text Input
Re-visiting adaptability
Provide the knowledge
User Study
Text-Entry Performance
Hand tremor
Apparatus
Tablet:20x10 mm
Mobile:10x10 mm
Participants
15 participants (4 males)
67 to 89 years old
Right-handed
No severe visual impairments
No familiarity with touch devices
Two Phases
1st - Familiarization
2nd - Evaluation
Familiarization
Explanation and exemplification
Copy tasks
30 minute practice session
Physiological tremor assessment
Action tremor (task-specific)Archimedes Spiral [Bain et al., 1993]
Postural tremorAccelerometer data [Selker et al., 2011]
Copy Task1 practice sentences / condition
5 test sentences / condition
Portuguese language representative corpus
Error correction was not available
Dependent MeasuresSpeed:Words per minute
Accuracy:Minimum String Distance error rateSubstitution error rateInsertion error rateOmission error rate
Results
Tremor Profile
Task-specific TremorArchimedes Spiral Drawings
Postural TremorHand Oscillation [Oulasvirta et al., 2011]
Peak Magnitude [Salarian et al., 2007][Elble and Koller, 1990]
Tremor Profile
Task-specific TremorArchimedes Spiral Drawings
Postural TremorHand Oscillation [Oulasvirta et al., 2011]
Peak Magnitude [Salarian et al., 2007][Elble and Koller, 1990]
Text-Entry Performance
Error RateMinimum String Distance (MSD) Error Rate
26% 17%Mobile Tablet
Tablet Compensates Errors
26% 17%Mobile Tablet
Minimum String Distance (MSD) Error Rate
Statistically Significant[Z=-2.417, p<.05]
Correlation with Hand Oscillation
26% 17%Mobile Tablet
Minimum String Distance (MSD) Error Rate
Hand OscillationNon-dominant hand
Y [Pearson r=.751, n=9, p<.05]
Z [Pearson r=.613, n=9, p=.079]
Types of Errors
6% 4%8% 4%13% 9%Mobile Tablet
Insertions Substitutions Omissions
Error Rate
Omissions
Omission were the most common
6% 4%8% 4%13% 9%Mobile Tablet
Insertions Substitutions Omissions
Error Rate
Omission were the most common
6% 4%8% 4%13% 9%Mobile Tablet
Insertions Substitutions Omissions
No Significant Difference[Z=-.722, p>.4]
Error Rate
Blank space was recurrently omittedOmission Error Rate in Mobile condition
28% 23%
16% 15%
SPA
CE a b c d e f g h i j k l
m n o p q r s t u v w x y z
Forgetfulness and coordination are real issues
#13 Usually forgot to transcribe words at middle and end of sentences
#8 “where was I?”
Unintentional touches
Insertions
Insertion Error Rate
6% 4%8% 4%13% 9%Mobile Tablet
Insertions Substitutions Omissions
Few Insertions with Tablet
6% 4%8% 4%13% 9%Mobile Tablet
Insertions Substitutions Omissions
Statistically Significant[Z=-2.103, p<.05]
Error Rate
Bounces and Accidental Touches
1.5% 2.2%3.3% 1.1%
Mobile Tablet
Bounces Accidental
Error Rate
Few Accidental Touches with Tablet
1.5% 2.2%3.3% 1.1%
Mobile Tablet
Bounces Accidental
Error Rate Statistically Significant[Z=-2.292, p<.05]
Error Rate
Correlations with Hand Tremor
1.5% 2.2%3.3% 1.1%
Mobile Tablet
Bounces Accidental
Dominant Hand Oscillation
X [Spearman rho=.596, n=14, p<.05]
Non-Dominant Hand Oscillation
Y [Spearman rho=.762, n=9, p<.05]
Deal with Insertion Errors
Required: r e c e i t a d o (English: prescribed)Transcribed: r r e c e i i t t a d o o
Substitutions
Substitution Error Rate
6% 4%8% 4%13% 9%Mobile Tablet
Insertions Substitutions Omissions
Few Substitutions with Tablet
6% 4%8% 4%13% 9%Mobile Tablet
Insertions Substitutions Omissions
Statistically Significant[Z=-2.731, p<.01]
Error Rate
Error Rate
Correlation with task-specific tremor
6% 4%8% 4%13% 9%Mobile Tablet
Insertions Substitutions Omissions
[Spearman rho=.624, n=15, p<.05]
[Spearman rho=.541, n=9, p<.05]
[Spearman rho=.539, n=15, p<.05]
Substitution PatternsMobile Error Rate
Right-Bottom Substitution PatternLift Points – Mobile condition
Similar and Symmetrical Substitutions
p -> qi -> j , i -> l
Participant #11: m -> w , n -> u
Cognitive errors?
Most Substitutions are due to Poor Aiming
1.1% 0.2%6.7% 3.5%
Mobile Tablet
Slip Poor Aiming
Error Rate
Most Substitutions are due to Poor Aiming
1.1% 0.2%6.7% 3.5%
Mobile Tablet
Slip Poor Aiming
Error RateStatistically Significant[Z=-2.944, p<.01]Statistically Significant
[Z=-3.107, p<.01]
Preferences and
Comments
Participants Preference
2 13Mobile Tablet
Participants Comments
“I am always hitting neighboring keys”
“The hardest thing is trying not to tremble while typing”
“The main difficulty for me is in knowing where the letters are. I am not used to it (the keyboard)”
Inclusive Keyboards
Implications
ImplicationsShift keyboard layout
ImplicationsShift keyboard layout
Avoid errors by understanding typing behaviors
ImplicationsShift keyboard layout
Avoid errors by understanding typing behaviors
Deal with poor aiming rather than finger slips
ImplicationsShift keyboard layout
Avoid errors by understanding typing behaviors
Deal with poor aiming rather than finger slips
Use language-based correctors
ImplicationsShift keyboard layout
Avoid errors by understanding typing behaviors
Deal with poor aiming rather than finger slips
Use language-based correctors
Allow personalization
ImplicationsShift keyboard layout
Avoid errors by understanding typing behaviors
Deal with poor aiming rather than finger slips
Use language-based correctors
Allow personalization
Compensate hand tremor
ConclusionElderly Text-Entry Performance
Empirical Body of Knowledge
Error Patterns
Design Implications
Future Work
Analyze hand tremor data
Develop touch models
Compensate input errors
Touch
Accelerometer data
+ Intended key
