elderly text-entry performance on touchscreens

Elderly Text-Entry Performance on Touchscreens

Hugo Nicolauhman@vimmi.inesc-id.pt

Joaquim Jorge

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

The End.

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