Investigating the Effectiveness of Assistive Technologies on Situationally Impaired Users

David Lucas Hugo Nicolau

Tiago Guerreiro Joaquim Jorge

Evolution …

On the move

Always near us

@ Home

@ Work

Outdoors

In car

@ Coffee shop

@ Subway

Many contexts

CONTEXT

Leading to …

SIID Situationally-Induced Impairments and Disabilities

Visual Attention

“Functionally Blind”

Technology transfer

Not quite the same

Yet, very similar

Text-entry

Screen Readers

VoiceOver

NavTouch

[Guerreiro, 2008]

User Evaluation

23 Participants

18 ~ 37 years old

Touchscreen experience

Texting experience

Apparatus

Text-entry Methods

QWERTY

VoiceOver

NavTouch

Visual Feedback

QWERTY

NavTouch

Mobility conditions

seated

corridor

navigation

Five word sentences

97% correlation

Measurements and Design

Words per Minute Error rate Minimum String Distance (MSD) Error Rate Preferred Walking speed

Text-entry speed

0

5

10

15

20

25

seated corridor navigation

Qwerty VoiceOver NavTouch

Text-entry speed

Text-entry sensitive to visually demanding conditions

AT were inefficient regarding speed

QWERTY the most sensitive (3.4 wpm)

Error Rate

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

seated corridor navigation

Qwerty VoiceOver NavTouch

Error Rate

More deletions with QWERTY

Fewer errors with Assistive Technologies?

Quality of Text

0%

1%

2%

3%

4%

5%

6%

seated corridor navigation

Qwerty VoiceOver NavTouch

Quality of Text

NavTouch the most erroneous

Audio feedback improves quality of text

QWERTY the most sensitive

Walking Speed

0%

10%

20%

30%

40%

50%

60%

70%

80%

corridor navigation

Qwerty VoiceOver NavTouch

Walking Speed

Navigation course was more demanding

Users decreased walking speed

ATs were ineffective, possibly due to

cognitive load

Conclusion

Users reduce walking speed due to visual demand

QWERTY outperformed ATs

ATs are cognitively demanding

Audio is overlooked when

visual feedback is available

Future work

More visually demanding conditions 1-step selection methods No visual feedback Play with visual attributes

THE END.

Tiago Guerreiro tjvg@vimmi.inesc-id.pt