Eve Hoggan, Stephen Brewster & Jody Johnston

Investigating the Effectiveness of Tactile Feedback for Mobile

Touchscreens

TopicsMobile touchscreen displays

Tactile feedback for fingertip interaction

Physical keyboards versus tactile touchscreen keyboards

Can high-spec virtual tactile feedback improve the usability of touchscreen keyboards further?

Dynamic mobile environments

Dynamic mobile environments

Dynamic mobile environments

Dynamic mobile environments

Touchscreens no longer need physical keyboards

Fingertip interaction

Touchscreen buttons cannot provide the natural haptic response that physical buttons can when touched

Mobile touchscreens

Feel the buttonsUsers can physically ʻfeelʼ the touchscreen interface

Haptic feedback: applying forces, vibrations or motion to the fingertip

We studied the effects of adding tactile feedback to a touchscreen mobile QWERTY keyboard

Tactile featuresFingertip-down and click events

Home keys

Fingertip-slip

Physical QWERY keyboard

Palm Treo 750

Comparison

Physical QWERY keyboard

Palm Treo 750

Comparison

Touchscreen keyboard

Samsung i718

Built in Immersion “Vibetonz” actuator

With and without tactile feedback conditions

MethodParticipants were shown a phrase and asked to memorise it, then type itErrors, keystrokes per character, time and workload were measuredLocations: lab and mobile (on a train)

Train environment

Noise, light, movement and vibration levels are very dynamic

Train environment

Noise, light, movement and vibration levels are very dynamic

Accuracy

Physical keyboard and tactile touchscreen performed best

Physical keyboard Standard touchscreen Tactile touchscreen

Accuracy

Physical keyboard and tactile touchscreen performed best

Lab Mobile0

10

20

30

40

50

60

70

80

90

100

Ave

rage

% p

hras

es e

nter

ed c

orre

ctly

Physical keyboard Standard touchscreen Tactile touchscreen

Accuracy

Physical keyboard and tactile touchscreen performed best

Lab Mobile0

10

20

30

40

50

60

70

80

90

100

Ave

rage

% p

hras

es e

nter

ed c

orre

ctly

Physical keyboard Standard touchscreen Tactile touchscreen

Accuracy

Physical keyboard and tactile touchscreen performed best

Lab Mobile0

10

20

30

40

50

60

70

80

90

100

Ave

rage

% p

hras

es e

nter

ed c

orre

ctly

Physical keyboard Standard touchscreen Tactile touchscreen

Keystrokes per character (KSPC)

Significantly more KSPC on tactile touchscreen

00.20.40.60.81.01.21.41.61.82.0

Lab Mobile

Ave

rage

KSP

C

Physical keyboard Standard touchscreen Tactile touchscreen

Time per phrase

Standard touchscreen slower than others

0

3.5

7.0

10.5

14.0

17.5

21.0

24.5

28.0

31.5

35.0

Lab Mobile

Ave

rage

tim

e pe

r ph

rase

(se

cs)

Physical keyboard Standard touchscreen Tactile touchscreen

Additional experiment

Specialised actuators Simple spatial location

AccuracyThe number of phrases entered correctly on the physical keyboard, tactile touchscreen and PDA with specialist actuator are very similar with no significant difference 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Lab Mobile

Ave

rage

phr

ases

ent

ered

cor

rect

ly

Physical keyboard Standard touchscreen Tactile touchscreenPDA with dual C2 actuators

KSPC

Users corrected significantly more errors on the tactile touchscreen

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Lab Mobile

Ave

rage

KSP

C

Physical keyboard Standard touchscreen Tactile touchscreenPDA with dual C2 actuators

SpeedUsers typed significantly faster on the physical keyboard and PDA with specialist actuators

0

5

10

15

20

25

30

35

Lab Mobile

Ave

rage

tim

e pe

r ph

rase

(se

cs)

Physical keyboard Standard touchscreen Tactile touchscreenPDA with dual C2 actuators

Workload

Levels of annoyance were highest on the PDA with specialist actuators

Perceived performance decreased and all other measures increased when using the standard touchscreen

Future workFingertip interaction with other types of traditional widgets

Novel tactile widgets, e.g. T-Bars (Hoggan et. al, MobileHCI 08)

Alternative mobile environments

Initial audio and crossmodal results

Audio feedback is as good as tactile in the lab but not on the train

Crossmodal feedback produces levels similar to tactile

ConclusionThe addition of tactile feedback significantly improved finger-based text entry

High-spec tactile actuators improve typing speeds even further

The benefits of touchscreen displays do not have to come at the cost of poorer text entry, we can regain some of the natural feeling lost

Thank youEve Hoggan & Stephen Brewster

{eve, stephen}@dcs.gla.ac.uk

www.tactons.org

Many thanks to Nokia, Immersion and SPT

iPhone version can be downloaded at iphone-haptics.googlecode.com