Empirical Investigation into the Effect of Orientation on Text Readability in Tabletop Displays

Daniel WigdorRavin Balakrishnan

Presented at ECSCW, Paris, France

2

Tabletop Displays

3

Text Orientation• .• Solutions:

1: 3:

2:

4

Multiple CopiesAdvantage:• Spatial proximity for freeDisadvantages:• More space used• SDG shared interaction space lost

5

Diff’ View for Each User• Agrawala et al 1997• Matsushita et al 2004Advantages• Conserves real-estate• Optimal to all usersDisadvantages• Loss of shared position of objects

6

Algorithmic Rotation• Many different techniques

(see Hancock et al Tabletop 2006)

Advantages:• Only one copy of object• Collaboration cues (CHI03)Disadvantages• Adds complexity to system• Optimal orientation to only 1 viewer

7

But, Why Reorient?• Orientation used for other things:

• Preferred for drawing & design• Denotes ownership• Denotes intention to share• See Kruger et al CHI ’03• See Fitzmaurice et al CHI ‘99

• Users may prefer right-side up, but what is performance penalty?

8

Past Work• Tinker 1972: Paragraphs• Koriat & Norman 1985: Words

9

• Used Chapman SoRT (1923)Tinker (1972)

Orientation Penalty

+/- 45o 52%+/- 90o 205%

10

Koriat & Norman (1985)• Classify real/fake words

Orientation Penalty+-60o Not significant> 60o > 120%

11

Limited Applicability• Head position constrained• Identification of non-conforming text• Does not allow for “natural” reading • Penalties may be exaggerated

12

Our Experiments• Study on tabletop• Free movement of the head• Task allows more natural reading• Apparatus:

13

Experiment 1: Speed of Reading• 3 types of text: phrase, word, number• Phrases:

• Coherent & Meaningful• Mackenzie phrase set (Mackenzie 2003)

• Words: 5-6 letters• Numbers: 6-digits

14

Procedure1. Location of string primed2. Text appears & timer begins3. User begins to type:

• text disappears, timer stops

1. 2. 3.

(printing error in proceedings)

15

Design3 treatments (single word, number, phrase) X4 on-screen positions (each corner of tabletop) X 8 orientations (starting at 0o, in 45o increments) X 3 strings at each position/orientation X 15 participants

= 4320 strings entered in total.

16

Hypotheses• Orientation on SoR significant• Not as dramatic as others showed• Numbers would be most affected

17

Results: Speed of Reading• Orientation on SoR:

• single word (F7,10 = 28.0, p < .0001)• short phrase (F7,10 = 64.28, p < .0001)• numbers (F7,10 = 7.76, p < .0001)

• Position not significant on SoR

18

Results: SoR Single Wordμ (seconds) σ % off 0o

-135o 1.19 0.67 64.70%-90o 0.92 0.40 26.60%-45o 0.78 0.60 7.98%0o 0.72 0.22 -45o 0.77 0.22 5.93%90o 0.91 0.37 25.78%135o 1.35 1.00 86.42%180o 1.11 0.57 53.67%

19

Results: SoR Short Phraseμ (seconds) σ % off 0o

-135o 3.82 1.52 107.13%-90o 2.66 1.07 44.25%-45o 2.07 1.02 12.62%0o 1.84 0.86 -45o 1.97 0.70 7.19%90o 3.09 1.30 67.71%135o 3.90 1.97 112.82%180o 3.69 1.89 100.27%

20

Results: SoR Numbersμ (seconds) σ % off 0o

-135o 2.85 1.06 17.48%-90o 2.85 1.63 17.19%-45o 2.36 1.17 -2.71%0o 2.43 1.57 -45o 2.39 1.19 -1.65%90o 2.78 1.21 14.56%135o 3.01 1.24 24.26%180o 3.03 1.16 24.87%

21

Design Implications• Effects of orientation less dramatic• Longer text should be reoriented• Menus with can be shared• Numerical data can be shared

22

Experiment 2• Orientation may play role in spatial

memory• “Correcting” orientation may hurt!• Measured performance repeated

search

23

Procedure1. Told word to find2. Presented with search field (static)

• User enters suffix (dynamic)

1. 2.

24

Design3 datasets:

no rotation small rotation (-45o, 0o, 45o)complete rotation (all 8 compass) X

24 strings per dataset (pos, orient random) X 3 searches per string (order random) X 9 participants

= 1944 searches in total.

25

Hypotheses• Harder to search rotated field at first• Learning faster for rotated fields

26

Results• Significant effect of orientation on search time (F2,215 =

9.80, p < .0001) • No effect of orientation on learning• But, penalty not as much as expected:

Condition Expected Penalty

Observed Penalty

No rotation - -Some rotation 5% 3%All rotations 34% 15%

27

Discussion• Orientation hurts search less than

reading: not previously reported• Measured only short-term learning• Effect may assert itself long-term

28

Thanks!• Jonathan Deber• John Hancock• Members of the DGP Lab• Mitsubishi Electric Research Labs • Experimental participants• ECSCW reviewers

29

Questions?

1. 2. 3.

1. 2.

30

Results: Errors• Error: user submits wrong text• Orientation on error: not significant• Type on error: F2,26 = 34.04, p < .0001