Outline of the talkThe effects of space insertion
into Japanese texts! Study question! Motivation & previous studies

Michiko Nakamura! Eye-tracking experiment! Results

Computational Linguistics
Laboratory! Discussion! Conclusion

October 28, 2004

COE technical presentation2

Research question

Motivation

Will space-insertion into Japanese texts
facilitate reading?
! Japanese written texts have no spaces
between words! On-going project on determining theoptimal format of a text
! To make information on the Internet

accessible to various users(e.g., elderly people, people with a disability)!"#$!%&'()*+,+-./01234! Automatic space insertion into texts canbe done by using parsing tools! If spaces are inserted,!"5#$!%&5'()5*+,+-5./051234! ChaSen (Matsumoto et. al 2003)! CaboCha (Kudo & Matsumoto 2002, 2003)

Is this easier to read?
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What do spaces do in reading?

How about in other languages?

! Spaces mark word boundaries! Thai uses alphabetic scripts, but nospaces between words

spaces are processed in peripheral vision!"#$#%&'()*)+$,-./)0)1%*2/"*!3)(4"0.50)$#6789+#!
2:;8/:1)5")<=>?5-./)!%)! Kohsom & Gobet (1997)! Spaced texts were read faster than

! In order for an eye to extract information

eye must land on appropriate points in a word

unspaced texts! Will Japanese readers use these cues

when present?
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Experiment: overview

Apparatus (EyelinkII)! Participants read spaced and unspaced! Head-mounted eyetexts! Eye movements were recorded during
reading! Examined if spacing has positive effects
on reading! Results from 16 native speakers ofJapanese (students from NAIST)

tracker with high speed
eye cameras! Binocular recording of eye
movements during reading! Sampling rate: 500 data
samples per second! Spatial resolution: < 0.5º
78Materials

Space insertion into texts! 20 (unspaced) texts! Used parsing tools developed at CL-lab! 13 texts from a science magazine! ChaSen added POS-tags into texts(science articles translated into Japanese)! 7 texts from a newspaper corpus! CaboCha (dependency analyzer) determinedbunsetsu boundaries! One segmentation error corrected manually! Length of texts( 67859:35!567589:3 )! Spaces! 286-386 characters! one half-width space between bunsetsu! 8-10 lines! one full-width space at the beginning of each! 1-3 paragraphs

paragraph
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Spaced and unspaced texts

Procedure! The amount of information per line was! Each participant had two reading

the samesessions (separated by a short break)! 8 spaced texts in one session and 8
unspaced texts in another session! 40 characters per line
! Line breaks appear at the same position! Line length is shorter in unspaced texts! Never read the same text in two different

spacing versions

than in spaced texts! Spacing-type and session-order wereequally distributed across participants1112

Procedure (cont.)

Types of data

! Each session begins with 2 practice texts! Data from comprehension questions! Q1: text readability! In the test trials! Q2 & Q3: content of the text

! A text is displayed on the screen! Eye movement data

! A participant reads the text silently forcomprehension! Three questions asked after each text

! Fixations! Total reading times

Q1:“Was the text easy to read?” [Yes or No]
Q2 & Q3:
About the content of the text [Yes or No]! Regressions! Significance level set at p<0.05
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Comprehension questions

Fixations

No difference in! Q1: text readability [Fs < 1]

The number of times an eye is fixatedwithin a text, and its average duration! Spaced texts (209ms) had shorter
fixations than unspaced texts (216ms)! Unspaced! Spaced

75.0%
77.3%

[Ps<0.005]! Q2 & 3: comprehension accuracy[Ps > 0.23]! Unspaced! Spaced! Tendency in Session 2 only
! Trade-off between duration and number

64.4%
68.7%

“many short fixations vs. fewer long fixations”
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Total reading times

Regressions (on the same line)! No difference [p1>0.22; p2>0.4]

eye’s backward movements to earlier
positions in a text
! No difference in latency and number! Length! Unspaced

62.8 sec! Spaced

58.9 sec! Spaced texts (151) had longer regressions

than unspaced texts (133) [p1>0.27; p2<0.05]! Could be due to spaces, but see…

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Distribution of regressions

Regressions (to previous lines)! No difference in length, latency, andThe number of regressions per length range!"#$%&'()*"+,#-()*"+./00012
8./00032
6./00042:./00092
7./00022
1../122
8..;

34531
4.54.
43577
43594
615:3
1.6594
76513

67571
49537
:8531
46531
665:3
2:5:3
76566

numberFewer regressions inspaced texts (47)than in unspaced
texts (53)[p1<0.07; p2<0.05]
No difference over
100 ranges
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Summary of the results

Discussion! Spaced texts produced! Spaces provide visual cues for word boundaries! Higher rating on text readability! Japanese has other cues

! Higher comprehension accuracy! Three sets of characters• Katakana• Hiragana! Shorter fixations (session 2 only)**! Fewer short-range (<100) regressions**• Kanji! Space insertion seems to have some! loan words! grammatical info
(e.g., verb-endings, case markers)! content words (e.g., nouns, verbs)! Segmentation cues are already available inpositive effects on reading

normal texts, and readers may be using them

! but the effects are relatively weak

! Then, space insertion may not have that large

effects
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Discussion (cont.)

Conclusions! Lack of statistical power! Examined the effects of space insertion! Comprehension questions slowed downon the reading of Japanese texts! The results suggest some positive effectsof space insertion! If space insertion does facilitate reading,potential applicability to natural
documents on the Internet

overall reading speed! This may obscure the subtle but significant

effects of space insertion

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