Reading and Writing (2005) 18:281–302
DOI 10.1007/s11145-005-3354-0

 Springer 2005

The eﬀect of morphemic homophony on the processingof Japanese two-kanji compound words
KATSUO TAMAOKA
International Student Center, Hiroshima University, Hiroshima, Japan

Abstract. Two experiments investigated the eﬀect of kanji morphemic homophonyon lexical decision and naming. Eﬀects were examined from both the left-hand andright-hand positions of Japanese two-kanji compound words. The number of homophones aﬀected the processing of compound words in the same way for both tasks.
For left-hand kanji, fewer morphemic homophones led to faster lexical decision andwhole-word naming. For right-hand kanji, the number of morphemic homophones
did not aﬀect either lexical decision or naming. This eﬀect of homophonic density
suggested that, when a kanji-compound word is to be processed, phonological information of its kanji constituents is automatically activated and reverberates back to
generate a series of orthographic representations of kanji morphemic homophones,
but not in a completely parallel fashion.
Key words: Kanji reading, Lexical decision, Morphemic homophones

Introduction
Some Japanese words are comprised of single character morphemes(kanji) having a high density of homophony. Because of this, it is commonly believed that phonology does not play as important a role inreading and writing as does orthography. Despite this belief, Japanesenative speakers often make mistakes when writing a kanji character
which shares its sound with many others. Hatta, Kawakami and Tamaoka (1998, 2002) reported that phonologically related writing errors(e.g.,/sja kai/ for/sja kai/) outnumber those related toorthography (e.g.,/i setju/ for/ki setju/). This ﬁnding suggests that phonology of Japanese kanji comes into play even in tasks
which are ostensibly devoted to the orthographic aspect of kanji writing. Given this, the question arises as to whether or not a two-way
interaction between orthography and phonology occurs when Japanese
kanji with a high density of kanji homophony are processed, and more
speciﬁcally, how the orthographic and phonological representations ofkanji are related in the mental lexicon.

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Mapping of a single kanji morpheme to multiple sounds
Kanji pronunciations can be divided into two types: the On-reading
derived from the original Chinese pronunciation, and the Kun-reading
originating from the Japanese way of reading kanji (see details in Kaiho& Nomura, 1983; Morton & Sasanuma, 1984; Tamaoka, 1991, 2003;
Wydell, Butterworth & Patterson, 1995; Wydell, Patterson & Humphreys, 1993). However, this mixture of material with two phonologicalorigins were usually distinguished by lexical items, rather multiple pronunciations of a single Japanese kanji were created by On-readings.
The Japanese ﬁrst encountered the written Chinese language aroundthe end of the fourth and the beginning of the ﬁfth century (Hadamitzky & Spahn, 1981; Miller, 1967; Seeley, 1984; Tsukishima, 1979).
They borrowed heavily from Chinese, but did not adopt the four tones
which exist in the standard Mandarin form of the Chinese language.
During this period of contact with China, the Japanese imitated thesounds of Chinese characters without the tones from the Chinese soundsystem. As a result of this, and the movement of the capital cities during diﬀerent periods of China’s political history, various Chinese dialects and diﬀering types of pronunciation were borrowed (Miller, 1967;
Sato et al., 1978). Systems were labeled according to the names of theChinese dynasties in political power during each period when Japan
interacted with China. Kanji pronunciations of On-readings are further
classiﬁed into three types: namely, Go-on, Kan-on and To-on (formerly
called So-on). These three diﬀerent systems of pronunciation simultaneously exist in the On-readings of kanji used in modern Japanese.
In dispensing with the Chinese tones and adapting three diﬀerent
sound systems from China, the Japanese created a great number ofmultiple On-readings for kanji. According to the Database for the 1945
Basic Japanese Kanji, 2nd edition (Tamaoka, Kirsner, Yanase, Miyaoka& Kawakami, 2002), the total number of kanji which have only one
pronunciation is 699 (667 kanji with a single On-reading and 32 kanji
with a single Kun-reading). This is 35.94% of the 1945 basic Japanese
kanji. Kanji which have only On- or only Kun-readings, regardless ofthe number of pronunciations, total 779 (739 for On-reading and 40 for
Kun-reading), or 40.05% of the 1945 basic Japanese kanji. In otherwords, although it is a commonly-held notion that a kanji has both an
On-reading and a Kun-reading, only 1166 kanji or about 59.95% of the1945 basic Japanese kanji have both types of pronunciations.
Let us examine one of the 1166 kanji which has multiple readingsof both the On and Kun types. As shown a mapping of a single kanji tomultiple sounds in Figure 1, the kanji(meaning ‘tree’ in English) is

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283

Figure 1. Mapping of a single kanji to multiple sounds.

pronounced as /moku/ and /boku/ in On-reading and /ki/ and /ko/ in
Kun-reading. When the orthographic representation of is activated, its
activation will spread not only into its semantic representation of ‘tree’
but also into its phonological representations. The activation of could
possibly and automatically spread to all four possible pronunciations
although its activation levels will diﬀer from one to another. In this type,the direction of activation moves from orthography to phonology.
For kanji, there is no systematic mapping from orthography to phonology in the same manner seen in alphabetic languages (Wydell et al.,
1993; Wydell et al., 1995). Thus, one can assume that in a two-kanji
compound each kanji will be read as a part of the whole word, and not
as a single kanji morpheme unit. If this is true, multiple pronunciations
held by kanji would have no eﬀect on the naming of two-morpheme
compound words because pronunciations would be identiﬁed at the unitof a word, not at the kanji morpheme level. Even if the spread activation from orthography to phonology does occur, it would not have astrong eﬀect on lexical decision and naming of two-morpheme compound words constructed by two kanji units with multiple readings.
Wydell et al. (1995) investigated kanji activations from orthography
to phonology. As depicted in Figure 1, a kanji(‘tree’) is pronounced/ki/ and /ko/ in Kun-reading while it is also read /moku/ and /boku/ in
On-reading. According to Wydell et al. (1995), these kanji with multiple

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pronunciations do not have any eﬀect upon the naming of two-kanji
compound words: the sounds of /moku/, /boku/, /ki/ and /ko/ do nothave any eﬀect on the naming of its compound words such as(‘lumber’/moku zai/),(‘a wooden sword’ /boku toR/),(‘agate’ /ki do/) and(‘the shade of a tree’ /ko kage/). Then, assumingthat the claim by Wydell et al. (1995) is correct, exhaustive activations
from orthography to phonology should not occur in kanji phonologicalprocessing for the naming task of two-kanji compound words.
Despite such an intensive study by Wydell et al. (1995), a study ofKayamoto, Yamada and Takashima (1998) suggested the existence ofprint-and-sound consistency eﬀects at the kanji level. This study’s claim
is based upon a naming task of single kanji morphemes. In Experiment
1, Kayamoto et al. found that kanji with multiple pronunciations are
named slower than kanji with a single pronunciation. However, kanji
with multiple pronunciations naturally have multiple correct sounds asinpronounced as /kazu/ or /suR/. The speed and accuracy of thesekanji were compared to others with a single sound as inpronounced
as /teN/. Under these conditions, native Japanese speakers must suppress one of the correct pronunciations of kanji with multiple-readings
so it is naturally expected that they will have higher error rates andslower response times in naming these kanji. As expected, they found
the results of consistency eﬀects at the kanji level.
In Experiment 2, Kayamato et al. (1998) further investigated consistency eﬀects using only kanji with a high frequency of written occurrence. This time, they obtained a conﬂicting result as there were no
consistency eﬀects at the kanji level. Subjects were able to name a kanji
with a single pronunciation as fast as a kanji with multiple pronunciations. This could be explained by the fact that kanji with a high frequency of written occurrence have an especially strong connection
between kanji orthography and one of their sounds. It could beassumed that one of the sounds in a single kanji with multiple pronunciations must have an equally high frequency of occurrences as anotherkanji with a single sound.
It is also interesting to note that some high-frequency kanji used byKayamoto et al. (1998) had highly concrete and easily imaginable
meanings when sounded in Kun-readings such as/natu/ meaning‘summer’,/mado/ meaning ‘window’,/hata/ meaning ‘ﬂag’. As
Hirose (1998), Kaiho and Nomura (1983) and Nomura (1978) suggest,
Kun-readings are strongly attached to kanji meanings, especially whenthose kanji are presented as a single kanji. Therefore, subjects are likely
to pronounce a single kanji by way of its Kun-reading which represents
a word with meaning by itself instead of having to combine with otherKANJI MORPHEMIC HOMOPHONY

285

kanji. Thus, the speed of the naming of a single kanji with multiple
sounds should be further examined based upon frequencies of kanji
sounds and semantic independency of kanji Kun-readings.
There is a fundamental diﬀerence in the stimulus items used by Wydell et al. (1995) and Kayamoto et al. (1998) to test kanji consistency
eﬀects. Wydell et al. used two-kanji compound words for naming
whereas Kayamoto et al. used single kanji. Consequently, regardless of
the ﬁndings of Kayamoto et al. (1998), the study done by Wydell et al.
(1995), indicating no eﬀects of kanji orthography-to-phonology exhaustive activations at the morpheme level, remain intact. The present study
also used two-kanji compound words as stimulus items in Wydell et al.
(1995). Nevertheless, taking the argument of kanji multiple exhaustive
activations as indicated by Kayamoto, et al. (1998) into consideration,
experiments in the present study saw ﬁt to control the number of kanji
pronunciations constructing two-kanji compound words, and focusedits research onto a single sound shared by multiple kanji orthography.

Mapping of a single sound to multiple kanji morphemes
Although Japanese kanji often have multiple pronunciations including
both the On- and Kun-readings, multiple kanji sharing the same soundare much greater and more commonly observed in On-readings. By theninth grade, Japanese speakers will have mastered the 1945 basic Japanese kanji. Even within this range of fundamental kanji, the Databasefor the 1945 Basic Japanese Kanji (Tamaoka et al., 2002; Tamaoka &Makioka, 2004) shows that the most-shared sound was /sjoR/1 which
was represented by 65 kanji (all On-reading) among the 1945 basic
kanji. This is approximately 3.3% of the total number of basic kanji.
The sound /koR/, having 64 On-readings and one Kun-reading, also
showed the same number of kanji symbols as the sound /sjoR/. Almost
all of these homophonic sounds are found to be On-readings.
The possible connection from a single sound to multiple kanji morphemes is illustrated in Figure 2. The sound /ka/ in morphemic phonology can be written as various kanji such as(‘ﬁre’),(‘chemical’),(‘section’),(‘ﬂower’),(‘house’) and(‘mosquito’). All these kanji
could be read as the sound /ka/ (most exclusively On-readings). Becausesuch a great number of kanji can represent the same sound, it would seemthat their pronunciation is not a reliable means of accessing their semantic information. It is not surprising that some previous studies on the Japanese language (e.g., Goryo, 1987; Kimura, 1984; Kimura & Bryant,1983; Saito, 1981; Sasanuma, 1986; Seidenberg, 1985) assumed that kanji

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KATSUO TAMAOKA

f

P
f

Figure 2. Mapping of a single sound to multiple kanji.

compound words are processed orthographically as a word unit to accesstheir semantic information and that no phonological reference isinvolved. However, other previous studies (e.g., studies on English by
Andrews, 1986; a study on French by Beauvillain 1994, Butterworth,
1983; studies on Japanese by Hirose, 1992; studies on the Chinese language by Perfetti & Zhang, 1991, 1995; Perfetti, Zhang & Berent, 1992;
Stanners, Neiser, Hernon & Hall, 1979; Taft, 1991, Tamaoka & Hatsuzuka, 1995, 1998; Tamaoka & Takahashi, 1999; Zhang & Peng, 1992;
Zhang & Perfetti, 1993) suggest that morphemic units of compoundwords were simultaneously activated while processing their lexical units.
If these experimental ﬁndings are true, the density of morphemic
homophony among Japanese kanji as depicted in Figure 2 would aﬀect
lexical decision and possibly the naming of two-kanji compound words.
One of examples in daily life often observed is a scene that native Japanese speakers ask which kanji was used for /keN/ as a part of the popular
Japanese male name /keN zi/ as having 29 diﬀerent kanji being the same
sound /keN/. As observed in this behavior, higher errors were found inkanji writing by mature native Japanese speakers (Hatta, Kawakami &KANJI MORPHEMIC HOMOPHONY

287

Tamaoka, 1998, 2002). Needless to say, presenting a single syllable suchas /keN/, /koR/ and /sjoR/ does not reach a single kanji as seen in Figure 2. A kanji is identiﬁed only if it is presented as a part of a word. Twokanji are identiﬁed only when shown as a part of the word
pronounced /keN koR/ as having 29 kanji for /keN/ and 64 kanji for /koR/among the commonly-used 1945 basic kanji. Although this mapping
characterizes a feature of single kanji, it is hypothesized that multiple
kanji morphemes would be automatically activated by a single kanji
sound even though a speciﬁc target kanji is embedded in a two-kanji compound word. The present study focused on eﬀects of kanji morphemic
homophony illustrated in Figure 2 of the mapping of a single kanji soundto multiple kanji during the processing of two-kanji compound words.

Experiment 1: Eﬀects of morphemic homophony on lexical decision
Experiment 1 examined the eﬀects of morphemic homophony on thelexical decision task for two-kanji compound words by altering thehomophonic density of both the left-hand and the right-hand position.
MethodSubjects. Twenty-three graduate and undergraduate students who were
native speakers of the Japanese language (12 female and 11 male) participated in the experiment. Their ages ranged from 19 to 25; on the
day of testing, the average age was 21 years and 4 months for females
and 22 years and 5 months for males.
Stimulus items. All kanji characters used for the experiment wereselected from the 1945 basic characters taught from the ﬁrst to ninth
grade, in order to assure that all the subjects would be acquainted withthem. The extent of kanji homophony was identiﬁed by the number ofcharacters which shared the same pronunciation. All possible pronunciations of the 1945 characters were examined to determine the density ofmorphemic homophony using the database (Tamaoka et al., 2002). In
the present study, a high density of homophony refers to sounds represented by more than 20 of the 1945 basic characters, consisting of only
29 such sounds. Sounds represented by less than 7 kanji characters weredeﬁned as having a low density of homophony. In this study, ‘sound’refers to either a single mora (counting the three special sounds as asingle mora) or single syllable (including special sounds as a part of asingle syllable).

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To separately examine the eﬀect of kanji morphemic homophony inthe left-hand and right-hand position of two-kanji compound words,
four categories of compound words, with 18 words in each category
were created: (1) compound words with a high density of homophonyin both the left and right kanji (HH condition), (2) words with a low
density of homophony in both the left and right kanji (LL condition),(3) words with a high density in the left kanji and a low density in theright (HL condition), and (4) words with a low density in the left and ahigh density in the right (LH condition). Examples of these four types
and their averages of morphemic homophones are shown in Table 1. In
this design, two factors (the density of kanji morphemic homophonyand the left/right-hand position) can be examined together. The compound words selected were not homophonic with other higher frequency words at the word level. All compound words used in thisexperiment are listed in the Appendix. One-way ANOVAs indicatedthat the four conditions of two-kanji compound words showed signiﬁcant main eﬀects on morphemic homophony in the left-hand position[F(3, 68) ¼ 62.27, P < 0.001], right-hand position [F(3, 68) ¼ 72.20,
P < 0.001] and both sides together [F(3, 68) ¼ 24.52, P < 0.001].
Thus, these results served the purpose of the experiment, which was toinvestigate the eﬀects of kanji morphemic homophony.
The other possible 11 factors (characteristics 2–12), which could aﬀect
the processing of kanji compound words, were controlled as shown in
Table 1. In the case of word frequency, all four stimulus conditions had
exactly the same average of 25.44 occurrences in the total of 1,967,575
printed words, calculated according to an index provided by the National
Institute for Japanese Language (1973). Abstractness/concreteness of thestimulus items was measured by a 7-point continuum scale as explainedin stimulus items of Experiment 1. Number of morae, radical frequency,
number of constituents, On-reading ratio, kanji frequency of both theindexes of 1976 and 1998, neighborhood size, and accumulative neighborhood size were all controlled so as not to have any main eﬀects (seedetailed explanations, Tamaoka et al., 2002). Detailed ﬁgures for thesecharacteristics across the four stimulus conditions are shown in Table 1.
The ﬁgures of kanji characteristics from 5 to 12 were taken from Tamaoka et al. (2002). ANOVAs indicated that variables 2–12 (listed inTable 1) did not show signiﬁcant main eﬀects across the four stimulus
conditions of two-kanji compound words together, kanji in the left-handposition and kanji in the right-hand position.
For correct ‘no’ responses in the lexical decision task, 72 nonwords were created by simply combining two kanji from the list of
the 1945 basic Japanese kanji such as
,
,
and
.

1 Total of both sides of kanji homophonic density
Kanji on the Left-hand position
Kanji on the right hand position
2 Word frequency(1973)
3 Abstract-to-concrete scale
4 Number of morae
5 Total of both sides of radical frequency
Kanji on the left-hand position
Kanji on the right-hand position
6 Total of both sides of number constituent
Kanji on the left-hand position
Kanji on the right-hand position
7 Average of both sides of On-reading ratio
Kanji on the left-hand position
Kanji on the right-hand position
8 Total of both sides of kanji stroke numbers
Kanji on the left-hand position
Kanji on the right-hand position

Characteristics of word stimuli

Example of a word
Kanji homophonic density of the examples+(35) (5)+(3) (45)+(3)+(5)

27.94
27.56
28.33
25.44
4.79
3.400
62.28
26.61
35.670
4.39
2.28
2.11
80.09%
76.56%
83.62%
18.89
9.00
9.89

High + High
15.25
26.56
3.94
25.44
4.73
3.55
75.39
40.5
34.89
4.22
2.11
2.11
85.86%
82.06%
89.66%
18.33
9.77
8.56

High + Low
18.22
3.06
33.39
25.44
4.61
3.40
42.77
20.33
22.44
4.11
1.94
2.17
81.92%
79.61%
84.22%
19.06
9.67
9.39

Low + Low
3.50
2.89
4.11
25.44
4.97
3.70
54.55
24.44
30.11
3.89
1.83
2.06
90.97%
90.56%
91.37%
19.89
10.39
9.50

Low + High

Left- and right-hand positions of two-kanji compound words+(30) (34)

Table 1. Examples and characteristics of two-kanji compound words for experiments 3 and 4.

**
**
**
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.

One-way
ANOVA Sig.

KANJI MORPHEMIC HOMOPHONY289+(35) (5)+(3) (45)+(3)+(5)High + High
0.44
0.28
0.17
74857
34312
40545
226.50118.8954.89
64.00
107.6143.17
64.44
1087.11529.39173.06356.33557.72High + Low
0.57
0.15
0.42
59268
21272
37996
256.39123.2867.06
56.22
133.11
49.17
83.94
1100.72364.39121.39243.00736.33

Low + Low
0.56
0.31
0.25
62308
30520
31788
254.11
123.3963.67
59.72
130.72
47.78
82.94
912.22378.22112.78265.44534.00Low + High

Left- and right-hand positions of two-kanji compound words+(30) (34)

9 Total of both sides of kanji frequency (1976)
0.52
Kanji on the left-hand position
0.38
Kanji on the right-hand position
0.14
10 Total of both sides of kanji frequency (1998)
69208
Kanji on the left-hand position
36419
Kanji on the right-hand position
32789
11 Total of both sides of neighborhood size
201.49Kanji on the Left-hand position
105.55Left-side to create compound words
59.83
Right-side to create compound words
45.72
Kanji on the right-hand position
95.94
Left-side to create compound words
38.61
Right-side to create compound words
57.33
12 Total of both sides of accumulative neighburhood size 707.67
Kanji on the Left-hand position
373.22
Left-side to create compound words
155.83Right-side to create compound words
217.39Kanji on the right-hand position
334.45Characteristics of word stimuli

Example of a word
Kanji homophonic density of the examples

Table 1. Continued.

n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.
n.s.

One-way
ANOVA Sig.

290
KATSUO TAMAOKA

Note: **p<0.01.

Left-side to create compound words
Right-side to create compound words

Characteristics of word stimuli

Example of a word
Kanji homophonic density of the examples

Table 1. Continued.
+(35) (5)+(3) (45)+(3)+(5)139.39195.06

High + High223.72334.00High + Low
276.72459.61

Low + Low
193.11340.89Low + High

Left- and right-hand positions of two-kanji compound words+(30) (34)

n.s.
n.s.

One-way
ANOVA Sig.

KANJI MORPHEMIC HOMOPHONY

291

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KATSUO TAMAOKA

These nonwords exist neither orthographically nor phonologically in
the Japanese language, so that they elicit neutral ‘No’ responses
without speciﬁc eﬀorts on the part of the test subjects.
Procedure. Compound words and nonwords were randomly presented
to subjects in the center of a computer screen (Toshiba, J-3100
Plasma display) 600 ms after the appearance of an eye ﬁxation point
marked by ‘*’. Stimulus randomization was operated in each subject,so that each subject received a diﬀerent order of stimulus presentation. The subjects were instructed to respond both as quickly and as
accurately as possible in deciding whether the item was a word ornot. The response was made by pressing a ‘Yes’ or a ‘No’ response
key. For instance, after the eye ﬁxation of ‘*’, stimulus item ofis presented, the subject should decide whether this word is real or
not as quickly and accurately as possible. In this case, the subject
must press the ‘Yes’ response key for the correct answer. After the
response, the subject presses the space key to initiate the next presentation. After 600 ms, the eye ﬁxation point ‘*’ appears for 600 ms. A
total of 1200 ms after initiation of the next presentation, a new stimulus word appeared in the position of the eye ﬁxation point. The subject repeated this process until all the words and nonwords were
presented. Each response time (i.e., reaction time) and its response
result of correct or incorrect (i.e., error rate in the total responses)
were recorded by the computer. Sixteen practice trials were given to
the subjects prior to the commencement of the actual testing.
Results
The mean reaction times and error rates of high/low kanji morphemic
homophony in the left- and right-hand position of the two-kanji compound words are presented in Table 2. Reaction times slower than2000 ms or faster than 200 ms were recorded as incorrect items. Three
responses for real words (correct ‘Yes’ responses) fell into this category.
Only items which were responded to correctly were used for an analysisof reaction times. Before performing the analysis, reaction times outsideof 2.5 standard deviations in both the high and low ranges among correct ‘Yes’ responses were replaced by the boundaries indicated by 2.5
standard deviations from the individual means of subjects in eachcategory. The total of 52 items (3.14%) out of 1656 ‘Yes’ responses(72 items · 23 subjects) were edited in this standard procedure. The
statistical tests which follow analyze both subject (F1) and item (F2)variability.

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KANJI MORPHEMIC HOMOPHONY

Table 2. Means of reaction times and error rates for lexical decision of two-kanji
compound real words.
Density of kanji morphemic homophony

Reaction time (ms)Error rate (%)

Left-hand position

Right-hand position

M

SD

M

High density
High density
Low density
Low density

High density
Low density
High density
Low density

762
738
705
725

111
95
94
89

9.90
8.70
5.07
6.28

A 2 (left-hand and right-hand position) · 2 (high and low homophonic density) ANOVA was carried out for reaction times required to perform the lexical decision task for real words. The interaction between
position and density was signiﬁcant in subject analysis[F1(1,22) ¼ 13.05, P<0.01] but not in item analysis [F2(1,17) ¼ 1.66,
P ¼ 0.21]. Further analysis was carried out to separately examine theeﬀect of kanji homophonic density in the left-hand and right-hand position of two-morpheme compound words. Analysis revealed that thereaction times diﬀered signiﬁcantly according to the density of morphemic homophony (High ¼ 750 vs. Low ¼ 715 ms) in the left-hand kanji[F1(1,22) ¼ 18.10, P < 0.001; F2(1,17) ¼ 6.92, P < 0.05] while no difference in reaction time was found when the morphemic homophony of
the right-hand kanji (High ¼ 734 vs. Low ¼ 732 ms) was altered[F1(1,22) ¼ 0.06, P ¼ 0.80); F2(1,17) ¼ 0.24, P ¼ 0.63]. This result indicated that the density of kanji homophony in the left-hand positionaﬀected lexical decision for compound words whereas the density ofkanji homophony in the right-hand position did not.
Likewise, the error ratios diﬀered according to the density of morphemic homophony in the left-hand kanji [F1(1,22) ¼ 8.89, P < 0.01;
F2(1,17) ¼ 6.39, P < 0.05], but not in the right-hand kanji[F1(1,22) ¼ 0.00, P < 1.00; F1(1,17) ¼ 0.00, P ¼ 0.95]. The interaction
between position and density was not signiﬁcant [F1(1,22) ¼ 1.85,
P ¼ 0.19; F2(1,17) ¼ 0.17, P ¼ 0.68]. Thus, similar eﬀects were foundfor both error ratios and reaction times.

Discussion
The density of kanji morphemic homophony was observed only in subject analysis, but not in item analysis. Thus, density of morphemic
homophony had no clearly evident eﬀect on lexical decision for whole

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KATSUO TAMAOKA

words. However, the eﬀects of morphemic homophonic density wereobserved with kanji in the left-hand position, but not in the right-handposition, which was conﬁrmed by signiﬁcance in both subject and item
analysis. One can explain this tendency by suggesting that the kanji situated in the left-hand position of a two-morpheme compound word
not only automatically activates its correct (in this compound) pronunciation but also exhaustively activates various other orthographic representations of its kanji morphemic homophony, regardless of whether
this has any practical or strategic value. A high density of kanji
homophony in the right-hand kanji could very well aﬀect lexical decision, but assuming that compound words are processed from left-toright as visually presented, this eﬀect was not apparent as lexicaldecision was made before the eﬀect of right-hand kanji homophonyarose. Experiment 2 was conducted to examine the same eﬀects of morphemic homophony on the separate task of naming these words.

Experiment 2: Eﬀects of morphemic homophony on naming
Experiment 1 demonstrated the eﬀects of morphemic homophony on lexical decision regarding two-kanji compound words even though the task
did not necessarily require phonological activation at the morpheme level.
In contrast, for the naming of two-kanji compound words, the response
is based on phonology. Therefore, phonological representations of kanji,
or at least words, must be activated in order to pronounce them. Thus,
the present study expected to ﬁnd an inhibitory eﬀect of kanji homophonic density on naming two-kanji compound words. However, since subjects were required only to name a word in the naming task, it was also
hypothesized that there would be no need of kanji orthographic activation from a target kanji sound to perform the naming task. Experiment 2,
therefore, investigated the eﬀects related to the density of morphemic
homophony using the naming task of two-kanji compound words. Nonwords used in Experiment 1 were not included in Experiment 2.
MethodSubjects. Twenty-four graduate and undergraduate students who were
native speakers of the Japanese language (12 female and 12 male) participated in the experiment. Their ages ranged from 19 to 31; on the
day of testing, the average age was 22 years and 6 months for females
and 23 years and 6 months for males. Those who were tested in Experiments 1 were not included in Experiment 2.

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Materials. The 72 compound real words used in Experiment 1 were also
used in Experiment 2 for the naming task. Since the nonwords with two
kanji combinations in Experiment 2 were not pronounceable due to themultiple kanji readings, nonwords were not included in Experiment 2.
Procedure. Compound word items were randomly presented (each subject receive a diﬀerent randomization) to subjects in the center of thecomputer screen 600 ms after the appearance of an eye ﬁxation point
marked by ‘*’. The subjects were required to pronounce the compound
word shown on the screen as quickly but as accurately as they could. A
voice-key turned oﬀ the timer to measure the naming latency. The correctness of pronunciation was entered into the computer by the examiner. The next ﬁxation point was presented 600 ms after the examinerpressed a key. Twelve practice trials were given to the subjects prior tocommencement of the actual testing.
Results
The mean latency times and error rates of high/low density of kanji
homophony in the left-hand and right-hand kanji of the compoundwords are presented in Table 3. Naming latencies longer than 2000 ms
or shorter than 200 ms were recorded as incorrect items. No responses
fell into this category. Only correctly pronounced items were used foran analysis of naming latencies. Before performing the analysis, naming
latencies outside of 2.5 standard deviations in both the high and low
ranges were replaced by the boundaries indicated by 2.5 standard deviations from the individual means of subjects in each category. The totalof 48 items (2.70%) out of 1776 ‘Yes’ responses (72 items · 24 subjects)
were edited in this standard procedure. The statistical tests follow theconvention of analyzing both subject (F1) and item (F2) variability.
Table 3. Means of naming latencies and error rates for lexical decision of two-kanji
compound real words.
Density of kanji morphemic homophony

Naming latency (ms)Error rate (%)

Left-hand position Right-hand position

M

SD

M

High density
High density
Low density
Low density

608
599
576
596

95
89
96
115

1.16
1.85
0.69
1.16

High density
Low density
High density
Low density

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As with Experiment 1, a 2 (left-hand and right-hand position) · 2(high and low kanji homophonic density) ANOVA was carried out fornaming latencies required to perform the naming task. The interaction
between the density of morphemic homophony and the position was
signiﬁcant in subject analysis [F1(1,23) ¼ 7.59, P < 0.01] but not initem analysis [F2(1,17) ¼ 1.66, P ¼ 0.21]. Further analysis was carriedout to separately examine the eﬀect of kanji homophony in the lefthand and right-hand positions. The naming latency diﬀered signiﬁcantly
according to the density of morphemic homophony in the left-handkanji (High ¼ 604 vs. Low ¼ 588 ms) [F1(1,23) ¼ 8.16, P < 0.01;
F2(1,17) ¼ 4.77, P < 0.05] while no diﬀerence was observed when thedensity of morphemic homophony was altered in the right-hand kanji(High ¼ 592
vs.
Low ¼ 598 ms)[F1(1,23 ¼ 1.53,
P ¼ 0.22);
F2(1,17) ¼ 0.10, P ¼ 0.75]. Thus, as the results of the lexical decisiontask in Experiment 1 illustrated, naming was also aﬀected by the density of kanji morphemic homophony in the left-hand kanji of the twokanji compound words.
In the analysis of the error ratios, neither the subject analysis nor
the item analysis was signiﬁcant. Error ratios did not diﬀer with thedensity of homophony in the left-hand kanji [F1(1,23) ¼ 2.00,
P ¼ 0.17; F2(1,17) ¼ 1.20, P ¼ 0.28] nor in the right-hand kanji[F1(1,23) ¼ 1.00, P ¼ 32; F2(1,17) ¼ 0.60, P ¼ 0.45]. The interaction
was not signiﬁcant [F1(1,23) ¼ 0.06, P ¼ 81; F2(1,17) ¼ 2.25,
P ¼ 0.15]. Consequently, there was no eﬀect of morphemic homophony on naming errors.
Discussion
As was the case in the lexical decision task of Experiment 1, the performance of the naming task was aﬀected by the density of morphemic
homophony only in the left-hand position. This conﬁrms the explanation given for the results of Experiment 1 being that kanji situated in
the left-hand position of two-kanji compound words activate kanji phonology, which further activate additional orthographic representationsof their homophones at the morpheme level.

General discussion
Previous studies on kanji sounds were mostly focused on the mappingof a single kanji to multiple sounds (see Figure 1) in either a single kanji (Kayamoto et al., 1998) or a two-kanji compound word (Wydell

KANJI MORPHEMIC HOMOPHONY

297

et al., 1995). However, much heavier density of kanji homophones isobserved in the opposite direction of the mapping of a single sound tomultiple kanji morphemes (see Figure 2). Thus, the present study investigated exhaustive activations from phonology to orthography createdat the kanji morphemic level during the processing of two-kanji compound words.
A high degree of morphemic homophony was deﬁned as kanji
having more than twenty commonly-used kanji homophones. A visually-presented word generates an activation of an orthographic representation which further activates its phonological representation. In
turn, the phonological representation reverberates back to generate aseries of orthographic representations of kanji morphemic homophones.
The present study made an assumption that these simultaneously activated orthographic representations at the morphemic level must be suppressed, therefore inhibiting the speed of task performance.
Experiments 1 and 2 investigated homophonic eﬀects at the morphemic level by controlling lexical homophony. Although the results were
not clear across the four conditions of homophonic density for twokanji compound words (i.e., two kanji combination of high/high, high/low, low/high and low/low homophonic density), the generally observable eﬀects of morphemic homophony are that kanji morphemic
homophony in the left-hand position seemed to aﬀect reaction times for
lexical decision and latencies for naming of two-kanji compound words.
This eﬀect was not seen at all in the right-hand position.
Although various homophonic kanji which share the same soundwith the right-hand kanji could be automatically activated during theprocessing of the compound word, the eﬀects of kanji homophony wereobserved only in the left-hand position. The following explanation is
given for the results of the present experiments. If the processing of a
two-morpheme compound word proceeds from left to right, activationof the morphemic unit presented on the left will commence before activation of the right-hand unit. A whole-word orthographic representation for lexical decision will then be activated to complete the task at
hand before the activations of kanji homophony from a kanji sound in
the right-hand kanji can start to aﬀect the processing of the compound
word. Therefore, based upon the results of Experiments 1, the present
study suggests that kanji orthographic activations from single kanji
phonology occur at the morphemic level. This exhaustive activation ofmultiple kanji orthography from a single kanji sound results in slower
processing for words with a high density of morphemic homophony,which is observed as an inhibitory eﬀect in the performance of the lexical decision task.

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In Experiment 2, the morphemic homophonic eﬀect on naming wasinvestigated, using stimuli of two-kanji compound words. It is assumed
that once the phonological representation of a target word like /saikoR/ is activated, it should be suﬃcient to perform the naming task
since the task only requires vocalization of the target word. Thus, it isexpected that no diﬀerence in naming latencies would be observed
between the high and low degree of morphemic homophony. Notwithstanding this expectation, an inhibitory eﬀect of morphemic homophony
was observed in the naming performance in Experiment 2. Therefore,
homophonic eﬀects on naming at the morphemic level indicated a very
similar trend to that of the lexical decision task, suggesting that thenaming of a two-kanji compound word slowed when a kanji with a highdegree of kanji homophony (i.e., having more than 20 kanji homophones) appears in the left-hand position. A single kanji presented aspart of a two-kanji compound word cannot provide enough information
for subjects to select the proper pronunciation from among its multiple
kanji pronunciations. Subjects would ﬁrst reference the second kanji as
a combination partner. The kanji phonology in the left-hand position(i.e., /sai/) will be automatically activated soon after an activation of thelexical phonology of the two-kanji compound word. However, in thenaming task, before kanji homophony in the right-hand position creates
activations of kanji orthographic representations from a kanji sound,the lexical level of phonology (i.e., /sai koR/) will come to function.
Thus, kanji homophony in the right-hand position will not cause signiﬁcant interference on the naming of two-kanji compound words.
Related to kanji homophony in the present study, Hatta et al. (1998,
2002) provided some interesting data regarding kanji writing errors. Of
the types of errors that native Japanese speakers make, phonologicallyrelated kanji writing errors were the most numerous (60.0%), followedby orthographically related errors (43.6%) and semantically related
errors (29.7%). The above percentages total more than 100% because a
degree of overlapping of these three types was also observed. Many ofthe phonological errors were found among kanji homophony: insteadof writing the correct kanji, subjects typically replaced it with one
which was incorrect but which commonly shared the same On-reading.
Thus, it is necessary to properly inhibit orthographic representations of
unrelated homophonic kanji, especially when the kanji to be written is
one with a high density of homophony. The research ﬁndings of Hatta
et al. (1998, 2002) in the kanji writing task also supports the assertion
that various orthographic representations of homophonic kanji are activated via the shared single kanji sound even though processing twokanji compound words.

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299

Notes
1. The pronunciation of Japanese words in this paper is transcribed using Japanesephonemic symbols which indicate three special sounds in Japanese: /N/ for nasal, /Q/ for geminate and /R/ for long vowel.
2. In this paper, an alphabetic description of Japanese names follows the commonlyused Hepburn style. Thus, the spelling of ‘Saito’ is used, even though this name is
pronounced /saitoR/ with a long vowel. However, as the Hepburn style does notdistinguish between long and short vowels, Japanese titles of research papers which
include long vowels are shown by repeating the same vowels twice, such as ‘oo’.

Appendix
Stimuli Used in Experiments 1 and 2

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KATSUO TAMAOKA

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Address for correspondence: Katsuo Tamaoka, PhD, International Student Center,
Hiroshima University, 1-1, 1-chome, Kagamiyama, Higashi-Hiroshima, 739-8524
JapanE-mail: ktamaoka@hiroshima-u.ac.jp