- Email: [email protected]
An Analysis of Writing Errors in Japanese Aphasic Patients: Kanji Versus Kana Words
AN ANALYSIS OF WRITING ERRORS IN JAPANESE APHASIC PATIENTS: KANJI VERSUS KANA WORDS Sumiko Sasanuma and Osamu Fujimura (Tokio Metropolitan Institute of Gerontology, and Research Institute of Logopedics and Phoniatrics, University of Tokyo)
INTRODUCTION
The results of our previous study on the visual recognition and transcription of kana (phonetic) and kanji (non-phonetic) words (Sasanuma and Fujimura, 1971) indicated that the processing of the two forms of word transcription could be impaired relatively independently of each other in different types of aphasia. It was found, for instance, that the processing of kana-transcribed words seemed to be selectively impaired in aphasics who had a concomitant problem of apraxia of speech as delineated by Darley (1968) and Johns and Darley (1970). These aphasics had significantly poorer performance in kana than in kanji, especially in writing tasks, while those aphasics who did not have apraxia of speech showed as a group an opposite trend, i.e., better performance with kana than with kanji. On the basis of these findings, it was suggested that the two types of transcriptions might be processed in distinct functional modes: the kana transcriptions may be assumed to be processed through a "phonological processor" (phonological mode of operation), while the kanji transcriptions can by-pass the phonological processor (especially when the latter is impaired) and would thus have direct access to (and from) the lexical items (non-phonological mode). The present study was conducted in an attempt to investigate this issue further by means of a more detailed analysis of the writing errors of the words transcribed into kana and kanji by a group of aphasic patients. On the basis of the earlier results, we should
266
Sumiko Sasanuma and Osamu Fujimura
expect to find that the kinds of errors made in kana and kanji will differ. Errors in kana should reflect the underlying phonological impairment; errors in kanji should be explained on some other basis. The specific questions to be asked included the following: 1. What kinds of errors do aphasic subjects make in the kana and kanij transcriptions of words?
2. Are there any individual differences among aphasic subjects in the kinds, as well as in relative frequencies, of the errors they make in each type of transcription? 3. How does the performance of non-aphasic hemiplegics in the same set of tasks compare with that of aphasic patients?
MATERIAL AND METHOD
Subjects
Fifty aphasic patients consecutively admitted to a large rehabilitation hospital and 30 non-aphasic hemiplegic (15 right hemiplegic and 15 left hemiplegic) patients in the same hospital served as the subjects of this experiment. All the subjects had incurred cerebro-vascular accidents as etiology and had confirmed brain lesions limited to one hemisphere. All aphasic subjects were right-handed and right hemiplegic. Any subject with signs of visual agnosia, visuo-spatial disorientation, or upper limb apraxia, was excluded from the experiment. Of the 50 aphasic patients, six showed either zero or 100% errors on both kanji and kana transcription tasks (see below for the testing and scoring procedures). The data for these six were excluded from the analysis to be described, and thus our results pertaining to the performance of the aphasics are based on the data obtained from the remaining 44 aphasic subjects. Twenty-four of these aphasic subjects had a concomitant problem of apraxia of speech while others did not. The age, educational level, and length of illness for these 44 aphasic patients are given in Table I together with the corresponding data for the non-aphasic subjects. Procedure
Each subject performed a task of wntmg 20 high-frequency nouns designating familiar objects, the same set of words that were used in our previous study (Sasanuma and Fujimura, 1971). Ten of these nouns are of foreign origin (imported words) which, as a rule, are represented in katakana in Japanese orthography; and another ten are non-imported words for which kanii transcriptions are most commonly used, but hiragana
Writing errors in Japanese aphasic patients
267
TABLE I
Age, Educational Level and Length of Illness (Months) for the Aphasic and Non-aphasic Group
Age (years)
Educational level (years)
Length of illness (months)
Aphasic N=44
range median mean
29-71 50 51
8 -18 11 11
2-24 10 11
Non-aphasic N= 30
range median mean
32- 68 52 52
8 -16 10 11
3 -16 11 12
tranSCtlptlOns can also be used. All of the words transcribed in kanji consist of two kanji characters, while the words transcribed in kana comprise two to four kana characters (see Figure 1 in Sasanuma and Fujimura, 1971, for the three types of transcriptions). Combined visual-auditory stimuli were employed for eliciting responses from the subject. Twenty picture cards, 10 for imported words (set 1) and the other 10 for non-imported words (set 2), were presented to each subject together with the name of the object in each picture spoken by the examiner. For each of the 10 pictures for non-imported words (set 2), which have both kanji and hiragana transcriptions, the subject was asked to write both, the order being left to his choice. The order of presenting the two sets of cards, as well as the arrangement of the 10 cards within each set, was randomized for each subject. For 71 of the 80 subjects, the whole test was administered in one session, but for nine of the aphasic subjects it was necessary to administer the test in two separate sessions to avoid fatigue, one set of cards being used in each session, with an interval of no more than a week between the sessions.
Scoring Any response which fell short of the standard orthography of a given word was scored as an error. If the subject did not make any response for five seconds after the first presentation of the stimulus (a picture and the corresponding word spoken by the examiner), he was given the spoken word again (the second presentation) with the picture still remaining in front of him; and if he was still unable to make any response 25 seconds after the second presentation of the stimulus, then this item was categorized as "no response." The test data from the 15 non-aphasic right hemiplegics have been combined with those from the 15 non-aphasic left hemiplegics, since the performance levels of the two groups were essentially the same.
Sumiko Sasanuma and Osamu Fujimura
268
RESULTS
The overall performance of the aphasic and non-aphasic groups is summarized in Table II. It can be seen that both the aphasic and non-aphasic groups made errors in the kanji transcriptions of the non-imported words. In the kana transcriptions of both the imported TABLE II
Range, Median and Mean Percentage of Errors of Kanji and Kana Words for the Aphasic and Non-aphasic Groups
Kanji
Hiragana
Katakana
Aphasic N=44
range median mean
0-70 40 38
0-100 60 57
0-100 60 53
Non-aphasic N= 30
range median mean
0- 80 15 22
0 0 0
0 0 0
(katakana) and the non-imported (hiragana) words, however, only the aphasic group made errors; moreover they made even more errors in kana than in kanji. 1 Analysis of kanji errors
Table II shows that aphasic subjects made a larger mean percentage of kanji errors (38%) than non-aphasic subjects (22%). This difference was statistically significant at the .05 level of confidence. As can be seen in Table III, however, the types of errors as well as their relative frequencies as exhibited by the two groups are essentially similar. These types of errors included, in decreasing order of frequency occurrence: ( 1 ) the substitution of a whole 1 This finding seems to be particularly noteworthy in light of the fact that, in general, kana transcriptions are less complex as graphic forms and are smaller in number in comparison to kanji; also, they are mastered by an average child much earlier than kanji, usually by the end of the first year in school. In fact, kana-sound associations are so well established in adults that, in normal situations, it is rare that a person cannot transcribe a spoken word in kana, while it is a common observation that an average person often forgets how to write the kanjis for some infrequently used words and represents them in such cases with the kana equivalents.
Writing errors in Japanese aphasic patients
269
TABLE III
Types of Kanji Errors and Percentage of Words Falling into Each Type for Aphasic and Non-aphasic Groups Graphical confusions
No response, "don't know"
Incomplete responses
Semantic confusions
Aphasic N=44
49
30
15
6
Non-aphasic N= 30
39
35
19
7
character or a constituent unit of it by a wrong character or unit, or the addition or omission of a stroke in a character (graphical confusion), (2) no response (or "don't know" response), (3) an incomplete response (correct writing of only part of a character, or one of the two characters representing a word), and (4) the substitution of a whole word by another word of a related meaning (semantic confusion). Of these types, "graphical confusion" comprised the largest group for both the aphasic and non-aphasic subjects (almost 50% of the total errors for the aphasic and about 40 % for the non-aphasic subjects). This type of error may be further divided into five subtypes. The relative frequency of occurrence of each type is shown in Table IV, together with typical examples of each. The most common sub-type for both the aphasic and non-aphasic groups (accounting TABLE IV
Sub-types of the Graphical Confusions and Percentage of Characters Falling into Each Sub-type for Aphasic and Non-aphasic Groups Compounding wrong units
Addition or omission of a stroke
A wholecharacter substitution
Metathesis
Complex metathesis
Aphasic N=44
60
29
10
1
(4)
Non-aphasic N= 30
68
24
8
0
(5)
Examples of ~*~ confusions ~ ~
,~
;fa. ~.la ,l
~ ;7s..~*
tfi
--+~ ""I)
~~
~ij~ ~~t~
fll ~ itfl it ---"":fi
270
Sumiko Sasanuma and Osamu Fuiimura
for 60% of all instances of graphical confusions for the aphasics and almost 70% for the non-aphasics) was the error of compounding two or more units of a character, with at least one unit remaining correct. (A small portion of the errors in this category, however, may be termed as "complex metatheses" because the errors in these cases involve a misarrangement of the units wIthin a character, in addition to the wrong choice of a component unit. See the last column of Table IV.) The second in frequency of occurrence for both aphasic and non-aphasic subjects was the error of adding an extraneous stroke or omitting an obligatory stroke to or from a character. In the third sub-type, a character was changed completely into another character with a different but more or less related meaning. The fourth subtype, metathesis of the two constituent characters of a word, appeared in one aphasic subject only. It may be of interest here to point out that all the errors in the transcription of kanji described above represent "permissible" forms according to the structural rules of kanji patterns (Fujimura and Kagaya, 1969), although some of them do not exist in the lexicon. Another fact to be noticed here is that the individuals with a greater total number of errors as well as those with a smaller total number of errors exhibited essentially the same distributional patterns of various types of errors. In other words, the types of errors do not differentiate high-error-rate subjects from low-errorrate subjects (just as they do not differentiate the aphasics from the non-aphasics). There were some differences in the level of difficulty among the 10 kanji words. In general, the sum total of the degree of complexity (in graphic form) of each of the two characters constituting a word seemed to be related to the level of difficulty of that word. Thus, the larger the total number of strokes contained in the two characters of a word, the greater was the percentage of subjects who tended to make errors. Analysis of kana errors
Since the non-aphasic subjects made no errors in the kana transcriptions, the analysis in this section will deal only with the performance of the aphasic group. A comparison of the data obtained for performance in the two
Writing errors in Japanese aphasic patients
271
kinds of kana transcriptions, i. e., writing in katakana (imported words) and in hiragana (non-imported words), revealed that there were no significant differences between the two in terms of either the types of errors or distributional patterns of these types. The following analyses, therefore, will be based on the combined data obtained on performance in these two kinds of kana transcriptions. The aphasic subjects exhibited as a group not only a larger mean percentage of errors in kana (55.1 %) than in kanji (37.6%), but also a quite different pattern of errors in kana compared with that in kanji (see Figure 1). Of particular interest is the fact that
o kana· transcribed words
60
•
kanji.transcribed words
50 40
30 20 10 0 ....._ .........._ ... .... :J:=~ '" til () s:::
.... 0 bO· ...
o til .... :::s
0 .... S:::S:: 00
..s:::() 0.
~QI QI
til
s::: 0
.... s:::
~.=.t $.0 s:::
o()
8.,fJ 0 0
s:::?
0.0 a 0.
...s:::
til
QI
$.0
.... til
'" () 0s::
......
..s:::
0.-4
til
() til
~6 s::: ....
$.0 s::
aZ
()
()
"'o.:::s .... bOO
'" til QI
til
s::
0
Types of Errors Fig. 1 - The types of errors on kana-transcribed and kan;i-transcribed words for 44 aphasic subjects.
272
Sumiko Sasanuma and Osamu Fu;imura
the frequency of occurrence of "graphical confusion," which was the predominant type of errors in the case of words transcribed in kanji, is almost negligible in words transcribed in kana. Of the total of 487 errors in kana-transcribed words, only two (.4%) can be categorized as "graphical confusions." Each of these two words contained a character form which does not exist in the kana syllabary; more specifically, the character (which is supposed to represent a syllable) was formed by erroneously adding a feature marker (a diacritical marker indicating a voiceless stop) which results in no possible phonetic form (syllable). The highest in frequency (59%) of all errors of words transcribed in kana are those which can best be explained in terms of some underlying "phonological confusions" involving syllables, phonemes or distinctive features. 2 The second in frequency are those errors categorized as "no response" or "don't know" (30%), the third being "incomplete responses" (correct transcription of only part of a word) which accounted for all the remaining errors (11 %). There were no errors involving "semantic confusion" in the kana transcriptions, while a certain amount of such confusion (6%) did appear in the kanji transcriptions. Feature analysis of the phonological confusions
There was a total of 712 instances of phonological errors in 314 words. Inspection of the data revealed that the errors varied considerably in degree of complexity from individual to individual, and to a smaller extent from word to word. In general, the representative errors exhibited by low-error-rate subjects (individuals with a smaller total number of errors in kana) tended to be simple or "transparent" in the sense that the errors usually were substitutions of consonants (or vowels) which differed from the target sound in only one or two phonetic features. The errors exhibited by high-error-rate subjects, on the other hand, 2 Since there are some kana characters (both katakana and hiragana versions) which share some degree of graphical similarities to each other and thus seem to offer more opportunities for substitutions among these characters (than would be expected with other characters), the data were scrutinized for possible incidences of graphical confusion of these graphically similar forms. The result indicated, however, that there were only a few instances where the expected substitutions did actually take place, and even there the interpretation of the errors in terms of phonological confusions made more sense than (or as much sense as) that in terms of graphical confusions.
Writing errors in Japanese aphasic patients
273
tended to be "complex," involving multi-feature confusions, such as "unrelated" substitutions, omissions or insertions of consonants and/ or vowels, or even extraneous insertions of a whole syllable or two. The complexity (as well as the types and relative frequencies) of these errors seems to depend also on the length and phonological structure of the individual word. Thus, for instance, (1) the subject tended to make less errors in shorter words than in longer words, (2) if he did make errors in shorter words, these errors tended to be less complex as compared to the errors in longer words, and (3) the types of specific errors tended to be related to the phonological context of the problematic sound (e.g., if a word of CV-CV structure contained a voiced consonant in the first syllable and a voiceless consonant in the second, then a frequent error was the substitution of the voiced consonant by its voiceless cognate, i.e., an assimilative dropping of the marked feature value of voicedness). These observations seem to suggest that the phonetic feature may well constitute the basic unit of the phonological errors, and that a further analysis of the data in terms of phonetic features may help clarify the essential nature of the errors. Only" simple" errors involving single- or double-feature confusions were selected for this analysis so that there should not be any ambiguity in the interpretation. Table V summarizes the results of tabulating all single-feature errors exhibited by the 44 aphasic subjects. These errors constitute about one fifth (156/712) of the total instances of phonological confusions, and are distributed through all levels of subjects although the ratio of complex errors to simple errors tends to be much higher in high-error-rate subjects than in low-error-rate subjects. A set of four consonantal features (voicedness, nasality, place of articulation and the stop/fricative distinction) and three elongation features (H, Q and N)3 were considered to be adequate for use in this analysis in that they allowed an exhaustive description of the majority of the simple errors. The denominators in each column represent the number of possibilities for the particular kind of error listed in that column for each of the 20 words, while the numerators are the accumulated number of actual error occurrences for all the subjects. 3 The symbols H, Nand Q following a vowel represent, respectively, the phonemically distinct elongation of the vowel, elongation with a heavy nasalization of the vowel toward the end of the syllable, and gemination of the succeeding (voiceless) consonant.
Sumiko Sasanuma and Osamu Fuiimura
274
TABLE
Single-feature Pl~<::e
Voicedness +~-
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
kodomo keito kimono yubiwa boHsi tokeH huHtoH taiyoH daikoN tebukuro basu koQpu kamera boHru beQto terebi seHtaH kaHteN toraQku nekutai
T %
4/1 1 4/1
9/1 4/1 2/1 7/1 2/1 3/1
35/9 8.8
-~+
1 1/2 1 1 2 1/1 1/1 1/1 1/2 3/1 4/2 1 1 1/1 2 2 2/2 2 15/26 1.3 3.3
Nasal
from: labial +to: d
p
p
+~-
-~
2/1
1
1/1
1
1/1 1
2/1 1 1
1 1 1
1 1 1 1/1 2/1 1/1 4/1
1 1 1 3/1 1 1 1
2
1 1 1 2/1
1 1/1 1/1
1 4/5 1.8
3/9 0.8 1.1
11/11 2.3
palatal
dental
3/11 0.6
d
1 1 2/1
1 3/1 1
1 1 1
1/1 1 1/1
1 1 1 1 1 1
2/1 1 1 1 1 1
1
1/1
1 1
2/1 1
1
1
1 1 1
2/1 3/1 2/1
1 1 1 1/1 1 2
1 1/1 1 2/1 1 2
3/16 8/16 1.1 .4 2.3
0/10 0
It will be seen that there were some differences among the relative frequencies of involvement of various features (represented by the percentage values in the bottom row). The voicedness feature showed the highest frequency of involvement, followed by the features pertaining to the place of articulation, nasality and the stop/ fricative distinction. The frequencies of errors involving elongation features were in a position intermediate between those of place of articulation and nasality. Further examination of the table shows, in addition, that each feature behaves in its own characteristic manner. Thus, for instance, voicedness as well as nasality exhibit a clear-cut directional asymmetry toward dropping rather than attaching the pertinent feature. For place of articulation and the stop/fricative distinction, on the other
12/10 5.5
275
Writing errors in Japanese aphasic patients
v Errors
Stop/Fricative
H
Q
N
s-7f f-7s
H-70 0->H H-7Q
Q-70 0--').QQ-7H
N-70 N-H
1 2 1 0 0 1/2 1/1 1 1 2 0 2/2
1 1/1
2/1 1 8/2 2/1
1
1
1/1
0 1 1/1 1/1 1/2 2 2
1/1
7/23
2/4
.7
1.1
0.8
5/2 4/1 22/9 5.6
3 2/3 3 3 1 1/1 3 1/2 3 4 2 1 3 2/1 1/1 2/3 1/2 4 10/43 0.5 1.5
1 1/1 1/1
1
1 1 1 1/0 1 1 1
4/4 2.3
2/1 2/1
1 2/1 1
1
1
7/1
1 1 1/0 2
1
7/3 5.3
2/11 0.4
4/3 3.0
1.7
T
8 6 5 1 7 6 11 6
10
7 5 8 6 12 7 13
1/1
2/1
1/2
2/2 2.3
1.1
9
13
14 2 156
1.7
hand, no such clear directional asymmetry can be concluded, when we consider the possible effects of contextual assimilation and the phonological imbalance of the test words employed. The manner with which the elongation features behave is much like that of voicedness and nasality, and show a significant directional asymmetry toward dropping the respective features rather than attaching them. Also, it happens frequently that where an extraneous attaching of H and Q ever takes place, the same element is found in the context (within the same word). In addition to the single-feature errors, double-feature errors were also analyzed for relative frequency of occurrence. The errors involving a simultaneous dropping of the voicedness and nasality features of consonants showed the highest relative frequency of
276
Sumiko Sasanuma and Osamu Fujimura
occurrence (2.7%), followed by those involving a voicedness dropping combined with a change in place of articulation (1.3%). The relative frequencies of errors involving a simultaneous attachment of voicedness and nasality, or the addition of voicedness combined with a change in place of articulation, in contrast, were much smaller (0.6% and 0.1 %, respectively). The frequency of occurrence of other doublefeature errors were either negligible or null. There was a tendency for most of the single- or double-feature errors described above to take place singly in a word, with only a few exceptional cases where two of them occurred in one word (of three or four syllables). All the rest of the phonological errors were more complex than double feature substitutions from the point of view of a distinctive feature representation of the sound shape: In addition to the errors described above, a special type of phonological confusions were observed. They involve the metathesis of adjacent or non-adjacent syllables, or their constituent phonemes of features (see Table VI for some examples). The relative frequency TABLE VI
Examples of Metathesis Adjacent type:
ka me ra te re bi ko do mo
~ ~ ~
ka ra me (syllable) te be ri (phoneme) ko no bo (nasality feature)
Non-adjacent type:
te bu ku ro ne ku ta i da i ko N
~ ~ ~
ku bu te ro (syllable) te ku na i (phoneme) ta i go N (voicedness feature)
• Assuming that the distinctive feature constitutes the unit of phonological errors, an analysis was made tentatively concerning the relationship between the error rate of a given individual and the average degree of phonological deviations in his errors (expressed in terms of the number of features involved in each error). The result showed a high linear correlation (r = .92), indicating that the subjects who made a greater total number of errors in the kana transcriptions did tend to make more complex phonological errors. On the same assumption as the above, the distributional pattern of various types of phonological errors for high-error-rate subjects was compared with that for lowerror-rate subjects. The result revealed that there was an overall similarity between the two, but with some exceptions: the elongation features Hand Q were distributed evenly through all levels of performance. This finding may be interpreted as suggesting that these phonological features are functionally different from other (segmentally inherent) features.
Writing errors in Japanese aphasic patients
277
of occurrence of this type of metathesis in a "pure" form is comparatively small (about 8 % of the total instances of phonological confusion), but there are a great many other instances where metathesis seems to be combined with other types of phonological errors.5 Consonants versus vowel errors
The types of phonological confusion described so far have been concerned with consonants. The question arises as to how the relative frequency of vowel errors compares with that of consonant errors. The answer was obtained by means of tabulating all the incidences of vowel substitution as well as of consonant substitution, and dividing each sum respectively by the number of possible substitutions in the given phonological environment. The result obtained indicates that the relative frequency of vowel substitutions (6.7%) is significantly smaller (p < .05) than that of consonant substitutions (10.6%), and the proportion of vowelto consonant-errors appears to remain constant for all subjects regardless of differences in performance levels. It was observed also that about two thirds of the vowel substitutions occurred in combination with a substitution error in the preceding consonant in a CV syllable, and that contextual assimilation of neighboring vowels played an important role in precipitating the vowel substitutions just as it did in the case with consonant substitutions. Comparison of the kanji and kana performances of each individual
We should ask how the level of performance in kanji transcriptions is related to that of kana transcriptions for each individual subject. Figure 2 provides the answer to this question, illustrating the relationship between the number of errors in kana-transcribed words and in kanji-transcribed words for each of the 44 aphasic subjects, represented by either a dot (subject with apraxia of speech) or a cross (subject without apraxia of speech). It is apparent from this figure that there is no substantial correlation between the sub5 There is no clear-cut difference between high-error-rate subjects and low-errorrate subjects in the relative frequency of occurrence of metathesis in a "pure" form. Those instances of metathesis which seemed to be combined with other types of errors, on the other hand, tended to appear more often in high-error-rate subjects
Sumiko Sasanuma and Osamu Fujimura
278
% 100 fJl
•
• • I • • • I• • •• •
90
'0 $.0
o
s:
80
• X
..... o fJl
t
20
..... o
10
r:tl
x
•
30
$.0
o
XX
•
•
~
XX X
IX
• •
•
XX
XX
X
•
X
)(
X
o
X
o
10
20
30
40
50
60
70
80
90
%
0/0 of Errors of Kanji- transcribed Words Fig. 2 - Relationship between the percentage of errors of kana-transcribed words (ordinate) and of kanji-transcribed words (abscissa) for 44 aphasic subjects. Dots represent individual subjects with apraxia of speech and crosses without it.
ject's performance in kanji and in kana: some of the subjects who made a relatively large number of errors in kana made a relatively small number of errors in kanji and vice versa. It might be noted, however, that the total set of subjects can be divided into two subsets in terms of the frequency of occurrence of errors in kana transcription, but the same is not true of errors in kanji transcription. It is further observed that, of the 23 high kana-error-rate subjects (clustering in the upper half of the figure), all but 3 (80%) had apraxia of speech accompanying aphasia (dots), while 18 of the 21 low kana-error-rate subjects (clustering in the lower half of the figure) (86%) did not have such a problem (crosses). This is in agreement with our previous findings (Sasanuma and Fujimura, 1971) and indi-
Writing errors in Japanese aphasic patients
279
cates a close relationship between the severity of kana impairment and the presence of apraxia of speech.
DISCUSSION
The results of this study show a clear-cut difference between performance in kana and kanji exhibited by the aphasic subjects in the writing tasks. In the kanji task, the majority of the errors were those which can best be categorized as "graphical confusions," and do not differ in kind from the errors made by the non-aphasic subjects. In the kana task, in contrast, the predominant errors were those which can best be interpreted as "phonological confusions," and these were exhibited only by the aphasic subjects; none of the non-aphasic subjects made any such errors whatsoever. It was also shown that there is no correlation between performance (of the aphasic subject) in kanji and in kana, whereas an apparent correlation exists between the total number of his errors in kana-transcribed words and the average degree of his phonological deviation from the target forms of these words. Taken together, these findings provide strong support for the hypothesis set forward in our previous study (Sasanuma and Fujimura, 1971): that the kana and kanji transcriptions can be processed in different modes, the former requiring some phonological device and the latter by-passing it. A preliminary analysis of "phonological confusions" in terms of the distinctive features has uncovered some interesting facts about the nature of these errors, i.e., the presence of some regularities in the manner with which various features are involved in the errors. In order to arrive at a more definite conclusion regarding this point, however, a further experiment using a better balanced word list will be necessary. Clinical types of aphasia and the kana impairment
One of the findings of our previous study was that those aphasics with a concomitant problem of apraxia of speech exhibited, as a group, a selective impairment of kana processing. The results of the present experiment with a different group of patients strongly support this previous conclusion.
280
Sumiko Sasanuma and Osamu Fu;imura
On the assumption that the selectively impaired phonological processor may constitute the common source of malfunctions both in articulation and in writing kana (although admittedly the two tasks may involve other processes that are inherent to each), one may naturally ask how each subject's error pattern when transcribing words in kana compares with that on his oral production of the same set of words. The answer is being sought in a pilot study in which the apraxic subjects are asked to repeat each word after the examiner. The results obtained so far seem to indicate that for the majority of the subjects, there is only a gross correspondence between the individual's performance levels, as well as between the error patterns, in the two tasks. It has been noted, however, that the patterns of phonetic confusions observed in the oral experiment in some subjects are strikingly similar to those observed in the writing task performed by other subjects, and vice versa. In fact, there are quite a few words in which the error patterns in the one task performed by a subjet are identical to those in the other task performed by another subject. These observations may indicate that there is possibility of a recovery process operating here, i.e., the graphic and oral productions of a given subject do not improve in a parallel fashion, but the error pattern in one modality at a particular stage of recovery may correspond to the error pattern in the other modality at a different stage of recovery. Further exploration, especially of a longitudinal nature, seems to be necessary in order to be able to conclude on this point. The nature of graphical confusions
The fact that "graphical confusions" constitute a small fraction of the kana errors and a large part of the kanji errors would seem to justify special notice. A possible explanation may be found in the different characteristics of the graphical forms of kana and kanji characters. As mentioned before, kana characters are less complex than kanji characters, in general, and each of them may be considered as consisting of a single unit, in the sense that none of them can be divided into further units and still be identifiable as a kana form. As for kanji, on the other hand, most characters consist of multiple units so that each character can be divided into two or more constituent units, each of which can exist by itself as an independent character or can combine with other units to make other characters.
\'('riting errors in Japanese aphasic patients
281
In other words, one may infer that each kana character is equivalent to a constituent unit of kanji, and constitutes a basic perceptual and/ or production unit by itself. Therefore, errors made by wrongly combining units of the graphical pattern (the predominant type of errors in the case of kanij writing) are hardly to be expected in the case of the kana. There are some exceptions, however, to this single-unit rule of the kana system. They are diacritical marks (" and 0) which can be attached to certain classes of kana letters but not to others. It was in connection with the latter of these diacritical marks that the two rare cases of "graphical confusion" cited above took place. In both cases the error consisted in using one of the diacritical marks with the wrong class of kana characters, thus producing non-existent character forms. This type of error may well be compared with the errors of adding a superfluous graphic element in the kanji task.
SUMMARY
Fifty aphasic and 30 non-aphasic hemiplegic patients, screened for vi suo-motor or visuo-spatial problems, performed a task of writing 20 high-frequency nouns designating familiar objects. For 10 of the nouns (non-imported words), the subject was required to write both in kanji (ideogram) and in hiragana (one type of phonogram) and for the other 10 (imported words) in katakana (another type of phonogram). Combined visual-auditory stimuli (the picture of the words and the names of the pictures spoken by the examiner) were employed for eliciting responses from the subject. Any response which fell short of the standard orthography of a given word was scored as an error and subjected to a detailed analysis. (The scates of the six aphasic subjects, which showed either zero error or 100% errors on the whole test, were excluded from the analysis.) The results may be summarized as follows: (1) In the kanji transcriptions of non-imported words, both the aphasic and non-aphasic groups made errors, the former group making a larger mean percentage of errors (38%) than the latter group (22%). (2) In the kana transcriptions of both imported and non-imported words, only the aphasic group made errors, the mean percentage errors being 53% for the former and 57% for the latter. (3) The types of kanji errors exhibited by both aphasic and non-aphasic groups were essentially similar to each other, "graphical confusions" being the most frequent type. (4) The types of kana errors, exhibited exclusively by the aphasic subjects, were quite different from those of kanji errors; "phonological confusion" accounted for the most of the errors while there was only a negligible amount of "graphical
282
Sumiko Sasanuma and Osamu Fujimura
confusion." (5) No correlation was found between the respective levels of performance of the aphasic patients in the kanji and kana tasks, indicating that the processing of kanji and kana can be impaired independently in different patients. (6) The aphasics with apraxia of speech showed, as a group, a significantly greater number of errors in the kana transcription of words than did the aphasics without it. These findings provide support for the hypothesis proposed therein, in part duplicating the previous result (Sasanuma and Fujimura, 1971), that kana and kanji transcriptions can be processed in different modes, the former involving a "phonological processor" and the latter without one.
Acknowledgement. Special words of thanks are due to Professor Alvin M. Liberman (Haskins Laboratories and University of Connecticut) for his penetrating discussions while he was visiting with the authors at the Research Institute of Logopedics and Phoniatrics, University of Tokyo.
REFERENCES DARLEY, F. 1. (1968) Apraxia of speech: 107 years of terminological confusion, paper read at the 44th American Speech and Hearing Association Convention. FUJIMURA, 0., and KAGAYA, R. (1969) Structural patterns of Chinese characters, "Ann. Bull." (Research Institute of Logopedics and Phoniatrics, University of Tokyo), 3, 131-148. JOHNS, J. F., and DARLEY, F. 1. (1970) Phonemic variability in apraxia of speech, "J. Speech Hear. Res.," 13, 556-583. SASANUMA, S., and FUJIMURA, O. (1971) Selective impairment of processing phonetic and non-phonetic transcriptions of words in aphasic patients: kana and kan;i in visual recognition and writing, "Cortex," 7, 196-218.
Sumiko Sasanuma, Tokyo Metropolitan Institute of Gerontology, 35-2, Sakaecho, Itabashiku, Tokio, Japan. Postal Code: 173.
INTRODUCTION
The results of our previous study on the visual recognition and transcription of kana (phonetic) and kanji (non-phonetic) words (Sasanuma and Fujimura, 1971) indicated that the processing of the two forms of word transcription could be impaired relatively independently of each other in different types of aphasia. It was found, for instance, that the processing of kana-transcribed words seemed to be selectively impaired in aphasics who had a concomitant problem of apraxia of speech as delineated by Darley (1968) and Johns and Darley (1970). These aphasics had significantly poorer performance in kana than in kanji, especially in writing tasks, while those aphasics who did not have apraxia of speech showed as a group an opposite trend, i.e., better performance with kana than with kanji. On the basis of these findings, it was suggested that the two types of transcriptions might be processed in distinct functional modes: the kana transcriptions may be assumed to be processed through a "phonological processor" (phonological mode of operation), while the kanji transcriptions can by-pass the phonological processor (especially when the latter is impaired) and would thus have direct access to (and from) the lexical items (non-phonological mode). The present study was conducted in an attempt to investigate this issue further by means of a more detailed analysis of the writing errors of the words transcribed into kana and kanji by a group of aphasic patients. On the basis of the earlier results, we should
266
Sumiko Sasanuma and Osamu Fujimura
expect to find that the kinds of errors made in kana and kanji will differ. Errors in kana should reflect the underlying phonological impairment; errors in kanji should be explained on some other basis. The specific questions to be asked included the following: 1. What kinds of errors do aphasic subjects make in the kana and kanij transcriptions of words?
2. Are there any individual differences among aphasic subjects in the kinds, as well as in relative frequencies, of the errors they make in each type of transcription? 3. How does the performance of non-aphasic hemiplegics in the same set of tasks compare with that of aphasic patients?
MATERIAL AND METHOD
Subjects
Fifty aphasic patients consecutively admitted to a large rehabilitation hospital and 30 non-aphasic hemiplegic (15 right hemiplegic and 15 left hemiplegic) patients in the same hospital served as the subjects of this experiment. All the subjects had incurred cerebro-vascular accidents as etiology and had confirmed brain lesions limited to one hemisphere. All aphasic subjects were right-handed and right hemiplegic. Any subject with signs of visual agnosia, visuo-spatial disorientation, or upper limb apraxia, was excluded from the experiment. Of the 50 aphasic patients, six showed either zero or 100% errors on both kanji and kana transcription tasks (see below for the testing and scoring procedures). The data for these six were excluded from the analysis to be described, and thus our results pertaining to the performance of the aphasics are based on the data obtained from the remaining 44 aphasic subjects. Twenty-four of these aphasic subjects had a concomitant problem of apraxia of speech while others did not. The age, educational level, and length of illness for these 44 aphasic patients are given in Table I together with the corresponding data for the non-aphasic subjects. Procedure
Each subject performed a task of wntmg 20 high-frequency nouns designating familiar objects, the same set of words that were used in our previous study (Sasanuma and Fujimura, 1971). Ten of these nouns are of foreign origin (imported words) which, as a rule, are represented in katakana in Japanese orthography; and another ten are non-imported words for which kanii transcriptions are most commonly used, but hiragana
Writing errors in Japanese aphasic patients
267
TABLE I
Age, Educational Level and Length of Illness (Months) for the Aphasic and Non-aphasic Group
Age (years)
Educational level (years)
Length of illness (months)
Aphasic N=44
range median mean
29-71 50 51
8 -18 11 11
2-24 10 11
Non-aphasic N= 30
range median mean
32- 68 52 52
8 -16 10 11
3 -16 11 12
tranSCtlptlOns can also be used. All of the words transcribed in kanji consist of two kanji characters, while the words transcribed in kana comprise two to four kana characters (see Figure 1 in Sasanuma and Fujimura, 1971, for the three types of transcriptions). Combined visual-auditory stimuli were employed for eliciting responses from the subject. Twenty picture cards, 10 for imported words (set 1) and the other 10 for non-imported words (set 2), were presented to each subject together with the name of the object in each picture spoken by the examiner. For each of the 10 pictures for non-imported words (set 2), which have both kanji and hiragana transcriptions, the subject was asked to write both, the order being left to his choice. The order of presenting the two sets of cards, as well as the arrangement of the 10 cards within each set, was randomized for each subject. For 71 of the 80 subjects, the whole test was administered in one session, but for nine of the aphasic subjects it was necessary to administer the test in two separate sessions to avoid fatigue, one set of cards being used in each session, with an interval of no more than a week between the sessions.
Scoring Any response which fell short of the standard orthography of a given word was scored as an error. If the subject did not make any response for five seconds after the first presentation of the stimulus (a picture and the corresponding word spoken by the examiner), he was given the spoken word again (the second presentation) with the picture still remaining in front of him; and if he was still unable to make any response 25 seconds after the second presentation of the stimulus, then this item was categorized as "no response." The test data from the 15 non-aphasic right hemiplegics have been combined with those from the 15 non-aphasic left hemiplegics, since the performance levels of the two groups were essentially the same.
Sumiko Sasanuma and Osamu Fujimura
268
RESULTS
The overall performance of the aphasic and non-aphasic groups is summarized in Table II. It can be seen that both the aphasic and non-aphasic groups made errors in the kanji transcriptions of the non-imported words. In the kana transcriptions of both the imported TABLE II
Range, Median and Mean Percentage of Errors of Kanji and Kana Words for the Aphasic and Non-aphasic Groups
Kanji
Hiragana
Katakana
Aphasic N=44
range median mean
0-70 40 38
0-100 60 57
0-100 60 53
Non-aphasic N= 30
range median mean
0- 80 15 22
0 0 0
0 0 0
(katakana) and the non-imported (hiragana) words, however, only the aphasic group made errors; moreover they made even more errors in kana than in kanji. 1 Analysis of kanji errors
Table II shows that aphasic subjects made a larger mean percentage of kanji errors (38%) than non-aphasic subjects (22%). This difference was statistically significant at the .05 level of confidence. As can be seen in Table III, however, the types of errors as well as their relative frequencies as exhibited by the two groups are essentially similar. These types of errors included, in decreasing order of frequency occurrence: ( 1 ) the substitution of a whole 1 This finding seems to be particularly noteworthy in light of the fact that, in general, kana transcriptions are less complex as graphic forms and are smaller in number in comparison to kanji; also, they are mastered by an average child much earlier than kanji, usually by the end of the first year in school. In fact, kana-sound associations are so well established in adults that, in normal situations, it is rare that a person cannot transcribe a spoken word in kana, while it is a common observation that an average person often forgets how to write the kanjis for some infrequently used words and represents them in such cases with the kana equivalents.
Writing errors in Japanese aphasic patients
269
TABLE III
Types of Kanji Errors and Percentage of Words Falling into Each Type for Aphasic and Non-aphasic Groups Graphical confusions
No response, "don't know"
Incomplete responses
Semantic confusions
Aphasic N=44
49
30
15
6
Non-aphasic N= 30
39
35
19
7
character or a constituent unit of it by a wrong character or unit, or the addition or omission of a stroke in a character (graphical confusion), (2) no response (or "don't know" response), (3) an incomplete response (correct writing of only part of a character, or one of the two characters representing a word), and (4) the substitution of a whole word by another word of a related meaning (semantic confusion). Of these types, "graphical confusion" comprised the largest group for both the aphasic and non-aphasic subjects (almost 50% of the total errors for the aphasic and about 40 % for the non-aphasic subjects). This type of error may be further divided into five subtypes. The relative frequency of occurrence of each type is shown in Table IV, together with typical examples of each. The most common sub-type for both the aphasic and non-aphasic groups (accounting TABLE IV
Sub-types of the Graphical Confusions and Percentage of Characters Falling into Each Sub-type for Aphasic and Non-aphasic Groups Compounding wrong units
Addition or omission of a stroke
A wholecharacter substitution
Metathesis
Complex metathesis
Aphasic N=44
60
29
10
1
(4)
Non-aphasic N= 30
68
24
8
0
(5)
Examples of ~*~ confusions ~ ~
,~
;fa. ~.la ,l
~ ;7s..~*
tfi
--+~ ""I)
~~
~ij~ ~~t~
fll ~ itfl it ---"":fi
270
Sumiko Sasanuma and Osamu Fuiimura
for 60% of all instances of graphical confusions for the aphasics and almost 70% for the non-aphasics) was the error of compounding two or more units of a character, with at least one unit remaining correct. (A small portion of the errors in this category, however, may be termed as "complex metatheses" because the errors in these cases involve a misarrangement of the units wIthin a character, in addition to the wrong choice of a component unit. See the last column of Table IV.) The second in frequency of occurrence for both aphasic and non-aphasic subjects was the error of adding an extraneous stroke or omitting an obligatory stroke to or from a character. In the third sub-type, a character was changed completely into another character with a different but more or less related meaning. The fourth subtype, metathesis of the two constituent characters of a word, appeared in one aphasic subject only. It may be of interest here to point out that all the errors in the transcription of kanji described above represent "permissible" forms according to the structural rules of kanji patterns (Fujimura and Kagaya, 1969), although some of them do not exist in the lexicon. Another fact to be noticed here is that the individuals with a greater total number of errors as well as those with a smaller total number of errors exhibited essentially the same distributional patterns of various types of errors. In other words, the types of errors do not differentiate high-error-rate subjects from low-errorrate subjects (just as they do not differentiate the aphasics from the non-aphasics). There were some differences in the level of difficulty among the 10 kanji words. In general, the sum total of the degree of complexity (in graphic form) of each of the two characters constituting a word seemed to be related to the level of difficulty of that word. Thus, the larger the total number of strokes contained in the two characters of a word, the greater was the percentage of subjects who tended to make errors. Analysis of kana errors
Since the non-aphasic subjects made no errors in the kana transcriptions, the analysis in this section will deal only with the performance of the aphasic group. A comparison of the data obtained for performance in the two
Writing errors in Japanese aphasic patients
271
kinds of kana transcriptions, i. e., writing in katakana (imported words) and in hiragana (non-imported words), revealed that there were no significant differences between the two in terms of either the types of errors or distributional patterns of these types. The following analyses, therefore, will be based on the combined data obtained on performance in these two kinds of kana transcriptions. The aphasic subjects exhibited as a group not only a larger mean percentage of errors in kana (55.1 %) than in kanji (37.6%), but also a quite different pattern of errors in kana compared with that in kanji (see Figure 1). Of particular interest is the fact that
o kana· transcribed words
60
•
kanji.transcribed words
50 40
30 20 10 0 ....._ .........._ ... .... :J:=~ '" til () s:::
.... 0 bO· ...
o til .... :::s
0 .... S:::S:: 00
..s:::() 0.
~QI QI
til
s::: 0
.... s:::
~.=.t $.0 s:::
o()
8.,fJ 0 0
s:::?
0.0 a 0.
...s:::
til
QI
$.0
.... til
'" () 0s::
......
..s:::
0.-4
til
() til
~6 s::: ....
$.0 s::
aZ
()
()
"'o.:::s .... bOO
'" til QI
til
s::
0
Types of Errors Fig. 1 - The types of errors on kana-transcribed and kan;i-transcribed words for 44 aphasic subjects.
272
Sumiko Sasanuma and Osamu Fu;imura
the frequency of occurrence of "graphical confusion," which was the predominant type of errors in the case of words transcribed in kanji, is almost negligible in words transcribed in kana. Of the total of 487 errors in kana-transcribed words, only two (.4%) can be categorized as "graphical confusions." Each of these two words contained a character form which does not exist in the kana syllabary; more specifically, the character (which is supposed to represent a syllable) was formed by erroneously adding a feature marker (a diacritical marker indicating a voiceless stop) which results in no possible phonetic form (syllable). The highest in frequency (59%) of all errors of words transcribed in kana are those which can best be explained in terms of some underlying "phonological confusions" involving syllables, phonemes or distinctive features. 2 The second in frequency are those errors categorized as "no response" or "don't know" (30%), the third being "incomplete responses" (correct transcription of only part of a word) which accounted for all the remaining errors (11 %). There were no errors involving "semantic confusion" in the kana transcriptions, while a certain amount of such confusion (6%) did appear in the kanji transcriptions. Feature analysis of the phonological confusions
There was a total of 712 instances of phonological errors in 314 words. Inspection of the data revealed that the errors varied considerably in degree of complexity from individual to individual, and to a smaller extent from word to word. In general, the representative errors exhibited by low-error-rate subjects (individuals with a smaller total number of errors in kana) tended to be simple or "transparent" in the sense that the errors usually were substitutions of consonants (or vowels) which differed from the target sound in only one or two phonetic features. The errors exhibited by high-error-rate subjects, on the other hand, 2 Since there are some kana characters (both katakana and hiragana versions) which share some degree of graphical similarities to each other and thus seem to offer more opportunities for substitutions among these characters (than would be expected with other characters), the data were scrutinized for possible incidences of graphical confusion of these graphically similar forms. The result indicated, however, that there were only a few instances where the expected substitutions did actually take place, and even there the interpretation of the errors in terms of phonological confusions made more sense than (or as much sense as) that in terms of graphical confusions.
Writing errors in Japanese aphasic patients
273
tended to be "complex," involving multi-feature confusions, such as "unrelated" substitutions, omissions or insertions of consonants and/ or vowels, or even extraneous insertions of a whole syllable or two. The complexity (as well as the types and relative frequencies) of these errors seems to depend also on the length and phonological structure of the individual word. Thus, for instance, (1) the subject tended to make less errors in shorter words than in longer words, (2) if he did make errors in shorter words, these errors tended to be less complex as compared to the errors in longer words, and (3) the types of specific errors tended to be related to the phonological context of the problematic sound (e.g., if a word of CV-CV structure contained a voiced consonant in the first syllable and a voiceless consonant in the second, then a frequent error was the substitution of the voiced consonant by its voiceless cognate, i.e., an assimilative dropping of the marked feature value of voicedness). These observations seem to suggest that the phonetic feature may well constitute the basic unit of the phonological errors, and that a further analysis of the data in terms of phonetic features may help clarify the essential nature of the errors. Only" simple" errors involving single- or double-feature confusions were selected for this analysis so that there should not be any ambiguity in the interpretation. Table V summarizes the results of tabulating all single-feature errors exhibited by the 44 aphasic subjects. These errors constitute about one fifth (156/712) of the total instances of phonological confusions, and are distributed through all levels of subjects although the ratio of complex errors to simple errors tends to be much higher in high-error-rate subjects than in low-error-rate subjects. A set of four consonantal features (voicedness, nasality, place of articulation and the stop/fricative distinction) and three elongation features (H, Q and N)3 were considered to be adequate for use in this analysis in that they allowed an exhaustive description of the majority of the simple errors. The denominators in each column represent the number of possibilities for the particular kind of error listed in that column for each of the 20 words, while the numerators are the accumulated number of actual error occurrences for all the subjects. 3 The symbols H, Nand Q following a vowel represent, respectively, the phonemically distinct elongation of the vowel, elongation with a heavy nasalization of the vowel toward the end of the syllable, and gemination of the succeeding (voiceless) consonant.
Sumiko Sasanuma and Osamu Fuiimura
274
TABLE
Single-feature Pl~<::e
Voicedness +~-
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
kodomo keito kimono yubiwa boHsi tokeH huHtoH taiyoH daikoN tebukuro basu koQpu kamera boHru beQto terebi seHtaH kaHteN toraQku nekutai
T %
4/1 1 4/1
9/1 4/1 2/1 7/1 2/1 3/1
35/9 8.8
-~+
1 1/2 1 1 2 1/1 1/1 1/1 1/2 3/1 4/2 1 1 1/1 2 2 2/2 2 15/26 1.3 3.3
Nasal
from: labial +to: d
p
p
+~-
-~
2/1
1
1/1
1
1/1 1
2/1 1 1
1 1 1
1 1 1 1/1 2/1 1/1 4/1
1 1 1 3/1 1 1 1
2
1 1 1 2/1
1 1/1 1/1
1 4/5 1.8
3/9 0.8 1.1
11/11 2.3
palatal
dental
3/11 0.6
d
1 1 2/1
1 3/1 1
1 1 1
1/1 1 1/1
1 1 1 1 1 1
2/1 1 1 1 1 1
1
1/1
1 1
2/1 1
1
1
1 1 1
2/1 3/1 2/1
1 1 1 1/1 1 2
1 1/1 1 2/1 1 2
3/16 8/16 1.1 .4 2.3
0/10 0
It will be seen that there were some differences among the relative frequencies of involvement of various features (represented by the percentage values in the bottom row). The voicedness feature showed the highest frequency of involvement, followed by the features pertaining to the place of articulation, nasality and the stop/ fricative distinction. The frequencies of errors involving elongation features were in a position intermediate between those of place of articulation and nasality. Further examination of the table shows, in addition, that each feature behaves in its own characteristic manner. Thus, for instance, voicedness as well as nasality exhibit a clear-cut directional asymmetry toward dropping rather than attaching the pertinent feature. For place of articulation and the stop/fricative distinction, on the other
12/10 5.5
275
Writing errors in Japanese aphasic patients
v Errors
Stop/Fricative
H
Q
N
s-7f f-7s
H-70 0->H H-7Q
Q-70 0--').QQ-7H
N-70 N-H
1 2 1 0 0 1/2 1/1 1 1 2 0 2/2
1 1/1
2/1 1 8/2 2/1
1
1
1/1
0 1 1/1 1/1 1/2 2 2
1/1
7/23
2/4
.7
1.1
0.8
5/2 4/1 22/9 5.6
3 2/3 3 3 1 1/1 3 1/2 3 4 2 1 3 2/1 1/1 2/3 1/2 4 10/43 0.5 1.5
1 1/1 1/1
1
1 1 1 1/0 1 1 1
4/4 2.3
2/1 2/1
1 2/1 1
1
1
7/1
1 1 1/0 2
1
7/3 5.3
2/11 0.4
4/3 3.0
1.7
T
8 6 5 1 7 6 11 6
10
7 5 8 6 12 7 13
1/1
2/1
1/2
2/2 2.3
1.1
9
13
14 2 156
1.7
hand, no such clear directional asymmetry can be concluded, when we consider the possible effects of contextual assimilation and the phonological imbalance of the test words employed. The manner with which the elongation features behave is much like that of voicedness and nasality, and show a significant directional asymmetry toward dropping the respective features rather than attaching them. Also, it happens frequently that where an extraneous attaching of H and Q ever takes place, the same element is found in the context (within the same word). In addition to the single-feature errors, double-feature errors were also analyzed for relative frequency of occurrence. The errors involving a simultaneous dropping of the voicedness and nasality features of consonants showed the highest relative frequency of
276
Sumiko Sasanuma and Osamu Fujimura
occurrence (2.7%), followed by those involving a voicedness dropping combined with a change in place of articulation (1.3%). The relative frequencies of errors involving a simultaneous attachment of voicedness and nasality, or the addition of voicedness combined with a change in place of articulation, in contrast, were much smaller (0.6% and 0.1 %, respectively). The frequency of occurrence of other doublefeature errors were either negligible or null. There was a tendency for most of the single- or double-feature errors described above to take place singly in a word, with only a few exceptional cases where two of them occurred in one word (of three or four syllables). All the rest of the phonological errors were more complex than double feature substitutions from the point of view of a distinctive feature representation of the sound shape: In addition to the errors described above, a special type of phonological confusions were observed. They involve the metathesis of adjacent or non-adjacent syllables, or their constituent phonemes of features (see Table VI for some examples). The relative frequency TABLE VI
Examples of Metathesis Adjacent type:
ka me ra te re bi ko do mo
~ ~ ~
ka ra me (syllable) te be ri (phoneme) ko no bo (nasality feature)
Non-adjacent type:
te bu ku ro ne ku ta i da i ko N
~ ~ ~
ku bu te ro (syllable) te ku na i (phoneme) ta i go N (voicedness feature)
• Assuming that the distinctive feature constitutes the unit of phonological errors, an analysis was made tentatively concerning the relationship between the error rate of a given individual and the average degree of phonological deviations in his errors (expressed in terms of the number of features involved in each error). The result showed a high linear correlation (r = .92), indicating that the subjects who made a greater total number of errors in the kana transcriptions did tend to make more complex phonological errors. On the same assumption as the above, the distributional pattern of various types of phonological errors for high-error-rate subjects was compared with that for lowerror-rate subjects. The result revealed that there was an overall similarity between the two, but with some exceptions: the elongation features Hand Q were distributed evenly through all levels of performance. This finding may be interpreted as suggesting that these phonological features are functionally different from other (segmentally inherent) features.
Writing errors in Japanese aphasic patients
277
of occurrence of this type of metathesis in a "pure" form is comparatively small (about 8 % of the total instances of phonological confusion), but there are a great many other instances where metathesis seems to be combined with other types of phonological errors.5 Consonants versus vowel errors
The types of phonological confusion described so far have been concerned with consonants. The question arises as to how the relative frequency of vowel errors compares with that of consonant errors. The answer was obtained by means of tabulating all the incidences of vowel substitution as well as of consonant substitution, and dividing each sum respectively by the number of possible substitutions in the given phonological environment. The result obtained indicates that the relative frequency of vowel substitutions (6.7%) is significantly smaller (p < .05) than that of consonant substitutions (10.6%), and the proportion of vowelto consonant-errors appears to remain constant for all subjects regardless of differences in performance levels. It was observed also that about two thirds of the vowel substitutions occurred in combination with a substitution error in the preceding consonant in a CV syllable, and that contextual assimilation of neighboring vowels played an important role in precipitating the vowel substitutions just as it did in the case with consonant substitutions. Comparison of the kanji and kana performances of each individual
We should ask how the level of performance in kanji transcriptions is related to that of kana transcriptions for each individual subject. Figure 2 provides the answer to this question, illustrating the relationship between the number of errors in kana-transcribed words and in kanji-transcribed words for each of the 44 aphasic subjects, represented by either a dot (subject with apraxia of speech) or a cross (subject without apraxia of speech). It is apparent from this figure that there is no substantial correlation between the sub5 There is no clear-cut difference between high-error-rate subjects and low-errorrate subjects in the relative frequency of occurrence of metathesis in a "pure" form. Those instances of metathesis which seemed to be combined with other types of errors, on the other hand, tended to appear more often in high-error-rate subjects
Sumiko Sasanuma and Osamu Fujimura
278
% 100 fJl
•
• • I • • • I• • •• •
90
'0 $.0
o
s:
80
• X
..... o fJl
t
20
..... o
10
r:tl
x
•
30
$.0
o
XX
•
•
~
XX X
IX
• •
•
XX
XX
X
•
X
)(
X
o
X
o
10
20
30
40
50
60
70
80
90
%
0/0 of Errors of Kanji- transcribed Words Fig. 2 - Relationship between the percentage of errors of kana-transcribed words (ordinate) and of kanji-transcribed words (abscissa) for 44 aphasic subjects. Dots represent individual subjects with apraxia of speech and crosses without it.
ject's performance in kanji and in kana: some of the subjects who made a relatively large number of errors in kana made a relatively small number of errors in kanji and vice versa. It might be noted, however, that the total set of subjects can be divided into two subsets in terms of the frequency of occurrence of errors in kana transcription, but the same is not true of errors in kanji transcription. It is further observed that, of the 23 high kana-error-rate subjects (clustering in the upper half of the figure), all but 3 (80%) had apraxia of speech accompanying aphasia (dots), while 18 of the 21 low kana-error-rate subjects (clustering in the lower half of the figure) (86%) did not have such a problem (crosses). This is in agreement with our previous findings (Sasanuma and Fujimura, 1971) and indi-
Writing errors in Japanese aphasic patients
279
cates a close relationship between the severity of kana impairment and the presence of apraxia of speech.
DISCUSSION
The results of this study show a clear-cut difference between performance in kana and kanji exhibited by the aphasic subjects in the writing tasks. In the kanji task, the majority of the errors were those which can best be categorized as "graphical confusions," and do not differ in kind from the errors made by the non-aphasic subjects. In the kana task, in contrast, the predominant errors were those which can best be interpreted as "phonological confusions," and these were exhibited only by the aphasic subjects; none of the non-aphasic subjects made any such errors whatsoever. It was also shown that there is no correlation between performance (of the aphasic subject) in kanji and in kana, whereas an apparent correlation exists between the total number of his errors in kana-transcribed words and the average degree of his phonological deviation from the target forms of these words. Taken together, these findings provide strong support for the hypothesis set forward in our previous study (Sasanuma and Fujimura, 1971): that the kana and kanji transcriptions can be processed in different modes, the former requiring some phonological device and the latter by-passing it. A preliminary analysis of "phonological confusions" in terms of the distinctive features has uncovered some interesting facts about the nature of these errors, i.e., the presence of some regularities in the manner with which various features are involved in the errors. In order to arrive at a more definite conclusion regarding this point, however, a further experiment using a better balanced word list will be necessary. Clinical types of aphasia and the kana impairment
One of the findings of our previous study was that those aphasics with a concomitant problem of apraxia of speech exhibited, as a group, a selective impairment of kana processing. The results of the present experiment with a different group of patients strongly support this previous conclusion.
280
Sumiko Sasanuma and Osamu Fu;imura
On the assumption that the selectively impaired phonological processor may constitute the common source of malfunctions both in articulation and in writing kana (although admittedly the two tasks may involve other processes that are inherent to each), one may naturally ask how each subject's error pattern when transcribing words in kana compares with that on his oral production of the same set of words. The answer is being sought in a pilot study in which the apraxic subjects are asked to repeat each word after the examiner. The results obtained so far seem to indicate that for the majority of the subjects, there is only a gross correspondence between the individual's performance levels, as well as between the error patterns, in the two tasks. It has been noted, however, that the patterns of phonetic confusions observed in the oral experiment in some subjects are strikingly similar to those observed in the writing task performed by other subjects, and vice versa. In fact, there are quite a few words in which the error patterns in the one task performed by a subjet are identical to those in the other task performed by another subject. These observations may indicate that there is possibility of a recovery process operating here, i.e., the graphic and oral productions of a given subject do not improve in a parallel fashion, but the error pattern in one modality at a particular stage of recovery may correspond to the error pattern in the other modality at a different stage of recovery. Further exploration, especially of a longitudinal nature, seems to be necessary in order to be able to conclude on this point. The nature of graphical confusions
The fact that "graphical confusions" constitute a small fraction of the kana errors and a large part of the kanji errors would seem to justify special notice. A possible explanation may be found in the different characteristics of the graphical forms of kana and kanji characters. As mentioned before, kana characters are less complex than kanji characters, in general, and each of them may be considered as consisting of a single unit, in the sense that none of them can be divided into further units and still be identifiable as a kana form. As for kanji, on the other hand, most characters consist of multiple units so that each character can be divided into two or more constituent units, each of which can exist by itself as an independent character or can combine with other units to make other characters.
\'('riting errors in Japanese aphasic patients
281
In other words, one may infer that each kana character is equivalent to a constituent unit of kanji, and constitutes a basic perceptual and/ or production unit by itself. Therefore, errors made by wrongly combining units of the graphical pattern (the predominant type of errors in the case of kanij writing) are hardly to be expected in the case of the kana. There are some exceptions, however, to this single-unit rule of the kana system. They are diacritical marks (" and 0) which can be attached to certain classes of kana letters but not to others. It was in connection with the latter of these diacritical marks that the two rare cases of "graphical confusion" cited above took place. In both cases the error consisted in using one of the diacritical marks with the wrong class of kana characters, thus producing non-existent character forms. This type of error may well be compared with the errors of adding a superfluous graphic element in the kanji task.
SUMMARY
Fifty aphasic and 30 non-aphasic hemiplegic patients, screened for vi suo-motor or visuo-spatial problems, performed a task of writing 20 high-frequency nouns designating familiar objects. For 10 of the nouns (non-imported words), the subject was required to write both in kanji (ideogram) and in hiragana (one type of phonogram) and for the other 10 (imported words) in katakana (another type of phonogram). Combined visual-auditory stimuli (the picture of the words and the names of the pictures spoken by the examiner) were employed for eliciting responses from the subject. Any response which fell short of the standard orthography of a given word was scored as an error and subjected to a detailed analysis. (The scates of the six aphasic subjects, which showed either zero error or 100% errors on the whole test, were excluded from the analysis.) The results may be summarized as follows: (1) In the kanji transcriptions of non-imported words, both the aphasic and non-aphasic groups made errors, the former group making a larger mean percentage of errors (38%) than the latter group (22%). (2) In the kana transcriptions of both imported and non-imported words, only the aphasic group made errors, the mean percentage errors being 53% for the former and 57% for the latter. (3) The types of kanji errors exhibited by both aphasic and non-aphasic groups were essentially similar to each other, "graphical confusions" being the most frequent type. (4) The types of kana errors, exhibited exclusively by the aphasic subjects, were quite different from those of kanji errors; "phonological confusion" accounted for the most of the errors while there was only a negligible amount of "graphical
282
Sumiko Sasanuma and Osamu Fujimura
confusion." (5) No correlation was found between the respective levels of performance of the aphasic patients in the kanji and kana tasks, indicating that the processing of kanji and kana can be impaired independently in different patients. (6) The aphasics with apraxia of speech showed, as a group, a significantly greater number of errors in the kana transcription of words than did the aphasics without it. These findings provide support for the hypothesis proposed therein, in part duplicating the previous result (Sasanuma and Fujimura, 1971), that kana and kanji transcriptions can be processed in different modes, the former involving a "phonological processor" and the latter without one.
Acknowledgement. Special words of thanks are due to Professor Alvin M. Liberman (Haskins Laboratories and University of Connecticut) for his penetrating discussions while he was visiting with the authors at the Research Institute of Logopedics and Phoniatrics, University of Tokyo.
REFERENCES DARLEY, F. 1. (1968) Apraxia of speech: 107 years of terminological confusion, paper read at the 44th American Speech and Hearing Association Convention. FUJIMURA, 0., and KAGAYA, R. (1969) Structural patterns of Chinese characters, "Ann. Bull." (Research Institute of Logopedics and Phoniatrics, University of Tokyo), 3, 131-148. JOHNS, J. F., and DARLEY, F. 1. (1970) Phonemic variability in apraxia of speech, "J. Speech Hear. Res.," 13, 556-583. SASANUMA, S., and FUJIMURA, O. (1971) Selective impairment of processing phonetic and non-phonetic transcriptions of words in aphasic patients: kana and kan;i in visual recognition and writing, "Cortex," 7, 196-218.
Sumiko Sasanuma, Tokyo Metropolitan Institute of Gerontology, 35-2, Sakaecho, Itabashiku, Tokio, Japan. Postal Code: 173.