特集　言語獲得

幼児の「だけ」の解釈における格と焦点の相互作用

この研究では日本語を母語とする幼児の「だけ」の解釈の実験結果にもとづき，焦点助詞と格助詞の相互作用について考察した。 真偽値判断課題において，幼児は「だけ」が主語と目的語に付加されている場合で異なった反応パターンを示した。また，同じ幼児は「だけ」が助詞と共起するか否かによっても異なる解釈を与えることも明らかになった。具体的には幼児は「だけ」が助詞と共起する際には「だけ」を主語と結びつけ，「だけ」が助詞なしで現れる場合には目的語と結びつけるというパターンが観察された。日本語の格を抽象格ととらえる統語理論では，上記のパターンに説明を与えることはできない。この実験結果は，主格と目的格の助詞の間に異なる性質を認め，「だけ」が主語または目的語に付加される場合と，助詞が共起するか否かの４つの可能な文型のそれぞれに対して異なる派生を仮定する青柳 (2006) に経験的支持を与えることを論じる。

特集　言語獲得

日本の子どもの初期の語彙発達

日本の子どもの初期の語彙の構成を日本語マッカーサー乳幼児言語発達質問紙 (JCDIs) 標準化データ，縦断データ，横断データから明らかにした。特に子どもの初期の語彙が名詞優位か動詞優位かの問題を検討した。第１にJCDIsで語彙の構成を調べた結果，名詞が一番高い比率を占めていた。第２にJCDIsで20ヶ月児158名の名詞，動詞，形容詞，閉じた語の語彙の構成を調べた結果，名詞の比率が高く，Bornstein et al. (2004) の7カ国の結果と一致していた。第３に2名の子どもの縦断データから 語彙急増期の後は名詞優位，その後，文法発達に伴い動詞優位になることを明らかにした。第４に，31名の日本の子どもと養育者の玩具場面と絵本場面の観察では絵本場面では一貫して名詞優位であったが，玩具場面では言語発達に伴い動詞優位に移行していった。玩具場面の養育者の発話は動詞優位で子どもの結果とは一致していなかった。以上の結果から，言語発達初期の子どもは名詞を学習しやすい概念的な傾向を有していると結論づけた。最後に名詞優位を引きこす語学習のメカニズムについて論じた。

特集　言語獲得

単一項文の理解から探る幼児の格助詞発達

幼児の格助詞に関する文法知識とその運用能力を探るため,他動詞の項が文中にひとつしか現れない単一項文を対象として,絵画選択法を用いた文理解実験を行った。第１実験で年長児は9割以上の正解率を示したが,年少児と年中児の正解率は全体的に低く,対格を含む単一項文の理解には多くの誤りが見られた。この誤りが文法知識を反映した結果なのか,運用に係わる動作主バイアスが原因なのかを探るため,第２実験では単一項文に先行文脈を与えて運用上の要因を取り除こうと試みた。その結果,正解率は年少児で6割程度,年中児で8割程度にまで伸び,主格と対格における差は見られなくなった。よって,文法知識の発達における主格と対格の差はないと考えられるが, 5歳前半までの幼児は,格助詞「が」と「を」の文法知識において未だ発達過程にある可能性があると考えられる。

論文

「以上(に)」「ぐらい」を用いた比較構文―日本語におけるComparisons of Deviation―

本稿では，日本語の「以上(に)」「ぐらい」を用いた比較構文は，機能的には英語のmore … thanやas … asを用いた比較構文と対応するように思えるのであるが，実際にはこれらとは異なり，常にcomparisons of deviation（cf. Bierwisch 1989, Kennedy 2001）として分析されなければならないことを主張する。つまり，日本語のこれらの構文は，二つの要素に関して，単にそれらがどれだけ当該の特性を有するかを比較するものではなく，その特性を有する度合いについて，両者がどれだけ平均基準を超えているかを比べる表現なのである。本稿では，「日本語の形容詞句は，本来degree variable or constantが占めるはずのspecifier位置を欠いている」というFukui 1986, Snyder et al. 1994の仮説を援用することにより，この特性を説明することができることを論じる。

フォーラム

カドリ語における語中の閉鎖音と破擦音

本稿の目的はカドリ語の語中子音の弁別について記述し，その分布を基に語中子音の音韻変化に関して提案をおこなうことである。他のオーストロネシア諸語と同様，カドリ語の標準的語形は C を随意的要素とする CVCCVC であり，この語形に含まれる子音連続 -CC- には，h＋無声閉鎖音・破擦音のもの（以下 -hT-）と，鼻音＋有声閉鎖音・破擦音のもの（以下 -ND-）がある。まず，-hT- と -T- の，（i）単一形態素における生起，（ii）単一形態素における反復生起，（ⅲ）人称代名詞や数詞などの頻用語彙における生起が，-ND- と -D- よりも高頻度であることをしめし，このような頻度差は各々の機能負担量の差に起因していることを指摘する。さらに，-T-，-D- が直前にそれぞれ h，N を伴うか否かという点のみで弁別される語彙のペアを挙げ，それらの量的な差に基づいて各々の機能負担量の差を明らかにする。これら語中の子音と子音連続の弁別についての記述は，Hudson（1967）が不完全に仮定していた *T > hT / V＿V および *NT > Tの音韻変化を補完するものである。

Featured Theme: Language

The Rhythm-based Prosodic Bootstrapping Hypothesis of Early Language Acquisition: Does It Work for Learning for All Languages?

Research in infant speech perception has demonstrated that young infants are sensitive to prosodic properties of language that are relevant to linguistic rhythm. In the Rhythm-based Prosodic Bootstrapping Hypothesis, it is proposed that infants' early sensitivity to the rhythmic properties of a language will enable them to adopt a metrical speech segmentation strategy appropriate for their language. Review of the literature shows that while infants are capable of discriminating languages from different rhythm classes, this does not necessarily lead them to adopt metrical segmentation strategies appropriate to each and every particular class. It is argued that the rhythm of a language may be salient for infants in all languages, but how this sensitivity is linked to other aspects of language acquisition needs to be re-considered.

Featured Theme: Language

Case/Focus Interaction in Young Children's Interpretation of dake (only) in Japanese

We present children's non-adult interpretation of sentences that contain the focus particle dake, using the Truth-Value Judgment Task (Crain and Thornton 1998). Our first observation is that children interpreted sentences with dake differently when dake was attached to the subject and to the object (the subject/object asymmetry in the interpretation of dake). We also observed that children interpreted sentences with dake differently when dake was followed by a case particle (the 'particle/no-particle asymmetry'). Any theory based on the assumption that the Japanese employs an abstract Case feature system fails to capture the systematic pattern shown in children's non-adult interpretations of dake. Our data provide empirical support for a syntactic theory proposed in Aoyagi (2006), which distinguishes the nature of Nominative and Accusative case particles (ga and o), as well as assumes different derivations for sentences containing dake, depending on whether it is followed by a case particle or not.

Featured Theme: Language

Early Lexical Development in Japanese Children

The present paper clarified the composition of early vocabulary in Japanese children through the standardized data of the Japanese MacArthur-Bates Communicative Development Inventories (JCDIs), the longitudinal data, and the cross sectional data. We examined especially the issue of noun and verb dominance in early child language. First, the composition of the first 50 words in JCDIs showed that common nouns had the highest proportion. Second, the opportunity scores of nouns, adjectives, verbs, and closed-class words on JCDIs for 158 Japanese children at 20 months of age showed the noun prevalence, and this result was consistent with the results of seven countries in the study by Bornstein et al. (2004). Third, the longitudinal study of two Japanese children showed noun dominance after vocabulary spurt and verb dominance after the emergence of grammar. Caregiver language was verb dominant. Fourth, 31 Japanese children showed the noun dominance in the book-reading context, but in the toy-playing context, there was a shift away as children developed from single words through the presyntactic stage to the syntactic stage. Caregiver language was verb dominant in a number of respects across development in the toy context, and thus was not closely related to child's lexical balance. We concluded that children have a conceptual disposition to learn nouns in early lexical development. Finally, we discussed the mechanisms of word learning which evoke noun dominance.

Featured Theme: Language

The Development of Japanese Case-markers Observed through Children's Comprehension of Single-Argument Sentences

This study investigates children's comprehension of a single-argument sentence that contains either a subject or a direct object of a transitive verb. Adopting the picture-selection task, Experiment 1 reveals 90% accuracy by the oldest group of children (mean age=5;11). This indicates that children have acquired the grammatical knowledge of ga and o by this age and that their competence is reflected in their linguistic performance. In contrast, the results disclose poor performance by the younger groups of children. Their errors were observed on the accusative case-marking more frequently than on the nominative case-marking. This asymmetry seems to reflect the developmental difference between the two case-markers: Nominative ga is acquired earlier than accusative o. In order to explore whether or not this asymmetry is rooted in the children's grammatical knowledge, Experiment 2 tries to eliminate the effects of agent priority, a possible bias for the children's agent interpretation of the single argument. For this purpose, test sentences were provided with discourse context in the picture-selection task. The results show that the children's performance greatly improved with the asymmetry between the nominative and accusative cases removed. These results suggest that the performance factor overrides children's grammatical knowledge in Experiment 1, and that the elimination of the agent bias discloses their linguistic competence in Experiment 2. However, the percentages of correct responses by the younger groups of children (age range=3;7–5;7) in the second experiment do not reach those of the oldest group in the first experiment, suggesting that they are still in the developmental process of acquiring the nominative and accusative case-markers.

Izyoo(ni)- and Gurai-comparatives: Comparisons of Deviation in Japanese

This paper investigates the syntax and semantics of Japanese comparative constructions that make use of words like izyoo(ni) 'more than' and gurai 'roughly equal to', which are functionally analogous to the English more- and as-comparatives. I argue that they are necessarily interpreted as comparisons of deviation in the sense of Bierwisch (1989) and Kennedy (2001). In explaining why these constructions cannot express comparisons of the absolute projections of two objects on a scale, as the English comparatives do, this paper advocates the line of thinking pursued by Fukui (1986) and Snyder et al. (1994) that AdjP in Japanese is impoverished in such a way that it lacks the position to host a degree variable or constant.

Forum

Word Medial Stops and Affricates in Kadorih

In this paper I describe the phonological distinctions between word medial consonants in Kadorih. On the basis of distributional facts, I give a strong support to the theory of the phonological changes of these consonants, proposed in Hudson (1967).

As in other Austronesian languages, Kadorih's canonical word shape is disyllabic CVCCVC where all of the consonants are optional. There are only two types of word medial consonant sequences (-CC-), viz. /h/ followed by a voiceless stop or an affricate (-hT-), and a nasal consonant followed by a voiced stop or an affricate (-ND-). I demonstrate that -hT- and -T- occur more frequently than -ND- and -D- in (i) monomophemic words, (ii) both of the word medial positions in trisyllabic monomophemic words, and (iii) frequently used words such as personal pronouns and numerals. Based on these observations, I show that the difference in frequency between -(h)T- and -(N)D- is due to their difference in functional loads. This claim is corroborated by comparing the quantities of their respective distinctive pairs: CVhTVC – CVTVC on the one hand, and CVNDVC – CVDVC on the other. The comparison presented in this paper provides evidence that -hT- and -T- have a higher functional load than -ND- and -D-. The phonological distinctions attested between these word medial consonants support Hudson's (1967) theory of the phonological changes, *T > hT / V_V and *NT > T, which he assumed in spite of insufficient evidence.