華語學前語言發展異常兒童的動詞學習機制

Abstract

過去的研究指出，三到四歲的幼兒若語言發展遲緩，其詞彙量可能呈現偏低的現象。除了詞彙量的發展外，研究也關注語言遲緩幼兒在語言的「質」方面，是否與一般發展幼兒有所不同。一般發展的幼兒在詞彙發展過程中表現出「名詞偏好（Noun bias）」的趨勢，即表達性詞彙的種類以名詞為主；相較之下，由於學習和語言特性，兒童對於動詞的學習比名詞學習更困難。與英語相比，華語是「動詞友善」的語言。因為從兒童的語言環境來看，華語比英語提供兒童更多的動詞輸入。此外，語言發展障礙兒童的研究，較少聚焦動詞的發展；而動詞的學習與語法能力高度相關。相較於正常發展的兒童，語言發展遲緩的幼兒在表達性詞彙和語法方面顯現出明顯的缺損。這是否是因為他們缺乏有效率的新詞學習機制？換言之，語言發展遲緩幼兒除了「名詞」學習困難，是否也同時出現「動詞」學習困擾？為了探討此議題，本研究利用新詞學習作業檢視語言發展遲緩幼兒的新詞學習機制，同時利用眼動軌跡技術來探究兒童的新詞即時學習歷程。 本研究對象為三到四歲之幼兒，包括了語言發展遲緩組（n = 25; 平均年紀 = 46 個月）和年齡配對的對照組 （n = 26; 平均年紀 = 48 個月）。新詞學習作業分為「新詞-指涉物配對」和「新詞記憶提取」兩個階段—分別檢驗幼兒是否能在學習新詞後，立即正確選擇與新詞配對之指涉物（即，名詞學習情境）或動作（即，動詞學習情境）。以及新詞學習五分鐘後，是否能記住該詞彙？本研究利用手指指認詞彙圖片之正確率、與眼動指標「注視目標新詞比例（Target-looking ratio）」及「目光移動到目標詞的時間（Latency）」，來評估幼兒的詞彙學習表現。 結果發現語言發展遲緩幼兒和一般發展幼兒，在新詞學習作業的兩個階段（新詞指涉物配對、新詞記憶）皆存在顯著的差異。另外，動詞和名詞學習也有顯著的詞類差異，兩組幼兒在動詞學習的表現皆較名詞來得差。此外，僅有動詞學習相關的指認表現與眼動指標有中度相關。階層性回歸模型結果顯示，在控制年齡和非語言智力後，兩組幼兒的動詞目標注視比例，可以預測新詞學習作業中動詞指涉物配對的正確率；而語言發展遲緩組中，注視目標時長比例預測名詞在指涉物配對階段之新詞學習表現；動詞學習方面，注視目標時間比例和目光移動到目標物的時間，預測其指涉物配對階段之新詞學習表現。總結而言，本研究結果顯示語言遲緩幼兒名詞及動詞的學習歷程缺損，而且這些缺損影響新詞的學習表現。本研究結果也意涵動詞詞彙學習能力在提升語言障礙兒童語言能力之重要性，建議納入語言早期療育的目標。

Previous studies highlighted word learning deficits in children with Developmental Language Disorder (DLD), focusing predominantly on noun learning (Golinkoff et al.,1992, Horst & Samuelson, 2008). However, given the ambiguity of verb-referent mapping, children often face more significant challenges in acquiring novel verbs compared to nouns (Gentner, 1982, 2006). Mandarin, renowned for its verb-friendly structure, raises questions about whether its argument-dropping feature facilitates verb learning in young children. Studies indicate that Mandarin-speaking toddlers exhibit a higher proportion of verbs in their lexicon, underscoring the significance of understanding the complexities of verb learning during early language development (Tardif et al., 1996). Addressing this gap on verb learning in DLD children, this study explored word learning differences between children with DLD (n = 25; M age = 46 months) and age-matched typically developing (TD) (n = 26; M age = 48 months) children, focusing on acquiring nouns and verbs across various phases of word learning. The word-learning experiment of this study integrated referential selection and new-word retention tasks with eye-tracking and picture pointing measures to assess word learning processes at three phases: training, word selection, and retention. Results reveal significant group differences in novel word learning between TD and DLD children, with consistent challenges observed across the word-referent selection and retention phases. A marked discrepancy in word classes emerges, indicating lower accuracy in verb learning than noun learning. Furthermore, results indicate moderate correlations between gaze patterns and picture pointing accuracy, particularly in verb conditions after controlling for age and nonverbal IQ. Specifically, a higher target-looking ratio during word-referent mapping was associated with more accurate pointing in both word-referent mapping and word retention phases. Hierarchical regression models of the whole sample further indicated that the target-looking ratio was a significant predictor of novel verb learning, particularly during the word-referent selection phase. For the DLD group, results of regression model revealed intriguing findings: latency emerged as a significant predictor of pointing accuracy during the word-referent selection phase for noun learning, while the target-looking ratio significantly accounted for the variance of verb learning. This indicated that the gaze duration on the target predicted picture-pointing accuracy in word-referent mapping phase among children with DLD, a pattern not observed in the TD group. This study offers valuable insights into word learning mechanisms in children with DLD, particularly emphasizing the challenges of learning novel verbs. Results of this study implicated that early verb word learning abilities would be vital in predicting language development in children with DLD and suggested that verb learning would be included in the early intervention program to better alleviate the language-learning difficulties in children with DLD.