本論文探討五歲漢語兒童情態詞習得的情形。實驗一利用隱藏盒子實驗(Hidden Box Task)探討五歲兒童對於認知情態詞(epistemic modal)「可能」和「一定」的理解。實驗結果顯示，兒童在確定情境(the determined condition)下表現與大人無異，然而在不確定的情境(the undetermined condition)下則非如此。兒童有正向偏誤(positive bias)及不成熟的結論(premature closure)的傾向都顯示出他們在不確定的情境中有認知上的困難。和Moscati & Crain (2014)和 Moscati, Zhan,& Zhou (2016)的研究綜合來看，我們推論語言中情態詞的數量對於兒童學習情態詞是有影響的。實驗二探討五歲兒童是否有等級隱涵(scalar implicature)的語用能力。實驗結果顯示，兒童無法在隱藏盒子實驗(Hidden Box Task)中，展現出等級隱涵的能力。意即在符合「一定」的情境中，兒童接受使用較弱的情態詞「可能」去描繪該情境。

實驗三利用真假值實驗判斷(Truth Value Judgment Task)的實驗方式探討五歲兒童對於否定句中的情態詞的理解。實驗結果支持語義次級原則(Semantic Subset Principle)。不論句法位置的先後次序，漢語兒童皆先習得語義較強的陳述，其次才是語義較弱的陳述。縱觀三個實驗的結果，五歲兒童在不確定的情境及在理解語義較弱的情態陳述所遇到的困難可能來自同一個因素—在認知上無法處理多重可能性。換而言之，五歲兒童在認知發展上尚未能處理多重可能性，此因素阻礙了兒童在情態詞上的習得。

The purpose of the thesis is to investigate 5-year-old Mandarin-speaking children’s interpretation of modals. Using the Hidden Box Task, Experiment 1 was designed to test 5-year-old Mandarin-speaking children’s understanding of the epistemic modals yiding ‘must’ and keneng ‘might’. The results revealed that children’s performance was adult-like in the determined condition but not in the undetermined condition. Children’s difficulty in contexts of uncertainty was reflected by both positive bias and the tendency of Premature Closure. Compared with the results from Moscati and Crain (2014) and Moscati, Zhan & Zhou (2016), we suggested that the lexical size of modal expressions had impacts on learning epistemic modals. Experiment 2 investigated children’s ability to derive scalar implicature. The results revealed that 5-year-old children did not generate scalar implicature in the Hidden Box Task. They consistently accepted the weak expression keneng ‘might’ when the scenario was compatible with the strong modal yiding ‘must’.
Experiment 3 examined children’s understanding of negative sentences with the epistemic modals yinggai ‘should’ and yiding ‘must’. The findings supported the Semantic Subset Principle that children acquire the strong expressions earlier than the weak expressions, regardless of the word order. By unifying the results of the three experiments, we suggested that the difficulty in undetermined condition and interpreting the weak expression may come from the same source: the cognitive difficulty in coping with multiple possibilities. That is, the cognitive difficulty in coping with multiple possibilities hinders 5-year-old Mandarin-speaking children from demonstrating their modal competence.

Acredolo, C. & Horobin, K. (1987). Development of relational reasoning and premature
closure. Developmental Psychology, 23(1), 13-21.
Byrnes, J. P., & Overton, W. E. (1986). Reasoning about certainty and uncertainty in concrete, causal, and propositional contexts. Developmental Psychology, 22, 793–799.
Byrnes, J. P., Duff, Michelle A. (1989). Young children's comprehension of modal expressions. Cognitive Development 4(4), 369-387.
Cinque, G. (1999). Adverbs and Functional Heads: A Cross-linguistic Perspective. New York: Oxford University Press.
Coates, J. (1983). The Semantics of the Modal Auxiliaries. London: Croom.
Coates, J. (1995). The expression of root and epistemic possibility in English. In Bybee, J. L. and Fleischman, S. (Eds.), Modality in Grammar and Discourse (pp. 55-66). Amsterdam and Philadelphia: John Benjamins.
Crain, S., Thornton, R., Boster, C., Conway, L., Lillo-Martin, D., & Woodams, E. (1996). Quantification without qualification. Language Acquisition, 5(2), 83-153.
Crain, S., Weijia N. & Laura C. (1994). Learning, parsing and modularity. In Charles Clifton, Lyn Frazier & Keith Rayner (Eds.), Perspectives on Sentence Processing (pp. 443-467). Hillsdale, NJ: Lawrence Erlbaum.
Drozd, Kenneth, and Erik van L.(1999). Weak quantification, plausible dissent, and the development of children’s pragmatic competence. In Annabel Greenhill, Heather Littlefield, and Cheryl Tano (Eds.), Proceedings of the 23rd Boston University Conference on Language Development (pp. 184–195). Somerville: Cascadilla Press.
Fay, A. L., & Klahr, D. (1996). Knowing about guessing and guessing about knowing: Preschoolers’ understanding of indeterminacy. Child Development, 67, 689–716.
Geurts, B. (2003). Quantifying kids. Language Acquisition, 11, 197-218.
Green, M. G. (1979). The developmental relation between cognitive stage and the comprehension of speaker’s uncertainty. Child Development, 50, 666–674.
Grice, H.P. (1975). Logic and conversation. In Cole, P. & Morgan, J. (Eds.), Syntax and Semantics, Volume 3 (pp. 41-58). New York: Academic Press.
Gualmini, A., & Moscati, V. (2009). The early steps of modal and negation interactions: Evidence from child Italian. In E.Aboh, E. van der Linden, J. Quer, & P. Sleeman (Eds.), Romance Languages and Linguistic Theory. Amsterdam, the Netherlands: John Benjamins.
Guo, J. S. (1994). Social Interaction, Meaning and Grammatical Form: Children’s Development and Use of Modal Auxiliaries in Mandarin Chinese (Unpublished doctoral dissertation). University of California, Berkeley.
Hintikka, J. (1969). Models for Modalities. Dordrecht: Reidel Publishing Company.
Hirst, W., & Weil, J. (1982). Acquisition of epistemic and deontic meaning of modals. Journal of Child Language, 9(3), 659-666.
Horobin, K., & Acredolo, C. (1989). The impact of probability judgments on reasoning about multiple possibilities. Child Development, 60, 183–200.
Howlin, P., Baron-Cohen, S., & Hadwin, J. A. (1999). Teaching Children with Autism to Mind-read: A Practical Guide for Teachers and Parents. J. Wiley & Sons.
Klahr, D., & Chen, Z. (2003). Overcoming the positive-capture strategy in young children: Learning about indeterminacy. Child Development, 74, 1275–1296.
Kripke, S. (1959). A completeness theorem in modal logic. Journal of Symbolic Logic, 24, 1–14.
Lin, J., & Tang, C. (1995). Modals as verbs in Chinese: A GB perspective. The Bulletin of the Institute of History and Philology, 66(1), 53-105.
Lin, T. (2012). Multiple-modal constructions in Mandarin Chinese and their finiteness properties. Journal of Linguistics, 48(1), 151-186.
Liu, C., & Lee, H. (2014). Modality and Children's Scope Understanding. Journal of Psycholinguistic Research, 43(5), 487-.506
Lyons, J. (1977). Semantics. Cambridge: Cambridge University Press.
Moore, C., Pure, K., & Furrow, D. (1990). Children's understanding of the modal expression of speaker certainty and uncertainty and its relation to the development of a representational theory of mind. Child Development, 61(3), 722-730.
Moscati, V., & Crain, S. (2014). When negation and epistemic modality combine: the role of information strength in child language. Language Learning and Development, 10(4), 345-380.
Moscati, V., Zhan, L., & Zhou, P. (2016). Children's on-line processing of epistemic modals. Journal of Child Language, 1-16.
Noveck, I. A. (2001). When children are more logical than adults: Experimental investigations of scalar implicature. Cognition, 78(2), 165-188.
Noveck, I. A., Ho, S., & Sera, M. (1996). Children's understanding of epistemic modals. Journal of Child Language, 23(3), 621-643.
Ozturk, O., & Papafragou, A. (2014). The acquisition of epistemic modality: From semantic meaning to pragmatic interpretation. Language Learning and Development, 1-24.
Palmer, F.R. (2001). Mood and Modality. 2nd edition. Cambridge: Cambridge University Press.
Papafragou, A. (1998). The acquisition of modality: Implications for theories of semantic representation. Mind & language, 13(3), 370-399.
Piaget,J., & Inhelder, B. (1969) The Psychology of the Child. New York: Basic Books, Inc.
Radden, G., & Dirven, R. (2007). Cognitive English Grammar. Amsterdam: John Benjamins.
Rizzi, Luigi. (1997). The Fine Structure of the Left Periphery. In Haegeman, L (Ed.), Elements of Grammar (pp. 281-338). Dordrecht: Kluwer.
Robinson, E., Rowley, M., Beck, S., Carroll, D., & Apperly, I. (2006). Children’s sensitivity to their own relative ignorance: Handling of possibilities under epistemic and physical uncertainty. Child Development, 77, 1642–1655.
Tsai, W.-T. Dylan. (2010). On the syntax-semantics correspondence of Chinese modals. Studies of the Chinese Language, 3, 208-221.
Tsai, W.-T. Dylan. (2015). On the Topography of Chinese Modals. In Ur Shlonsky (Ed.), Beyond Functional Sequence (pp. 275-294). New York: Oxford University Press.
von Fintel, Kai, & Sabine Iatridou. (2008). How to say ought in Foreign: the composition of weak necessity modals. In J. Guéron & J. Lecarme (Eds.), Time and Modality (pp. 115–141). Dordrecht: Springer.
von Fintel, Kai. (2006). Modality and language. In Donald M. Borchet (Ed.), Encyclopedia of Philosophy (pp. 20-27). New York: Macmillan.