我們反對不徵（underpsecification），取而代之的是可視性理論（the Visibility Theory）。在該理論中，基底的音徵是全部標出的，同時，規則∕限制可以標誌成是和對比（contrastive）、有標（marked）或全部的音徵作用。利用這樣的分別解釋（不）透明性且不會導致連接線交叉的情形。
我們將可視性理論套用到台灣話的鼻化及匈牙利語的元音和諧。
我們提出兩條鼻音擴散規則以解釋台灣話的鼻化。其中一條是以音節為範疇、與有標音徵作用；另一條則是以音步為範疇、與全部音徵作用。鼻母音和音節鼻音的[+鼻]可以擴散但鼻音的卻不可以，藉由不同類型的音徵得到了解釋。為了照顧音節縮略和祕密語，我們認為這兩條規則是循環性（cyclic）的。音節縮略後有一個循環，然而祕密語其後則有兩個循環。
我們視匈牙利語的元音和諧為與對比音徵作用、從詞根擴散有標[+後]至後綴的結果。關於[epsilon]作為中性（neutral）母音還是和諧母音此一爭論已久的問題，可視性理論認為是後者—此一觀點有部分的實證支持。再者，e[length]-a[length]轉換不視為是元音和諧的一部份，因為e[length]的不對比性致使其無法被和諧現象所見。就可視性理論來說，排除該轉換於和諧現象之外，實提升了匈牙利語音韻的經濟性。

Underspecification is argued against. The vacancy thus created is replaced by the Visibility Theory. In the Visibility Theory, features are fully specified in the underlying representation and rules/constraints are said to have access to contrastive, marked, or all feature specification. Different accessibilities account for the transparency/opacity without association line crossing.
The Visibility Theory is put into use to cope with the nasalization in Taiwanese and the vowel harmony in Hungarian.
The nasalization in Taiwanese is explained by two nasal spreading rules. In one, the rule has syllable as its domain and access to marked feature specification. In the other, the rule has foot as its domain and access to all feature specification. That [+nasal] of nasal vowel or syllabic nasal can be spread but of (plain) nasal cannot is explained by the accessibility difference. Syllable contraction and secret language transformation are dealt with by assuming that the two rules are cyclic. There is one cycle after syllable contraction, but there are two cycles after secret language transformation.
The vowel harmony in Hungarian is realized as having access to contrastive feature specification and spreading the marked [+back] from root to suffix. That long-debated question of whether [epsilon] is a neutral or harmonic vowel is answered by the Visibility Theory as being harmonic, which is partially supported by the empirical evidence. The alternation e[length]-a[length] is not considered as vowel harmony because the vowel harmony rule cannot see the noncontrastive e[length]. The elimination of the alternation from the vowel harmony enhances the economicity of the Hungarian phonology from the Visibility Theory perspective.

Ang, Uijin [洪惟仁]. 2002. Taiwanhua biyin shentou de OT fensi [An OT analysis of nasal percolation in Taiwanese; 台灣話鼻音滲透的OT分析]. Tsing Hua Journal of Chinese Studies 31.3 (new series): 197-248.
Archangeli, Diana. 1984. Underspecification in Yawelmani Phonology and Morphology. Ph.D. dissertation, Massachusetts Institute of Technology.
Bao, Zhiming [包智明]. 1990. Fanqie languages and reduplication. Linguistic Inquiry 21.3: 317-350.
Blevins, Juliette. 1995. The syllable in phonological theory. In Goldsmith. 206-244.
Bromberger, Sylvain, and Morris Halle. 1989. Why phonology is different. Linguistic Inquiry 20.1: 51-70.
Calabrese, Andrea. 1988. Towards a Theory of Phonological Alphabets. Ph.D. dissertation, Massachusetts Institute of Technology.
Calabrese, Andrea. 1993. The notion of phonological complexity in phonological theory. In Höskuldur Thráinsson, Andrea Calabrese, Jill Carrier, Mark Hale, and Calvert Watkins (eds.), Harvard Working Papers in Linguistics 2. Cambridge, MA: Harvard University Department of Linguistics. 3-75.
Calabrese, Andrea. 1994. A constraint-based theory of phonological inventories. In W. U. Dressler, M. Prinzhorn, and J. R. Rennison (eds.), Phonological 1992: Proceedings of the 7th Inernational Phonology Meeting. Torino: Rosenberg & Sellier. 35-54.
Calabrese, Andrea. 1995. A constraint-based theory of phonological markedness and simplification procedures. Linguistic Inquiry 26.3: 373-463.
Calabrese, Andrea. 2005. Markedness and Economy in a Derivational Model of Phonology. Berlin: Mouton de Gruyter.
Calabrese, Andrea. 2009. Markedness theory versus phonological idiosyncrasies in a realistic model of language. In Raimy and Cairns. 261-304.
Carr, Philip. 2008. A Glossary of Phonology. George Square, Edinburgh: Edinburgh University Press.
Catford, J. C. 1977. Fundamental Problems in Phonetics. George Square, Edinburgh: Edinburgh University Press.
Cheng, Ming-chung [鄭明中]. 2006. A unified OT analysis of labial dissimilation, nasalization and nasal dissimilation in Taiwanese. Journal of Shu-Te University 8: 75-86.
Cho, Tsai-Yun [周彩雲]. 2001. An Optimality-Theoretic Analysis on Southern Min Nasality. MA thesis, National Kaohsiung Normal University.
Chomsky, Noam. 1993. Lectures on Government and Binding: The Pisa Lectures. 7th ed. Berlin: Mouton de Gruyter.
Chung, Inkie. 2007. Ecology of PF: A Study of Korean Phonology and Morphology in a Derivational Approach. Ph.D. dissertation, University of Connecticut.
Chung, Raung-fu [鍾榮富]. 1996. The Segmental Phonology of Southern Min in Taiwan. Taipei City: The Crane Publishing Co., Ltd.
Clements, G. N. 1993. Underspecification or nonspecification?. In Andreas Kathal and Michael Bernstein (eds.), ESCOL ’93: Proceedings of the Tenth Eastern States Conference on Linguistics. Ithaca, NY: Cornell University Department of Modern Languages and Linguistics. 58-80.
Clements, George N. 2000. In defense of serialism. The Linguistic Review 17.2-4: 181-197.
Clements, G. N. 2001. Representational economy in constraint-based phonology. In T. Alan Hall (ed.), Distinctive Feature Theory. Berlin: Mouton de Gruyter. 71-146.
Clements, G. N. 2003. Feature economy in sound systems. Phonology 20.3: 287-333.
Clements, G. N. 2009. The role of features in phonological inventories. In Raimy and Cairns. 19-68.
Crystal, David. 2008. A Dictionary of Linguistics and Phonetics. 6th ed. Malden, MA: Blackwell Publishing.
Dahl, Anne. 2004. Negative evidence in L2 acquisition. In Kristine Bentzen (ed.), Nordlyd: Tromsø University Working Papers on Language and Linguistics 32.1: Tromsø Working Papers in Language Acquisition. Tromsø: University of Tromsø Faculty of Humanities. 28-45.
Davis, Stuart. 2000. Some analytical issues in Optimality Theory. The Linguistic Review 17.2-4: 117-133.
Durand, Jacques. 1990. Generative and Non-Linear Phonology. London: Longman.
Elson, Mark J. 2003. Book notice of Siptár and Törkenczy (2000). Language 79.3: 668.
Fikkert, Paula. 1995. The role of negative evidence in the acquisition of phonology. Publikaties van het Instituut voor Algemene Taalwetenschap 67: 33-52.
Frampton, John. 2002. What kind of thing is a language faculty?: A critical evaluation of OT phonology. Glot International 6.1: 3-11.
Fromkin, Victoria A. 1972. Discussion paper on speech physiology. In UCLA Working Papers in Phonetics 23. Los Angeles, CA: UCLA Department of Linguistics. 37-60.
Goldsmith, John. 1985. Vowel harmony in Khalkha Mongolian, Yaka, Finnish and Hungarian. In Colin J. Ewen and John M. Anderson (eds.), Phonology Yearbook 2. Cambridge: Cambridge University Press. 253-275.
Goldsmith, John A. (ed.). 1995. The Handbook of Phonological Theory. Cambridge, Massachusetts: Blackwell Publishers.
Goldsmith, John, and Manuela Noske. 2006. Autosegmental phonology and underspecfication theory. In Sylvain Auroux, E. F. K. Koerner, Hand-Josef Niederehe, and Kees Versteegh (eds.), History of the Language Sciences: An International Handbook on the Evolution of the Study of Language from the Beginnings to the Present. Vol. 3. Berlin: Walter de Gruyter. 2280-2292.
Halle, Morris. 1995. Feature geometry and feature spreading. Linguistic Inquiry 26.1: 1-46.
Halle, Morris. 2002. Introduction. In Morris Halle, From Memory to Speech and Back: Papers on Phonetics and Phonology 1954-2002. Berlin: Mouton de Gruyter. 1-17.
Halle, Morris. 2005. Palatalization/velar softening: What it is and what it tells us about the nature of language. Linguistic Inquiry 36.1: 23-41.
Halle, Morris, Bert Vaux, and Andrew Wolfe. 2000. On feature spreading and the representation of place of articulation. Linguistic Inquiry 31.3: 387-444.
Hume, Elizabeth, and Georgios Tserdanelis. 2002. Labial unmarkedness in Sri Lankan Portuguese Creole. Phonology 19.3: 441-458.
Idsardi, William J. 2000. Clarifying opacity. The Linguistic Review 17.2-4: 337-350.
Jensen, John T. 1984. A lexical phonology treatment of Hungarian vowel harmony. Linguistic Analysis 14.2-3: 231-253.
Kager, René. 1999. Optimality Theory. Cambridge: Cambridge University Press.
Kaisse, Ellen M. 1992. Can [consonantal] spread?. Language 68.2: 313-332.
Kaisse, Ellen M., and Patricia A. Shaw. 1985. On the theory of Lexical Phonology. In Colin J. Ewen and John M. Anderson (eds.), Phonology Yearbook 2. Cambridge: Cambridge University Press. 1-30.
Katamba, Francis. 1989. An Introduction to Phonology. London: Longman.
Kaye, Jonathan D. 1971. Nasal harmony in Desano. Linguistic Inquiry 2.1: 37-56.
Kaye, Jonathan. 1989. Phonology: A Cognitive View. Hillsdale, New Jersey: Lawrence Erlbaum Associates, Publishers.
Kenesei, István, Robert M. Vago, and Anna Fenyvesi. 1998. Hungarian. London: Routledge.
Kenstowicz, Michael. 1994. Phonology in Generative Grammar. Malden, MA: Blackwell Publishing.
Kiparsky, Paul. 1973. “Elsewhere” in phonology. In Stephen R. Anderson and Paul Kiparsky (eds.), A Festschrift for Morris Halle. New York: Holt, Rinehart and Winston, Inc. 93-106.
Kiparsky, Paul. 1982. From cyclic phonology to lexical phonology. In Harry van der Hulst and Norval Smith (eds.), The Structure of Phonological Representations. Part I. Dordrecht: Foris Publications. 131-175.
Kiparsky, Paul. 1993. Blocking in nonderived environments. In Sharon Hargus and Ellen M. Kaisse (eds.), Studies in Lexical Phonology. San Diego: Academic Press, Inc. 277-313.
Kuhn, Thomas S. 1996. The Structure of Scientific Revolutions. 3rd ed. Chicago: The University of Chicago Press.
Ladefoged, Peter. 1973. The features of the larynx. Journal of Phonetics 1.1: 73-83.
Li, Paul Jen-kuei [李壬癸]. 1992. Minnanyu de biyin wunti [The nasality problem in Taiwanese; 閩南語的鼻音問題]. In Academia Sinica Institute of History and Philology Publications Editing Committee (ed.), Chinese Language and Linguistics I: Chinese Dialects. Taipei City: Academia Sinica Institute of History and Philology. 423-435.
Lin, Yen-Hwei [林燕慧]. 1989. Autosegmental Treatment of Segmental Processes in Chinese Phonology. Ph.D. dissertation, The University of Texas at Austin.
Liu, Chia-long [劉家隆]. 2005. Nasalization in Southern Min: An Optimality Theory Analysis. MA thesis, National Kaohsiung Normal University.
Maddieson, Ian. 1984. Patterns of Sounds. Cambridge: Cambridge University Press.
McCarthy, John J. 2002. A Thematic Guide to Optimality Theory. Cambridge: Cambridge University Press.
McCarthy, John J. 2003. Sympathy, cumulativity, and the Duke-of-York Gambit. In Caroline Féry and Ruben van de Vijver (eds.), The Syllable in Optimality Theory. Cambridge: Cambridge University Press. 23-76.
Mohanan, K. P. 1991. On the bases of radical underspecification. Natural Language and Linguistic Theory 9.2: 285-325.
Murray, Thomas E. 1995. The Structure of English: Phonetics, Phonology, Morphology. Boston: Allyn and Bacon.
Nespor, Marina, and Irene Vogel. 1986. Prosodic Phonology. Dordrecht: Foris Publications.
Nespor, Marina, and Irene Vogel. 2007. Foreword to the second edition. In Marina Nespor and Irene Vogel, Prosodic Phonology: With a New Foreword. Berlin: Mouton de Gruyter. xiii-xxx.
Nevins, Andrew. 2007. Review of Calabrese (2005). Journal of Linguistics 43.1: 223-229.
Nevins, Andrew, and Ioana Chitoran. 2008. Phonological representations and the variable patterning of glides. Lingua 118.12: 1979-1997.
Nevins, Andrew, and Bert Vaux. 2008. Introduction: The division of labor between rules, representations, and constraints in phonological theory. In Vaux and Nevins. 1-19
Newton, Brian. 1972. The Generative Interpretation of Dialect: A Study of Modern Greek Phonology. Cambridge: Cambridge University Press.
Odden, David. 1992. Simplicity of underlying representation as motivation for underspecification. In Elizabeth Hume (ed.), The Ohio State University Working Papers in Linguistics 41: Papers in Phonology. Columbus, Ohio: The Ohio State University Department of Linguistics. 85-100.
Olson, Kenneth S., and Paul H. Schultz. 2002. Can [sonorant] spread?. In J. Albert Bickford (ed.), Work Papers of the Summer Institute of Linguistics, University of North Dakota Session 46. Grand Forks, ND: The Summer Institute of Linguistics at the University of North Dakota. 1-7.
Ploch, Stefan. 2001. Book review of Siptár and Törkenczy (2000). Available on http://linguistlist.org/pubs/reviews/get-review.cfm?SubID=3927. Last accessed March 1, 2009.
Prince, Alan, and Paul Smolensky. 2004. Optimality Theory: Constraint Interaction in Generative Grammar. Malden, MA: Blackwell Publishing.
Raimy, Eric, and Charles E. Cairns (eds.). 2009. Contemporary Views on Architecture and Representations in Phonology. Cambridge, Massachusetts: The MIT Press.
Reiss, Charles. 2001a. Book review of Siptár and Törkenczy (2000). Available on http://linguistlist.org/pubs/reviews/get-review.cfm?SubID=4053. Last accessed March 1, 2009.
Reiss, Charles. 2001b. Book review of Siptár and Törkenczy (2000). Available on http://linguistlist.org/pubs/reviews/get-review.cfm?SubID=4031. Last accessed March 1, 2009.
Reiss, Charles. 2003. Deriving the feature-filling/feature-changing contrast: An application to Hungarian vowel harmony. Linguistic Inquiry 34.2: 199-224.
Rice, Keren. 2008. Book review of Calabrese (2005). Language 84.3: 622-626.
Ringen, Catherine O. 1988. Transparency in Hungarian vowel harmony. Phonology 5.2: 327-342.
Ringen, Catherine O. 2005. Book review of Siptár and Törkenczy (2000). Acta Linguistica Hungarica 52.4: 427-434.
Ringen, Catherine O., and Robert M. Vago. 1998. Hungarian vowel harmony in Optimality Theory. Phonology 15.3: 393-416.
Ritter, Nancy Ann. 1995. The Role of Universal Grammar in Phonology: A Government Phonology approach to Hungarian. Ph.D. dissertation, New York University.
Roca, Iggy. 1994. Generative Phonology. London: Routledge.
Rubach, Jerzy. 1994. Affricates as strident stops in Polish. Linguistic Inquiry 25.1: 119-143.
Siptár, Péter, and Miklós Törkenczy. 2000. The Phonology of Hungarian. Oxford: Oxford University Press.
Steriade, Donca. 1995. Underspecification and markedness. In Goldsmith. 114-174.
Turcsán, Gábor. 2002. Short notice of Siptár and Törkenczy (2000). Journal of Linguistics 38.1: 189-190.
Vago, Robert M. 1976. Theoretical implications of Hungarian vowel harmony. Linguistic Inquiry 7.2: 243-263.
Vajda, Edward J. 2004. Book review of Siptár and Törkenczy (2000). Word 55.3: 491-495.
Varga, László. 2001. Book review of Siptár and Törkenczy (2000). Phonology 18.2: 301-305.
Vaux, Bert. 2003. Syllabification in Armenian, universal grammar, and the lexicon. Linguistic Inquiry 34.1: 91-125.
Vaux, Bert. 2008. Why the phonological component must be serial and rule-based. In Vaux and Nevins. 20-60.
Vaux, Bert, and Andrew Nevins (eds.). 2008. Rules, Constraints, and Phonological Phenomena. Oxford: Oxford University Press.
Wang, H. Samuel [王旭]. 1995. Nasality as an autosegment in Taiwanese. In H. Samuel Wang [王旭], Experimental Studies in Taiwanese Phonology. Taipei City: The Crane Publishing Co., Ltd. 66-85.
Yip, Moira. 1982. Reduplication and C-V skeleta in Chinese secret languages. Linguistic Inquiry 13.4: 637-661.