Optimality Theory account of height alternations

165

5.4 Explanation of height-changing alternations

It is interesting to consider the motivation and possible explanations for Ikoma’s unusual prefix alternations. Stewart 1967, in an effort to understand cross-height vowel harmony, says, “Assimilation, in my experience, always involves the assimilated sound becoming more like the sound to which it is assimilated.” By this standard definition, we have already noted that Ikoma’s prefix patterns cannot rightly be considered a case of assimilation. Instead, it more closely resembles what we might consider to be dissimilation. What could the motivation be for such an interesting pattern? Arguments explaining Ikoma’s prefix patterns could be made from a number of different perspectives, but here I outline two in particular. In §5.4.1 I argue that the height change can be modeled in Optimality Theory, and is in fact a predicted repair strategy for an [ATR] harmony clash. In §5.4.2 I suggest that it is possible that the pattern is motivated by perceptual factors as well. These are not necessarily mutually exclusive arguments, so I do not attempt to argue between them.

5.4.1 Optimality Theory account of height alternations

In this section, I offer an account of prefix height alternations in Optimality Theory. I propose a set of constraints and illustrate them with variable constraint rankings and tableaus. I show that different orderings of the same set of constraints are capable of producing not only the Bantu C pattern of [-ATR] spreading to prefixes, but also the less- typical [-ATR]-triggered height alternations which are found in Ikoma. The analysis I present here assumes a vowel system in which [-ATR] is marked, especially since the evidence in the prefix patterns points strongly to [-ATR] markedness. Two points in particular are convincing. First, as previously established, [-ATR] vowels 166 trigger the alternation, which is evidence of their markedness. Second, the [-ATR] vowels [ ] do not occur at all in prefixes. This distributional restriction is also an indication of their markedness, since marked features and segments often have greater distributional restrictions than unmarked ones Rice 2007. Based on this evidence, I choose to use underspecification as a way to directly encode [-ATR] markedness. 66 See also §7.2 for more discussion on [ATR] markedness. An analysis of the Ikoma pattern could go two different ways. A positional markedness analysis could prohibit [-ATR] mid vowels from surfacing in prefixes. 67 The fact that [ ] never occurr in prefixes is a striking generalization that should be accounted for somewhere. Another option is a positional faithfulness analysis, in which, instead of prohibiting [-ATR] in some positions, we instead preserve it in other positions, especially in the stem. This second option is the one I use here, though both strategies could achieve the same goal. Prefix dissimilation could be formalized using the set of constraints in 134 below. Note that my purpose here is not to argue any specific theoretical points concerning the types of constraints used, but simply to illustrate what a possible OT analysis of these patterns might look like. 66 Though the standard OT notion of Richness of the Base does not allow for crucial reliance on underlying representations, underspecification is nonetheless a clear and direct way of encoding markedness. Some e.g. Causley 1999, Casali 2003 argue that the use of underspecification in OT should not be so quickly dismissed. 67 Note that Anderson 1999 describes a situation in Akposso, which is a ten-vowel system in which has a phonemic [+ATR] counterpart . The low [+ATR] vowel is allowed only in roots, not in affixes. In affixes, however, the less marked vowel e serves as the [+ATR] counterpart to . The Akposso pattern could be seen as similar to the situation in Ikoma in which the more natural prefix alternation would result in [ ] in prefixes, but because these vowels are not allowed to surface in prefixes, the high vowels i u are used instead. 167 134 Constraints relevant to Ikoma’s prefix alternation a. A GREE [ATR] Adjacent vowels must agree in their specification for the feature [ATR]. b. A GREE - HI [ATR] Adjacent [-HI] vowels must agree in their specification for the feature [ATR] with any other [-HI] vowel. c. [-ATR] No [-ATR] vowels. d. M AX -ATR A [-ATR] feature in the input must have a corresponding feature in the output. e. M AX - STEM -ATR A [-ATR] feature in the stem of the input must have a corresponding feature in the output. f. D EP -ATR A [-ATR] feature in the output must have a corresponding feature in the input. g. M AX -H I A [HI] feature in the input must have a corresponding feature in the output. Because there are clearly restrictions on adjacent mid and low vowels with different [ATR] values, we need a constraint enforcing [ATR] harmony. For this purpose I use a set of A GREE [ATR] constraints similar to the “no disagreement” constraints proposed by Pulleyblank 2002, one of which applies generally to all vowels, and one of which applies only to [-high] vowels. As I show below, the more specific constraint referring to [-high] vowels is the active one in Ikoma, whereas the general one is ranked lower and does not have an effect in the prefix dissimilation pattern. Adjacent vowels can have different [ATR] values as long as they have different values for [high]. A sequence of u… is then ok, because u is high and is mid, but o…a is not allowed because they are both [-high]. Aside from the A GREE constraints, I also use the markedness constraint [-ATR] and the two faithfulness constraints M AX -ATR and M AX - STEM -ATR to preserve [-ATR] in the stem while disallowing it in prefixes. As shown below, the ranking M AX - STEM -ATR [-ATR] M AX -ATR has this effect, even if we have a [-ATR] 168 underlying form. Another constraint, M AX -H I , is relevant because Ikoma prefix dissimilation violates it, while the Bantu C-type [-ATR] spreading does not. I begin by illustrating the Bantu C-type pattern in order to show how these constraints work with a more normal assimilation process. The constraints above are ordered into the ranking in 135 below, which is illustrated in the tableau in 136. 135 Relative ordering of constraints for [-ATR] spreading Bantu C type A GREE -HI [ATR], M AX -H I , M AX - STEM -ATR M AX -ATR, D EP -ATR, [-ATR], A GREE [ATR] 136 Tableau showing the Bantu C ranking ko- k A GREE -HI [ATR] M AX -H I M AX - STEM -ATR M AX -ATR D EP -ATR [-ATR] A GREE [ATR] ku- k k - k ko- k ko- oko For the sake of comparing the prefix patterns in Ikoma and Bantu C, in these tableaux I ignore the augment vowel which is not present in Bantu C, and which does not alternate in Ikoma and focus only on the alternation of the noun class prefix. As shown above, the correct form, in which the prefix remains mid but alternates to [-ATR], is easily derived with this ranking. A GREE -HI [ATR] requires the surface form to be harmonic. M AX -H I prevents a height change, and M AX - STEM -ATR ensures that harmony is not enforced by altering the stem vowels. Reranking the same set of constraints also results in the height alternation in Ikoma prefixes, shown in 137 below and illustrated in the tableaux in 138 and following. 169 137 Relative ordering of constraints for height alternation Ikoma type D EP -ATR, A GREE -HI [ATR], M AX - STEM -ATR [-ATR] M AX -ATR, A GREE [ATR], M AX -H I 138 Tableau showing the Ikoma ranking with a [-ATR] mid-vowel stem ko- k D EP -ATR A GREE -HI [ATR] M AX - STEM -ATR [-ATR] M AX -ATR A GREE [ATR] M AX -H I ku- k k - k ko- k ko- oko The tableau above illustrates the proposed ranking for Ikoma using underlying [-ATR] mid vowels in the stem. D EP -ATR prevents [-ATR] spreading to the prefix, but A GREE -HI [ATR] requires that something else must be done to enforce [ATR] agreement. Even though the winning candidate [ku- k ] violates A GREE [ATR] by having a [+ATR] prefix and a [-ATR] stem, it does not violate A GREE -HI [ATR], since mid and high vowels do not have to agree for [ATR]. The tableaux in 139 and 140 show how the same ranking applies to [+ATR] mid vowel stems and high vowel stems, respectively. In both cases, the losing candidates unnecessarily violate M AX -HI. 139 Tableau showing the Ikoma ranking with a [+ATR] mid-vowel stem ko- oko D EP -ATR A GREE -HI [ATR] M AX - STEM -ATR [-ATR] M AX -ATR A GREE [ATR] M AX -H I ko- oko ku- oko 170 140 Tableau showing the Ikoma ranking with a high-vowel stem ko- uku D EP -ATR A GREE -HI [ATR] M AX - STEM -ATR [-ATR] M AX -ATR A GREE [ATR] M AX -H I ko- uku ku- uku A tableau for a stem vowels is in 141 below. 141 Tableau showing the Ikoma ranking with a low-vowel stem ko- aka D EP -ATR A GREE -HI [ATR] M AX - STEM -ATR [-ATR] M AX -ATR A GREE [ATR] M AX -H I ku- aka ko- aka k - aka Once again, D EP -ATR prevents [-ATR] spreading to the prefix, yet A GREE -HI [ATR] still requires [ATR] agreement. Therefore, lowly-ranked M AX -HI is violated, and the optimal candidate has a high prefix vowel. This same set of constraints also prevents [ ] from surfacing in prefixes, even in the case of a [-ATR] prefix, if such an underlying form existed. For example, in 142 below, even if we suppose an underlying form such as k - k , this analysis still ensures that [ku- k ] is the optimal candidate. 142 Tableau showing the Ikoma ranking with a [-ATR] prefix underlyingly k - k D EP -ATR A GREE -HI [ATR] M AX - STEM -ATR [-ATR] M AX -ATR A GREE [ATR] M AX -H I ku- k k - k ko- k ko- oko 171 As the above examples show, the same set of constraints predicts both the Bantu C pattern and the Ikoma pattern. And the same ranking of constraints predicts the correct height alternations for all four types of stem vowels high, mid [+ATR], mid [-ATR] and low. A summary of three different rankings of these constraints and their outcomes is in 143 below. 143 Typological predictions for underlying form ko- k Crucial Constraint Rankings Outcome Example a. D EP -ATR, A GREE -HI [ATR], M AX - STEM -ATR [-ATR] M AX -ATR, A GREE [ATR], M AX -H I prefix height alternation Ikoma ku- k b. A GREE -HI [ATR], M AX -H I , M AX - STEM -ATR M AX -ATR, [-ATR], A GREE [ATR], D EP -ATR prefix ATR alternation some Bantu C languages k - k c. M AX -H I , M AX -ATR, M AX - STEM -ATR, D EP -ATR A GREE -HI [ATR], [-ATR], A GREE [ATR] no harmony some Bantu C languages ko- k Ranking a works for Ikoma, and b for the Bantu C pattern. Note that ranking c was not discussed above. It results in a language with no prefix harmony at all, which is actually the case for a number of other Bantu C languages Leitch 1997.

5.4.2 Perceptual motivation