2.1 The language

Southern Pomo is one of seven Pomoan languages of Northern California, which were traditionally spoken in the area around Clear Lake and the Russian River Valley. Kashaya (previously Southwestern Pomo) is genealogically the closest of these to Southern Pomo. Southern Pomo was the largest of the Pomo languages at the time of European contact, spoken by somewhere from 2,000 to 7,000 people in the area between modern-day Santa Rosa and Sebastopol, north to Cloverdale (Walker Reference Walker2020: 8). Colonial genocide of indigenous communities and the suppression of their languages left fewer than 100 speakers of Southern Pomo by 1900.

Elizabeth Dollar (1895–1971), Annie Burke (1876–1962) and her daughter Elsie Allen (1899–1990) were the primary contributors to Southern Pomo documentation. The majority of linguistic description was done by Abraham Halpern (e.g., Halpern Reference Halpern and Bright1964), Robert Oswalt (e.g., Oswalt Reference Oswalt, Langdon and Silver1976) and Neil Alexander Walker (Walker Reference Walker2020). The language is recently dormant, but there are active revitalisation efforts.Footnote ⁴

2.2 Syncope in Southern Pomo

2.2.2 Syncope, stress and metrical structure

Main stress in Southern Pomo falls on the penult (in words in isolation), with iterating secondary stresses on every other syllable from right to left (McLendon Reference McLendon1973; Walker Reference Walker2020). That is, the surface metrical structure counts from the right edge of the word in what has been characterised as a trochaic system (Buckley Reference Buckley2019), though I assume an unbracketed grid-based approach (Prince Reference Prince1983). Stress is quantity-insensitive: it falls on both light and heavy syllables, is not attracted to heavy syllables and is strictly alternating.Footnote ¹³ In strings with an odd number of syllables, syncope targets syllables which would be weak given regular surface stress, in line with the characterisation of syncope as targeting vowels in metrically weak positions. However, in underlying strings with even syllable parity, syncope targets positions that would be stressed if deletion had not occurred – an apparent misapplication. In both cases, there are also unstressed vowels in surface forms, unlike in Macushi. This pattern is schematised above in Table 1, partially reproduced below in Table 2:

Table 2 Syncope is irregular relative to stress.

Syncope is therefore not predictable based on surface metrical structure. The non-isomorphism between stress and syncope suggests that these two metrical phenomena are calculated based on separate metrical structures, which disagree in their direction of application: syncope occurs in the weak positions defined by a left-to-right alternating count, while surface stress corresponds to a right-to-left alternating count. The Southern Pomo data suggest a derivation with conflicting metrical structures at sequential stages and syncope taking place at the second stage.

The alternating-syllable deletion seen in these data is a quintessential mark of metrical conditioning, where deletion has occurred weak positions. The crosslinguistic evidence for vowel deletion in strong positions is only tenuous, and the existence of this phenomenon is disputed (McCarthy Reference McCarthy2008). We can thus conclude that the derivation first builds metrical structure from left to right, only assigning prominence to syllables which are not ultimately targeted for vowel deletion. Next, the weak positions undergo syncope, driven by a constraint against vowels in these positions. Finally, metrical structure must be reparsed from right to left, generating the observed surface stress. (11) presents a condensed rule-based schematisation of this system; in §3, I demonstrate a formal analysis of this pattern using SOT.

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The mechanics of the constraint-based analysis differ slightly – for instance, the second and third of the steps in (11) (syncope and reparsing) will occur in tandem. The crucial similarity in these accounts is that the metrical structure which conditions syncope must be different from the one responsible for surface stress. Syncope is metrically opaque, whether this pattern is formalised with rules or constraints.

2.3 Fourth-syllable syncope

The derivation in (22) identifies the location of syncope in the vast majority of Southern Pomo forms. However, a number of words instead exhibit deletion of what would be a penultimate fourth syllable, rather than deletion of the third underlying vowel (in what would be the antepenult). Several of these are shown in (23), alongside paradigmatically related words showing third-syllable deletion.

The examples in (23a)–(23c) show deletion in the fourth syllable when syncope in the third syllable would produce a licit form. (23d) shows fourth-syllable syncope occurring in a string where deletion of the vowel in the third syllable would produce an illicit cluster *[-t̪’md-], so syncope is not expected. This pattern does not appear to be related to the identity of the lexical root, as paradigmatically related words have syncope in the third position, nor is it explained by the specific suffixal morphology, as these morphemes appear in other words with the third-syllable pattern of deletion. Because the pattern of deletion varies within paradigms, it cannot be attributed to an item-specific process indexed to particular lexical roots, morphemes or morphosyntactic phases. Syncope also does not seem to ‘compromise’ by deleting in a position that produces a phonotactically licit form, as evidenced by the forms in (9) where syncope is blocked. Additionally, these forms show an implicational asymmetry: for any paradigm where fourth-syllable syncope occurs, there are also forms with third-syllable syncope, but the reverse does not hold. Further, as discussed below in §2.4, the regularity of third-syllable deletion in likely low-frequency contexts suggests that this process is productive. Deletion in the fourth syllable thus appears to be an exception to the descriptive generalisation that syncope targets vowels in the third syllable, which holds in all but a handful of words across the language.

However, we will see later in §4.3 that the grammar which produces these exceptional fourth-syllable forms also makes correct predictions for most (but not all) Southern Pomo words. Specifically, this grammar only generates the fourth-syllable syncope pattern in strings that would, without syncope, surface with five syllables and a light penult. §4.2 evaluates a parallel OT analysis where syncope is driven by the Stress-to-Weight Principle (SWP) and shows that it differs from the predictions of the stratal derivation for exactly these forms. To explain the variability between this SWP syncope grammar and the stratal syncope grammar, §5 approaches this conflict as a matter of grammar competition in the ranking of constraints (in particular, SWP) propelled of the scarcity of disambiguating evidence. First, I lay out a stratal analysis in §2.4 which accounts for the third-syllable syncope pattern.

2.4 Syncope as a productive process

Recent work has suggested that rhythmic syncope may be particularly prone to restructuring because of the computational complexity induced by alternating deletion (Hao & Bowers Reference Hao, Bowers, Nicolai and Cotterell2019; Bowers & Hao Reference Bowers and Hao2020). Rhythmic syncope systems in other languages such as Nishnaabemwin (Bowers Reference Bowers2019) and Eastern Slavic (Isačenko Reference Isačenko1970, :95–6) are reported to have quickly collapsed. In Southern Pomo, syncope is further complicated by the imposition of a different structure (surface stress) which could, in theory, condition further deletion. As a result, there is no surface-true generalisation about weak positions which explains the process. In addition, Gordon (Reference Gordon, Heinz, Goedemans and Hulst2016: 43) notes that phonological systems with competing iterative parses are not only rare but also unstable, with one metrical system typically fossilising in exceptions and morphologisation.

Given this, we must address whether rhythmic deletion was a synchronic process. Learning syncope requires robust evidence for vowel-zero alternations across the paradigm – evidence that is clearly present in Southern Pomo, as discussed in §2.2.2 and §2.4 There are robust vowel alternations in syncope with reduplication (shown in (6)–(8)), as the base of reduplication surfaces with the vowel that is absent in the reduplicant and most of these reduplicative bases also surface elsewhere as non-reduplicated forms. This strongly suggests that speakers are aware of the underlying phonological shape of the roots which undergo syncope. (4) and (5) show a number of intra-paradigm vowel– $\varnothing $ alternations in highly productive functional morphemes, as well. It seems likely that learners are able to learn accurate underlying representations, with vowels still in place. That is, they have evidence that syncope is a synchronically active process.

However, as we will see, the question is not simply whether deletion per se was synchronically active, but which mechanism was responsible. This requires an analysis of the systems underlying both the third- and fourth-syllable patterns of deletion. In §5, I return to this question, and propose that Southern Pomo at the time of observation was undergoing a change in progress, with ongoing grammar competition between these two systems.

3.1 Stratal Optimality Theory

Stratal OT is a derivational variant of classic Optimality Theory that recasts Lexical Phonology and Morphology in a constraint-based system. Phonological operations are driven by the interaction of constraints on input–output faithfulness and surface-oriented markedness, and candidate forms are evaluated on their satisfaction of all of these constraints in parallel. SOT differs from classic OT in that, while there is fully parallel evaluation, there are also multiple ordered stages, corresponding to morphological domains – typically the stem, word and post-lexical phrase. The constraint ranking of each subgrammar is fully independent of the others, such that marked structure may be preserved from an earlier stage by the promotion of a faithfulness constraint.

Stratal analyses of metrical opacity have been proposed to describe similar asymmetries between stress and metrically conditioned phenomena, including pre-pausal stress shift in Tiberian Hebrew (Churchyard Reference Churchyard1999), vowel lengthening and stress interactions in Tübatulabal (Uto-Aztecan, California; Benz Reference Benz2018; similarly suggested in Heath Reference Heath and Clements1981) and stress freezing in Washo (isolate, California; Benz Reference Benz2018). The use of strata in these accounts is predicated on the observation that the relevant process cannot be predicted from surface structure and is thus metrically opaque.

Because syncope is dependent on the existence of metrical structure, the first stratum (the word level) must be responsible for assigning the prominences which then condition rhythmic vowel deletion. (This analysis will not account for stem-level phonological patterns.) The second stratum (the phrase) is then able to reference existing structure, and because of this it can accomplish both syncope and stress realignment in parallel. In the remainder of §2.4, I demonstrate a SOT analysis of Southern Pomo syncope and several other phonological processes. This is certainly not the only set of constraint interactions which successfully derives syncope in SOT – rather, this is merely a mechanical illustration using widely-adopted constraints. What is essential is that this analysis is able to generate the third-syllable deletion pattern in all cases, in contrast to the counter-analyses seen in §4.

3.2 Stratum I: the word level

As described above, the first task of the derivation must be to generate a metrical structure which defines the correct weak positions for syncope. Though this account is amenable to a foot-based treatment, I use an unbracketed grid representation (Prince Reference Prince1983) instead: it is prominence per se that appears to matter, rather than the locations of foot boundaries or hierarchical relationship between feet. This account also collapses across primary and secondary stress, as this distinction does not affect any phonological processes, and assumes stress alignment constraints produce the correct edge alignment of main stress. The surface regularity of rhythmic stress is accomplished by *Clash (‘no consecutive stressed syllables’) and *Lapse (‘no consecutive unstressed syllables’), which are undominated throughout (Gordon Reference Gordon2002). These are ranked over the faithfulness constraint Ident(Stress) – that is, ‘don’t change the stressedness of a syllable,’ henceforth Id(Str) – in motivating the building of metrical structure. The undominated ranking of *Clash and *Lapse is assumed throughout for presentational simplicity. For this reason, candidates with stress clashes or lapses are not shown.

To define the correct weak positions that syncope acts on in the second stratum, the essential ranking is that between two Trough constraints:

In the word stratum, Trough-L dominates Trough-R, which has the effect of assigning stress from left to right, with an initial weak syllable. The first stratum thus outputs left-to-right alternating stress, and the syllables which will be targeted for syncope in the phrase stratum are unstressed. In addition, assuming a ranking of Max-V (‘don’t delete vowels’) over *V̆ guarantees that deletion does not occur at the word level. The third syllable (ultimately, the site of deletion at the phrase level) is underlined.

The tableaux in (25) and (26) demonstrate that Max-V must also outrank Trough-R – ruling out candidate (25c) – and Id(str), ruling out candidates (25d) and (26d). A definitive ranking of Trough-L and *V̆ cannot be established. This gives us the ranking in Figure 1.

Figure 1 Hasse diagram of constraint rankings for Stratum I.

The tableaux in (27) and (28) demonstrate this ranking using attested Southern Pomo forms.

The crucial aspect of these outputs is that the syllables targeted for syncope – odd syllables counting from the left word edge – are unstressed. In the phrasal stratum, these syllables are deleted by reranking *V̆, which penalises vowels in weak syllables, above the faithfulness constraint Max-V which had preserved these positions at the word level.

3.3 Stratum II: the phrase level

The second stratum inherits the metrical structure assigned by the first stratum as its input. With this, it must both propel deletion in the weak positions defined by that structure, as well as reassign prominences from the right edge leftward, beginning with an unstressed syllable. The second of these effects is accomplished by inverting the ranking between the trough constraints, such that Trough-R is re-ranked above Trough-L.

To generate syncope, *V̆ is re-ranked above Max-V. However, the targets of deletion are motivated not by surface stress, but by the metrical structure from the first stratum. This entails a constraint demanding faithfulness to stressed syllables in the input, Max-V́ (‘don’t delete vowels which are stressed in the input’), which has the effect of protecting those vowels from deletion regardless of whether they remain stressed in the output of the second stratum.Footnote ²²

This constraint is undominated at the phrase level and may be considered undominated at the word level as well; there, it is vacuously satisfied, irrespective of the input, because deletion is prevented by the high ranking of Max-V. As a more specific constraint, Max-V́ is less stringent than Max-V – it is violated by only a proper subset of the deletions which would violate Max-V. Thus, vowels that are unstressed in the input may be deleted, while deletion of their stressed counterparts is barred. The crucial phrase-level ranking to motivate syncope in the appropriate syllables is therefore Max-V́ $\gg $ *V̆ $\gg $ Max-V. This ranking ensures that only syllables that are unstressed at the word level are deleted at the phrase level. The tableaux in (30) and (31) demonstrate this result for even and odd syllable parities, again with undominated *Clash and *Lapse, and the assumption that phonotactic constraints bar the deletion of vowels in the initial syllable or consecutive syllables:

In these tableaux, we can see that higher-ranked Trough-R successfully reverses the direction in which metrical structure is built, *V̆ propels deletion in weak syllables, and Max-V́ prevents deletion from occurring in syllables which were stressed in the input. (30) demonstrates several rankings: candidate (30b) is eliminated by the ranking of Trough-R over both Max-V and Id(str), and (30e) similarly shows that Trough-R outranks *V̆. Further, we see that Trough-L is still active at the phrase-level stratum and must be ranked above Max-V to eliminate candidates without deletion like (30c). Interestingly, it is this alignment constraint, rather than *V̆, which motivates syncope for even-parity forms. This can be thought of as a peculiarity of this OT implementation, rather than an important feature of the system; as we have seen, this can instead be rendered in terms of rule-based processes.

(31) demonstrates two further critical rankings: *V̆, which motivates deletion by dominating Max-V, must also dominate Trough-L and Id(str) in order to rule out candidate (31b), which violates neither Trough constraint. The full ranking is shown in the Hasse diagram in Figure 2.

Figure 2 Hasse diagram of constraint rankings, Stratum II.

These constraint rankings demonstrate that Trough-R and *V̆ have been re-ranked above Trough-L and Max-V, and further articulate the ranking between these constraints. This propels both deletion and the reconfiguration of the metrical structure in a way which must satisfy *Clash by shifting stress away from derived clashes (e.g., in forms like *[ʔah.tìm._kó.ʧin]). Because Trough-R now outranks Trough-L, stress appears to be ‘shifted’ leftward onto the initial syllable (in odd-parity inputs); in even-parity inputs, this results in one less stressed syllable. We thus see deletion (in the odd medial syllables) and alternating stress shifted to the penult, iterating leftward. The tableaux below show that this results in the desired outputs for our two example words from §3.2:

We have now seen that the Southern Pomo data are generable using a two-stage derivation in SOT. The first of these strata, corresponding to the word level, defines weak positions from the left edge, and the second stratum (phrase level) deletes vowels in these positions and re-assigns prominence from the right edge. The positions where syncope occurs are determined by word-level metrical structure assigned in the first stratum, but deletion itself is applied at the phrase level. This seems at odds, however, with the observation that the location of syncope is insensitive to a word’s position within a larger prosodic constituent. Syncope occurs in the same syllable regardless. This outcome is in fact consistent with the strata above. Vowel deletion is determined by an output-oriented markedness constraint against unstressed vowels (*V̆), but the targets and extent of deletion are governed by higher-ranked faithfulness constraints. Max-V́ ensures that deletion occurs in positions determined by word-level metrical structure, even though deletion takes place in the phrase-level phonology. Recall the form in (16b) (repeated below), which shows that syncope is not affected by the placement of phrasal stress:

Compare the prediction for the morpheme string /maʔ-dakad-en/ in isolation (in (34)) to the form predicted when this is followed by three syllables, as in (16b), shifting stress to the ultima (in (35)). These tableaux demonstrate that the locus of deletion does not change, and the outputs are both [maʔ.dak _.den]; the account predicts the observed invariance in the locus of deletion.

We have also seen that word-final syllables do not undergo syncope even when they do not receive word-level stress in Stratum I, for example, the word-final syllable in [ts’íh.ta] ‘birds’ in (12) above, reproduced here in (36).

This suggests the activity of an independent constraint which protects positions at word edges from deletion. To this end, I propose an Anchor constraint, Anchor-Right-Edge-Word, which assigns violations for deletion of vowels occurring word-finally in the input:

This constraint is undominated, with the result that vowels in final syllables in the word domain are not eligible for deletion in the phrasal domain.Footnote ²³

The discussion of enclitics above indicated that these are introduced into the derivation at the phrase level and are not assigned stress in the word-level stratum. This means that, in the latter stratum, Max-V́ (which causes deletion to be rhythmic elsewhere) will be vacuously satisfied no matter the pattern of deletion in the clitic field. Syncope in these morphemes is therefore free to occur anywhere – any vowel in the clitic field is liable to be deleted. Combined with the activity of *Clash, *Lapse and the syncope-driving constraint *V̆, this predicts that the clitic field will undergo as much deletion as is allowed by phonotactics. This deletion is predicted to occur regardless of the position of encliticised material relative to either word- or phrase-level stress. That is, clitics should not show rhythmic vowel deletion, nor the vowel– $\varnothing $ alternations that word-internal suffixal morphemes do. Clitics should instead surface with the minimal amount of phonological material allowed by phonotactics. This prediction is illustrated in (38):Footnote ²⁴

This prediction cannot be tested, because the clitics of Southern Pomo are predominantly monosyllabic and appear to be irreducible: any further vowel deletion results in phonotactically illicit sequences. There are thus no synchronic vowel– $\varnothing $ alternations in the clitics themselves, and the tableau above represents an earlier stage in the language’s development. However, some evidence emerges from comparison to the patientive pronominal clitics [=ʔt̪o] ‘1.sg.pat’ and [=mt̪o] ‘2.sg.pat’, both of which have unreduced forms (and cognates in other Pomo languages) that appear as independent words, [ʔaːt̪o] and [miːt̪o]; I analyse the underlying realisations of these morphemes as /ʔat̪o/ and /mit̪o/, respectively (i.e., I attribute vowel length and thus syllable weight in the initial syllables of these two forms to the laryngeal increment). When encliticised, these pronouns are always reduced, irrespective of the position of surface stress. Similarly, Walker proposes that ‘regular syncope’ is responsible for the synchronic forms of many clitics which were historically multimorphemic (380), though this did not apparently rely on the rhythmic properties of the host word like syncope elsewhere in the language.

This suggests that the clitic field was once subject to deletion of unstressed vowels, but that this was a non-rhythmic process, as predicted by this stratal analysis. Deletion has seemingly occurred wherever possible and is non-alternating. It therefore appears that the lexicon has undergone diachronic restructuring, what has been called lexical or input optimisation (Prince & Smolensky Reference Prince and Smolensky1993). The learner, as a default, assumes that the surface form of a word violates as few faithfulness constraints as possible – that is, that the surface form and underlying representation are maximally similar. Without alternations providing evidence for the presence of underlying vowels, learners acquire the reduced forms of these morphemes, the only observed surface forms, as underlying representations (Bermúdez-Otero & Hogg Reference Bermúdez-Otero, Hogg and Eric Holt2003). The synchronic forms of these clitics represent historically frozen patterns of deletion.

I have now shown how SOT accounts for the third-syllable pattern of syncope in Southern Pomo. The theoretical consequences of this analysis are significant: with the stratal framework needed to account for metrically incoherent syncope in Southern Pomo, we allow for counter-typological overgeneration. We should thus consider whether this syncope pattern can also be achieved in parallel, without a derivation, or in a more restrictive framework with a static constraint ranking, like Harmonic Serialism (HS), OT with Candidate Chains (OT-CC; McCarthy Reference McCarthy2006), or Transderivational Faithfulness (Benua Reference Benua1997). §4 considers such analyses, which are ultimately unsuccessful at generating this pattern. However, we will also see that the parallelist analysis utilising the Stress-to-Weight Principle (Prince Reference Prince1990) generates fourth-syllable deletion.

4.1 Non-stratal derivation

In HS and OT-CC architectures, opacity arises from satisfying constraints sequentially, from highest- to lowest-ranked, rather than in parallel. This system does not allow those constraints to be violated in later stages of the derivation; there is only one constraint ranking in the derivation, and constraints are not re-ranked (unlike SOT). Metrical structure in an HS or OT-CC account is determined by highly ranked constraints, and no candidate can harmonically improve if it is not fully compatible with these constraints (McCarthy Reference McCarthy2008; Pruitt Reference Pruitt2010; Elfner Reference Elfner, McCarthy and Pater2016; Calamaro Reference Calamaro2017). HS is thus unable to produce metrical reversals due to inherent features of its architecture. In syncope processes, HS enforces an inherent ordering of metrical parsing before the deletion that it conditions. This captures rhythmic vowel deletion like that seen in Awajún (Aguaruna) and Tonkawa (McCarthy Reference McCarthy2008), but by design is unable to produce the Southern Pomo pattern: even in the absence of syncope, surface stress in Southern Pomo must be realigned to the right edge of a postlexical phrase, which necessitates metrical reparsing. These factors militate for an account in Stratal OT, with free re-ranking of constraints between strata.

Another set of analyses, utilising base–output correspondence (i.e., Transderivational Faithfulness; TF), have been put forward for the Tripoli and Palestinian dialects of Levantine Arabic (Kager Reference Kager, Hermans and Oostendorp1999). These analyses derive opacity in morphologically complex forms by enforcing faithfulness to their less-complex stems. TF was devised to handle opacity arising from morphologically conditioned opaque inheritance, such that transparent phonological alternations from base forms appear in more morphologically complex forms as over- or underapplication of a phonological process. In Southern Pomo, there is no form in the paradigm with transparent application of deletion that can serve as such a base, and as such there is not a clear way to discuss this pattern of opaque deletion in terms of faithfulness to such a base.

Derivational frameworks which depend on a single ranking are not able to realign stress without making a candidate less harmonic. However, these frameworks may be able to generate the attested pattern using disjoint metrical tiers (also called disjoint footing; Rappaport Reference Rappaport1984; Halle & Vergnaud Reference Halle and Vergnaud1987; Parker Reference Parker1998; Aion Reference Aion2003; González Reference González, Miestamo and Wälchli2007; Vaysman Reference Vaysman2008). Such analyses utilise multiple tiers of distinct metrical structure that coexist within a word, each conditioning the application of one of the two rhythmic phenomena in question.

Here, unlike in analyses involving incoherent surface prominence (e.g., Gordon Reference Gordon, Heinz, Goedemans and Hulst2016), one metrical structure corresponds to prominence, and the other to a rhythmic segmental process (e.g., vowel deletion). However, because surface stress in Southern Pomo is alternating and postlexical, it must be calculated based on the syllable string after deletion. Therefore, disjoint footing processes must still be derivationally ordered, syncope followed by stress assigment. Though similar analyses have been proposed for stress and syncope in Tiberian Hebrew (Rappaport Reference Rappaport1984; cf. Dresher Reference Dresher, Hanson and Inkelas2009), the interaction of vowel lengthening and stress in Tübatulabal (Heath Reference Heath and Clements1981; Aion Reference Aion2003; cf. Benz Reference Benz2018), and alternating epenthesis and stress in Huariapano (González Reference González, Miestamo and Wälchli2007; Parker Reference Parker1998; cf. Bennett Reference Bennett2013b), the necessity of sequential derivation makes this analysis qualitatively different from other uses of disjoint footing. This approach thus appears to merely recapitulate the predictions of SOT, including the same set of counter-typological rhythmic processes criticised by Wolf (Reference Wolf2012). In addition, Disjoint footing is unable to account for non-rhythmic derivational phenomena such as compensatory lengthening. For further argumentation against this approach, I direct the reader to Bennett (Reference Bennett2013a), Churchyard (Reference Churchyard1999) and the references therein.

4.2 Parallelist approaches

A number of successful analyses of syncope – such as those for Southeastern Tepehuán (Kager Reference Kager and Roca1997; Gouskova Reference Gouskova2003), Tonkawa, Hopi (Gouskova Reference Gouskova2003; cf. Blumenfeld Reference Blumenfeld2006), Bedouin Hijazi Arabic and Central Alaskan Yupik (Gordon Reference Gordon2001) – rely only on surface-oriented constraint interactions and are generable in parallel OT. Some of these analyses utilise Foot- or Stress-to-Edge Alignment constraints, which penalise intervening syllables between a word edge and foot edge or stressed syllable. Others make use of the Stress-to-Weight Principle (SWP, which penalizes stress on light syllables; Prince Reference Prince1990), or other quantity-sensitive constraints on stress. All of these constraints maximise the wellformedness of surface metrical structure and can promote deletion to either minimise the number of syllables between a prominence and word edge (Alignment) or ensure that stress only falls on syllables containing enough phonological material (SWP).

As I demonstrate below, parallel OT and surface-oriented constraints – those that militate for stress to fall on certain types of syllables, and those that militate for reducing phonological material – cannot generate the observed third-syllable deletion pattern, precisely because third-syllable deletion is not surface-optimising. Instead, this syncope pattern requires reference to metrical positions defined at an earlier derivational stage. While syncope in the stratal account is conditioned by a surface-oriented markedness constraint (*V̆), it is faithfulness to metrically strong positions in the input that determine where deletion occurs.

Given that surface metrical structure in Southern Pomo is aligned to the right edge of the word, we might hypothesise that syncope can be explained by the ranking of Align-Right(σ́,ω) (McCarthy & Prince Reference McCarthy, Prince, Booij and Marle1993) over Max-V. This ranking would have the effect of promoting deletion when this results in a prominence closer to the right word edge. As a result, this constraint, and its sibling Align-Left, suffer from the same shortcoming: deletion in any syllable can improve harmony by reducing word length, and worse yet, this promotes deletion of as many syllables as possible (to the extent allowed by other constraints). Perhaps SWP will fare better?

Syncope appears to always result in fewer stressed light syllables, due to the phonotactic restrictions of the language and to the fact that initial syllables in the language are always heavy due to laryngeal incrementation (discussed above in §2.2.1). Deletion of the vowel in a given syllable results in the re-syllabification of that syllable’s onset as a coda consonant in the preceding syllable. That is, /-cv $_2$ .c $\underline {\textbf {v}}_3$ .cv $_4$ -/ becomes [-cv $_2$ c._cv $_4$ -]. Therefore, deletion in the third syllable creates a heavy peninitial syllable, and deletion in the fifth syllable creates a heavy fourth syllable:

SWP, which assigns violations to stressed light syllables, is thus a plausible constraint to motivate syncope, and maximally well-formed words will avoid light stressed syllables. Impressionistically, this appears to reflect the data. Syncope is blocked in closed syllables by phonotactic constraints, and so words which have undergone syncope invariably have one less light syllable. The resulting heavy syllable is frequently stressed. As the tableaux in (41) show, the syncopated candidates are in fact more harmonic than their faithful competitors:

Forms that have undergone syncope are more harmonic for SWP than candidates without deletion. As previously mentioned, this is typically because deletion shifts stress leftward: in words with an odd parity of underlying syllables, this results in the heavy initial syllable receiving a secondary stress; in even-parity words, this results in one less stressed syllable overall, and stress falls on a now-heavy peninitial syllable. The resulting well-formedness is not necessarily local, as can be seen in (42), where the derived heavy syllable is not stressed:

Here, main stress remains on a light syllable, and the heavy syllable formed by vowel deletion is itself unstressed. The word, however, is globally more harmonic with respect to SWP, because stress is shifted leftward onto the heavy initial syllable. Syncope does not result in a heavy stressed syllable locally, but there is one less light stressed syllable. This is an example of how parallelist approaches to syncope have generally resolved apparent opacity: a process may seem unmotivated or opaque locally, but results in a more harmonic form under global evaluation (Gouskova Reference Gouskova2003; Blumenfeld Reference Blumenfeld2006).

Syncope always increases global harmony with respect to SWP, and SWP accurately predicts the majority of Southern Pomo surface forms. But we cannot conclude that syncope is transparent: like the alignment constraints, SWP is not able to correctly predict the location of syncope in every case. The optimal candidate for SWP is always one where all stressed syllables are heavy. As shown in (43), deletion in the fourth syllable, rather than the third, would result in a maximally harmonic candidate for SWP:

As this tableau shows, the attested form (43a) is indeed harmonically bounded by a competitor (43c) in which V₄ has deleted, resulting in a candidate without light stressed syllables. When V₄ is light, deletion of V₄ shifts stress leftward to σ $_3$ , which is then heavy, having resyllabified the onset of σ₄ as a coda. The optimal location for deletion in these cases is V₄, the vowel in the even penult, but syncope instead targets vowels in the odd (third and fifth) syllables of the word. The only forms where we observe this are four-syllable words like those in (44), derived from underlying five-syllable strings:

The predictions of an SWP-driven system are usually in line with the observed Southern Pomo data, but SWP cannot be responsible for driving the third-syllable pattern of rhythmic deletion because a subset of forms is not surface-optimising.

These forms – surface strings bearing stress on odd, light penults – provide crucial evidence for opacity, but are only a small portion of the language. How heavily do learners weigh this evidence when most of the input is equivocal? Tellingly, the subpattern of fourth-syllable syncope discussed in §2.3 appears to delete in exactly these surface-optimising positions, and these forms resist analysis by stratal derivation. I propose that this reflects restructuring of the synchronic grammar, due to the limited learnability of the opaque stratal pattern.

4.3 Parallelism and fourth-syllable syncope

Examples of these forms are given again in (45), along with the expected forms (based on the SOT account) that do not appear.

Compare the forms in (45a), where syncope results in forms without light stressed syllables, to those in (45b), where syncope is not surface-optimising for SWP. The pattern of syncope in third-syllable forms is not surface-optimising because they have light stressed penultimate syllables on the surface. In contrast, the fourth-syllable forms have syncope of the underlying fourth vowel, resulting in a heavy stress-bearing penult, and thus transparent surface optimisation relative to SWP (as no stresses fall on light syllables). These forms cannot be morpheme-specific, as shown in (23). They instead suggest a re-analysis of the grammar, where syncope and metrical parsing occur in parallel, such that syncope is metrically coherent (in the sense that the language makes use of a consistent metrical structure across derivational stages; Dresher & Lahiri Reference Dresher and Lahiri1991; see also Bennett Reference Bennett2013b). The constraints driving syncope here are output-oriented, unlike the third-syllable deletion pattern seen in similar forms.

This analysis still requires strata because of phrasal stress shift, and two separate computations of stress are thus necessary to produce the observed structure.Footnote ²⁵ However, under this analysis, syncope does not involve inter-stratal dependencies, and instead takes place at the word level, alongside word level stress. It is only in larger prosodic constituents that metrical opacity is introduced by shifts in stress. An example derivation is presented below; the tableaux in (46) show word-level Stratum Ib, and the one in (47) shows a sample derivation of phrasal stress (Stratum IIb). *Clash, *Lapse and phonotactic constraints are again assumed to be undominated and are not shown.

The word stratum outputs the isolation forms; in most cases these look identical to those derived by the derivation outlined in §3. The notable exception is the winning candidate (a) in (46b), which has no light stressed syllables, whereas the opaque derivation results in candidate (c), with a light penult that is not surface-optimising. (46c), showing six-syllable forms, demonstrates how SWP optimises globally, rather than locally. Deletion in the winning candidate seems to overapply, in that the second syllable is heavy because of deletion, but stress does not actually fall on it. Instead, deletion causes stress to fall on the obligatorily heavy initial syllable, reducing the overall number of light stressed syllables.

The second stratum in this alternative derivation maintains the same ranking; the key difference is the size of the input. Further deletion in the stem is prevented by phonotactics: deleting any medial vowels would result in illicit onset or coda clusters. The tableau in (47) demonstrates this with a (derived) four-syllable word followed by a three-syllable word.

This second stratum outputs the shifted stress in phrases without necessitating a reranking, with further syncope nevertheless prevented by phonotactic constraints. That is, the language requires a single uniform parsing algorithm across strata, making it metrically coherent.Footnote ²⁶