On the past tense debate; Part 3: the overestimation of overirregularization

One final, and still unresolved, issue in the past tense debate is the role of so-called overirregularization errors.

It is well-known that children acquiring English tend to overregularize irregular verbs; that is, they apply the regular -d suffix to verbs which in adult English form irregular pasts, producing, e.g., *thinked for thought. Maratsos (2000) estimates that children acquiring English very frequently overregularize irregular verbs; for instance, Abe, recorded roughly 45 minutes a week from ages 2;5 to 5;2, overregularizes rare irregular verbs as much as 58% of the time, and even the most frequent irregular verbs are overregularized 18% of the time. Abe appears to have been exceptional in that he had a very large receptive vocabulary for his age (as measured by the Peabody Picture Vocabulary Test), giving him more opportunities (and perhaps more grammatical motivation) for overregularization,¹ but Maratsos estimates that less-precocious children have lower but overall similar rates of overregularization.

In contrast, it is generally agreed that overirregularization, or the application of irregular patterns (e.g., in English, of ablaut, shortening, etc.) are quite a bit rarer. The only serious attempt to count overirregularizations is by Xu & Pinker (1995; henceforth XP). They estimate that children produce such errors no more than 0.2% of the time, which would make overirregularizations roughly two orders of magnitude rarer than overregularizations. This is a substantial difference. If anything, I think that XP overestimate overirregularizations. For instance, XP count brang as an overirregularization, even though this form does exist quite robustly in adult English (though it is somewhat stigmatized). Furthermore, XP count *slep for *slept as an overirregularization, though this is probably just ordinary (td)-deletion, a variable rule that is attested already in early childhood (Payne 1980). But by any account, overirregularization is extremely rare. The same is found in nonce word elicitation experiments such as those conducted by Berko (1958): both children and adults are loath to generate irregular past tenses for nonce verbs.²

This is a problem for most existing computational models. Nearly all of them—Albright & Hayes’ (2003) rule-based model (see their §4.5.3), O’Donnell’s (2015) rules-plus-storage system, and all analogical models and neural networks I am aware of—not only overregularize, like children do, but also overirregularize at rates far exceeding what children do. I submit that any computational model which produces substantial overirregularization is simply on the wrong track.

Endnotes

It is amusing to note that Abe is now, apparently, a trial lawyer and partner at a white-shoe law firm.
As I mentioned in a previous post, this is somewhat obscured by ratings tasks, but that’s further evidence we should disregard such tasks.

References

Albright, A. and Hayes, B. 2003. Rules vs. analogy in English past tenses: a computational/experimental study. Cognition 90(2): 119-161.
Berko, J. 1958. The child’s learning of English morphology. Word 14: 150-177.
Maratsos, M. 2000. More overregularizations after all: new data and discussion on Marcus, Pinker, Ullman, Hollander, Rosen & Xu. Journal of Child Language 27: 183-212.
O’Donnell, T. 2015. Productivity and Reuse in Language: a Theory of Linguistic Computation and Storage. MIT Press.
Payne, A. 1980. Factors controlling the acquisition of the Philadelphia dialect by out-of-state children. In W. Labov (ed.), Locating Language in Time and Space, pages 143-178. Academic Press.
Xu, F. and Pinker, S. 1995. Weird past tense forms. Journal of Child Language 22(3): 531-556.

Thought experiment #3

[The semester is finally winding down and I am back to writing again.]

Let us suppose one encounters a language in which the only adjacent consonants are affricates like [tʃ, ts, tɬ].¹ One might be tempted to argue that these affricates are in fact singleton contour phonemes² and that the language does not permit true consonant clusters.³

Let us suppose instead that one finds a language in which word-internal nasal-stop clusters are common, but nasal-glide and nasal-liquid clusters are not found except at transparent morpheme boundaries.⁴ One then might be tempted to argue that in this language, nasal-stop clusters are in fact sequences of nasal followed by an oral consonant rather than singleton contour phonemes.

In my opinion, neither of these argument “go through”. They follow from nothing, or at least nothing that has been explicitly stated. Allow me to explain, but first, consider the following hypothetical:

The metrical system of Centaurian, the lingua franca of the hominid aliens of the Alpha Centauri system, historically formed weight-insensitive trochees, with final extrametricality for prosodic words with odd syllable count of more than one syllable. However, a small group of Centaurian exiles have been hurtling towards the Sol system at .05 parsecs a year (roughly 1m MPH) for the last century or so. Because of their rapid speed of travel it is impossible for these pioneers to stay in communication with their homeworld, and naturally their language has undergone drift over the past few centuries. In particular, Pioneer Centaurian (as we’ll call it) has slowly but surely lost all the final extrametrical syllables of Classical Centaurian, and as a result there are no longer any 3-, 5-, 7- or 9- (etc.) syllable words in the Pioneer dialect.

As a result of a phonetically well grounded, “plausible”, Neogrammarian sound change, Pioneer Centaurian (PC) lacks long words with an odd number of syllables, though it still has 1-syllable words. What then is the status of this generalization in the grammar of PC speakers? The null hypothesis has to be that it has no status at all. Even though the lexical entries of PC have undergone changes, the metrical grammar of PC could easily be identical to Classical Centaurian: weight-intensitive trochees, with a now-vacuous rule of final extrametricality. Furthermore, it is quite possible that PC speakers have simply not noticed the relevant metrical facts, either consciously or subconsciously. Would PC speakers rate, say, 4-syllable nonce words as ill-formed possible words? No one knows. When PC speakers inevitably come in contact with English, will be they be reluctant to borrow a 6-syllable words like anthropomorphism or detoxification into their language, or will they feel the need to append or delete a syllable to conform to their language’s lexicon? Once again, no one knows.

The same is essentially true of the aforementioned language in which the only consonant clusters are affricates, or the aforementioned language in which nasal-consonant clusters are highly restricted. It might be the case that the grammar treats the former as single segments and the grammar treats the latter as clusters, but absolutely nothing presented thus far suggests it has to be true.

Let us refer to the idea that the grammar needs to encode phonotactic generalizations (somehow) as the phonotactic hypothesis. I have argued—though more for the sake of argument than out of genuine commitment—for a constrained version of this hypothesis; I note that any surface-true rule will rule out certain surface forms. Thus, if desired, one can derive—or perhaps more accurately, project—certain phonotactic generalizations by taking a free-ride on surface-true rules.⁵ But note: I have not argued that the phonotactic hypothesis is correct. Rather, I have simply provided a way to derive some phonotactic generalizations using entrenched grammatical machinery (i.e., phonological alternations). And this can only account for a subset of possible phonotactic generalizations.

Let us consider the language with word-initial affricates again. Linguists are often heard to say that one needs to posit phonotactic generalizations to “rule out” consonant clusters in this language. I disagree. Imagine that we have two grammars, G and G’. G has a set of URs, which includes contour phoneme affricates (/t͡ɬakaʔ-/ ‘people’, /t͡sopelik-/ ‘sweet’, etc., where the IPA tie bar symbolizes contour phonemes) but no consonant clusters. G also has a surface constraint on consonant clusters other than the affricates (which can be assumed to be contour phonemes, for sake of simplicity). G’ has the same set of URs, but lacks the surface constraint. Is there any reason to prefer G over G’? With the evidence given so far, I submit that there is not. Of course, there might be some grammatical patterns which, if otherwise unconstrained, would produce consonant clusters, in which case the phonotactic constraint of G may have some work to do. And, there may additional facts (perhaps the adaptation of loanwords, or wordlikeness judgments, though these data are not applied to this problem without making additional strong assumptions) may also militate in favor of G. But rarely if ever are these additional facts presented when positing G’. Now let us consider a third grammar, G”. This grammar is the same as G’, except that the affricates are now represented as consonant clusters (/tɬakaʔ-/ ‘people’, /tsopelik-/ ‘sweet’, etc.) rather than contour phonemes. Is there any reason to prefer either G’ or G” given the facts available to us thus far? It seems to me there is not.

This is a minor scandal for phonemic analysis. But it is not a purely philosophical issue: it is the same issue that children acquiring Nahuatl face. “Phonotacticians” have largely sidestepped these issues by making a completely implicit assumption that grammars (or perhaps, language learners) abhor a vacuum, in the sense that phonotactic constraints need to be posited to rule out that which does not occur. The problem is that there is often no reason to think these things would occur in the first place. If we assume that grammars do not abhor a vacuum—allowing us to rid ourselves of the increasingly complex machinery used to encode phonotactic generalizations not derived from alternations—we obtain exactly the same results in the vast majority of cases.

Endnotes

One language with this property is Classical Nahuatl.
Whatever that means! It’s not immediately clear, since there does not seem to be a fully-articulated theory that explains what it means to be a single segment in underlying representation to correspond to multiple articulatory targets on the surface. Without such a theory this feels like mere phenomenological description.
Recently, Gouskova & Stanton (2021) express this heuristic, which has antecedents going back to at least Trubetzkoy, as a simple computational model.
One language which supposedly has this property is Gurindji (McConvell 1988), though I only have only seen the relevant data reprinted in secondary sources. Thanks to Andrew Lamont (p.c.) for drawing my attention to this data. Note that in this language, the nasal-obstruent clusters undergo dissimilation when preceded by another nasal-obstruent cluster, which might—under certain assumptions—be a further argument that nasal-obstruent sequences are really clusters.
See also Gorman 2013, particularly chapters 3-4.

References

Gorman, K. 2013. Generative phonotactics. Doctoral dissertation, University of Pennsylvania.
Gouskova, M. and Stanton, J. 2021. Learning complex segments. Language 97(1): 151-193.
McConvell, P. 1988. Nasal cluster dissimilation and constraints on phonological variables in Gurundji and related languages. Aboriginal Linguistics 1: 135-165.

On the past tense debate; Part 2: dual-route models are (still) incomplete

Dual-route models remain for the most part incompletely specified. Because crucial details are missing from their specification, they have generally not been implemented as computational cognitive models. Therefore, there is far less empirical rigor in dual-route thinking. To put it starkly, dual-route proponents have conducted expensive, elaborate brain imaging studies to validate their model but have not proposed a model detailed enough to implement on a $400 laptop.

The dual-route description of the English past tense can be given as such:

Use associative memory to find a past tense form.
If this lookup fails, or times out, append /-d/ and apply phonology.

Note that this ordering is critical: one cannot ask simply ask whether a verb is regular, since by hypothesis some or all regular verbs are not stored as such. And, as we know (Berko 1958), novel and nonce verbs are almost exclusively inflected with /-d/, consistent with the current ordering.¹ This model equates—rightly, I think—the notions of regularity with the elsewhere condition. The problem is with the fuzziness in how one might reach condition (2). We do not have any notion of what it might mean for associative memory lookup to fail. Neural nets, for instance, certainly do not fail to produce an output, though they will happily produce junk in certain cases. Nor do we much of a notion of how it might time out.

I am aware of two serious attempts to spell out this crucial detail. The first is Baayen et al.’s 1997 visual word recognition study of Dutch plurals. They imagine that (1) and (2) are competing activation “routes” and that recognition occurs when either of the routes reaches activation threshold, as if both routes run in parallel. To actually fit their data, however, their model immediately spawns epicycles in the form of poorly justified hyperparameters (see their fn. 2) and as far as I know, no one has ever bothered to reuse or reimplement their model.²The second is O’Donnell’s 2015 book, which proposes a cost-benefit analysis for storage vs. computation. However, this complex and clever model is not described in enough detail for a “white room” implementation, and no software has been provided. What dual route proponents owe us, in my opinion, is a next toolkit. Without serious investment in formal computational description and reusable, reimplementable, empirically validated models, it is hard to take the dual-route proposal seriously.

Endnotes

There’s a lot of work which obfuscates this point. An impression one might get from Albright & Hayes (2003) is that adult nonce word studies produce quite a bit of irregularity, but this is only true in their rating task and hardly at all in their “volunteering” (production) task, and a hybrid task finds much higher ratings for noce irregulars. Schütze (2005) argues—convincingly, in my opinion—that this is because speakers use a different task model in rating tasks, one that is mostly irrelevant to what Albright & Hayes are studying.
One might be tempted to fault Baayen et al. for using visual stimulus presentation (in a language with one of the more complex and opaque writing systems), or for using recognition as a proxy for production. While these are probably reasonably critiques today, visual word recognition was still the gold standard in 1997.

References

Albright, A. and Hayes, B. 2003. Rules vs. analogy in English past tenses: a computational/experimental study. Cognition 90(2): 119-161.
Baayen, R. H., Dijkstra, T., and Schreuder, R. 1997. Singulars and plurals in Dutch: evidence for a parallel dual-route model. Journal of Memory & Language 37(1): 94-117.
Berko, J. 1958. The child’s learning of English morphology. Word 14: 150-177.
O’Donnell, T. 2015. Productivity and Reuse in Language: a Theory of Linguistic Computation and Storage. MIT Press.
Schütze, C. 2005. Thinking about what we are asking speakers to do. In S. Kepser and M. Reis (ed.), Linguistic Evidence: Empirical, Theoretical, and Computational Perspectives, pages 457-485. Mouton de Gruyter.

On the past tense debate; Part 1: the RAWD approach

I have not had time to blog in a while, and I really don’t have much time now either. But here is a quick note (one of several, I anticipate) about the past tense debate.

It is common to talk as if connectionist approaches and dual-route models are the two opposing approaches to morphological irregularity, when in fact there are three approaches. Linguists since at least Bloch (1947)¹ have claimed that regular, irregular, and semiregular patterns are all rule-governed and ontologically alike. Of course, the irregular and semiregular rules may require some degree lexical conditioning, but phonologists have rightly never seen this as some kind of defect or scandal. Chomsky & Halle (1968), Halle (1977), Rubach (1984), and Halle & Mohanan (1985) all spend quite a bit of space developing these rules, using formalisms that should be accessible to any modern-day student of phonology. These rules all the way down (henceforth RAWD) approaches are empirically adequate and have been implemented computationally with great success: some prominent instances include Yip & Sussman 1996, Albright & Hayes 2003,² and Payne 2022. It is malpractice to ignore these approaches.

One might think that RAWD has more in common with dual-route approaches than with connectionist thinking, but as Mark Liberman noted many years ago, that is not obviously the case. Mark Seidenberg, for instance, one of the most prominent Old Connectionists, has argued that there is a tendency for regulars and irregulars to share certain structural similarities. To take one example, semi-regular slept does not look so different from stepped, and the many zero past tense forms (e.g., hit, bid) end in the same phones—[t, d]—used to mark the plural. While I am not sure this is a meaningfuly generalization, it clearly is something that both connectionist and RAWD models can encode.³ This is in contradistinction to dual-route models, which have no choice but to treat these observations as coincidences. Thus, as Mark notes, connectionists and RAWD proponents find themselves allied against dual-route models.

(Mark’s post, which I recommend, continues to draw a parallel between dual-routism and bi-uniqueness which will amuse anyone interested in the history of phonology.)

Endnotes

This is not exactly obscure work: Bloch taught at two Ivies and was later the president of the LSA.
To be fair, Albright & Hayes’s model does a rather poor job recapitulating the training data, though as they argue, it generalizes nonce words in a way consistent with human behavior.
For instance, one might propose that slept is exceptionally subject to a vowel shortening rule of the sort proposed by Myers (1987) but otherwise regular.

References

Albright, A. and Hayes, B. 2003. Rules vs. analogy in English past tenses: a computational/experimental study. Cognition 90(2): 119-161.
Bloch, B. 1947. English verb inflection. Language 23(4): 399-418.
Chomsky, N., and Halle, M. 1968. Sound Pattern of English. Harper & Row.
Halle, M. 1977. Tenseness, vowel shift and the phonology of back vowels in Modern English. Linguistic Inquiry 8(4): 611-625.
Halle, M., and Mohanan, K. P. 1985. Segmental phonology of Modern English. Linguistic Inquiry 16(1): 57-116.
Myers, S. 1987. Vowel shortening in English. Natural Language & Linguistic Theory 5(4): 485-518.
Payne, S. R. 2022. When collisions are a good thing: the acquisition of morphological marking. Bachelor’s thesis, University of Pennsylvania.
Pinker, S. 1999. Words and Rules: the Ingredients of Language. Basic Books.
Rubach, J. 1984. Segmental rules of English and cyclic phonology. Language 60(1): 21-54.
Yip, K., and Sussman, G. J. 1997. Sparse representations for fast, one-shot learning. In Proceedings of the 14th National Conference on Artificial Intelligence and 9th Conference on Innovative Applications of Artificial Intelligence, pages 521-527.

The Wordlikeness Project

We (myself, Karthik Durvasula, and Jimin Kahng) recently got the good news that our NSF collaborative research proposal has been funded. This works springs ultimately from my dissertation. There I argue—using a mix of logical argumentation and “archival” wordlikeness data mostly taken from appendices of previously published work—that the view of phonotactic grammar as statistical patterns or constraints projected from the lexicon is not strongly supported by the available data. My conclusions are perhaps weakened by the low overall quality of this archival data, which is drawn from various stimulus presentation modalities (i.e., auditory vs. orthographic) and response modalities (Likert scale vs. binary forced-choice vs. transcription). In the NSF study, we will be collecting wordlikeness data in English and Korean, manipluating these stimulus presentation and response modalities, and this data will be made publicly available under the name of the Wordlikeness Project. (Here we draw inspiration from the English Lexicon Project and spinoffs.) We will also be using this data for extensive computational modeling, to answer some of the questions raised in my dissertation and in Karthik and Jimin’s subsequent work.

Stop being weird about the Russian language

As you know, Russia is waging an unprovoked war on Ukraine. It should go without saying that my sympathies are with Ukraine, but of course both states are undemocratic, one-party kleptocracies and I have little hope for anything good coming from the conflict.

That’s all besides the point. Since the start of the war, I have had several conversations with linguists who suggested that the study of the Russian language—one of the most important languages in linguistic theorizing over the years—is now “cringe”. This is nonsense. First, official statistics show that a majority of Ukrainian citizens identify as ethnically Russian, and that a substantial minority speak Russian as a first language (and this is probably skewed by social-desirability bias). Secondly, it is wrong to identify a language with any one nation. (It is “cringe” to use flag emojis to label languages; just use the ISO codes.) Third, it is foolish to equate the state with the people who live underneath them, particularly after the end of the kind of mass political movements that in earlier times could stop this kind of state violence. It is a basic corollary of the i-language view that children learn whatever languages they’re sufficiently exposed to, regardless of their location or of their caretakers’ politics. The iniquity of war does not travel from nation to language to its speakers. Stop being weird about it.

Noam on phonotactics

(Emphasis mine.)

Take the question of sound structure. Here too the person who has acquired knowledge of a language has quite specific knowledge about the facts that transcend his or her experience, for example, about which nonexistent words are possible words and which are not. Consider the forms strid and bnid. Speakers of English have not heard either of these forms, but they know that strid is a possible word, perhaps the name of some exotic fruit they have not seen before, but bnid, though pronounceable, is not a possible word of the language. Speakers of Arabic, in contrast, know that bnid is a possible word and strid is not; speakers of Spanish known that neither strid nor bnid is a possible word of their language. The facts can be explained in terms of rules of sound structure that the language learner comes to know in the course of acquiring the language.

Acquisition of the rules of sound structure, in turn, depends on fixed principles governing possible sound systems for human languages, the elemnts of which they are constituted, the manner of their combination and the modifications that they may undergo in various contexts. These principles are common to English, Arabic, Spanish, and all other human languages and are used unconsciously by a person acquiring any of these languages…

Suppose one were to argue that the knowledge of possible words is derived “by analogy.” The explanation is empty until an account is given of this notion. If we attempt to develop a concept of “analogy” that will account for these facts, we will discover that we are building into this notion the rules and principles of sound structure. (Chomsky 1988:26)

References

Chomsky, N. 1988. Language and Problems of Knowledge: the Managua Lectures. MIT Press.

Magic and productivity: Spanish metaphony

In Gorman & Yang 2019 (henceforth GY), we provide an analysis of metaphonic patterns in Spanish. This is just one of four or five case studies and it is a bit too brief to go into some interesting representational issues. In this post I’ll try to fill some of the missing details as I understand them, with the caveat that Charles does not necessarily endorse any of my proposals here.

The tolerance principle approach to productivity is somewhat unique in that it is not tied to any particular theory of rules or representations, so long as such theories provide a way to encode competing rules applying in order of decreasing specificity (Pāṇini’s principle or the elsewhere principle). Yet any particular tolerance analysis requires us to commit to a specific formal analysis of the phenomenon⁠—the relevant rules and the representations over which they operate—so that we know what to count. The way in which I apply the tolerance principle also presumes that productivity (e.g., as witnessed by child overregularization errors) or its lack (as witnessed by inflectional gaps) is a first-class empirical observation and that any explanatorily-adequate tolerance analysis ought to account for it. What this means to me is that the facts productivity can adjudicate between different formal analyses, as the following example shows.

The facts are these. A large percentage of Spanish verbs, all of which have a surface mid vowel (e or o) in the infinitive, exhibit alternations targeting the nucleus of the final syllable of the stem. In all three conjugations, one can find verbs in which this surface mid vowel diphthongizes to ie [je] or ue [we], respectively.¹Furthermore, in the third conjugation, there is a class of verbs in which the e in the final syllable of certain forms alternates with an i.²

The issue, of course, is that there are verbs which are almost identical to the diphthongizing or e–i stems but which do not undergo these alternations (GY:178f.). One can of course deny that magic is operating here, but this does not seem workable.³ We need therefore to identify the type of magic: the rules and representations involved.

There is some reason to think that conjugation class is relevant to these verb stem alternations. For example, Mayol et al. (2007) analyzes verb stem errors in a sample of six children acquiring Spanish, a corpus of roughly 2,000 verb tokens. Nearly all errors in this corpus involve underapplication of diphthongization to diphthongizing verbs in the first and second conjugation; errors in the third conjugation are extremely rare. Secondly the e-i alternations are limited to the third conjugation. As Harris (1969:111) points out, the e form surfaces only when the stem is followed by an i in the first syllable of the desinence. This suggests that the alternation is a lowering rather than a raising one, and explains why this pattern is confined to the third (-i-) conjugation. Finally, there are about a dozen Spanish verbs, all of the third conjugation, which are defective in exactly those inflectional forms—those in which there is either stress on the stem or those in which the stem is followed by a desinential /i/ in the following syllable—which would reveal to us whether the stem is diphthongization or lowering. These three facts seem to be telling us that these alternations are sensitive to conjugation class.

Jim Harris has long argued for an abstract phoneme analysis of Spanish diphthongization. In Harris 1969, diphthongization reflect abstract phonemes, present underlyingly, denoted /E, O/; no featural decomposition is provided, but one could imagine that they are underspecified for some features related to height. Harris (1985) instead supposes that the vowels which undergo diphthongization under stress bear two skeletal “x” slots, one linked and one unlinked, as follows.

o
|
X X

This distinguishes them from ordinary non-alternating mid vowels (which only have one “x”) and non-alternating diphthongs (which are prelinked to two “x”s). Harris argues this also provides explanation for why stress conditions this alternation.

One interesting property of Harris’ account, one which I do not believe has been remarked on before, it is that it seems to rule out the idea that diphthongization vs. non-diphthongization is “governed by the grammar”: it is purely a fact of lexical representation and surface forms follow directly from applying the rules to the abstract phonemic forms. To put it more fancifully, there is no “daemon” inside the phonemic storage unit of the lexicon deciding where the diphthongs or lowering vowels go; such facts are of interest for “evolutionary” theorizing, but are accidents of diachrony.

However, I believe the facts of productivity and the conditioning effects of conjugation support an alternative—and arguably more traditional—analysis, in which diphthongization and lowering are governed by abstract diacritics at the root level, in the form of rule features of the sort proposed by Kisseberth (1970) and Lakoff (1970).

I propose that verbs with mid vowel in the final syllable of their stem which do not undergo diphthongization, like pegar ‘to stick to’; (e.g., pego ‘I stick to’), are marked [−diph], and those which do undergo diphthongization, like negar ‘to deny’ (niego ‘I deny’) are marked [+diph]; both are assumed to have an /e/ in underlying form. Similarly, I propose that verbs which undergo lowering, like pedir ‘to ask for’ (e.g., pido ‘I ask for’), are specified [+lowering] and non-lowering verbs, like vivir ‘to live’ (vivo ‘I live), are specified [−lowering]; both have an underlyingly /i/. Then, the rule of lowering is

Lowering: i -> e / __ C_0 i

or, in prose, an /i/ lowers to /e/ when followed by zero or more consonants and a /i/. I assume a convention of rule application such that rule R can apply only to those /i/s which are part of a root marked [+R]; it is as if there is an implicit [+R] specification on the rule’s target. Therefore, the rule of lowering does not apply to vivir. This rule feature convention is assumed to apply to all phonological rules, including diphthongization.

I furthermore propose that [diph] and [lowering] rule features are inserted during the derivation according to GY’s tolerance analysis. For first (-a-) and second (-e-) conjugation verbs, [−diph] is the default and [+diph] is lexically conditioned.

[] -> [+diph] / __ {√neg-, ...}
   -> [-diph] / __

For third (-i-) conjugation verbs, I assume that there is no default specification for either rule feature.

[] -> [+lowering] / __ {√ped-, ...}
[] -> [-lowering] / __ {√viv-, ...}

I have not yet provided formal machinery to limit these generalizations to the particular conjugations, but I wish to stay agnostic about morphological theory and so I assume that any adequate model of the morphophonological interface ought to be able to encode conjugation class-specific generalizations like the above.

I leave open the question as to how roots which fail to satisfy the phonological conditions for lowering (like those which do not contain a final-syllable /i/) or diphthongization (like those which do not contain a final-syllable mid vowel) are specified with respect to the [diph] and [lowering] features. I am inclined to say that they remain underspecified for these features throughout the derivation. However, all that is essential here is that such roots are not in scope for the tolerance computation.

Let us suppose that we wish to encode, synchronically, phonological “trends” in the lexicon with respect to the distribution of diphthongizing and/or lowering verbs, such as Bybee & Pardo’s claim that e–ie diphthongization is facilitated when followed by the trill rr. Such observations could be encoded at the point in which rule features are inserted, if desired. It is unclear how a similar effect might be achieved under the abstract phoneme analysis. I remain agnostic on this question, which may ultimately bear on the past tense debate.

In future work (if blogging can be called “work”), it would be interesting to expand the proposal to other cases of morpholexical behavior studied by Kisseberth (1970), Lakoff (1970), and Zonneveld (1978), among others. Yet my proposal does not entail that we draw similar conclusions for all superficially similar case studies. For instance, I am unaware at present of evidence contradicting Rubach’s (2016) arguments that the Polish yers are abstract phonemes.

Endnotes

Let us assume, as does Harris, that the appearance of the [e] in both diphthongs is the result of a default insertion rule applying after diphthongization converts the nucleus to the corresponding glide.
This of course does not exhaust the set of verbal alternations, as there are highly-irregular consonantal and vocalic alternations in a handful of other verbs.
Albright et al. (2001) and Bybee & Pardo (1981) are sometimes understood to have found solid evidence for a “non-magical” analysis, in which the local context in which a stem mid vowel is found is the sole determinant. This is a massive overinterpretation. Bybee & Pardo identify some local contexts which seem to favor diphthongization, and the results of a small nonce word cloze task are consistent with these findings. Albright et al. use a simple computational model to discover some contexts which seem to favor diphthongization, and find that subjects’ ratings of possible nonce words (on a seven-point Likert scale) are correlated with the models’ predictions for diphthongization. Schütze (2005) gives a withering critique of the general nonce word rating approach. Even ignoring this, neither study links nonce word tasks in adult knowledge of, or child acquisition of, actual Spanish words.

References

Albright, A., Andrade, A., and Hayes, B. 2001. Segmental environments of Spanish diphthongization. UCLA Working Papers in Linguistics 7: 117-151.
Baković, E., Heinz, J., and Rawski, J. In press. Phonological abstractness in the mental lexicon. In The Oxford Handbook of the Mental Lexicon, to appear.
Bale, A., and Reiss, C. 2018. Phonology: a Formal Introduction. MIT Press.
Bybee, J., and Pardo, E. 1981. Morphological and lexical conditioning of rules: experimental evidence from Spanish. Linguistics 19: 937-968.
Gorman, K. and Yang, C. 2019. When nobody wins. In F. Rainer, F. Gardani, H. C. Luschützky and W. U. Dressler (ed.), Competition in Inflection and Word Formation, 169-193. Springer.
Harris, J. 1969. Spanish Phonology. MIT Press.
Harris, J. 1985. Spanish diphthongisation and stress: a paradox resolved. Phonology Yearbook 2:31-45.
Lakoff, G. 1970. Irregularity in Syntax. Holt, Rinehart and Winston.
Kisseberth, C. W. 1970. The treatment of exceptions. Papers in Linguistics 2:44-58.
Mayol, Laia. 2007. Acquisition of irregular patterns in Spanish verbal morphology. In Proceedings of the Twelfth ESSLLI Student Session, 1-11.
Schütze, C. 2005. Thinking about what we are asking speakers to do. In S. Kepser and M. Reis (ed.), Linguistic Evidence: Empirical, Theoretical, and Computational Perspectives, pages 457-485. Mouton de Gruyter.
Zonneveld, W. 1978. A Formal Theory of Exceptions in Generative Phonology. Peter de Ridder.

Noam on neural networks

I just crashed a Zoom conference in which Noam Chomsky was the discussant. (What I have to say will be heavily paraphrased: I wasn’t taking notes.) One back-and-forth stuck with me. Someone asked Noam what people interested in language and cognition ought to study, other than linguistics itself. He mentioned various biological systems, and said however, that they probably shouldn’t bother to study neural networks, since they have very little in common with intelligent biological systems (despite their branding as “neural” and “brain-inspired”). He stated that he is grateful for Zoom closed captions (he has some hearing loss), but that one should not conflate that with language understanding. He said, similarly, that he’s grateful for snow plows, but one shouldn’t confuse such a useful technology with theories of the physical world.

For myself, I think they’re not uninteresting devices, and that linguists are uniquely situated to evaluate them—adversarily, I hope—as models of language. I also think they can be viewed as powerful black boxes for studying the limits of domain-general pattern learning. Sometimes we actually want to ask whether certain linguistic information is actually present in the input, and some of my work (e.g., Gorman et al. 2019) looks at that in some detail. But I do share some intuition that they are not likely to greatly expand our understanding of human language overall.

References

Gorman, K., McCarthy, A. D., Cotterell, R., Vylomova, E., Silfverberg, M., and Markowska, M. Weird inflects but OK: making sense of morphological generation errors. In Proceedings of the 23rd Conference on Computational Natural Language Learning, pages 140-151.

The role of phonotactics in language change

How does phonotactic knowledge influence the path taken by language change? As is often the case, the null hypothesis seems to be simply that it doesn’t. Perhaps speakers have projected a phonotactic constraint C into the grammar of Old English, but that doesn’t necessarily mean that Middle English will conform to C, or even that Middle English won’t freely borrow words that flagrantly violate C.

One case comes from the history of English. As is well known, modern English /ʃ/ descends from Old English sk; modern instances of word-initial sk are mostly borrowed from Dutch (e.g., skipper) or Norse (e.g., ski); sky was borrowed from an Old Norse word meaning ‘cloud’ (which tells you a lot about the weather in the Danelaw). Furthermore, Old English forbids super-heavy long vowel-consonant cluster rimes. Because the one major source for /ʃ/ is sk, and because a word-final long vowel followed by sk was unheard of, V̄ʃ# was rare in Middle English and word-final sequences of tense vowels followed by [ʃ] are still rare in Modern English (Iverson & Salmons 2005). Of course there are exceptions, but according to Iverson & Salmons, they tend to:

be markedly foreign (e.g., cartouche),
to be proper names (e.g., LaRouche),
or to convey an “affective, onomatopoeic quality” (e.g., sheesh, woosh).

However, it is reasonably clear that all of these were added during the Middle or Modern period. Clearly, this constraint, which is still statistically robust (Gorman 2014:85), did not prevent speakers from borrowing and coining exceptions to it. However, it is hard to rule out any historical effect of the constraint: perhaps there would be more Modern English V̄ʃ# words otherwise.

Another case of interest comes from Latin. As is well known Old Latin went through a near-exceptionless “Neogrammarian” sound change, a “primary split” or “conditioned merge” of intervocalic s with r. (The terminus ante quem, i.e., the latest possible date, for the actuation of this change is the 4th c. BCE.) This change had the effect of temporarily eliminating all traces of intervocalic s in late Old Latin (Gorman 2014b). From this fact, one might posit that speakers of this era of Latin might project a *VsV constraint. And, one might posit that this would prevent subsequent sound changes from reintroducing intervocalic s. But this is clearly not the case: in the 1st c. BCE, degemination of ss after diphthongs and long monophthongs reintroduced intervocalic s (e.g., caussa > classical causa ’cause’). It is also clear that loanwords with intervocalic s were freely borrowed, and with the exception of the very early Greek borrowing tūs-tūris ‘incense’, none of them were adapted in any way to conform to a putative *VsV constraint:

(1) Greek loanwords: ambrosia ‘id.’, *asōtus ‘libertine’ (acc.sg. asōtum), basis ‘pedestal’, basilica ‘public hall’, casia ‘cinnamon’ (cf. cassia), cerasus ‘cherry’, gausapa ‘woolen cloth’, lasanum ‘cooking utensil’, nausea ‘id.’, pausa ‘pause’, philosophus ‘philosopher’, poēsis ‘poetry’, sarīsa ‘lance’, seselis ‘seseli’
(2) Celtic loanwords: gaesī ‘javelins’, omāsum ‘tripe’
(3) Germanic loanwords: glaesum ‘amber’, bisōntes ‘wild oxen’

References

Gorman, K. 2014a. A program for phonotactic theory. In Proceedings of the 47th Annual Meeting of the Chicago Linguistic Society, pages 79-93.
Gorman, K. 2014b. Exceptions to rhotacism, In Proceedings of the 48th Annual Meeting of the Chicago Linguistic Society, pages 279-293.
Iverson, G. K. and Salmons, J. C. 2005. Filling the gap: English tense vowel plus final
/š/. Journal of English Linguistics 33: 1-15.