The theoretical interest of this article is that the Nanni effect lets us arbitrate between two possible definitions of the constraint *LAPSE. In grid-based theories of stress (e.g. Prince 1983; Gordon 2002), *LAPSE regulates the distribution of prominence by penalizing strings of stressless material. It is usually if not always assumed that *LAPSE is defined over stress-bearing units, which I will assume to be syllables (though cf. Steriade 2012; Garcia 2017 on intervals). A possible definition for *LAPSE (based on Gordon 2002: 502) is in (2), and its use is illustrated with reference to the form àbracadábra (3). (For alternative formulations of *LAPSE, including some that make reference to foot boundaries, see Green & Kenstowicz 1995; Elenbaas & Kager 1999; Alber 2005; a.o.).

I refer to this constraint as syllabic *LAPSE, as the number of assigned violations depends on the number of consecutive stressless syllables. This can be contrasted with a phonetic definition, where the number of assigned violations depends on duration: the longer the stressless string, the more violations that string receives. The definition of phonetic *LAPSE adopted for now (in (4)) assumes that *LAPSE takes into account the raw phonetic duration of a stressless string, hypothesized to be the interval between the two stressed vowels, and assigns a violation for each millisecond (this definition will be revised in Section 5, where we will see evidence suggesting that phonetic *LAPSE in English only penalizes stressless strings that meet some minimum durational threshold).1 As shown in (5), the version of phonetic *LAPSE in (4) would identify two stressless strings in àbracadábra, δ₁ (bracad) and δ₂ (bra), and assign more violations to δ₁.2

The syllabic and phonetic definitions of *LAPSE make different predictions about whether or not the content of a stressless string should play a role in lapse resolution phenomena. Under a syllabic definition of *LAPSE, the contents of the stressless string should not matter: all stressless strings that comprise a given number of syllables are penalized equally. Under a phonetic definition of *LAPSE, however, the contents of a stressless string should matter: the longer the stressless string, the greater penalty phonetic *LAPSE assigns. This is illustrated below for àbracadábra and àbraskladábra. While both receive an equal number of syllabic *LAPSE violations (6), the longer interstress interval in àbraskladábra is penalized more severely by phonetic *LAPSE (7).

If it is correct to define *LAPSE syllabically, we would not expect lapse resolution phenomena to be sensitive to the duration of stressless strings, if those strings contain the same number of syllables. If it is correct to define *LAPSE phonetically, however, we would expect lapse resolution phenomena to be sensitive to the duration of a stressless string: under an appropriate model of constraint interaction, we might expect a language to exhibit a greater dispreference for words like àbraskladábra (with a longer interstress interval) than words like àbracadábra (with a shorter one). In this way, we will see that the Nanni effect arbitrates in favor of phonetic *LAPSE.

The proposal that gradient phonetic distance plays a role in rhythmic phenomena is not new. The most direct antecedent of this proposal is Hayes’s (1984: 70–73) Phonetic Spacing Hypothesis, under which “the spacing requirements of eurythmy are phonetic, either based on actual physical time, or perhaps some more abstract phonological timing measure”. Hayes’s discussion focuses mostly on the potential role of phonetic distance as it is applicable to English rhythm rule phenomena. For example, he claims that the propensity of Korbél to undergo stress retraction depends on the duration between Korbél’s final stress and the stress in the next word: retraction in Korbél whískey is more likely than retraction in Korbél tequíla, which is more likely than retraction in Korbél champágne. Korbél tequíla and Korbél champágne are alike in that one stressless syllable separates the two stresses; the interstress distance in Korbél champágne is however longer than that in Korbél tequíla, which correlates with a reduced likelihood of retraction. Related observations on this point come from Nespor & Vogel (1989: 79–110), who note that clashes can be ameliorated in Italian through “the lengthening of the first syllable […] or the insertion of a pause between two stressed syllables” (see also Marotta 1983 and Esposito & Truckenbrodt 1998). These options are also available in Catalan, Greek, and English (on English see also Liberman & Prince 1977: 320). Nespor & Vogel also note that there is a tendency for lapses in English and Polish to be resolved not through the addition of stresses, but through an increase in speech rate: speakers “speed up a bit and maintain the string of weak syllables”.

The finding that speech rate impacts the acceptability of a stress clash or lapse suggests that the factors governing rhythmic alternation reference physical time, not more abstract durational properties of segments or sequences of segments, independent of the rate at which they are produced. The results presented in this article, too, are consistent with this hypothesis: as discussed in Section 5, small, phonetically predictable differences in segmental duration affect the rate at which -at- bears stress. While effects of speech rate are not investigated in this article, further work in this area could help determine whether it is indeed correct to define phonetic *LAPSE in terms of raw duration (as hypothesized in this article) or if some abstract measure is more appropriate.

A distinct but related thread of work proposes that *LAPSE and *CLASH (Prince 1983; Kager 1994; Gordon 2002; a.o.) should be gradiently defined at the syllabic level. It is common to assume that what I have referred to as syllabic *LAPSE should be evaluated gradiently, with one violation assigned for each sequence of two stressless syllables (Steriade 1999; Gordon 2005; a.o.). A word of the form σ́₁σ₂σ₃σ́₄σ₅ receives one violation of gradient *LAPSE (for σ₂σ₃), while a word of the form σ́₁σ₂σ₃σ₄σ́₅ receives two violations (one for σ₂σ₃ and one for σ₃σ₄). Equivalent proposals for gradient, syllabically-defined *CLASH are rarer, but Gouskova & Roon (2013) show that the right definition of syllabic *CLASH as it applies to Russian compounds must be gradient: the more syllables that separate the two stresses, the more well-formed the compound.

Whether or not the phenomena that have been analyzed with gradient, syllabically-defined *LAPSE and *CLASH can be recast in terms of phonetically defined *LAPSE and *CLASH is not a question I address here. Similarly, for this article I assume that *LAPSE and *CLASH come in syllabic and phonetic versions; the question of whether this is correct, or if phonetic *LAPSE and *CLASH render syllabic *LAPSE and *CLASH unnecessary, is not one that I take up. Rather, the focus of this article is to demonstrate that phonetic *LAPSE provides us with one potential answer to the question of why stress in -ative appears to depend on the identity of the segments that directly precede -at-. While the proposed explanation has implications for our understanding of the constraints that regulate prominence and makes predictions regarding crosslinguistic patterns of stress assignment, these broader topics are left for future work.

The data confirm Nanni’s claim that -at- stress is rhythmically conditioned; the table in (13) contains two comparisons that show this. First, if -at- stress would cause a violation of syllabic *CLASH, as in òrnátive and incùlpátive, -at- is significantly less likely to bear stress (the asymmetry between (13a–b) is significant at p < .001, Fisher’s Exact Test). Second, if we consider only those forms in which -at- stress would not violate *CLASH, there is an additional rhythmic effect. Forms of this type can be subdivided into two classes: those in which -at- stress would result in syllabic *LAPSE satisfaction (as in législàtive, where the alternative législatìve contains two consecutive stressless syllables) and those in which -at- stress would result in syllabic *EXTLAPSE satisfaction (as in amélioràtive, where the alternative amélioratìve contains three consecutive stressless syllables). As is clear from (13a.i–ii), forms in the *EXTLAPSE category stress -at- at higher rates than those in the *LAPSE category. The statistical significance of this comparison depends on whether the variable -at- stress cases are grouped with the consistently stressed cases, as in (13) (p > .1), or the consistently stressless cases (*LAPSE = 180/334 stressed; *EXTLAPSE = 9/10 stressed; p < .01), but the asymmetry is in any case clear.6

Together, these facts support the general proposal that -at- stress is a lapse resolution strategy, which occurs with increasing frequency as the lapse lengthens.

To investigate the contribution of the pre-at- segments to -at- stress, I focus on only those 334 words in the *LAPSE category in (13a.i), as there is too little data in the *EXTLAPSE category to investigate the factors that favor or disfavor -at- stress in those forms. (For brief discussion of segmental identity in the “*CLASH violated” subset (13b), see Section 5.6.)

As shown in (14), the OED data provide support for Nanni’s (1977) claim that segmental identity is a predictor of -at- stress. They also reveal additional distinctions among segment types as well as quite a bit of variability. When -ative is preceded by a vowel (palliative), -at- is stressed in 50% (22/44) of the lexical items; when -ative is preceded by a sonorant (speculative), -at- is stressed in 58% (88/152); when -ative is preceded by an obstruent (deprecative), -at- is stressed in 84% (92/110); and when -ative is preceded by a consonant cluster (legislative), -at- is stressed in 96% (27/28).

To ensure that this effect is not random and cannot be attributed to other factors, a logistic regression was fit to the data in (14). The dependent variable had a value of 0 if -at- was stressless, and a value of 1 if -at- was (variably or consistently) stressed. The role of segmental information, along with several other potentially relevant factors, were included as independent variables. All predictors included in the model are described below.

The logistic regression was fit using the glm function of R’s lme4 package (Bates et al. 2015). Effects were considered significant if p ≤ .05 (roughly, if the z-statistic’s absolute value ≥ 2), as assessed by the Wald test. A full model including all four factors indicated a significant effect of V/R/O/CC, but not any of the frequency-related factors (Freq_ative, Freq_ate, or Freq_ation). A likelihood ratio test (LRT) was then performed, comparing a model that included all four predictors to one that included only V/R/O/CC. The LRT indicated that the model including all predictors is not a significantly better fit to the data than is the model including only V/R/O/CC (χ² (3) = 3.28, p > .1), and thus the simpler model is to be preferred. The output of this simpler model is summarized in (15). The positive coefficient indicates that as the pre-at- segments change from a vowel to a sonorant to an obstruent to a cluster, -at- becomes significantly more likely to bear stress.

Because V/R/O/CC is a continuous factor, the model does not indicate which differences among these four categories, if any, are statistically significant. To address this point, I fit a second model to the data in (14), where V/R/O/CC was coded as a four-level factor (with 0, or V, as the reference level). Pairwise differences were assessed with Tukey’s honestly significant difference tests, using the glht function of R’s multcomp package (Hothorn et al. 2008). All comparisons except vowel-sonorant and obstruent-cluster were significant at p < .05 or lower thresholds. Note however that the vowel and cluster groups are fairly small (44 forms are in Vowel and 28 are in Cluster, compared to 152 in Sonorant and 110 in Obstruent), so the lack of an effect for the vowel-sonorant and obstruent-cluster comparisons could be due to a lack of statistical power.

It is clear, then, that the identity of the pre-at- segments plays a significant role in determining whether or not -at- bears stress. Furthermore, the effect of segmental material cannot be reduced to more general considerations of lexical frequency.

The present results confirm Nanni’s claims regarding rhythmic and segmental influences on -at- stress. They also suggest that -at- stress is more variable and sensitive to more distinctions among segment types than was previously known.

There are several possible questions about the dictionary study not addressed here. One is whether or not focusing on four segmental categories (V, R, O, and CC) has obscured finer distinctions within them: are clusters with three members, for example, associated with higher rates of -at- stress than clusters with two?8 Another is the extent to which the OED data are representative of American English speech. Given that the OED is a large dictionary with transcriptions for many varieties of English, might the results change if we take the potential diversity of transcription sources into account? The answers to both of these questions is no; for discussion on these points and for a partial extension of the investigation discussed here to other dictionaries, see Stanton (to appear).

Stimuli for the first task, which varied the identity of the pre-at- segments, were composed of one of four “stems” (19) and one of twenty “endings” (20). Three stems were trochaic and one was iambic. The twenty endings included -ative, -ative preceded by a sonorant (r, l, n, or m), -ative preceded by an obstruent (b, d, g, p, k, f, s, or z), and -ative preceded by a cluster (kl, pr, skl, spr, dl, dm, or dn). Each stem was combined with each ending to yield a total of 80 words.

Stimuli for the second task, which varied the identity of the poststress segments, were also composed of one of four “stems” (21) and one of twenty “endings”. As above, forms starting in b-, k-, and l- had trochaic stems; words beginning in s- had iambic stems. The twenty endings for the trochaic forms were similar to those employed in the first task and included bare -adjative, plus -adjative preceded by a sonorant (r, l, n, m), obstruent (b, d, g, p, k, f, s, z), or cluster (kl, pr, skl, spr, dl, dm, dn). Iambic forms differed only in the identity of the medial vowel, which was written as o; endings for the iambic stems included -odjative, -rodjative, etc. Each stem combined with each ending for a total of 80 words.

Two versions of each form, one at-stressed ([eɪɾɪv]~[eɪɾəv]) and one ive-stressed ([ət^hɪv]) were recorded by the author, a native speaker of American English. Each -ative form was produced in the frame X paper. Recordings were made on a Marantz PMD661 MKIII recorder and a Shure SM35 head-mounted microphone in a soundproof booth at New York University. All recordings and text grids created for their analysis are available on the author’s website.

Interstress duration was measured for each token (in Praat, Boersma & Weenink 2017) by summing the interval of time between the offset of the first stressed vowel and the onset of the second stressed vowel. For example, in kédjamàtive, the interstress duration comprises the total durations of [dʒ] through [m]; in kédjamatìve, it comprises [dʒ] through the end of [t^h]’s aspiration (Figures 1–2).

Tokens in which the poststress consonant was r or l were occasionally difficult to segment due to coarticulatory effects on the stressed vowel. In these cases, I inspected the waveform and spectrogram to find the earliest likely vowel-liquid boundary. This hypothesis was then tested auditorily by playing the recording starting from the sonorant and confirming that none of the preceding vowel was audible. In the event that it was, the boundary was moved to the next zero-crossing and tested again; this process iterated as necessary. For example, in keladjative, the boundary was placed at the zero-crossing indicated in Figure 3, where the spectrogram also showed a sharp decrease in amplitude. None of the preceding e is audible when playing the recording starting from this boundary.

Inspection of the resulting interstress durations reveals several generalizations. First, the identity of the pre-at- material has the expected effect on overall lapse duration in the ive-stressed forms: the V/R/O/CC cline observed in the dictionary data is present in the acoustic data (Figure 4). This finding correlates with the dictionary data in the way predicted by the hypothesis. It is thus plausible that -CCative forms bear stress at higher rates than -Oative forms, and -Oative forms at higher rates than -Rative forms, and -Rative forms at higher rates than -Vative forms, because the length of the potential lapse decreases across these categories. While Figure 4 reveals that there is considerable variability in the durations of the various members of these categories – voiced stops, for example, are shorter than nasals – the fact that the rough categories of V/R/O/CC arrange themselves in the cline familiar from the dictionary data is of interest.

The second generalization of interest is that the contribution of the segment types is the same in poststress position as it is in pre-at- position: across contexts, as the material changes from V to R to O to CC, interstress duration of the ive-stressed form increases. This is evident from comparing the durations plotted in Figure 5 with those in Figure 4. This is not exactly what was expected – in the dictionary data, forms with a poststress sonorant (celebrative) bear -at- stress at higher rates than forms with a poststress obstruent (mediative) – but the general shape of the data (V is associated with shorter lapses than CC, and R/O fall somewhere in the middle) is familiar.9

Finally, the third generalization of interest has to do with the relationship between the interstress durations of forms that differ only in the location of suffixal stress (e.g. kédjamàtive vs. kédjamatìve). The average interstress duration of the ive-stressed forms (at 401 ms.) is longer than the average interstress duration of the at-stressed forms (at 223 ms.), and this comparison holds for each item: the àt-to-ìve ratio for interstress duration is fairly constant across items (.59 on average; see also Section 5.3 on this point). It is thus plausible to hypothesize that a speaker would prefer an at-stressed form to an ive-stressed form on account of the at-stressed form’s shorter interstress duration.

In sum, analysis of these nonce -ative forms reveals that the trends discovered in the dictionary study are largely reflected in properties of the stimuli. This is the first step in showing that the current hypothesis regarding the source of the Nanni effect is plausible.

The nonce words discussed in Section 5.1 were normalized for amplitude and pitch-smoothed by 50% (using Praat Vocal Toolkit, Corretge 2012); this was done to lessen differences in amplitude and intonation. The experimental items were constructed by pairing forms that differed in suffixal stress but were otherwise identical. Task 1 had 80 items: 60 trochaic test items (bádjamàtive vs. bádjamatìve) and 20 iambic fillers (sidjómàtive vs. sidjómatìve). Task 2 had 79 items: 60 trochaic test items (bámadjàtive vs. bámadjatìve) and 19 iambic fillers (simódjàtive vs. simódjatìve; one iambic item was excluded due to speaker error). As the OED suggests that the rate of -at- stress in trochaic forms is generally high, the hope was that including iambic items – where -ive stress is necessary to avoid a clash – would encourage variety in response strategy.

For both tasks, participants were presented with an item’s orthographic representation (lidjakative) and instructed to choose which of the two possible pronunciation options they preferred (lídjakàtive vs. lídjakatìve). The stimuli were presented only auditorily, and recordings were played by pressing a radio button (see Figure 6 for an example of how the items were presented). To ensure that participants listened to the recordings in the desired order, the radio button linked to the second recording (“Option 2”) was only available after the first (“Option 1”) had been pressed. In addition, participants were not able to indicate their preferred choice until both “Option 1” and “Option 2” had been pressed. Order of items was randomized by participant, and order of the at- and ive-stressed recordings was randomized by item and by participant.

The tasks were constructed with Experigen (Becker & Levine 2013) and 100 participants, 50 per task, were recruited using Amazon’s Mechanical Turk. To be eligible to participate, participants had to have a US IP address, 500 previously accepted tasks, and an approval rating of 97% or above. Participants were compensated $2.00 for their time. When deciding whether or not to include the responses from each participant, I checked that they were a native speaker of American English and that they were attending to the stimuli, in the ways discussed below.

One Task 1 participant selected the first pronunciation option for all 80 items, so their results were excluded. The analysis of Task 1 that follows takes into account the responses of the remaining 49 participants, while the analysis of Task 2 takes into account the responses of all 50 of its participants.

Responses for Task 1 indicate a positive correlation between interstress duration of the ive-stressed form and the likelihood of a preference for -at- stress. This result is visualized in Figure 7. Figure 7’s x axis represents interstress duration of the ive-stressed form; the raw results are represented as point ranges, where the point represents the percentage of -at-stress responses and the line represents the 95% binomial proportion confidence interval. To aid readability, data were binned into 10 ms. intervals. The absence of a point range at 470 ms. reflects an absence of items for which the ive-stressed form’s interstress duration falls between 470 and 480 ms.

The best-fit line in Figure 7 was obtained from a mixed effects logistic regression model, using the Effect function of R’s effects package (Fox 2003; Fox & Weisberg 2018). The dependent variable for the model was the preferred pronunciation (a 1 for -at- stress, and a 0 for -ive stress). Independent variables included interstress duration (a continuous predictor) and the identity of the pre-at- material (a categorical predictor, sum-coded, with “vowel” as the reference level); this second variable was included to account for the possibility that -at- stress might be preferred or dispreferred in certain segmental contexts (like -skative or -lative) for reasons independent of interstress duration.10 Random effects included a random intercept for item (1|Item) and a by-participant random slope and intercept for interstress duration (1+Interstress|Participant). The model was fit with the glmer function of R’s lme4 package (Bates et al. 2015) and p-values were obtained with R’s lmerTest package (Kuznetsova et al. 2017).

As is evident from the summary in (22), the effect of interstress duration is significant: the observed correlation between longer interstress duration of the ive-stressed form and greater likelihood of -at- stress is unlikely to be due to chance. In addition, significant effects of ending identity indicate that the segmental composition of the items played a role in participant judgments. -at- stress was preferred less than expected (given interstress duration) for forms ending in -dmative, -dnative, -fative, -native, and -rative; -at- stress was preferred more than expected (given interstress duration) for forms ending in -skative. An LRT indicates that a model including the predictor for interstress duration is a significantly better fit to the data than an otherwise equivalent model that does not (χ² (1) = 7.57, p < .01).

An anonymous reviewer expresses surprise that the results in this section are modeled as a function of the interstress duration of the ive-stressed form, rather than the àt-to-ìve ratio for interstress duration. The reason for this is reflected in Figure 8, which plots for each item the interstress duration of the ive-stressed form against that of the at-stressed form (e.g. lídjakatìve-lídjakàtive). The ratio of àt-to-ìve interstress duration is roughly constant across forms of all lengths (as discussed briefly in Section 5.1); the best-fit line has a slope of 0.97 (p < .001, linear regression).

Given this, differences in the àt-to-ìve ratio do not seem a likely predictor of participant responses. This was confirmed by fitting another mixed effects logistic regression to the data, similar to the one reported in (22), but with the àt-to-ìve ratio replacing interstress duration of the ive-stressed form in the fixed and random effect components. The effect of the àt-to-ìve ratio was not significant in this model (z = –0.67, p > .1), and goodness of fit measures indicate that it is a poorer fit to the data than is the model reported in (22).11

This result is interesting because it indicates that participants’ dispreference for an ive-stressed form is likely linked to the interstress duration of that form in isolation and does not take into account the relationship between that longer interstress duration and the shorter one that could be obtained by stressing -at-. In other words, participants appeared to make decisions about whether -at- stress or -ive stress was preferable on the basis of the ive-stressed form alone; there is no evidence that properties of the at-stressed form, alone or in comparison to those of the ive-stressed form, were taken into account. It is possible to imagine a different response strategy, where a preference for -ive stress would increase proportional to the difference between the at- and the ive-stressed forms’ interstress durations. This, however, is not what was observed.

Participant responses for Task 2, which manipulated the identity of the poststress segments (e.g. baladjative vs. baskladjative) also indicate a positive correlation between interstress duration of the ive-stressed form and the likelihood of a preference for -at- stress. Figure 9’s best-fit line was again obtained from a mixed effects logistic regression model with the Effect function of R’s effects package. The dependent variable for the model was the preferred pronunciation (1 for -at- stress, 0 for -ive stress). Independent variables were interstress duration (a continuous predictor) and the identity of the poststress material (a categorical predictor, sum-coded, with “vowel” as the reference level). Random effects were a random intercept for item (1|Item) and a by-participant random slope and intercept for interstress duration (1+Interstress|Participant). In this way, the model fit to the Task 2 data was identical to that fit to the Task 1 data (and as before, the model was fit using the glmer function of R’s lme4 package, with p values obtained with R’s lmerTest package).

Model results (23) indicate that interstress duration plays a significant role in participant responses: the longer the interstress duration of the ive-stressed form, the more likely participants are to prefer -at- stress. An LRT confirms that a model including this fixed effect is a better fit to the data than an otherwise equivalent model that does not (χ² (1) = 5.94, p < .05). The coefficient of this effect (8.36) is close to the coefficient of the equivalent effect in Task 1 (8.6), indicating that the magnitude of the effect was fairly consistent across the two tasks. In addition, the results indicate that participants prefer -at- stress for forms with a poststress consonant of d (e.g. kedadjative) at a higher rate than is predicted based on the ive-stressed forms’ interstress duration alone.12

Why is there an apparent discrepancy between the raw results plotted in Figure 9 and the mixed effect model’s best fit line? Because the best fit line takes other sources of variance into account. In particular, the identity of the poststress segment(s) often influences participants’ judgments in the opposite direction than what is expected from interstress duration. For example, participants were less likely to prefer at-stressed forms with poststress skl than is expected given their interstress duration (p = .1), and more likely to prefer at-stressed forms with poststress l than is expected given their interstress duration (p > .1). For complete information along these lines, see the appendix, which contains a summary of the statistical models fit to both sets of experimental data.

Two other differences between the tasks should be addressed before moving on. First, the effects of interstress duration are visually apparent in the raw data from Task 1 but not Task 2. While I do not have an explanation for this finding, this difference between the Task 1 and Task 2 raw results mirrors differences observed in the dictionary data: the effect of V/R/O/CC comes through clearly when one categorizes the forms by their pre-at- segments, though not their poststress ones. Perhaps the segmental factors responsible for the appearance of the raw data in Figure 9 are responsible for the shape of the dictionary data as well. Second, the mean rate of -at- stress differs across the two tasks. Task 1 participants preferred -at- stress for 55.4% of the items, while Task 2 participants preferred it for 33.2%. One possible explanation for this observation is that -at- stress is preferred when the pre-at- consonant is [dʒ] (as was the case for all Task 2 items) due to a potential OCP effect: if -at- were stressless, the result would be words in which obstruents sharing the same major place of articulation are separated only by a schwa ([-dʒət^hɪv]). Whether or not this is plausible would need to be confirmed by running variants of Task 2 with different pre-at- segments.

In any case, the result of interest here is that interstress duration of the ive-stressed form is a significant predictor of participant preference for -at- stress. Furthermore, the magnitude of this effect does not appear to depend on whether the manipulated segments are in pre-at- position (as in badjalative-badjasklative, Task 1) or poststress position (as in baladjative-baskladjative, Task 2). This result – that segments distal to -at- should matter, just as proximal ones do – is predicted by the current hypothesis.

For a preliminary constraint-based analysis of these results, I focus on participant responses to four of the Task 1 items: badjasprative, badjapative, badjalative, and badjanative. As is evident from (24), the shorter the duration of the ive-stressed form, the more likely participants are to prefer it. Unsurprisingly given the above discussion, participant responses were not correlated with the àt-to-ìve ratio nor the raw differences in their interstress duration.

For an analysis I assume two constraints. The first is phonetic *LAPSE. To capture to the observation that participants’ responses only took into account the interstress duration of the ive-stressed form, I assume that phonetic *LAPSE only penalizes stressless strings that exceed a certain durational threshold. For the purposes of this preliminary analysis I assume, somewhat arbitrarily, that this threshold is 381 ms.: this is both the longest duration of an at-stressed form (Task 2, líspradjàtive) and the shortest interstress duration of an ive-stressed form (Task 1, bádjabatìve). As a result, the version of phonetic *LAPSE in (25) only penalizes lapses in ive-stressed forms. This allows the grammar to take into account only the interstress duration of the ive-stressed form.13

The second necessary constraint is STRESS_-ive, repeated from (4) as (26). This constraint prefers ive-stressed forms, and acts as a counterbalance to phonetic *LAPSE.

Weights for these constraints were computed with the Maxent Grammar Tool (Hayes et al. 2009), using the input-output pairs and violations summarized in (27). The tool found a weight of 0.02 for *LAPSE and 0.79 for STRESS_-ive. When the ive-stressed form has a relatively long lapse, as in (27a), the penalty assigned by *LAPSE is severe and the at-stressed form is preferred. When the ive-stressed form has a relatively short lapse, as in (27d), the penalty assigned by *LAPSE is minimal and the ive-stressed form is preferred. The close resemblance of the predicted probabilities to the attested responses (in (24)) indicates that this model provides a relatively good fit to participants’ preferences regarding stress in these four items.

In a full analysis, segment-specific effects like the preference for -at- stress in -skative forms could be captured by incorporating further markedness constraints, like *skə.

An anonymous reviewer asks how to reconcile the probabilistic behavior exhibited by participants in the nonce word experiments with the observation that many existing -ative words have a fixed stress. It is however unclear exactly how many -ative words actually have a fixed stress: while the OED records only 75/344 of the trochee-final -ative forms as carrying variable -at- stress, judgments from native speakers suggest that variability is more pervasive. To give one example: fabricative is transcribed as bearing -ive stress, but the speakers I have consulted consider -at- stress possible as well. Among the relatively few forms for which speakers do have consistent judgments, there are two possible sources of this consistency. The first is that the penalty assessed by *LAPSE is so severe that the probability of producing the ive-stressed form approaches zero. This could be the case for rémonstràtive, with a four-consonant cluster preceding -at-. The second possibility is that speakers have memorized the -ative form, together with its stress, and the consistent stress placement reflects faithfulness to the lexical item’s input stresses (see Zuraw 2000 for a proposal that can distinguish real and nonce words in this way). This could be the case for légslàtive, a frequent form with invariant stress.

Recall from the discussion in Section 3.1 that stress in -ative is rhythmically conditioned. -at- stress is frequent in a context where it does not result in clash: in 69% of the relevant forms in the OED, -at- is variably or consistently transcribed as bearing stress (as in législàtive). -at- stress is however much less frequent in a context where it results in a stress clash: only 6% of the relevant forms in the OED bear -at- stress in this context (as in órnàtive). We would thus expect participants’ preferences to reflect this. Concretely, preference for an at-stressed form should be more likely with trochaic items like bádjasprative (where it does not result in a clash) than in iambic items like sidjósprative (where it does). As shown in Figure 10, this prediction is borne out: across both tasks, participants are more likely to prefer -at- stress for forms with trochaic stems (p < .001 for both tasks, logistic regressions).

I assume that the dispreference for -at- stress in iambic forms is due to *CLASH, a constraint that penalizes adjacent stressed syllables. An alternative interpretation under which the relevant constraint is really phonetic *CLASH, which would assign violations for interstress durations that fall below a certain threshold, is not supported by consideration of further results. This is demonstrated in Figures 11–12, where participant responses to the iambic items are plotted by the interstress duration of the at-stressed form. In the case of the Task 1 iambic forms (Figure 11), the best-fit line has a slight negative slope, which would be unexpected were phonetic *CLASH active (though p > .1). In the case of the Task 2 iambic forms (Figure 12), the best-fit line has a positive slope, as would be expected if phonetic *CLASH were active (though p > .1). (For both sets of data, the dependent variable was the participants’ stress judgment; independent variables included a continuous predictor for interstress duration of the at-stressed form and random intercepts for item and participant.14)

The dictionary data are largely consistent with this picture: while clash in -ative is dispreferred, there are no clear further subdivisions within that class. Of the 41 cases where -at- stress would involve a clash across a sonorant (compéllative), 3 (7%) stress -at-; of the 75 cases where -at- stress would involve clash across an obstruent (légative), 5 (6%) stress -at-; and of the 115 cases where -at- stress would involve clash across a cluster (cálmative), 7 (or 6%) stress -at-.

It is worth noting however that these investigations into *CLASH in -ative are based on relatively little data, and as such should not be taken as evidence against the possibility that phonetic *CLASH is active in English. The experimental results summarized in Figures 11–12 are based on responses to a small number of items: since there was only one iambic “stem”, each pre-at- or poststress value (e.g. pr, kl) was found in only one item. This means that any effect of interstress duration in these forms cannot be dissociated from an item effect (perhaps certain recordings sounded unnatural) or a segmental effect (perhaps clash is better across pr than kl, for independent reasons). An experiment with a larger and more varied set of stimuli would be necessary to further investigate the effect of interstress duration in iambic -ative forms. In the case of the dictionary data, only 15 words exhibit clash with -at-, meaning that the numbers are too small to reliably investigate any differences according to segment type. Thus any dictionary study attempting to locate potential evidence for phonetic *CLASH would need to focus on a class of words where clash is more common. For a potential example of this sort, see Section 7.2 on -ization.

If phonetic *LAPSE is active in American English, why is it necessary to look at -ative forms to find evidence for it? In this section I first show that -ative is one of the few corners of English where phonetic and syllabic definitions of *LAPSE can be differentiated, as -ative forms are one of the only classes of forms in English in which lapses are both allowed and can be variably resolved. In addition, I argue that the relative infrequency of forms in -ative provides support for the notion that the factors regulating their stress are entirely general.

To review and expand on points from Section 2: in forms in -ative, two preferences conspire to create lapses. The first is a dispreference for shifting stress in the stem domain, such that législative must be produced as législàtive or législatìve (*legíslatìve). I assume that this dispreference for shifted stress is due to a requirement for the stem of an -ative derivative to resemble the stem of its morphological base: thus the stem of législative must resemble that of législàtion and législàte, while stress in the suffixal domain is governed by other constraints.20 I formalize this dispreference against shifting stem stress as BASE.DERIVATIVE(stress)_stem (abbreviated as BD.IDENT(stress)_stem); see Benua (1997) on transderivational correspondence constraints. To simplify the presentation, in (30) I assume a syllabic definition of *LAPSE.

Candidate (30c), with shifted stress relative to lègislát(ion), is ruled out by BD.IDENT (stress)_stem: the initial stress of législàt(ion) has been removed, and a peninitial stress has been added. Candidate (30a), which violates STRESS_-ive, ties with candidate (30b), which violates *LAPSE(syll). The ultimate preference for législàtive is due to the fact that the stressless string preceding -at- is long.

Forms in -ative are not alone in allowing large numbers of lapses. Of those forms in -able that end in trochaic or dactylic bases (e.g. challengeable, from chállenge), a large majority (375/393) permit *LAPSE(syll) violations in order to satisfy BD.IDENT(stress)_stem (Stanton & Steriade in prep). chállengeable, for example, must resemble related chállenge and in doing so violates *LAPSE(syll) twice (31). This indicates that BD.IDENT(stress)_stem dominates *LAPSE(syll), as above.

Forms ending in -able differs from those ending in -ative in that they typically do not resolve *LAPSE violations except under specific morphophonological circumstances. Take, for example, the case of remédiable, which takes its stress not from its likely morphological base rémedy but from its co-derivative remédial (Steriade 1999; Stanton & Steriade in prep). Here, the stress shift of remédiable relative to its base rémedy is plausibly licensed by the form remédial, and thus has no bearing on whether or not *LAPSE should be defined in phonetic or syllabic terms: the stress of remédial is preferable by either. Further evidence that the shift in remédiable is licensed by the related form remédial comes from the fact that stress shift in -able only arises when such a related form is available. Medícinable, for example, resembles not médicine but its co-derivative medícinal; compániable resembles not cómpany but its co-derivative compánion. For justification of assumptions regarding the identity of morphological bases and for analysis of this phenomenon, see Steriade (1999) and Stanton & Steriade (in prep). What matters here is that the circumstances under which -able allows lapses to be avoided are restricted, and in this sense, -able is very different from -ative.

The question arises as to why -ative and -able are different in this way: why can lapses be avoided in -ative (by stressing -at-, as in législàtive) but not in -able, as the impossible *chállengeàble makes clear? I am not sure that there is a more insightful answer than the observation that -able, when word-final, never bears stress on either of its syllables (and thus whatever constraint requires -able to be stressless must dominate *LAPSE). Thus -ative is special in three ways. First, base-derivative faithfulness to stem stress is high-ranked, meaning that the conditions for lapse licensing (e.g. a trochee-final stem, like législ-) can be met. Second, STRESS_-ive works to pull stress off -at-, creating a context where lapses are preferred. And third, *LAPSE can be resolved in these forms by stressing a suffix. These three factors work together to create a large class of forms in which lapses are sometimes licensed and sometimes resolved. This combination of factors is attested in only one other type of form that I am aware of (-ization forms, discussed in Section 7.2), making -ative one of the only corners of English in which the conditions that make lapse licensing or resolution more likely can be investigated in a quantitatively robust way.

It is worth emphasizing that the relative obscurity of forms ending in -ative provides support for the hypothesis that the Nanni effect reveals something very general about the phonology of American English, and against an additional alternative hypothesis that the effect reflects a grammatical principle peculiar to -ative. Of the 548 -ative forms considered in this study, the mean OED frequency band is 2.8. As noted by the OED, forms in band 2 “occur fewer than 0.01 times per million words in typical modern English usage” and are “almost exclusively terms which are not part of normal discourse and would be unknown to most people”. The rarity of -ative forms makes it unlikely that a typical English-acquiring child would be exposed to many of them (if any at all), a hypothesis that is supported by the complete absence of all -ative forms from the CHILDES Parental Corpus (Li & Shirai 2000; MacWhinney 2000). Given the probable lack of -ative forms from the typical child’s input, the fact that we find the Nanni effect robustly attested in dictionary and behavioral data suggests that the factors governing stress on -at- must be general: the learner must be able to acquire the Nanni effect even with little or no information from -ative.

This section presents potential evidence for phonetic *LAPSE and *CLASH from -ization forms. As is true for -at- in -ative, stress on -ize- in -ization is variable: the OED transcribes ruggedization with and without -ize- stress, dogmatization with -ize- stress, and migmatization without it. I show here that the rhythmic and segmental factors implicated in -at(ive) stress are implicated in -iz(ation) stress as well.

For this small study, I extracted 759 -ization forms from the OED. These include all -ization forms associated with a transcription, and a number of duplicates: in some cases there were multiple possibilities for stem stress in a given word (e.g. notarization can have trochaic [ˈnoʊdər-] or monosyllabic [ˈnoʊdr-]), so these instances were counted separately. In line with the counts that were done for -ative, -ize- is counted as “stressed” if it is consistently or variably stressed, and “stressless” if it is never stressed. Examples follow in (32), with transcriptions from the OED.

There is an overall preference for -ize- stress: it is stressed in 705/759 forms. I assume that this is due to the activity of some markedness constraint, which prefers stress to fall on -ize- (e.g. STRESS_-ize). The question investigated below is whether or not the distribution of the 54 forms in which -ize- does not bear stress can be predicted given rhythmic or segmental factors. The discussion in this section is largely speculative, as it does not include statistical models that take factors like lexical frequency into account, or any investigation into the phonetic properties of -ization forms.

This article has argued, on the basis of words ending in -ative (and secondarily -ization), that constraints regulating the distribution of prominence must be able to reference fine-grained durational information. But if the majority of evidence for phonetically-defined accentual constraints comes from rare Latinate forms, like the -ative and -ization cases discussed above, this result raises the question of how the English-learning child knows that phonetic versions of *LAPSE and *CLASH exist. While one possibility is that these constraints are universal, in the sense of Prince & Smolensky (2004), I believe the more likely possibility is that the evidence for phonetically-defined *LAPSE and *CLASH is more general than we have seen in this article, and that the learner applies to -ative and -ization what they have induced from more general facts about the distribution of lexical stress in English. Understanding exactly what these more general facts are is a topic I leave for future work.

Before closing, it is worth noting that the argument for phonetically-defined rhythmic constraints may have broader implications for theories of stress. Throughout this article I have tacitly assumed that English stress ought to be analyzed in a foot-free framework (e.g. Gordon 2002): the distribution of prominence is regulated by grid-based constraints like *LAPSE and *CLASH, not constraints that regulate the size and placement of metrical constituents. The evidence that *LAPSE (and perhaps *CLASH) is phonetically defined presents a problem for theories of stress that do not appeal to rhythmic constraints (like Martínez-Paricio & Kager 2015) as it is not clear how the effect documented in this article – the positive correlation of -at- stress with interstress duration – could be captured in these theories. In short, the Nanni effect provides an argument that rhythmic constraints must be able to reference fine-grained durational information, and potentially an argument for the inclusion of rhythmic constraints in theories of stress more generally.