## 1 Introduction

How can we account for the processing and distribution of verb phrase (VP) ellipsis structures? (See Johnson 1996; 2001; Kehler 2000; Merchant 2015; and Kobele & Merchant 2016 for discussion of the space of possibilities.) Here we assume that it is a theory of grammar together with a theory of processing that, taken jointly, accounts for actual data such as the acceptability and interpretation of elided constituents. We assume that the grammar requires syntactic matching of antecedent and elided constituent. This assumption is supported by the systematic finding of a strong decrement in acceptability for antecedent clauses which mismatch an ellipsis clause with no corresponding decrement in acceptability for the full counterparts of the ellipsis examples (Kim & Runner 2018; Clifton et al. 2019; see Kim et al. 2011 for a different account of the mismatch penalty). Following Arregui et al. (2006) and subsequent work (e.g., Frazier & Clifton 2015), the processor repairs a syntactic antecedent that nearly matches the elided constituent syntactically if the repair is a simple and natural one, i.e., one with few operations, lots of evidence for those operations, and where the input corresponds to a natural speech error.

Given this repair (or “recycling”) theory of ellipsis, an obvious question is whether split-antecedent ellipsis, see (3) below, is a case of repair. We will argue that it is not. Instead it shows the hallmarks of accommodation (see discussion below immediately preceding Section 3.1), and none of the usual characteristics of repair. This leads to the question of the circumstances under which mismatch ellipsis is repaired and the circumstances under which an antecedent can be felicitously accommodated. Below we present preliminary evidence for the following hypothesis.

Activated Syntactic Memory (ASM) hypothesis: Memory holds the syntactic representation of the current sentence and the last potentially independent clause (assuming clauses of average size and complexity). An antecedent is repaired if it is within ASM. If an antecedent is not within ASM, a detailed syntactic structure of the antecedent may not be available to repair.

The structure of the paper is as follows. We give a synopsis of the evidence supporting the repair/recycling account in Section 2. Section 3 takes up split-antecedent ellipsis, arguing that it is not a case of repairing the antecedent to a grammatical/matching antecedent. Section 4 investigates the effect of having distant antecedents on the processing of pronouns and ellipsis, and presents preliminary evidence that split antecedents cannot be repaired because at least one of the conjuncts is too far away. Section 5 looks more carefully at the ASM hypothesis, explores its predictions about the circumstances of repair vs accommodation, and presents an initial test of one of its predictions. Section 6 concludes.

## 2 The Recycling account

The recycling account of mismatch ellipsis is based on the idea that the processor searches for a grammatical analysis of an input. Lacking a fully grammatical analysis, it may make certain repairs, especially if the input corresponds to a likely speech error, e.g., syntactic blend of an antecedent clause with one voice and an ellipsis clause in a different voice. The processor in general seems able to reverse natural speech errors (Frazier & Clifton 2011a; 2015). Making a slight repair to an input structure may be considered a type of cooperative comprehension. Interestingly, ellipsis repairs share features of garden path repairs, in that repairs are done when only few operations are needed and there is lots of evidence for them (e.g., Frazier & Clifton 1998). In both garden path repair and input repair, semantic plausibility matters, with repair being easier if the first interpretation is implausible and the final interpretation is plausible. Neither in the case of garden path repair nor in the case of ellipsis repair is it possible at present to say precisely how many repair operations can be accomplished successfully. This is at least in part because the ability to revise or repair depends on the amount of evidence indicating the need for a repair and the informativeness of the repair signal (and possibly even on the motivation of the comprehender).

In studies of mismatch ellipsis, the acceptability decrement observed for a mismatching antecedent is related to the number of additional or repair steps required in comprehension (Arregui et al. 2006). Acceptability drops from an available matching VP antecedent (1a), to a matching VP embedded inside a determiner phrase (DP) in a non-canonical position for a VP (1b), to replacing the empty object of see in (1c) with its ultimate binder (1c), with the worst (we assume) unacceptable ungrammatical case in (1d), where an appropriate antecedent would need to be built from scratch after ripping see out of the adjective in (1d).

 (1) a. None of the astronomers saw the comet, /but John did. (Available verb phrase) b. Seeing the comet was nearly impossible, /but John did. (Embedded verb phrase) c. The comet was nearly impossible to see, /but John did. (Verb phrase with trace) d. The comet was nearly unseeable, /but John did. (Negative adjective)

These results, provided in Table 1 and Figure 1, and others presented in the Arregui et al. paper, for example showing that verbal gerundive antecedents are more acceptable than nominal gerundive antecedents for VP ellipsis, suggest the processor repairs antecedents and the result is relatively acceptable under particular circumstances.1

Table 1

Percentage acceptable responses and reaction time (ms), Experiment 1. “/” marks the division of each sentence into two portions, which participants moved through by button-press.

% Acceptable Reaction Time
a. Available verb phrase 82.8 2146
b. Embedded verb phrase 66.1 2230
c. Verb phrase with trace 43.9 2399
Figure 1

Percentage acceptable responses from Arregui et al. (2006) Expt. 1.

Garnham & Oakhill (1987) presented readers with mini-discourses like (2) containing VP ellipsis that would result in either a plausible or implausible interpretation. The answer to questions about the final sentence indicated that only with the nurse as subject of the final sentence did participants report any non-matching interpretations where the final clause is interpreted as having active rather than passive voice.

 (2) It had been a busy morning in the hospital. The elderly patient had been examined by the doctor. The child/nurse had too.

The results, in our view, suggest repair to a plausible interpretation (the nurse examined the patient) is possible, but not to an implausible one (the child examined the patient).2

Acceptability of an ungrammatical form in general and in the case of ellipsis in particular depends on its ease of repair (number of operations needed, amount of evidence for them), the plausibility of the ultimate form (the token based parsing system only delivers plausible meanings, Frazier 2015), and the likelihood or naturalness of the input as a speech error (see Coppock 2006). Relevant evidence derives from the existence of a voice mismatch asymmetry predicted by the human tendency to misremember a passive as an active more often than the other way around (Mehler 1963; Arregui et al. 2006; Clifton et al. 2019; but also Merchant 2008). The idea that speakers/hearers may forget the form of an antecedent clause predicts that the acceptability of mismatches will be higher when common syntactic alternatives are available for encoding a message (e.g., as a coordinate VP vs S, Frazier & Clifton 2011b). Other studies indicate that the acceptability of mismatches is lower when attention is directed to the form of the input, and higher when the imperfect form comments on the question under discussion (QUD) (Grant et al. 2012). Given this evidence for repair of mismatch ellipsis, we now ask whether processing split antecedent ellipsis involves repair.

## 3 Split antecedents

The marquee example of split antecedent VP ellipsis is in (3), due to Bonnie Webber (1978).

 (3) Webber (1978) Bob wants to sail round the world and Alice wants to climb Kilimanjaro, but neither of them can [ ], because money is too tight.

Split antecedent ellipsis is a label for a particular kind of mismatch ellipsis that can be relatively acceptable despite the fact that there is no surface matching antecedent for the elided VP. There are many theories of split antecedent ellipsis. Starting with Hardt (1999) there has been the idea that a null pro-form is present after the auxiliary, rather than an elided constituent, and that there has to be an accessible antecedent recoverable in the discourse context (see Dalrymple et al. 1991; Miller & Hemforth 2014 on polar noun antecedents for VP ellipsis; Miller & Pullum 2014 for discussion of exophoric examples; and Poppels & Kehler in this volume for an anaphoric account based on discourse anaphora). Elbourne (2008) presents an approach based on constructing a maximal plural predicate. A context variable restrictor R then supplies the constraint on how the plural predicate is mapped to referents, e.g., with a “respectively” relation.3

What would a repair theory of split antecedents look like? The processor could use conjunct 1 and conjunct 2 to build a VP (cf. Fiengo & May 1992; 1994 on syntactic reconstruction), as sketched in (4). The distributivity of the subject might determine whether the VPs are conjoined or disjoined.

 (4) a. Bob wants to [VP1 sail round the world] and Alice wants to [VP2 climb Kilimanjaro], but neither of them can [ ], because money is too tight.but neither of them can: “VP1 or VP2” b. Bob doesn’t want to [VP1 sail round the world] and Alice doesn’t want to [VP2 climb Kilimanjaro], but they will [ ], because they made a promise to each other.but they will: “VP1 and VP2”and they each can “VP1 or VP2 respectively”

The central repair would thus be building a single VP from the VPs in two source clauses. So the question is whether indeed it is a repair that produces the antecedent needed for split antecedent ellipsis.

We will approach this question by asking whether the operations used in processing split antecedents look like other syntactic repair operations that change the form of the input, e.g., is an example requiring repair less acceptable than one not needing repair, are simpler repairs preferred? In the case of processing garden path sentences revisions of structure are needed, e.g., after incorporating the old torn sock as the object of mend in While Mary was mending the old torn sock fell off her lap., the postverbal DP must be reanalyzed as the subject of fell off. Having more evidence for the repair facilitates processing (e.g., Pickering & Traxler 2000; Fodor & Ferreira 1998). Revisions with more operations are known to be difficult especially when there is not clear evidence indicating which operations are needed (e.g., The horse raced past the barn fell.).

In contrast to repair, the operations involved in split antecedent ellipsis might instead involve some form of accommodation, i.e., semantically adjusting the common ground (CG) to make the discourse coherent or to satisfy presuppositions (Stalnaker 2002), justify the epistemic state of the speaker, or the like.

Repair and accommodation are expected to have different properties, flowing from a core difference in targets. Repairs have syntactic structure as their targets, whereas accommodation is a matter of propositions. Consequently, the distance between the input and the adjusted representation differs depending on whether repair or accommodation is involved: for repair, the distance metric depends on the number and cost of operations defined on a syntactic structure, but for accommodation, the relevant distance might be a function of the differences between a proposition and the existing common ground. We also expect that the initiation of a repair should be the result of an accumulated amount of evidence to its necessity, while accommodation can be dependent on, e.g., a particular presupposition trigger. Further, repair comes with a measurable processing and acceptability cost, whereas accommodation can be easier or more acceptable than a counterpart not requiring accommodation (compare: Josh’s wife is sick. vs Josh has a wife. She is sick.).

Below we present three experiments designed to arbitrate between these accommodation and repair theories of split antecedent ellipsis.4

### 3.1 Experiment 1: Paraphrase elicitation

We conducted a pilot experiment investigating the paraphrases proposed by participants for elliptical clauses like but neither of them can in (3). This showed that the most common paraphrase of (3) was “but neither of them can [do what they want]” though a range of paraphrases were given. This does not fit neatly with a repair theory of split antecedents since we would expect a minimal repair of the surface form, using the copied VPs. In other words, if a VP has just been formed by conjoining two VPs we might expect participants to provide something like this form as a paraphrase. The pilot results motivated a larger-scale investigation to determine whether paraphrases of split antecedent ellipsis stay close to the structure of a repaired antecedent, which we report below.

#### 3.1.1 Method and materials

We recruited 25 adult native speakers of English on Amazon’s MechanicalTurk platform. Each participant was presented with a form containing four questions consisting of a tri-clausal sentence and a completion prompt soliciting a paraphrase for the final clause. Two sample questions are demonstrated in (5) and (6). The tri-clausal sentences were each composed of two parallel coordinates and a corresponding split antecedent ellipsis site.

 (5) Wendy is eager to sail around the world and Bruce is eager to climb Mt. Kilimanjaro, but neither of them has so far. Please say what you took that to mean by completing this sentence: “So far, neither of them …..”
 (6) Katherine plans to work in her hometown in January and Sam plans to help his parents, and both of them will without complaint. Please say what you took that to mean by completing this sentence: “Without complaint both of them …..”

#### 3.3.2 Results

The mean naturalness ratings are presented in Table 4 and Figure 3.

Table 4

Mean naturalness ratings (1–7) (with standard errors).

–Pronoun +Pronoun
–Ellipsis 4.62 (0.13) 4.77 (0.13)
+Ellipsis 4.21 (0.13) 5.04 (0.13)
Figure 3

Mean naturalness ratings (1–7) (with standard errors) from Experiment 3.

In addition to a main effect of subject type such that pronominal subjects exhibited a naturalness advantage (b = 0.79, z = 4.35, p < .001), we find a significant interaction of subject type × ellipsis (b = 1.15, z = 3.45, p < .001), with elliptical examples showing a greater pronoun advantage (Pronoun – Coordinate = 0.83) compared to the non-elliptical examples (Pronoun – Coordinate = 0.15).

This is as expected on an accommodation approach to split antecedents, but not on a repair account.

### 3.4 General Discussion

To summarize, the processing of split antecedent ellipsis does not exhibit the same properties as syntactic repair, e.g., repair in garden path sentences (Fodor & Ferreira 1998; Frazier & Clifton 1998), and repair in the processing of mismatch ellipsis (Arregui et al. 2006; Frazier & Clifton 2005). We have shown here that:

1. paraphrases vary but need not stay close to the structure of the input

2. the source material for the repair can come from two distinct independent sentences

3. parallel examples are better than non-parallel but there appears to be no interaction with ellipsis

4. they + VPE” with split antecedent is more acceptable than “DP and DP + VPE” with split antecedent (attributed to having another accommodation in the ellipsis clause)

We conclude that split-antecedent ellipsis is not a matter of repair, and conjecture that it is due instead to accommodation.

But this leaves us with a puzzle: Examples of acceptable mismatches sometimes involve repair, sometimes not. For the repair theory to be explanatory, it is essential to be able to predict the circumstances under which repair takes place. It is to this puzzle that we now turn.

## 4 Distance effects and ASM

Following Frazier & Clifton (2005), we will assume that syntactic representations are couched in the vocabulary of DP, VP, c-command, etc.; salience relations in the syntactic representation are based on recency. Discourse representations are couched in the vocabulary of information structure (topic…) and show distinct salience relations based on focus, main assertion and the like. Given our assumption that the grammar requires a syntactically matching antecedent for elided constituents, it is then predicted that a larger distance effect should obtain for ellipsis than for discourse anaphora, which requires only a referent in the discourse representation. Although surely an idealization, we further suggest that it is the current clause/sentence and the last potentially independent clause that tend to be active in ASM as a discourse is processed.

Below we report three studies that test this prediction. The distance facts are of some interest in their own right. But in the present paper they will also serve to underpin assumptions about what syntactic material is readily accessible in ASM. This will be critical for our explanation of when the processor makes repairs of mismatch ellipsis and when it accommodates an antecedent.

We begin with the results of a small pilot study in which 12 local participants provided naturalness ratings (1–7) for 8 sentences like those in (12). The question is whether the distance effect (±Distant) for ellipsis (Ell), the (c)–(d) difference, is larger than it is for pronouns (Pro), i.e., the (a)–(b) difference.7

 (12) a. Carl will go to college now that Sally dropped out, according to their friends.She was going to Brooklyn Tech. (Pro, +Distant) b. Carl will go to college now that Sally dropped out.She was going to Brooklyn Tech. (Pro, –Distant) c. Carl will go to college now that Sally dropped out, according to their friends.Joanna did too. (Ell, +Distant) d. Carl will go to college now that Sally dropped out.Joanna did too. (Ell, –Distant)

The means are presented in Table 5 and Figure 4. Though no statistical analysis was performed, the difference between the distant and the nearby antecedent conditions was twice as large for ellipsis examples compared to the pronoun examples.

Table 5

Mean naturalness ratings (1–7) in a small pilot study.

–Distant +Distant Difference
Pronoun 4.66 4.29 0.37
Ellipsis 3.00 2.37 0.63
Figure 4

Mean naturalness ratings (1–7) in a small pilot study.

Below we will present full scale studies that will reinforce this conclusion. The comparison is of interest, we think, because the pronominal DP and the VP ellipsis do not compete with each other as ways to express the same message. In comparisons of VP ellipsis and “do + pronoun” anaphora, one has superficially closer forms (did vs did it vs did so) but the results might reflect in part the non-choice of the competing form (see Miller 2011 for corpus studies capturing some of the environments in which the various forms tend to be used).

### 4.1 Experiment 4: Distance and antecedent choice in ellipsis and discourse anaphora

Returning to the question of what material is readily accessible in ASM, we performed an interpretation experiment testing the accessibility of antecedents in main clauses as compared to subordinate clauses. As main clauses, we use conjoined clauses introduced by the connective but, compared to subordinate conjoined clauses introduced by the connective after. We assume clauses conjoined with and or but function as independent sentences (they are V2 in languages like German) and are distinct from subordinate clauses.

As mentioned above, pronouns and ellipsis are distinct types of dependencies, taking antecedents in distinct representations (discourse representation vs syntactic representation respectively). However, they may both be influenced by effects of connective type and their impact on the status of the clause: with a coordinating conjunction like but the clause is salient in the discourse representation and acts like a main clause in the syntax; whereas with a subordinating conjunction like though, it is presumably backgrounded in the discourse and syntactically subordinate. More specifically, we assume that resources are devoted to keeping the syntactic representation of the main clause available in ASM, and thus it is accessible for longer than the syntactic representation of a subordinate clause. The prediction of our general assumptions about syntactic vs discourse representation is that ellipsis — and syntactic representation in general (Frazier & Clifton 2005) — shows larger recency effects (salience in syntax) than pronouns do. Further, examples containing but should show more recent antecedents than examples containing after.8

#### 4.1.1 Method and materials

Examples like those in (13) were tested in a forced choice interpretation study. 40 MechanicalTurk users, all adult native speakers of English, indicated whether the pronoun/elided constituent in the final sentence was interpreted using the first (Carl/went to college) or later (Bill/dropped out) antecedent. The first sentence of a two sentence discourse contained a main clause and either an after-clause (+Dep) (13a, c) or a but-clause (–Dep) (13b, d). In addition, a subordinate though-clause appeared either at the end (+Distant) (13a–d) or at the beginning (–Distant) (13e–h) of the first sentence. The second sentence contained either a pronoun (Pro) (13a, b, e, f) or an elided VP (Ell) (13c, d, g, h). The boldface in (13) is used for expositional purposes and did not occur in the actual experiment; it indicates the last potentially independent clause when the final sentence of the discourse is being processed.

 (13) a. Carl went to college after Bill dropped out though economic times were tough. He was scared. (+Distant, Pro, +Dep) b. Carl went to college but Bill dropped out though economic times were tough. He was scared. (+Distant, Pro, –Dep) c. Carl went to college after Bill dropped out though economic times were tough. Sally did too. (+Distant, Ell, +Dep) d. Carl went to college but Bill dropped out though economic times were tough. Sally did too. (+Distant, Ell, –Dep) e. Though economic times were tough, Carl went to college after Bill dropped out. He was scared. (–Distant, Pro, +Dep) f. Though economic times were tough, Carl went to college but Bill dropped out. He was scared. (–Distant, Pro, –Dep) g. Though economic times were tough, Carl went to college after Bill dropped out. Sally did too. (–Distant, Ell, +Dep) h. Though economic times were tough, Carl went to college but Bill dropped out. Sally did too. (–Distant, Ell, –Dep)

#### 4.2.2 Results and discussion

The mean naturalness ratings are presented in Table 7 and Figure 6.

Table 7

Mean naturalness ratings (1–7) (with standard errors).

–Distant +Distant
Pronoun 6.06 (0.08) 5.16 (0.08)
Ellipsis 6.17 (0.11) 4.73 (0.11)
Figure 6

Mean naturalness ratings (1–7) (with standard errors) from Experiment 5.

There was a significant effect of distance (b = –1.04, z = –9.69, p < .001), and an interaction with a larger penalty for non-local antecedents with ellipsis than with pronouns (b = –0.30, z = –3.65, p < .001). This interaction was expected and is consistent with the results of the prior studies (replicating the results of the pilot study and coherent with the interpretation results of the immediately preceding study).

The mean reading times in ms are presented in Table 8 and Figure 7.

Table 8

Mean reading times on final sentences (ms) (with standard errors).

Local Distant
Pronoun 565 (25) 622 (25)
Ellipsis 358 (18) 505 (23)
Figure 7

Mean reading times on final sentences (ms) (with standard errors) from Experiment 5.

Both main effects and their interaction were significant. Clauses containing pronouns took longer to read than clauses containing elided VPs (b = –112.39, t = –3.77).12 This cannot be interpreted since it might be due to the pronoun items being slightly longer on average. Distant items took longer to read than local items (b = 70.34, t = 4.30), as expected. Most interesting is the interaction: the distance penalty is greater with ellipsis than with pronouns (b = 46.06, t = 3.58). Again this is expected if the ellipsis examples require a syntactic antecedent.

### 4.3 Experiment 6: Interference effects in antecedent choice?

We turn now to an issue about the underlying source of the rating and reading time cost for distant antecedents. One possibility is that it is due to retrieval difficulty: in the distant conditions there may be similarity interference effects from the presence of a potential antecedent for the elided VP (see Lewis, Vasishth & Van Dyke 2006; Martin & McElree 2008). If so, given that do VP ellipsis cannot have an antecedent with a be auxiliary, then an intervening be-auxiliary VP, not a potential antecedent, should impose a smaller distance penalty than a suitable antecedent VP. This was systematically manipulated in the next experiment using examples like those in (14). If, on the other hand, the distance effects are due to what is currently active in syntactic memory, then the presence of a be auxiliary in the intervening clause shouldn’t matter.

#### 4.3.1 Method and materials

As a preliminary test of these possibilities, 40 MechanicalTurk users were tested on 20 sentences like those in (15) in a self-paced reading study with a following interpretation question, with a forced choice answer. The items were two sentence discourses, with VP ellipsis in the second sentence. The first sentence contained a though-clause with (15a, b) or without (15c, d) bebe), thus being an impossible or possible antecedent for the ellipsis. The position of the though-clause was also manipulated, highlighted here by boldface: it appeared at the beginning of the first sentence (–Intervening) (15a, c) or at the end of the first sentence (+Intervening) (15b, d).

 (15) Region 1 | Region 2 | Region 3 a. Though the global economy was uncertain due to the recession, | Carl went to college but Bill dropped out. | Sally did too. (+be, –Intervening) b. Carl went to college but Bill dropped out, | though the global economy was uncertain due to the recession. | Sally did too. (+be, +Intervening) c. Though the recession brought on economic uncertainty across the globe, | Carl went to college but Bill dropped out. | Sally did too. (–be, –Intervening) d. Carl went to college but Bill dropped out, | though the recession brought on economic uncertainty across the globe. | Sally did too. (–be, +Intervening) What did Sally do? [“Sally went to college.”, “Sally dropped out.”]

#### 5.1.2 Results and discussion

The results are presented in Table 12 and Figure 10.

Table 12

Mean naturalness judgements (1–7) (with standard errors).

–Distant +Distant
a. Available verb phrase 6.0 (0.1) 5.6 (0.1)
b. Embedded verb phrase 5.2 (0.1) 4.7 (0.2)
c. Verb phrase with trace 4.6 (0.2) 4.5 (0.2)
d. Negative adjective 3.3 (0.2) 3.5 (0.2)
Figure 10

Mean naturalness judgements (1–7) (with standard errors) from Experiment 7.

The full range of difficulty effects, examined through reverse Helmert contrast, was significant (a vs b: b = –0.43, z = –5.01, p < .001; a/b vs c: b = –0.25, z = –5.61, p < .001; a/b/c vs d: b = –0.34, z = –8.27, p < .001), and there was an only barely-significant interaction of distance and the final difficulty step between the first three conditions and the adjective condition (b = 0.11, z = 1.96, p = .050).

We don’t consider the crucial interaction reliable evidence as to our predictions, but present a post-hoc analysis combining the grammatical conditions (Available VP, Embedded VP) (a, b) and ungrammatical conditions (VP + Trace, Adjective) (c, d), to more directly target the most important prediction: that distance should affect the grammatical (a, b) ellipsis conditions differently than the ungrammatical (c, d). This analysis, depicted in Table 13 and Figure 11, found a significant effect of ungrammaticality (b = –1.00, z = –9.14, p < .001) and an interaction with locality (b = 0.30, z = 2.00, p = .046).

Table 13

Mean naturalness judgments (1–7).

–Distant +Distant
Grammatical 5.62 5.14
Ungrammatical 3.94 3.99
Figure 11

Mean naturalness judgements (1–7) grouping only by grammaticality.

Qualitatively, it looks like conditions (a) and (b) are penalized by distance, (c) is unaffected (though histograms show a 10% increase in “4–5” responses in the distant condition), and (d) actually gets numerically better (histograms show the distant conditions lose a substantial amount of “hate” responses “1,2,3”).1819

In sum, the effect of distance varied along with the structural condition with an apparent rating penalty for distant conditions for grammatical sentences, and a slight increase in ratings for unacceptable ungrammatical sentences when distant. Acceptable ungrammatical sentences show a smaller effect in ratings. Further investigation will be necessary before we truly understand the underlying processes giving rise to the variation observed across these distance effects.20

## 6. Summary and Conclusions

In this paper we have pursued a repair account of VP ellipsis based on the assumption that the grammar requires syntactic matching of antecedent and elided VP. We note that larger effects of matching are observed in items containing ellipsis than counterparts without ellipsis (Tanenhaus & Carlson 1990; Kim et al. 2011; Miller & Hemforth 2014; among others). This is not surprising if ellipsis grammatically requires a matching antecedent.

The present studies also show that the distance between antecedent and anaphor/ellipsis site matters more for ellipsis than for discourse anaphora, as would be expected if ellipsis requires a syntactic antecedent whereas for discourse anaphora an entity (discourse referent) in the discourse representation would suffice.

We present new evidence concerning ASM. Our experimental results show that the connective matters: a coordinate clause with but acts like an independent clause, reducing the accessibility of preceding clauses more than a subordinate clause with after does. This fits with a view where ASM typically has ready access to the syntactic representation of the current clause and the last potentially independent clause. Of course, in actuality it will matter how long and complex clauses are; the claims we make here are clearly idealizations approximating the behavior of the human processing system with input that is not particularly complex.

The position of an adjunct clauses also mattered in our study, and it interacted with the type of “anaphor” (ellipsis vs pronoun). An intervening though clause mattered more for ellipsis than for a pronoun. This interaction again suggests that it is the availability of a syntactic representation of the antecedent that matters for ellipsis more than for a pronoun.

Although it is only suggestive, we presented evidence that the present memory effects, and the difference between ellipsis and pronouns, are not due to cue-based retrieval: no difference in the effect of an intervening clause was observed based on whether the clause included a licit or illicit VP-ellipsis antecedent.

Finally, initial evidence suggested that grammatical examples of ellipsis and acceptable ungrammatical examples, and unacceptable ungrammatical examples respond differently to manipulations placing their antecedent outside ASM. There were indications that the grammatical examples became worse with the presence of an intervening sentence, whereas the unacceptable ungrammatical examples got slightly better. The implication is that the syntactic form of the antecedent required for repair is not reliably available in distant antecedent examples including cases of split antecedent ellipsis.

Turning to relevant properties of memory, we have presented evidence that ASM typically includes the last potentially independent clause. Repair takes place when a mismatching antecedent (small mismatch, lots of evidence…) is present in ASM. Standard cases of split antecedent ellipsis will involve source material too far away for systematic repair.

Once a role for accommodation has been recognized, one might wonder why anything else (repair) is needed? Why not just assume that accommodation is responsible for all ellipsis processing? The answer comes in three parts. First, empirical evidence suggests the existence of form-based effects indicating that distance from the matching form influences the level of acceptability of mismatch ellipsis. Arregui et al. present various studies of this sort, e.g., if the antecedent for VP ellipsis is a verbal gerundive a sentence is rated more acceptable than a counterpart where the antecedent is a nominal gerundive.

Second, there is evidence that the grammar requires syntactic matching between antecedent and elided constituent (see Kim & Runner 2018 in particular). Many studies show that the effect of a syntactic mismatch between an antecedent clause and a subsequent conjoined clause is larger in sentences containing ellipsis in the second clause than in sentences with the full VP: Grant et al. (2002), Miller & Hemforth (2014), Kim & Runner (2018), Clifton et al. (2019) (or sentences with a pronoun, Tanenhaus & Carlson 1990). As Kim & Runner (2018) argue, presence of a mismatch effect just for sentences with ellipsis argues for a matching constraint in the grammar. On this assumption, then one need only assume that the processor, as always, attempts to find a grammatical analysis of the input. When the antecedent for an elided constituent does not match perfectly, then a repair takes place.

Third, when the syntactic form of an antecedent is by hypothesis not available to be repaired, the processor, as is usual, does not just give up but rather attempts to make sense of the input. These are cases we have labelled as “accommodation”, but there seem to be limits as shown below. Accommodation seems to take place only with vary specific types of context or extremely rich contexts. In the classic split-antecedent ellipsis examples of the type studied by Webber (1978), there are semantically parallel conjuncts which easily give rise to a superordinate predicate (e.g., what they wanted to do). Indeed, the superordinate relation might be inferred simply as part assigning a similarity coherence relation to the conjunction (Kehler 2002), and thus it might be available before the ellipsis clause was even encountered. Although a full account of the limited circumstances allowing accommodation of an antecedent goes beyond the scope of the present paper, it is clear that once the possibility of a superordinate relation is eliminated, a split antecedent becomes very difficult indeed, as in (19).

 (19) #John argued that the university should reduce the amount of university bureaucracy although/and Sam was arguing for only trained assistants to be allowed to update websites, and the administration did too.

The content of the conjuncts in (19) is loosely contradictory and thus a similarity relation is not invited (this can be demonstrated by the acceptability of although as the conjunction). Repair should not be possible in this case because some of the source material is outside active syntactic memory. But accommodation also seems not to be possible.

In sum, the evidence we’ve presented here compels a theory of mismatch ellipsis which cannot be solely either repair or accommodation, but instead must recognize some condition which governs when the processor turns to one or the other, and when neither mechanism will succeed. We think the data support the limitations on ASM proposed here as being exactly such a condition. As to why repair is needed once a role for accommodation is recognized, we submit that this is because the human language processor always tries to find a grammatical analysis of linguistic input, and it uses a grammar that requires syntactic matching of an elided constituent and its antecedent.

Supplementary file 1

Materials from the experiments reported in “Repair or accommodation?” DOI: https://doi.org/10.5334/gjgl.728.s1

## Abbreviations

ASM = Activated Syntactic Memory, DP = determiner phrase, QUD = question under discussion, VP = verb phrase, VPE = verb phrase ellipsis

## Notes

1. In the grammar and in language production, it is relatively straightforward to check whether there is matching between antecedent and elided constituent. In comprehension, however, one might be concerned that the silent structure at the ellipsis site can only be determined by the structure of the antecedent, raising questions about how matching could be enforced. We assume that a sentence like Alice did. contains sufficient information to determine the need for an active-voice VP that takes auxiliary do; more detailed structure is presumably dependent on the structure internal to the antecedent. [^]
2. In general reanalysis of a structure implicates not only syntactic but also semantic and pragmatic information (Pickering and Traxler 2000, Frazier and Clifton 1998). Thus, the fact that plausibility can influence repairs is not surprising or exceptional. [^]
3. Messick, Saab & Vicente (2016) place R not in the fragment but in the ellipsis site. This accounts for the obligatoriness of a restrictor in the Barros effect, i.e., the obligatory restrictor in (ib) and the obligatory inheritance of the restrictor (students) in (iib).
 (i) Jack kissed Sally, and he also kissed someone else. a. #but I don’t know who he kissed. b. but I don’t know who.
 (ii) A: Which students were dancing in the quad? a. B: Some Germans were dancing in the quad. (don’t have to be students) b. B’: Some Germans. (must be students)
A similar account is offered for split antecedent sluicing in cases like (6).
 (iii) Whenever Jack wants to interview an athlete or Sally wants to profile a politician, the editor asks which.
[^]
4. The experiments in this section were conducted with the generous assistance of Chuck Clifton. [^]
5. 99 of the 100 responses were coded. The remaining response, “needs to take care of family.”, given for prompt (9), was deemed unclassifiable. [^]
6. All naturalness judgement data are analyzed with ordinal mixed-effects regression, with Participant and Item as random predictors, using the ordinal package in R. We report the estimated slope, z score, and p-value for all predictors of interest. Regressions were performed in R (R Core Developers 2018) using the ordinal package (Christensen 2018). [^]
7. A reviewer was concerned that the ellipsis examples are ambiguous whereas the pronoun is disambiguated by gender. This could limit the conclusions that could be drawn. However, in Experiment 5 there is only one possible antecedent for the verb phrase ellipsis and, again, significantly larger distance effects are found for ellipsis compared to pronouns. [^]
8. Note this follows either on the assumption that the last potentially independent clause is accessible in ASM, or from the main assertion hypothesis, cf. Frazier and Clifton (2005). These are not mutually exclusive hypotheses and we will not attempt to tease them apart here. [^]
9. We analyze all forced-choice data with logistic mixed-effects regression, with Participant and Item as random predictors, using the lme4 package (Bates et al. 2015) in R. We report the estimated slope, Wald Z score, and p-value for all predictors of interest. [^]
10. A reviewer asked whether the larger effect of distance for but than for after was predicted. Our account claims that the but clause VP is a more attractive antecedent than the after clause VP and thus it is not particularly surprising that distance had a large effect on the former. Philip Miller (pers. comm.) points out that the discourse conditions he proposes (that asserting a clause p makes the alternative not-p salient and thus makes it a preferred antecedent for ellipsis) might account for this result. [^]
11. It is possible that distinct coherence relations were assigned to but-clauses and after-clauses. In principle, this might account for why the connective had an effect for pronouns as well as for ellipsis, though many additional factors may also be relevant. [^]
12. All reading time data are analyzed with linear mixed-effects regression on raw reading times, with Participant and Item as random predictors, using the lmer package in R. We report the estimated slope and t score for all predictors of interest. [^]
13. For comparison of personal pronouns, presumably of a lower type, and propositional that, see Göbel (to appear). [^]
14. In recent years, investigators have focused on cue-based memory models (Lewis, Vasishth & Van Dyke 2006; Martin & McElree 2008) and the question of how phrases are accessed from memory, assuming that all of memory is accessed. In the early days of psycholinguistics, the emphasis was instead on what is available to be accessed. To our knowledge the ASM hypothesis is broadly consistent with these early results (Fodor, Bever & Garrett 1974). What we suspect is that understanding memory for sentence processing requires both identifying what material is available to be accessed and looking at how subparts of representations are accessed in whatever representations are available. [^]
15. In an analysis of scalar implicatures, Katzir (2007) proposed that alternatives may be at most as complex as the original expression. In his analysis of ellipsis, Thoms (2015) builds on this theory of alternatives, allowing deletion, contraction and substitution as operations defining admissible alternatives. These alternatives may serve as antecedents for elided constituents. Since these operations are limited by the form of the original expression, they do not really count as a clear case of accommodation in the sense relevant for the present discussion. Rather they straddle the present categories of repair vs accommodation. See also Paape (2016) for evidence suggesting that antecedents should not be treated as word strings that can be reparsed. [^]
16. Brian Dillon points out that this hypothesis is similar to the hypothesis defended in the text processing literature claiming that inferences beyond those needed to establish coherence are only drawn when they involve local material available in working memory (McKoon and Ratcliff 1992). [^]
17. A reviewer asks why (20d) is not completely out if it is unacceptable and ungrammatical. In the Arregui study it received 17% yes responses. This could be due to errors where participants don’t pay attention or press the wrong button. [^]
18. We also collected and analyzed reading times on the final clause. The only significant reading time effect is the comparison of reading times for VP with trace compared to the available and embedded VP conditions (b = 17.69, t = 2.83). [^]
19. It is possible that (17ʹc) exhibits a mixture of facilitation from distance, because it is ungrammatical, and interference from the lesser availability of material needed for a repair. Further work is needed to determine exactly what is going on. A reviewer further suggests that polarity focus and subject focus VP ellipsis may show distinct distance effects (Miller 2011) possibly predicting further differences in the effect of manipulating distance. [^]
20. We could compare the sizes of the penalty for voice mismatches in simple VP ellipsis and split antecedent VP ellipsis, as pointed out by a reviewer, who supplied the examples below.
 (i) This year, Bob climbed Kilimanjaro and Susan hiked the entire Appalachian trail. I’m surprised they were each able to. (ii) This year, Kilimanjaro was climbed by Bob and the entire Appalachian trail was hiked by Susan. I’m surprised they were each able to.
The prediction is that the mismatch penalty in (ii) should be smaller than in (ii) than in (iv). For what it’s worth, ratings supplied by four individuals (including the authors) supported the prediction.
 (iii) This year, Bob climbed Kilimanjaro. I’m surprised he was able to. (iv) This year, Kilimanjaro was climbed by Bob. I’m surprised he was able to.
However, the reason why we have not carried out such a study is that there is a problem interpreting such ratings because the split examples are also in a lower range of the scale, and thus might show smaller differences for this reason alone. [^]

## Ethics and Consent

All experiments were conducted in accordance with the approval of the UMass Amherst Institutional Review Board, approval number #2102-1360.

## Acknowledgements

We are very grateful to Brian Dillon, Kyle Johnson and Chuck Clifton for discussion of the material presented here, and to the editors and three anonymous reviewers for helpful comments. We are particularly indebted to Philip Miller for detailed comments on the manuscript. In addition to being a full-fledged member of the split-antecedent project, Chuck Clifton provided invaluable advice and assistance on the anaphora vs ellipsis studies.

## Competing Interests

The authors have no competing interests to declare.

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