Nambu, Satoshi & Nakatani, Kentaro. 2023. An experimental study of theadjacency constraint on the genitive subject in Japanese. Glossa: a journalof general linguistics 8(1). pp. 1–30. DOI: https://doi.org/10.16995/glossa.9509

An experimental study of the adjacency constraint
on the genitive subject in Japanese
Satoshi Nambu, Monash University, Australia, satoshi.nambu@monash.edu
Kentaro Nakatani, Konan University, Japan, kentaron@konan-u.ac.jp

We present the results of two acceptability judgment and three self-paced reading experiments
exploring the source of degradation effects on the acceptability of genitive subjects caused byhaving them not adjacent to the verb. From a syntactic perspective, Miyagawa (2011) attributes
this adjacency constraint to his assumption that the genitive subject is situated in Spec-vP, lower
than adverbials adjoined to vP or higher. This theory thus predicts that adverbials lower thanvP can intervene between the genitive subject and the verb without degrading acceptability. To
test this issue and examine the time course of the intervention effects, our experiments varied
the number and the types of interveners. Whereas the results of our acceptability judgment
experiments straightforwardly confirmed the purported intervention effects, the self-paced
reading experiments provided results that cannot be explained in structural terms alone. First,
the reading times of the verb and/or the head noun were greater when the genitive subject was
adjacent to the verb, an effect that has not been reported in the previous literature. Secondly,
the summed reading times of the preverbal regions showed opposite patterns: i.e., the reading
times were greater when the genitive subject was not adjacent. Finally, regarding the types ofinterveners, we found that temporal adverbs and locative PPs, but not manner adverbs, wereread significantly slower when they followed the genitive subject. We argue that a hybrid accountincorporating a syntactic hypothesis with expectation-based incremental processing theories iscalled for to account for the whole range of data.

Glossa: a journal of general linguistics is a peer-reviewed open access journal published by the Open Library of
Humanities. © 2023 The Author(s). This is an open-access article distributed under the terms of the Creative Commons
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OPEN ACCESS

2

1. Introduction
Subjects in Japanese can be marked with either the nominative marker ga or the genitive marker
no in adnominal clauses such as relative clauses, in contrast to other types of subordinate clauses
and main clauses, which do not allow genitive subjects, as shown in (1).
(1)

a.

Naomi-wa [Taro-ga/no
kai-ta]hon-oyon-da.
Naomi-Top Taro-Nom/Gen write-Pst book-Acc read-Pst“Naomi read the book that Taro wrote.”b.

Taro-ga/*nohon-o
kai-ta.
Taro-Nom/*Gen book-Acc write-Pst“Taro wrote a book.”c.

Taro-ga/*nohon-o
kai-te,Naomi-gasendens-ita.
Taro-Nom/*Gen book-Acc write-Grd Naomi-Nom advertise-Pst“Taro wrote a book, and Naomi advertised it.”This phenomenon, often called ga/no conversion, has been studied in theoretical syntax for many
years (Harada 1971; Shibatani 1975; Inoue 1976; Nakai 1980; Miyagawa 1993; 2011; Ura 1993;

Watanabe 1996; Ochi 2001; 2017; Kikuta 2002; Hiraiwa 2005; Maki & Uchibori 2008; among

others). These theoretical studies mainly concentrate on the syntactic mechanism that should

enable the conversion, especially the genitive subject structure. In contrast, what has not been
extensively studied is the intervention effect in the genitive subject structure, first pointed out
by Harada (1971): the acceptability of a genitive subject is said to be degraded when it is not

adjacent to its corresponding predicate, while nominative subjects do not show such an effect,as illustrated below.
(2)

Kodomotati-ga/*no minna-de ikioiyoku kakenobot-ta
kaidanchildren-Nom/*Gen all-with vigorously run.climb.up-Pst stairway‘the stairway that those children ran up together vigorously’(Harada 1971; Acceptability judgments are those reported in Harada 1971)

One previous study that attempts to give an account for this intervention effect is Miyagawa (2011),
who advocates a “D-licensing” theory of the genitive subject structure, which hinges primarily ona structural difference between nominative and genitive subjects (we return to this in Section 3).
Even though Harada (1971) observed intervention effects for genitive subjects across Japanese
speakers when more than one intervener is present, Miyagawa (2011) argues that such an effectmay be found even when there is only one intervener. No formal experimental studies have yettested the acceptability of non-adjacent genitive subjects such as the one illustrated in (2). Our

goal is to examine to what extent non-adjacent genitive subjects are in fact accepted by native
speakers of Japanese and explicate the source of degraded acceptability if any. As a working
hypothesis, we assume that the results of experimental studies should reflect syntactic properties

3of the tested constructions, so we designed and conducted experiments to test the predictions ofspecific syntactic theories, particularly those of Hiraiwa (2005) and Miyagawa (2011). However,it should be noted that the results of experimental studies do not necessarily stem exclusively fromgrammaticality issues. For example, even though theoretical linguists tend to make a distinction

between grammaticality and acceptability, non-linguists are often not aware of this distinction.
Therefore, acceptability judgment studies do not always directly reflect issues of grammaticality.

However, even trained linguists may fail to make clearcut grammaticality judgments when it
comes to delicate cases,1 and the present investigation includes such cases: there seem to be noclear judgments in the previous theoretical studies as to the degree of the degradation effect ofintervening elements between a genitive subject and its predicate. The aim of the present study is

to test whether a specific syntactic theory can fully account for the experimental results regarding
intervention effects on genitive subjects. If it can only partially do so, we also attempt to examine
what processing theories can account for that syntactic theories cannot.

As the first step, we report in Section 2 the results from two acceptability judgment studies

testing the intervention effect. Then in Section 3, we briefly introduce two types of theoreticalsyntactic accounts of the ga/no conversion and discuss the predictions made from these theories

regarding the intervention effect on the genitive subject. We also present alternative processing-based theories that may account for the intervention effect. One is a retrieval-based theory andthe other is an expectation-based theory. To tease apart these various theories, in Section 4 we
present the results of a series of self-paced reading experiments that were designed to (i) dissect
the effects of different types of interveners and (ii) pin down the loci of the effects. In Section

5, we discuss the implications of the results for the theoretical accounts and their relations to
on-line processing. Section 6 concludes this article.

2. Acceptability judgment experiments #1 and #2
2.1 Procedure

In order to verify the effect of intervening elements, which has not been empirically confirmedin the literature, we conducted two acceptability judgment experiments using a five-point Likert

scale (1: very unnatural, 5: natural). The experiments were paper-and-pencil questionnaires.
Regarding the target stimuli of the experiment, the Adjacency factor (Adjacent vs. Non-adjacent)and the Case-marking factor (Nominative vs. Genitive) were manipulated in a 2 × 2 factorial

design, yielding a total of four experimental conditions. The Non-adjacent conditions contained
two interveners, a temporal adverb and a locative postpositional phrase (locative PP), in the firstexperiment (AJ1) and one intervener, a temporal adverb, in the second experiment (AJ2). Recall
1

For debates regarding the tension between linguists’ informal judgment studies and large-scale formal judgment
studies, see Phillips (2009), Gibson & Fedorenko (2010), Culicover & Jackendoff (2010), Sprouse & Almeida (2013),
among others.

4

that Harada (1971) argues that the intervention effect is strong across Japanese speakers when

there are two interveners, whereas Miyagawa (2011) argues that one intervener may be enoughto cause such an effect. The Adjacent conditions were constructed by scrambling the intervenersof the Non-adjacent conditions to the front of the sentences. The four conditions are exemplified
below, where locative PPs, parenthesized, are included in AJ1 but omitted in AJ2.
(3)a.

Adjacent × {Nominative ga | Genitive no}
Kyoo (zyuku-de)
kodomotati-{ga | no} narat-ta rekisi-wa
today (cram.school-at) children-{Nom | Gen} study-Pst history-Top
Heianzidai-nituite-dat-ta.
Heian.period-about-Cop-Pst‘The history that the children studied at a cram school today was about the Heianperiod.’b.

Non-adjacent × {Nominative ga | Genitive no}
Kodomotati-{ga | no} kyoo (zyuku-de)narat-ta rekisi-wa
children-{Nom | Gen} today (cram.school-at) study-Pst history-Top
Heianzidai-nituite-dat-ta.
Heian.period-about-Cop-Pst‘idem’

Experimental procedures were identical in AJ1 and AJ2. For both experiments, we created
64 target sentences using 16 lexical sets across the four conditions and distributed them into
four questionnaires using a Latin Square procedure, so that a participant assigned one of thequestionnaires would not see more than one sentence from one lexical set. We included 32 filler
items in each questionnaire, which were balanced to ensure an equal number of acceptable andunacceptable sentences in order to lead each participant to make the full range of acceptability

judgments. All of the questionnaires started with the same 5 practice items, so that they all
consisted of 53 items in total. The order of items within each questionnaire was pseudo-

randomized to avoid items with the identical condition presented successively. Then, to control

for potential order effects, an additional four questionnaires with the reverse item orders werecreated, resulting in eight different questionnaires in total.

The participants were 40 native speakers of Japanese in AJ1 and 67 native speakers ofJapanese in AJ2, all recruited at a university in Japan.

2.2 Results and analysis
The mean ratings for the four conditions are summarized in Figure 1. By comparing the graphicalsummaries of these two experiments, we can observe the trend that having two adjuncts (AJ1)rather than one (AJ2) decreased the ratings in the genitive subject conditions but not in thenominative subject conditions.

5

Figure 1: Mean rating scores in AJ1 (left panel) and AJ2 (right panel). Error bars represent
95% confidence intervals.
Prior to the analyses, we transformed the ratings of each participant to z-scores forstandardization in order to correct any possible scale bias between participants (Schütze &Sprouse 2013). For each experiment, a linear mixed-effects model was fitted with Case andAdjacency and their interaction (Case × Adjacency) as fixed factors and by-participant andby-item intercepts and slopes as random effects. The analyses were conducted using the lmerTest

package for the R statistic program (R core team 2016). For AJ1, we found a significant interaction
between Case and Adjacency (t = 4.80, p = .000) indicating that intervening elements between

the subject and the verb degraded the acceptability of the genitive subject but not that of thenominative subject. Planned pairwise comparisons confirmed the trend (the effect of Adjacency
on the nominative subject: t = 0.14, p = .887; on the genitive subject: t = –5.88, p = .000). We
also found a main effect of Case such that the genitive subject was overall rated lower than thenominative subject (t = 5.25, p = .000) and of Adjacency such that the non-adjacent structure
was rated lower (t = –5.14, p = .000). As for AJ2, we also found an interaction of the two factors(t = 4.33, p = .000). Planned pairwise comparisons revealed that the intervention effect was

detected exclusively on the genitive subject (nominative: t = 1.16, p = .256; genitive: t = –3.82,

p = .000). A main effect of Adjacency was found such that the non-adjacent structure was rated
lower (t = –3.99, p = .000), as well as a marginal effect of Case such that the genitive subject
was rated lower (t = 1.9, p = .060).

As given in Table 1, the observed trends are consistent with the data from written andspoken corpora reported in Nambu (2013b).2

2

Table 1 contains examples of the non-adjacent environment, including cases where elements such as adverbs occur
before subjects.

6

Adjacent

Non-adjacent

Written (MJD)

Spoken (CSJ)

Written (MJD)

Spoken (CSJ)

Nominative

82.9%

88.9%

98.5%

99.8%

Genitive

17.1%

11.1%

1.5%

0.2%

subject
subject(4,371/5,274)(903/5,274)(3,222/3,624)(402/3,624)(2,291/2,326)(35/2,326)(1,318/1,321)(3/1,321)

Table 1: Frequency of nominative/genitive subject in the adjacent/non-adjacent environment(MJD = Minutes of Japanese Diet, CSJ = Corpus of Spontaneous Japanese) (Nambu 2013b).
Table 1 shows that (i) genitive subjects are overall used less than nominative subjects, and (ii)genitive subjects are used less in the non-adjacent environment than in the adjacent environment,
as opposed to nominative subjects, which are not sensitive to adjacency.3 Importantly, Nambu(2013b) reports that all of the interveners between the genitive subjects and their predicatesin the reported data (35 examples in MDJ and 3 in CSJ in Table 1) were VP-level adverbs or
postpositional phrases.

In summary, the acceptability judgment study quantitatively confirmed the adjacency

constraint: the acceptability of genitive subjects was degraded in the non-adjacent condition, as

opposed to nominative subjects, which were not sensitive to adjacency. The results also identified
the main effect of the case-marking factor as well, in such a way that the nominative subjects

were overall rated higher than the genitive ones. Finally, the effect of the adjacency constraint
was found even when there was only one intervener, confirming Miyagawa’s (2011) argument
based on introspection.

3. Syntactic accounts and processing-based accounts
With the adjacency constraint on genitive subjects in Japanese empirically confirmed throughthe judgment experiments, we attempt to explicate the source of the constraint through self-

paced reading experiments. In this section, we first review two major theories of genitive subjects
in Japanese proposed in the generative literature, and then introduce processing-based accounts
as alternatives. We report our experimental results in the next section.

3.1 Competing theoretical approaches and the adjacency constraint
As illustrated in (1), genitive subjects in modern Japanese are predominantly found in adnominal
clauses, which strongly suggests that the nominal feature in such clauses is responsible for the3

Regarding the inferior status of genitive subjects, see Nambu (2007; 2019) and Ogawa (2018) for discussion in termsof ongoing linguistic change, whereby the use of genitive subjects has been decreasing over time, while the use of
nominative subjects has increased.

7

licensing of the genitive case. Two well-known approaches are the C-licensing theory (Watanabe
1996; Hiraiwa 2005) and the D-licensing theory (Ochi 2001; Miyagawa 2011).

The C-licensing account proposed in Hiraiwa (2005) assigns the same structure, whichcontains a CP, to both the nominative and genitive subjects. The tree diagram in (4) illustrates
the assumption.
(4)

C-licensing account (modified from Hiraiwa 2005)

Under this approach, the genitive subject is licensed through the C-T relationship only when
C comes with a categorial feature [+N], while the nominative subject is licensed irrespectiveof this feature (Hiraiwa 2005: 99). This C-licensing theory predicts that the nominative andgenitive on a subject are freely interchangeable under the structure with C[+N]. Therefore, thistheory does not explain the interaction between adjacency and case marking because both thenominative and genitive subjects under C[+N] have exactly the same structural properties.

In contrast, under the D-licensing account, the genitive subject must be licensed in thedomain of an NP with D, which corresponds to the head noun of the clause. The tree diagrams
given in (5) illustrate the structures of the nominative and genitive subjects under Miyagawa’s(2011) approach, where the nominative structure contains a CP (5a), in contrast to the genitive
subject structure without it (5b).
(5)

D-licensing account (modified from Miyagawa 2011)a. Nominative subject

8b.

Genitive subject

Miyagawa (2011) argues that the nominative subject is licensed by T in conjunction with C
but not by D because CP is a phase and blocks the D-licensing due to a violation of the Phase
Impenetrability Condition (Chomsky 2001). On the other hand, the genitive structure does notcontain a CP, which would block the D-licensing. According to Miyagawa, the absence of CP in
the genitive structure is supported by its incompatibility with CP-level adverbs such as speechact, evaluative, and evidential adverbials. This is illustrated below.
(6)a.

[kittoTaro-ga/-no
yon-da] honprobably Taro-Nom/Gen read-Pst book‘the book that Taro read for certain’b.

[saiwaini Taro-ga/*-noyon-da] hon
fortunately Taro-Nom/Gen read-Pst book‘the book that Taro fortunately read’

The TP-level adverb kitto ‘probably’ in (6a) is compatible with both the nominative and genitive
subjects, whereas the CP-level adverb saiwaini ‘fortunately’ in (6b) is not acceptable with thegenitive subject, which can be accounted for under the assumption that the genitive structure
lacks a CP.

Furthermore, according to Miyagawa (2011), this D-licensing theory is advantageous inthat it can account for the intervention effect (adjacency constraint) on the genitive subject.

T without C in the genitive structure fails to inherit any formal grammatical features from C
and thus lacks an EPP feature, which is assumed to be the trigger for movement of the subject
to Spec-TP (Chomsky 1995); as a result, there is no formal motivation to move the genitive

subject into Spec-TP. Therefore, the genitive subject preferably stays at Spec-vP, in contrast to
the nominative subject, which must move to Spec-TP due to the EPP feature. This approach canprovide an account for the intervention effect, according to Miyagawa, because the genitive

subject is closer to V than the nominative subject is. In other words, genitive subjects are “moreadjacent” to the predicate by default, so making them non-adjacent to it would necessitate some9extra “unmotivated” and “uneconomical” operations. Miyagawa (2011: 1274) attributes thecontrast between the following examples to this structural position of the genitive subjects.
(7)[Koozi-no mattaku sir-ana-i]
kakudoKoji-Gen at.all
know-Neg-Prs angle‘an angle that Koji doesn’t know at all’(8)??[kodomotati-no minna-de kake-nobot-ta] kaidan
children-Gen
all-with run-climb.up-Pst stairwary‘the stairway which those children ran up together’According to Miyagawa, mattaku ‘at all’ is a VP-adverb that sits lower than vP, and thus, there isno need to move the genitive subject to derive the surface order in (7). In contrast, the degraded

acceptability of (8) indicates that the genitive subject kodomotati ‘children’ must undergo“unmotivated” and “uneconomical” movement (Miyagawa 2011: 1274), leading to degradednaturalness. Although Miyagawa (2011) does not explicitly state so, it implies that he assumes
that minna-de ‘all-with (=together)’ in (8) is situated above vP.

Miyagawa’s (2011) discussion on the intervention effect for genitive subjects is rather

brief, and there are some issues left open. Although Miyagawa’s theory makes clear predictions

regarding the interaction between the structural positions of adjuncts relative to vP and thepossibility of intervention in the genitive subject structure, no detailed discussion is provided

regarding which adjuncts are assumed to be placed above vP or under vP. Miyagawa discusses

saiwai ‘fortunately’, which is a CP-level adverb, kitto ‘probably’, which is a TP-level adverb,

minna-de ‘together’, which Miyagawa regards as an adjunct attached to vP, and mattaku ‘at all’,which Miyagawa regards as a VP-level adverb. What then of other adverbs such as locative PPs
and manner adverbs? This issue is worth examining.4

In summary, the interaction between case-marking and adjacency is straightforwardly given

a structural account from Miyagawa’s D-licensing theory, according to which genitive subjects
stay under vP unlike nominative subjects. Then, can we conclude that the D-licensing theory ismore tenable than the C-licensing theory on the grounds that it can account for the intervention

effect (adjacency constraint)? More specifically, are the predictions of Miyagawa’s D-licensing
theory regarding the intervention effect in relation to the structural positions of the interveners
empirically supported? In the experiments we conducted, we investigated the online processingof the intervention effects on genitive subjects, varying the type of intervener to test Miyagawa’s

4

On another matter, if Miyagawa’s account based on “uneconomical” movement is correct, it seems to predict thathaving vP- and VP-adjuncts to the left of nominative subjects would also incur an effect similar to the intervention
effect for genitive subjects, because in such a case, the adjuncts should undergo “uneconomical” movements.

10

structural hypothesis. The adverbial interveners we used in the experiments were (i) temporaladverbs, (ii) locative PPs, and (iii) manner adverbs.

It seems plausible and uncontroversial to assume that temporal adverbs are TP-level adjuncts

and that manner adverbs are VP-level adjuncts. If so, Miyagawa’s D-licensing theory predicts
that temporal adverbs would cause intervention effects for genitive subjects, whereas manneradverbs would not. The structural position of locative PPs, however, is far from obvious. It

seems that there is a consensus in the theoretical literature that cross-linguistically, locative
PPs are situated somewhere between temporal and manner adverbials (Cinque 1999; 2006;
Maienborn 2001; Ernst 2002; 2004; Frey 2003; Pittner 2004). For example, Cinque (2006: 154)

suggests that “a unique (universal) order of merge” is “Temp > Loc > Mann > complements> VP”. As for Japanese, Takamine (2010) demonstrates that the syntactic domain of locative
phrases is higher than that of manner adverbs. In the experimental literature, Tamaoka et al.

(2004) and Koizumi & Tamaoka (2006) measured reaction times of sentences with various
adverbs including manner adverbs and locative phrases in Japanese, and conclude that the

canonical word order of a transitive structure with a manner adverb is either Subject-AdverbObject-Verb or Subject-Object-Adverb-Verb, whereas that with a locative phrase is Subject-Adverb-

Object-Verb. All these studies suggest that manner adverbs are placed close to the verb, andlocative PPs are placed higher than manner adverbs. However, the position of locative PPs

relative to vP is not clear. Takamine (2010) argues that locative phrases and temporal adverbs

behave similarly in terms of scope relations, which may or may not show that locative phrases
are syntactically as high as temporal adverbs. Frey (2003) and Pittner (2004) claim that “eventrelated adverbials” including temporals are structurally higher than the highest argument,“process adverbials” including manner adverbials are situated lower than the other arguments,

and “event-internal adverbials” including instrumentals and locatives are situated lower thanthe highest argument and higher than the other arguments. Maienborn (2001) investigateslocatives in detail, suggesting that locatives could be either frame-setting modifiers, external
modifiers or internal ones:
(9)

a.
b.
c.

In Argentina, Eva still is very popular.
Eva signed the contract in Argentina.
Eva signed the contract on the last page.

(Frame-setting modifier)(External modifier)(Internal modifier)Based on binding and other data, Maienborn (2001) concludes that the base position of frame-setting modifiers is higher than the subject, that of internal modifiers is lower than the object, andthat of external modifiers is between the subject and the object. For example, the following setof German data regarding the coindexing between fronted referential expressions and pronouns

convincingly shows the base positions of locatives relative to subject and object (Maienborn
2001: 12, 14).

11

(10)
Object > Internal modifier
*[In Petersi Auto]j hat der Chef ihni tj nach hause gefahren.
[in Peteri’s car]j has the boss himi tj athome driven.
(Intended) ‘In Peteri’s car, the boss drove himi home.’
(11)

a.

External modifier > Object[In Petersi Büro]j hat der Chef tj ihmi die Akten gezeigt.
[in Peteri’s office]j has the boss tj himi the files shown‘In Peteri’s office, the boss showed himi the files.’b. Subject > External modifier
*[In Petersi Büro]j hat eri tj dem Chef die Akten gezeigt.
[in Peteri’s office]j has hei tj the boss the files shown(Intended) ‘In Peteri’s office, hei showed the boss the files.’(12)

Frame-setting modifier > Subject[In Petersi Firma]j
entscheidet tj eri allein über die Ausgaben.
[In Peteri’s business]j decides
tj hei alone about the expenses.
‘In Peteri’s business, hei decides about the expenses alone.’

Maienborn (2001: 14) further points out that the base order of Subject > External modifier holds
even with unaccusative predicates:(13)*[In Petersi Büro]j ist eri tj eingeschlafen.
[In Peteri’s office]j has hei tj fallen.asleep(Intended) ‘In Peteri’s office, hei fell asleep.’
Taking into consideration all these observations and the standard assumption that R-expressions
must not be bound (Chomsky 1981), it seems unlikely that locative PPs as external modifiers are

situated above vP at least in German and possibly in English and in Japanese if the base orderis assumed to be universal (Cinque 1999; 2006). As we will see in Section 4, the locative PPs
used in our experimental materials are external modifiers, and thus the prediction according

to Miyagawa’s D-licensing theory would be that these locatives should not cause intervention
effects for genitive subjects.

3.2 Processing-based accounts
Note that Miyagawa’s account regarding the potential intervention effects of genitive subjects

does not hinge upon the categorical distinction between grammaticality and ungrammaticality,
but rather resorts to the relative notion of derivational economy (Miyagawa 2011: 1274). Froma processing perspective, it can be assumed that structures associated with less economical

12

derivations would be less preferred, yielding experimental results indicating degradedness

such as lower acceptability rates and slower reaction times. Alternatively, different types offactors that are independent of Miyagawa’s structural hypothesis may influence the processingof genitive subjects. At least two processing-based possibilities can be thought of: a cue-based

retrieval account and an anticipatory, expectation-based account. The former is concerned withthe processing cost of retrieving a stored item from working memory. According to a cue-based
retrieval theory (Van Dyke & Lewis 2003; Lewis et al. 2006), the items stored in working memory

are represented as “feature bundles”, and thus the retrieval cues are also feature-based. For

example, when a verb is encountered, it triggers a cue-based search for its subject. Because
this search attempts to tap into an item with a nominal feature, the presence of nominal items

intervening between the subject and the verb is expected to incur some processing complexity
at the verb, a variant of what is often called a locality effect (cf. Gibson 2000). Thus, the searchshould be easier when the subject is placed right next to the verb than when it is placed far
from the verb. Also, the search may be more difficult if the subject is genitive-marked because

genitive case is not a prototypical subject-marker. This may explain the adjacency constraint on
the genitive subjects.

Another processing account would be based on a proactive, anticipatory search for specificfeatures to come (Hale 2001; Konieczny & Döring 2003; Levy 2008). Genitive-marked NPs

themselves are ambiguous between an adnominal-modifier analysis and a subject analysis;
the former is attained when the genitive NPs are successfully integrated with nominal heads,
while the latter is attained when they are integrated with verbs or adjectives. According to

Levy’s (2008) expectation-based, fully parallel parsing theory (a theory of surprisal), the parser

computes possible continuations to the inputs encountered so far, and it allocates different

amounts of processing resources to different possible continuations in proportion to theirprobabilities. The processing difficulty of the actual continuation would then be in proportion

to the degree to which this resource allocation has to be revised: if the actual continuation
turns out to be a less expected one, the probabilistic resource allocation will have to berevised to a greater extent, and hence leads to a difficulty. From this perspective, the subject
analysis of a genitive NP would be more difficult than the adnominal analysis because it isless probable. Nambu (2013a) explored the probability of possible interpretations of genitive-

marked NPs using a sentence completion task and found that the adnominal completion ismore dominant.

Therefore, it is predicted that some processing load is incurred when a genitive NP is notfollowed by a nominal element but is followed by an adverbial because it will raise the probabilityof the less expected continuation, i.e., the subject analysis. However, it should be noted that themere presence of an adverbial or a predicative element immediately following a genitive NP does
not completely rule out an adnominal analysis. Consider the following set of examples:

13

(14)

a.

boku-no [totemo omosiro-i]
hanasi
I-Gen[very
interesting-Prs] story‘a very interesting story of mine’b.

[boku-no totemo hoshi-i] kuruma[I-Genvery
want-Prs] car‘the car I really want’c.

boku-no kyonen kat-ta ie
I-Gen
last.year buy-Pst housec’. Subject analysis: [boku-no kyonen kat-ta] ie ‘the house I bought last year’c”. Possessive analysis: bokui-no [proi kyonen kat-ta] ie ‘my house I bought last year’
The genitive NP in (14a) must eventually be analyzed as an adnominal, possessive modifier even

if it is followed by an adverbial totemo ‘very’ and a predicate omosiroi ‘interesting’, because thesubject of the predicate is the head noun hanasi ‘story’; in contrast, in (14b), the same genitive

NP must be analyzed as the subject of the predicate of the relative clause because pragmatically,
the head noun kuruma ‘car’ cannot be the subject of the predicate hosii ‘want’. Finally, (14c) isan ambiguous case, for which both subject and possessive readings are possible: although thesubject reading is probably the preferred one, it is also possible to set up a null subject within
the relative clause, especially if we put a pause after the genitive NP, forcing the genitive NP outof the relative clause, in which case the genitive NP is interpreted as an adnominal, possessive

modifier for the head noun. This ambiguity is subtle because in either case, the interpretation willbe almost identical (i.e., ‘(the) house I bought last year’ vs. ‘my house (I) bought last year’). Notethat the latter type of analysis is not possible for (14b), because it is pragmatically anomalous tointerpret it as ‘my car I really want’ (because the car I really want is not yet possessed by me).

These examples show that the ambiguity of the genitive NP will not be resolved unless aproper thematic relation is computed between the genitive NP and the predicate. To make thesituation even more complicated, the ambiguity resolution may be postponed until the headnoun is encountered. Consider the following pair:
(15)

a.

[boku-no ason-dei-ru] basyo[I-Genplay-Prg-Prs] place‘the place where I’m playing around’b.

boku-no [ason-dei-ru] inu
I-Gen[play-Prg-Prs] inu‘a dog of mine that is playing around’

Because Japanese lacks relative pronouns, the computation of the thematic relation between thehead noun and the predicate of the relative clause must be done by considering the thematic fit

14

between the two. For this reason, the syntactic status of the genitive NP in (15) cannot be fully
determined until the thematic relation between the head noun and the predicate is computed. In(15a), the head noun basyo ‘place’ is not a plausible subject of the predicate asondeiru ‘playing

around’, and thus, the genitive NP should be regarded as the subject of the relative clause; incontrast, the head noun inu ‘dog’ in (15b) is a plausible subject and an implausible adjunct for thepredicate, and thus the subject analysis of the genitive NP is rejected and its adnominal analysis
is forced.

All these considerations lead to the conclusion that in online incremental processing, neither

adnominal nor subject analyses of a genitive NP in Japanese can be fully discarded until thepredicate or the head noun is encountered. If so, both adnominal and subject analyses of agenitive NP should be kept active during the processing of the relative clause, while different

amounts of processing resources are allocated to them in proportion to their likelihood. This canbe a possible account for the intervention effect.

Finally, it should be noted that as for the retrieval region, namely the verb region, an

expectation-based account predicts an effect in the opposite direction of that predicted by thecue-based retrieval theory discussed earlier. Because genitive case is more frequently used as an
adnominal marker, a surprisal effect is predicted at the verb if the genitive subject is immediately
followed by the verb. On the other hand, if adverbial items follow the genitive NP, they should

elevate the probability of genitive subject structures. Thus, the presence of interveners should
facilitate the processing of the verb, contrary to the prediction of cue-based retrieval theories.

The present study attempts to tease apart these structural and processing accounts for theintervention effect of the genitive subject in Japanese. To sum up, the predictions from the various

theories would be the following. (i) Miyagawa’s D-licensing theory predicts that the intervention

effect is a function of the type of intervener: adjuncts whose base positions are higher than vP(such as temporal adverbials) should induce an intervention effect on genitive subjects, while

those lower than Spec vP (such as manner adverbs and possibly locative PPs) should not. (ii) As

for processing-based accounts that do not hinge upon a particular theory of syntactic derivation,cue-based retrieval theories assume that intervention effects on genitive subjects are incurredby the presence of nominal features between the target of the retrieval (the genitive subject)

and the retrieval site (the verb); thus, it is predicted that intervention effects should be found at

the verb regions. (iii) Expectation-based theories predict processing load when a genitive NP isfollowed by an adverbial intervener because such a continuation is less probable. (iv) Finally,

expectation-based theories in general predict an advantage of interveners when it comes to theprocessing of the verb region, contrary to the cue-based theories. In the next section, we present
a series of self-paced reading studies to dissect the effects of various types of interveners and pin
down the loci of the effects.

15

4. Self-paced reading experiments #1, 2, 3
We conducted a series of self-paced reading experiments to progressively identify the sourceof the intervention effect, investigating whether the effect can be boiled down to the syntactic
properties proposed in Miyagawa’s D-licensing theory or whether it calls for a processing-based

explanation. In the literature, Kahraman (2012) reports that in the adjacent condition, there
was no significant difference in reading times between sentences with nominative and genitive

subjects. However, it is yet to be understood how the non-adjacent conditions are processed,
especially in terms of the type of interveners.

In a self-paced reading task, a participant silently reads a given sentence with a relevant

linguistic condition on a computer screen, region by region in a noncumulative, moving-windowmanner as the participant pushes the space bar (Just et al. 1982). In our experiments, eachregion contained one free morpheme (such as verbs, adjectives, and adverbs) as well as boundmorphemes attached to it (such as case markers, postpositions and conjunctions). Assuming thata slowdown in reading time represents a cost in sentence comprehension, identifying whichelement of a sentence induces the cost may uncover the source of the intervention effect. To thisend, we manipulated the types of interveners to see which adverbials would or would not incur
intervention effects and to what magnitude.

All three self-paced reading experiments (henceforth, SPR1, SPR2, SPR3) were based on thesame 2×2 factorial design, crossing the Adjacency factor (Adjacent vs. Non-adjacent, varied byscrambling) and the Case factor (Nom(inative) subjects vs. Gen(itive) subjects). Thus, the target
items in all SPRs we conducted share the same sentential frames as illustrated below:
(16)

a.

Adjacent × {Nom | Gen}
[Adv1] [Adv2] NP-{Nom | Gen} V HeadN ...

b.

Non-adjacent × {Nom | Gen}
NP-{Nom | Gen} [Adv1] [Adv2] V HeadN ...

Adv1 and Adv2 were selected from temporal adverbs (Temp), locative PPs (Loc) and manneradverbs (Mann). The combinations of the two adverbs were <Temp, Loc> in SPR1, <Mann,

Loc> in SPR2, and <Temp, Mann> in SPR3. We could not put Loc in the Adv1 position because

the adnominal, non-subject analysis of NP-Gen was grammatically possible in the Non-adjacentcondition (NP-Gen NP-P).5
5

An anonymous reviewer suggests a possible experimental design in which the locative consists of a proper name oradverbial pronoun. In this design, we might be able to put the locative PP immediately after the genitive subject
without letting the participants choose the adnominal analysis of NP-Gen. Although we still worry about the possibility that such a design induces a temporary confusion due to the matching of the nominal features between NP-Gen
and the locative, this might be worth pursuing in future research.

16

4.1 Method
4.1.1 Participants
Native speakers of Japanese participated in the experiments, and the number of participants

were 67 for SPR1, 86 for SPR2, and 68 for SPR3. They were mainly recruited at a university
in Japan, and were paid 1,000 yen or received course credit for participation. None of them
participated in more than one experiment.

4.1.2 Materials
As mentioned earlier, all three SPRs had a 2×2 factorial design crossing the Adjacency factor andthe Case factor, showing the sentential frames illustrated in (16). As for lexicalization, the target
items for SPR1 adopted the same 16 lexicalized sets as the ones tested in the first acceptability
judgment experiment (ADJ1 in Section 2). The target items in SPR2 were based on those in SPR1

with slight modifications apart from varied adverbs to adjust plausibility, and those in SPR3

were based on those in SPR2. Thus, lexicalizations were slightly different among the three SPR
experiments, but they were mostly similar to each other. Sample materials are shown below,

where slashes indicate region boundaries for SPR presentation. The translations of the Nonadjacent conditions are identical to the Adjacent ones and thus are omitted in what follows.
(17)

SPR1: <Temp, Loc>
a. Adjacent × {Nom | Gen}
Kyoo / juku-de/ kodomotati-{ga | no} / narat-ta / rekisi-wa
today / cram.school-at / children-{Nom | Gen} / learn-Pst / history-Top/ Heianzidai-nituite / dat-ta.
/ Heian.period-about / Cop-Pst‘The history that the children learned at a cram school today was about the Heianperiod.’b.

(18)

Non-adjacent × {Nom | Gen}
Kodomotati-{ga | no} / kyoo / juku-de/ narat-ta / rekisi-wa
children-{Nom | Gen} / today / cram.school-at / learn-Pst / history-Top/ Heianzidai-nituite / dat-ta.
/ Heian.period-about / Cop-Pst

SPR2: <Mann, Loc>
a. Adjacent × {Nom | Gen}
Sibusibu/ juku-de/ kodomotati-{ga | no} / narat-ta
grudgingly / cram.school-at / children-{Nom | Gen} / learn-Pst/ eikaiwa-wa/ ryokoosaki-de/ yaku-ni / tat-ta.
/ conversational.English -Top / travel.destination-at / role-Dat / rise-Pst‘The conversational English that the children grudgingly learned at a cram school
turned out to be useful at the travel destination.’

17

b.

(19)

Non-adjacent × {Nom | Gen}
Kodomotati-{ga | no} / sibusibu/ juku-de/ narat-ta
children-{Nom | Gen} / grudgingly / cram.school-at / learn-Pst/ eikaiwa-wa/ ryokoosaki-de/ yaku-ni / tat-ta.
/ conversational.English -Top / travel.destination-at / role-Dat / rise-Pst

SPR3: <Temp, Mann>a. Adjacent × {Nom | Gen}
Sensyu/ sibusibu/ kodomotati-{ga | no} / narat-ta
last.week / grudgingly / children-{Nom | Gen} / learn-Pst/ eikaiwa-wa/ ryokoosaki-de/ yaku-ni tat-ta.
/ conversational.English -Top / travel.destination-at / role-Dat rise-Pst‘The conversational English that the children grudgingly learned last week turned
out to be useful at the travel destination.’b.

Non-adjacent × {Nom | Gen}
Kodomotati-{ga | no} / sensyu/ sibusibu/ narat-ta
children-{Nom | Gen} / last.week / grudgingly / learn-Pst/ eikaiwa-wa/ ryokoosaki-de/ yaku-ni tat-ta.
/ conversational.English -Top / travel.destination-at / role-Dat rise-Pst

In each SPR, the 16 item sets were distributed into four lists using a Latin Square procedure. Filler
items were added to each list; the number of fillers was 90 in SPR1 (of which 66 were items forother unrelated experiments), 64 in SPR2 (of which 32 were items for other unrelated experiments),

and 56 in SPR3 (of which 24 were items for another unrelated experiment). One list was assigned
to each participant, and the target and filler sentences in a list were presented in a pseudo-random
order for each participant, such that no two target items were presented consecutively.

4.1.3 Procedure
All three experiments were conducted with Linger (v.2.88), a Tcl/Tk sentence presentation

program written by Douglas Rohde, using Apple Mac mini computers on Mac OS X and 17-inch
TFT displays. In all three SPRs, participants were asked to read the sentences silently, notaloud. The experiment was preceded by brief instructions and 9 practice items. Each stimulus
was immediately followed by a simple sentence that may or may not have matched the content
of the sentence that was presented, and the participants were instructed to push either the F

key (for yes) or the J key (for no) on a keyboard depending on the match. Visual feedback wasprovided for wrong answers only. An opportunity for a break was given after every 20 trials.

4.1.4 Analysis
For analyses, we trimmed the data to eliminate noise using four procedures. First, we excluded

participants who had correct answers for less than two thirds of the comprehension questions;

18three, zero, two participants were excluded by this criterion for SPR1, SPR2, SPR3, respectively.
Second, we excluded the data points from the incorrectly answered trials, which corresponded to
5.3%, 8.8%, 19.3% of the target data points in SPR1, SPR2, and SPR3, respectively. The size of thetrimmed data based on the comprehension question responses was notably larger in SPR3 than in

SPR1 or SPR2, for which we could not figure out the reasons. However, the mean comprehension

accuracy rate for the target items in SPR3 was still reasonably high (>80%), so we assumed thatthe participants were making fair efforts in this experiment. Third, we interpreted reading times
shorter than 150 ms to be missteps and excluded them, which corresponded to less than 1% of

the data. Finally, after removing the data points exceeding 10,000 ms, we calculated the z-scoredreading times of each region for each condition, and excluded the data points whose z-scores
were greater than 3 as outliers.

For statistical analyses, linear mixed-effects models were fitted using the lmerTest package

in statistical software R4.1.1 (2021-08-10). We fitted the models with Case and Adjacency as
fixed effects, and by-participant and by-item intercepts and slopes as random effects; then the
random effects structure was simplified from a maximal model (which often led to singular fit

warnings) using backwards step- wise regression using the step function from lmerTest to avoid
overparameterization (Bates et al. 2015).

In addition, for comparisons where the immediately preceding regions were not constantacross the conditions (such as the analysis of Region 4, the verb region, which was preceded
either by the subject NP (the Adjacent conditions) or by one of the interveners (the Non-adjacentconditions)), the centered and scaled RTs of the immediately preceding regions were included asanother fixed effect labeled “spillover”.

4.2 Results
Our interest is in the reading times in the first five regions of the stimuli, i.e., up to the head nounof the embedded clause, as shown in (17-19). Two critical regions were the verb region (R4) andthe head noun region (R5). We were also interested in how adverbial regions were incrementallyprocessed, especially in the Non-adjacent conditions (R2, R3). Mean reading times of the first

five regions plus two spillover regions are graphically summarized in Figure 2 for Non-adjacentconditions and Figure 3 for Adjacent conditions.

4.2.1 R4 (Verb region) and R5 (Head noun region)
We first report the analyses of the interaction between the Adjacency and Case factors in theverb region (R4) and the head noun region (R5). The mean reading times for the combinationsof the two factors are graphically summarized in Figures 4 and 5, and a summary of the resultsfrom the best-fitting LME models is shown in Table 2. In the verb region (R4), no interaction

19

was found in SPR1 (t = –0.66, p = .507) or in SPR2 (t = –1.12, p = .276), but a significant
interaction was found in SPR3 (t = –2.80, p = .006) in the direction that the genitive subject
condition was significantly slowed down when the genitive subject was adjacent (pairwise

comparisons in SPR3: the effect of the Adjacency factor was significant for the Gen conditions (t= –4.51, p = .000), while not significant for the Nom conditions (t = –0.61, p = .542)). In thehead noun region (R5), no interaction was found in SPR1 (t = –0.73, p = .463) or in SPR3 (t =–1.48, p = .141), while a significant interaction was found in SPR2 (t = –2.24, p = .027) in thesame direction as the interaction found in R4 in SPR3 (pairwise comparisons: the effect of the

Adjacency factor for the Gen conditions: t = –3.38, p = .001; for the Nom conditions: t = –0.04,
p = .967). In summary, the slowdown effect from having the genitive subject adjacent to theverb was found in SPR2 and SPR3, but the effect was delayed in SPR2 until R5. No interaction
was found in SPR1.

Figure 2: The mean reading times in milliseconds in the Non-adjacent conditions in SPR1
(left), SPR2 (middle), and SPR3 (right), with error bars representing 95% confidence intervals.
Regions 2 and 3 were the intervener regions (<Temp, Loc> in SPR1, <Mann, Loc> in SPR2,<Temp, Mann> in SPR3), and Regions 4 and 5 were the verb and head noun regions.

Figure 3: The mean reading times in the Adjacent conditions in SPR1 (left), SPR2 (middle),
and SPR3 (right), with error bars representing 95% confidence intervals. Regions 1 and 2 were
the intervener regions (<Temp, Loc>, <Mann, Loc>, <Temp, Mann>), R3 was the subject
region, and Regions 4 and 5 were the verb and head noun regions.

20

Figure 4: The mean reading times in the verb regions (R4) in SPR1 (left), SPR2 (middle), andSPR3 (right), with error bars representing 95% confidence intervals.

Figure 5: The mean reading times in the head noun regions (R5) in SPR1 (left), SPR2 (middle),
and SPR3 (right), with error bars representing 95% confidence intervals.
As for main effects of the factors, main effects of the Case factor were found in all threeexperiments (R5 in SPR1, R4 and R5 in SPR2, R4 in SPR3) such that the Gen conditions were readslower on average. In some cases, these effects were found even when there were no significant
interactions (R5 in SPR1, R4 in SPR2), indicating that genitive-marked subjects generally
tended to cause greater reading times at the verb and/or head noun regions. Main effects of the

Adjacency factor were also found in some regions (R5 in SPR2, R4 in SPR3) in the direction that
the Adjacent conditions were read slower. These effects are likely by-products of the significant
interactions in which the Gen × Adjacent conditions were read considerably slowly.

4.2.2 Sum of the preverbal regions R1-3
Our next step was to examine the effects in preverbal regions. Because the words in the first

three regions were not lined up across the conditions (due to the Adjacency factor, which varied
the word order), we collapsed the first three regions into one and analyzed the summed reading

times of the three regions. The results are graphically summarized in Figure 6. The fitted linear

mixed-effects models, summarized in Table 3, showed not only constant main effects of the–19.2 (16.3)

Estimate (SE)

5.3 (15.0)

Estimate (SE)–81.3 (25.2)

90.8 (10.9)–122.6 (43.7)
8.33

–2.80

–3.22

2.18

24.42

t-value

4.58

–1.12

0.35

2.17

31.64

t-value

4.30

–0.66

–1.18

0.74

28.89

.000

.006

.002

.032

.000

Pr(>|t|)

.000

.276

.730

.030

.000

Pr(>|t|)

.000

.507

.240

.458

.000

***

**

**

*

***

***

*

***

***

***

Case:Adjacency

Adjacency

Case(Intercept)

SPR3

Case:Adjacency

Adjacency

Case(Intercept)

SPR2

Case:Adjacency

Adjacency

Case(Intercept)–58.7 (39.8)–1.9 (20.1)

0.3 (19.9)

628.9 (33.1)

Estimate (SE)–70.3 (31.3)–35.4 (15.1)

58.2 (20.0)

617.6 (27.8)

Estimate (SE)–25.46 (34.7)–22.5 (17.4)

51.7 (21.2)

593.2 (25.1)

Estimate (SE)

–1.48

–0.10

0.02

19.0

t-value

–2.24

–2.34

2.91

22.22

t-value

–0.73

–1.30

2.44

23.67

t-value

.141

.924

.987

.000

Pr(>|t|)

.027

.020

.007

.000

Pr(>|t|)

.463

.195

.018

.000

Pr(>|t|)

***

*

*

**

***

*

***

Table 2: Results of linear mixed effects model analyses of the RTs in the verb region (R4) and the head noun region (R5) for SPR1,
SPR2, SPR3.
Signif. codes: 0 '***' .001 '**' .01 '*' .05 '.' 0.1 ' ' 1.

spilloverCase:Adjacency

51.4 (23.6)

Adjacency

Case

632.5 (25.9)(Intercept)

20.4 (4.4)

SPR3

spillover–45.4 (40.4)

Case:Adjacency

28.6 (13.2)

Adjacency

Case

586.5 (18.5)(Intercept)

32.9 (7.7)

SPR2

spillover–21.7 (32.6)

Case:Adjacency

12.1 (16.3)

Adjacency

Case

580.1 (20.8)(Intercept)

Pr(>|t|)SPR1

t-value

SPR1

Estimate (SE)

R5 (Head N)

R4 (Verb)

21

22

Adjacency factor (in contrast with the verb and head noun regions, the Non-adjacent conditions
were slower: t = 4.03, p = .000 in SPR1; t = 2.41, p = .017 in SPR2; t = 2.20, p = .028 in SPR3)

but also interactions of the two factors in the direction that having the subject non-adjacent to its
verb incurred a greater load when the subject was genitive-marked (t = 1.83, p = .071 in SPR1;
t = 2.75, p = .006 in SPR2; t = 2.03, p = .043 in SPR3). Thus, overall, a slowdown was incurredin the pre-verbal regions when the genitive subject was not adjacent to its verb, but it should
be noted that an opposite pattern tended to emerge in the verb region or the head noun region.

Figure 6: The mean reading times of the sum of the first three regions in SPR1 (left), SPR2
(middle), and SPR3 (right), with error bars representing 95% confidence intervals.
SPR1

Estimate (SE)t-value

Pr(>|t|)Case

120.0 (58.59)

2.05

.043

(Intercept)
Adjacency

Case:Adjacency
SPR2(Intercept)
Case

Adjacency

Case:Adjacency
SPR3(Intercept)
Case

Adjacency

Case:Adjacency

2133.4 (94.33)
236.5 (58.8)

223.9 (122.6)

Estimate (SE)2065.7 (72.5)
69.4 (46.8)

115.29 (47.8)
229.3 (83.5)

Estimate (SE)1938.9 (88.0)
17.9 (43.2)
95.3 (43.4)

174.7 (86.3)

22.62
4.03
1.83

t-value
72.5
1.49
2.41
2.75

t-value
22.03
0.41
2.20
2.03

.000

***

.000

***

.071

Pr(>|t|)

*
.

.000

***

.017

*

.140
.006

Pr(>|t|)

**

.000

***

.028

*

.679
.043

*

Table 3: Results of linear mixed effects model analyses of the summed RTs of the preverbal,
first three regions for SPR1, SPR2, SPR3.
Signif. codes: 0 '***' .001 '**' .01 '*' .05 '.' 0.1 ' ' 1.

23

4.2.3 R1, R2, and R3 in the Non-adjacent conditions
Finally, to pin down the locus of the pre-verbal slowdowns in the Genitive × Non-adjacentconditions, we conducted pairwise comparisons between the two Non-adjacent conditions ineach of the first three regions (see Figure 2). The transitions of the mean reading times acrossthe regions are graphically shown in Figure 2 above. No effect of Case was found in R1, thenominative/genitive subject region in any of the three experiments (SPR1: t = –0.62, p = .536;

SPR2: t = 0.93, p = .353; SPR3: t = –0.38, p = .706). In R2, the first adverbial region, a main
effect of Case was found only in SPR3 (t = 3.16, p = .002), where the adverbial was a temporaladverbial, such that the Genitive conditions were read slower, but no such effect was found in

SPR1 (t = 1.57, p = .121), where the adverbial was also a temporal adverbial, nor in SPR2 (t =–0.52, p = .607), where the adverbial was a manner adverbial. As for R3, the second adverbial

region, a strong main effect of Case was found when this region was a locative PP (SPR1: t =3.31, p = .002; SPR2: t = 4.88, p = .000) in the direction that the Genitive conditions were readslower than the Nominative conditions, while no such effect was found when this region was amanner adverb (SPR3: t = 0.84, p = .361).

In sum, from the perspective of the type of interveners, (i) post-subject temporal adverbs tended

to be read slower when the subject was genitive-marked (in SPR3 but not in SPR1), (ii) post-subject
locative PPs were consistently read considerably slower in the Genitive conditions (SPR1 andSPR2), and (iii) post-subject manner adverbs did not show any such effect (SPR2 and SPR3).

4.3 Discussion
Through the three self-paced reading experiments varying (i) the case-marking of the subjectof the relative clause (the Case factor: Nominative vs. Genitive), (ii) the distance between thesubject and the predicate (the Adjacency factor: Adjacent vs. Non-adjacent), and (iii) the types of

the adverbials (SPR1: a temporal adverb and a locative PP; SPR2: a manner adverb and a locative
PP; SPR3: a temporal adverb and a manner adverb), we found the following.

First, at the loci of the thematic integrations, namely the verb region (R4) and the headnoun region (R5), the main effects of Case were overall constantly found (R4 in SPR2 andSPR3; R5 in SPR1, SPR2) such that the Genitive conditions were read slower, which conforms

to the results of the acceptability judgment experiments (Section 2), those of Nambu’s (2013a)

sentence-completion study, and those of a corpus frequency study (Nambu 2013b). However,
the interaction between the Case and Adjacency factors in these regions emerged in the opposite
direction to these off-line studies: the Genitive conditions were read more slowly when the genitive
subjects were adjacent to the verb while no such effects were found for nominative subjects. The

disadvantage of having a predicate immediately follow a genitive subject can be accounted forin terms of expectation-based surprisal models such as Hale (2001) and Levy (2008), because
a genitive-marked NP is much more frequently understood as an adnominal element than as a

24subject (Nambu 2013a, b). Having a predicate immediately follow a genitive NP would defy

this expectation, inducing a surprisal, while distancing the genitive NP away from the predicate

and inserting adverbial elements in between would significantly facilitate the subject analysisof the genitive NP before the parser encounters the predicate. One may object that an adverbial

following a genitive NP should also incur a processing difficulty. However, it is not the case thatan adverbial and a verb should cause the same level of processing load. An adverbial merely
triggers a revision of the processing resource allocation such that the expectation for a genitive

subject structure is elevated. In contrast, an encounter with a verb works differently because it

is a theta assigner searching for an argument. The verb that immediately follows the genitive NP

does not merely elevate the possibility of the genitive subject analysis, but it forces the parser

to reject the highly frequent adnominal analysis of the genitive NP. This should cause a greater
processing load than having an adverbial following the genitive NP.

Interestingly, the interactions were only found in SPR2 (a significant interaction in R5) andin SPR3 (a significant interaction in R4), but not in SPR1. If we compare what preceded the verb

region in the Adjacent conditions, both SPR2 (<manner, locative >) and SPR3 (<temporal,

manner >) had a manner adverb in one of the pre-subject regions whereas SPR1 (<temporal,
locative >) did not. It might be the case that the presence of a manner adverb led to a stronger
surprisal effect when processing the genitive NP that came after it. Under the assumption thata manner adverb is generated lower than the subject in syntactic structure, an “unmotivated”
movement must be set up to yield a ‘manner-adverb subject’ word order (Miyagawa, 2011).

Therefore, the presence of a manner adverb preceding a genitive NP in SPR2 and SPR3 may have
driven the adnominal analysis of the genitive NP more strongly than in the case where a manneradverb is not involved (i.e., SPR1). This stronger preference driven by a manner adverb may haveyielded greater surprisal effects, leading to significant slowdown in the Genitive × Adjacentconditions in SPR2 and SPR3, in contrast with SPR1. Therefore, even though the disadvantageof putting a genitive subject adjacent to the verb, found in the verb and head noun regions, does
not follow from Miyagawa’s structural hypothesis, the negative effect of putting a manner adverb
before the genitive subject may necessitate a hierarchical structural assumption like Miyagawa’s.
Second, the disadvantage of separating the genitive subject from the predicate was foundin the pre-verbal regions. When the summed reading times of the pre-verbal regions werecompared, interactions of the two factors were found in the direction that the Genitive × Non-adjacent conditions were read slower. This conforms to the results of the acceptability judgment

experiments (Section 2), those of Nambu’s (2013a) completion study, and those of a corpus
frequency study (Nambu 2013b), as well as what has been pointed out in theoretical studies(Harada 1971; Miyagawa 2011, among others).

Third, regarding the type of adverbials responsible for intervention effects, we found the

Non-adjacent × Genitive disadvantage in the temporal adverb regions (though not consistently),

25

and particularly in the locative PP regions, but not in the manner adverb regions. The contrast
between temporal adverbs and manner adverbs seems to conform to the prediction of Miyagawa’s(2011) D-licensing theory coupled with the syntactic hierarchical analyses of adverbials in theprevious syntactic literature (Cinque 1999; 2006; Maienborn 2001; Ernst 2002; 2004; Frey 2003;
Pittner 2004; etc.), where manner adverbs are assumed to be syntactically situated very low while

temporal adverbs are assumed to be very high. Specifically, Miyagawa (2011) hypothesizes thatgenitive subjects are base-generated syntactically higher than manner adverbs and lower than

temporal adverbs, and thus, having a temporal adverb follow a genitive subject is expected tocause some processing load while having a manner adverb follow it is not.

In contrast, notable slowdowns found in the locative PP regions in the Genitive × Non-adjacent conditions in SPR1 and SPR2 are unlikely to be attributable to Miyagawa’s structural
hierarchy because there seems to be no strong evidence that locative PPs are base-generated

syntactically higher than the Spec of vP, where genitive subjects are supposed to be situated.
Particularly, our findings that the slowdowns in locative PP regions were even stronger thanthose in temporal adverb regions are inexplicable in terms of relative structural height because
the consensus in the syntactic literature seems to be that locative PPs should be generated
somewhere closer to vP than temporal adverbs and thus their intervention effects on genitive

subjects should be smaller than those of temporal adverbs, a prediction not supported in our
experimental studies. The reason for a seemingly huge disadvantage of a locative intervener is notentirely clear, but we speculate that this could be accounted for by a version of an expectationbased theory. Although an adverbial immediately following a genitive NP drastically elevates thepossibility of its subject analysis, its adnominal analysis still has a chance, as we saw in (14a) and(14c) of Section 3.2 where genitive NPs must be adnominal even though immediately followedby an adverbial. Thus, we assume that the parser retained both the subject analysis, probing

for a verbal feature, and the adnominal analysis, probing for a nominal feature, even after anadverbial was encountered. When a locative PP followed, it also triggered an expectation for a

verbal feature (because the postpositions used in our experiments were always morphologically
adverbial). However, the NP in the PP might have sidetracked the parser into the adnominal
analysis because of its nominal feature matching the adnominal expectation. This analysis was

ungrammatical because of the presence of an adverbial between the genitive NP and the PP. We
conjecture that this ungrammatical attraction from the nominal feature of the locative PP was
the source of the elevated reading times.

5. General discussion and conclusion
The present article reported several important empirical findings on the intervention effecton genitive subjects. First of all, against the background of some disagreement regarding themagnitude of the intervention effect that was often documented in theoretical studies based on

26

introspection, the present study is the first to present evidence of this purported intervention

effect using both off-line and on-line experiments. Our acceptability judgment studies revealed
that the presence of interveners worsened the acceptability of the genitive subject sentences toa statistically greater extent compared with the nominative subject sentences, even when only
one intervener was present. Our three self-paced reading experiments also showed consistentand robust interaction between the Adjacency factor and the Case-marking factor such that there

was an intervention effect for the genitive subject, but not for the nominative subject, when thesum of the reading times of the first three pre-verbal regions were compared. Interestingly, theeffect was reversed in the verb and/or head noun regions such that the Genitive conditions wereread slower when the genitive subject was adjacent to the verb. This goes against the prediction

based on hierarchical structural complexity or cue-based retrieval, but it can be accounted for interms of surprisal (Hale 2001; Levy 2008). Additionally, our study suggests a negative effect ofplacing the manner adverb immediately before the genitive subject, which may be explained by
a combination of surprisal and Miyagawa’s (2011) structural hierarchy.

Furthermore, the series of self-paced reading studies designed to identify the loci of theintervention effects with reference to structural and processing-based accounts revealed effects of

temporal adverbs and locative PPs but not that of manner adverbs. The results are not compatible

with the view that any type of intervener is harmful for the genitive subject or the hypothesisthat having one intervener is tolerable but having a second intervener is harmful. We haveshown that the intervention effect for the genitive subject is clearly sensitive to intervener types.

Regarding the loci of the effects, the contrast between temporal and manner adverbs lends support
to Miyagawa’s syntactic hypothesis on the genitive subject structure in comparison to othersyntactic hypotheses that do not assume any structural difference from the nominative subject

structure. However, our finding that the slowdown effects at locative PPs were even stronger

than those at temporal adverbials is not accountable by Miyagawa’s D-licensing hypothesis. We

suggest that this finding may be accounted for by a version of an expectation-based theory: thatis to say, the nominal feature of a locative PP may interfere with the parser’s proactive search fora verbal feature triggered by the genitive subject. All in all, these fine-grained findings suggestthat the intervention effects require a hybrid account grounded in theories of syntactic derivationand of expectation-based processing.

27

Data accessibility statement
Analysis scripts and raw data for the acceptability judgment and self-paced reading experiments

are available in the supplementary materials at Open Science Framework: https://osf.io/
v9ery/?view_only=8af6791cf8c847df96e0cfde0300a485

Abbreviations
Acc = accusative, Cop = copula, Dat = dative, Gen = genitive, Neg = negation, Nom =nominative, Prg = progressive, Prs = present, Pst = past, Top = topic, Grd = gerundive

Ethics and consent
The study was approved by Monash University Human Research Ethics Committee (Project
number 14343).

Acknowledgements
We are truly grateful to the three anonymous reviewers for their invaluable comments.
Preliminary findings from an early version of this research were presented at Formal Approaches
to Japanese Linguistics 7, TL/MAPLL 2020, and the 75th Kyushu Branch meeting of the English
Literary Society of Japan. We deeply appreciate the constructive feedback from the audience.

Funding information
This work was partially supported by JSPS KAKENHI Grant JP20H01263.

Competing interests
The authors have no competing interests to declare.

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