Intervention effects in relative pronoun pied-piping: experimental evidence∗
Hadas Kotek — McGill University
Michael Yoshitaka Erlewine — National University of Singapore

Abstract. This paper contributes experimental evidence regarding the question of how relative
pronouns are interpreted in English non-restrictive relative clauses with relative pronoun piedpiping (RPPP). Kotek and Erlewine (2015) and Erlewine and Kotek (to appear b) claim that the whrelative pronoun is sensitive to intervention effects inside its pied-piping constituent (cf Sauerlandand Heck 2003, Cable 2010, Kotek and Erlewine to appear). In this paper we present the results ofa web-based grammaticality judgment survey which supports this claim. We discuss the nature of
the intervention judgment, which is notoriously subtle, and how it might be modeled in grammar.
The sensitivity of RPPP to intervention effects has important implications for the formal analysis ofEnglish non-restrictive relative clauses, supporting the view that relative pronouns are interpreted
in-situ without covert movement out of its pied-piping.
Keywords: relative pronoun, pied-piping, non-restrictive relative clause, intervention effects,
grammaticality judgment survey, gradience in grammar
1. Introduction
The literature of the past three decades on the syntax/semantics of wh-constructions has identified
broadly two different strategies for the scope-taking of surface in-situ wh-words: covert movement
and in-situ interpretation. See e.g. Pesetsky (1987), Tsai (1994), Reinhart (1998), Cheng (2009)
for discussion of these two strategies. Although this literature has overwhelmingly focused on theinterpretation of wh-in-situ in wh-questions, wh-words are also used for a range of other purposes
and their scope-taking can also be investigated in similar terms. Against this backdrop, in thispaper we investigate the interpretation of wh-words as relative pronouns in English non-restrictive
relative clauses.
Relative pronouns in English relative clauses undergo obligatory fronting to the edge of the relative
clause, as in (1). In this simple case, we can interpret the overt movement step as abstracting over
the object position of find, resulting in the interpretation of the derived predicate “λx . we found a
copy of x in the archive” which must hold of the head noun (here, this letter by Lincoln). See Heimand Kratzer (1998) for one standard treatment, focusing on English restrictive relative clauses.
(1)

Obligatory relative pronoun fronting in English relative clauses:in the archive].
We read this letter by Lincoln, [RC which we found a copy of∗

For comments and discussion we would like to thank Amy Rose Deal, Danny Fox, Martin Hackl, Chris Kennedy,
David Pesetsky, Gary Thoms, and audiences at Sinn und Bedeutung 20, CLS 51, and McGill University. The firstauthor is supported by a Mellon fellowship at McGill University. Errors are each other’s.

To appear in Proceedings of Sinn und Bedeutung 20. Submitted 2016.

The interpretation of the relative clause is complicated by the availability of relative pronoun piedpiping (RPPP). Consider the variant of (1) with pied-piping in (2), which has the same interpretation as (1). In this case, there is not a straightforward way of retrieving the same predicate “λx . wefound a copy of x in the archive” which must hold of the head noun. Although overt wh-movementtakes place in the derivation of the relative clause, the possibility of pied-piping forces us to consider the interpretation of the relative pronoun as an in-situ wh-word, inside its pied-piping.
(2)

Optional relative pronoun pied-piping (RPPP) (cf 1):
We read this letter by Lincoln, [RC [RPPP a copy of which] we foundin the archive].

Following the literature on different interpretational strategies for wh-in-situ in wh-questions, weconsider two approaches to the interpretation of relative clauses with RPPP, schematized in (3–4)
below. Option 1 involves covertly moving the relative pronoun out of the RPPP to the edge of therelative clause at LF (3), which straightforwardly yields the same derived predicate for the relative
clause as in the non-pied-piped variant in (1).1 Option 2 involves interpreting the wh-relative
pronoun in-situ within the pied-piping at LF (4). We indicate overt movement with solid arrows,
covert movement with dashed arrows, and areas of in-situ interpretation with squiggly arrows.
(3)

Option 1: covertly move the relative pronoun out of the RPPP
a. LF: [RC which λy [[RPPP a copy of y] λx . we found x in the archive]]
b. JRCK = λy . (λx . we found x in the archive) (a copy of x)= λy . we found a copy of y in the archive(4)

Option 2: interpret the relative pronoun in-situ within RPPP
LF: [RC [RPPP a copy of which] λx . we found x in the archive]
in-situ interpretation

movement

These two options for the analysis of RPPP in non-restrictive relatives make different predictions
for the region between the relative pronoun and the edge of the relative clause. The covert movement option (3) predicts that the relative pronoun cannot be inside a syntactic island, inside thepied-piping, whereas alternative computation (4) is not sensitive to islands (see e.g. Rooth 1985).
In contrast, the use of Rooth-Hamblin alternative computation to interpret relative pronouns in-situ(4) is susceptible to so-called intervention effects, which we introduce in the following section, but
the covert movement option (3) predicts no such sensitivity.
1

Heim and Kratzer (1998: p. 106) presents Option 1 for pedagogical purposes. Option 1 here also stands in forother options which involve a movement relation between the overt position of the relative pronoun and the edge of therelative clause. For example, a derivation where the head NP (here, letter by Lincoln) is moved to its surface position
from the position of the relative pronoun, as in the analyses of Kayne (1994), Bhatt (2002), a.o., would also yield asimilar structure at LF.

This paper is structured as follows. In section 2 we present background on intervention effects andtheir use in diagnosing regions of in-situ interpretation. In section 3 we return to the problem of
relative pronoun pied-piping (RPPP) and the predictions of the intervention effect diagnostic. We
present our experimental paradigm and results in section 4 and conclude in section 5.
2. Background: Detecting in-situ interpretation through intervention effects
2.1. Intervention effects in wh-questions
The term intervention effect is traditionally used to describe a situation in which a wh-question isrendered ungrammatical because an in-situ wh-phrase is c-commanded by an intervener—certain
quantificational and negative elements, as well as focus-sensitive items—at LF (Beck 2006; seealso Beck 1996, Kim 2002, a.o.).
Intervention effects are most easily observed in wh-in-situ languages such as Japanese and Korean.2
In the following paradigm from Beck and Kim (1997), example (5a) shows that Korean questions
generally do not require wh-fronting. However, when the subject above the in-situ wh-word ischanged from ‘Minsu’ to the focus-sensitive expression ‘only Minsu,’ the question becomes ungrammatical (5b). This problem can be avoided by scrambling the wh-word over ‘only Minsu’as in (5c), so that the intervener no longer c-commands the wh-word. Interveners are bolded andwh-words are italicized throughout.
(5)Intervention effect in Korean wh-questions:(Beck and Kim 1997)a.
Minsu-nun nuku-lûl po-ass-ni?
Minsu-TOP who-ACC see-PAST-Q‘Who did Minsu see?’po-ass-ni?
b. * Minsu-man nuku-lûl po-ass-ni?
c. XNuku-lûl Minsu-man
see-PAST-Q
Minsu-only who-ACC see-PAST-Q
who-ACC Minsu-only
Intended: ‘Who did only [Minsu]F see?’ ‘Who did only [Minsu]F see?’

The intervention effect in (5b) and its amelioration through scrambling in (5c) motivate the ideathat intervention effects affect regions of in-situ interpretation, not movement (Beck 2006, Beckand Kim 2006, Kotek 2014). The authors cited here assume a theory of in-situ interpretationthat is based on Rooth-Hamblin alternative computation (see Hamblin 1973, Rooth 1985: a.o.).
Informally, interveners interrupt the projection of alternatives before they reach the interpreting
operator—in this case, interrogative C.3 Interveners do not affect overt or covert movement possibilities. The schema in (6) from Beck (2006) reflects the contrast in (5b–c):
2

Intervention effects can also be observed in wh-fronting languages such as English and German, under certain
circumstances. See Pesetsky (2000) and Beck (2006) for details.
3
Here we will concentrate on the distribution of intervention effects and be less concerned with the mechanism thatcauses intervention. See Beck (2006) for one prominent view.

(6)Intervention affects in-situ interpretation (alternative computation), not movement:a. * [CP C ... intervener ... wh ]
(5b)
b.

X

[CP C ... wh ... intervener ... t ](5c)Here we note that judgments concerning intervention effects are notoriously difficult.4 As a result,different authors studying intervention effects have reported the degradation of examples caused
by intervention as “*”, “?*”, or “??”. We will simply indicate degraded examples throughout witha “*”. We return to this issue after presenting our experiment in section 4.

2.2. Intervention effects in interrogative pied-piping
Sauerland and Heck (2003), Cable (2007), and Kotek and Erlewine (to appear) show that intervention effects also occur inside pied-piped constituents triggered by interrogative wh-movement:5(7)

Intervention effect in English interrogative pied-piping: (based on Cable 2007: p. 262)?
a. X [pied-piping A picture of which president] does Jim own
b. * [pied-piping No pictures of which president] does Jim own?
c. * [pied-piping Few pictures of which president] does Jim own?
d. * [pied-piping Only PICTURES of which president] does Jim own?

If an intervener is placed between the wh-word and the edge of pied-piping, the result is ungrammatical due to an intervention effect. This is explained by the view that interrogative wh-words areinterpreted in-situ within pied-piping constituents, using Rooth-Hamblin alternative computation(Cable 2010, Kotek and Erlewine to appear), as schematized in (8). In (7), only example (7a) is
grammatical, because (7b–d) involve an intervener occurring inside the region where alternatives
must be projected for the interpretation of the question.
(8)

The pied-piping intervention schema:*[pied-piping ... intervener ... wh ... ] λx .
alt. computation... x ...

movement

We know that it is specifically this region within the pied-piping that is sensitive to intervention
because different choices of pied-piping size can lead to structures where the intervener is stranded
4

For example, see discussions in Pesetsky (2000), Tomioka (2007, 2009), and Kotek (2014), as well as Beck (1996:
fn. 2) and Butler (2001: fn. 1).
5
See also Erlewine and Kotek (2014) for parallel results from overt and covert focus movement in English.

outside the pied-piped material. Such questions are grammatical, as seen in (9) in comparison
with (7b) above. This reflects the fact that intervention effects affect Rooth-Hamblin alternative
computation, here used to interpret the wh-word in-situ within the pied-piping constituent, but not
structures that are derived through movement chains and interpreted through λ-abstraction.
(9)Intervention avoided with smaller pied-piping (cf 7b):a. X [pied-piping Of which president] does Jim own no pictures
b. X [pied-piping Which president] does Jim own no pictures of(Cable 2007)?
?

3. Intervention effects in RPPP
We now return to the question of relative pronoun pied-piping (RPPP). Recall from the introductionthat there are broadly two approaches to the interpretation of the relative pronoun inside RPPP:
movement and in-situ interpretation. These options from (3–4) above are schematized here in(10). Following previous work on the interpretation of interrogative wh pied-piping, reviewed in§2.2 above, we take the mechanism of in-situ interpretation in Option 2 to be Rooth-Hamblin
alternative computation.
(10) Two options for the interpretation of relative pronouns with pied-piping:a. Option 1: covertly move the relative pronoun out of the RPPP
LF: [RC whRP λy [[RPPP ... y ... ] λx . ... x ... ]]b. Option 2: interpret the relative pronoun in-situ within RPPP
LF: [RC [RPPP ... whRP ... ] λx . ... x ... ]alt. computation

movement

Previous work on the semantics of relative pronouns have largely favored Option 1, or similar
movement derivations which yield a substantially equivalent LF representation (e.g. Kayne 1994,
Bhatt 2002; see footnote 1), with some authors arguing that in fact a Rooth-Hamblin alternativesbased approach cannot be made to work for RPPP (Sternefeld 2001, Sauerland and Heck 2003;
see discussion in Kotek and Erlewine 2015). Against this backdrop, in Kotek and Erlewine (2015)
and Erlewine and Kotek (to appear b), we develop a semantics for non-restrictive relatives whichinterprets the relative pronoun in-situ through alternative computation within its RPPP (Option 2),
solving the objections to this approach raised by previous authors.
Our proposal which interprets the relative pronoun in-situ using alternative computation (Option2) was motivated by two new facts regarding RPPP. First, embedding a relative pronoun inside
a syntactic island does not lead to ungrammaticality, as observed in (11), reproduced from ourprevious work. This is unexpected if the interpretation of RPPP necessarily involves movement(Option 1).

(11) The relative pronoun can be inside an island, inside RPPP:
This portrait,a. X [RC [RPPP the background of which] is quite stunning],b. X [RC [RPPP the background [RC that was chosen for which]] is quite stunning],...sold for a million dollars at auction.
The second fact is that the relative pronoun is sensitive to intervention effects inside its RPPP,
in the same way that interrogative wh-pied-piping is sensitive to intervention (section 2.2 above).
The motivating example for this fact is also reproduced here. Example (12a) provides a baseline.
Examples (12b–d) contain interveners and judged as significantly degraded, whereas examples(12e–g) contain various non-intervening determiners and do not exhibit intervention effects.6 Notethat the set of interveners presented in (12b–d) parallel the determiners shown to be interveners in
English interrogative wh pied-piping, as in example (7) above.
(12) Intervention effect in RPPP with known interveners no, very few, only:
I want to try this recipe,
Baseline:a.

X[RC [RPPP the ingredients for which] I (already) haveat home].

Interveners:

b.
c.
d.

* [RC [RPPP no ingredient(s) for which] I haveat home].
* [RC [RPPP very few ingredients for which] I haveat home].
* [RC [RPPP only [one]F ingredient for which] I haveat home].

e.
f.
g.

X

Non-interveners:[RC [RPPP an ingredient for which] I’m missing].
[RC [RPPP three ingredients for which] I (already) haveX
[RC [RPPP many ingredients for which] I (already) haveXat home].
at home].

Finally, as is also the case with interrogative wh pied-piping (9), intervention is avoided if a smaller
pied-piping constituent is chosen which does not contain the intervener:(13) Intervention avoided with smaller RPPP:
I want to try this recipe,a. * [RC [RPPP no ingredients for which] I haveb. X [RC [RPPP for which] I have no ingredientsc. X [RC [RP which] I have no ingredients for6

at home].
at home].
at home].

(=12b)We report examples (12c–d) with ?? in Erlewine and Kotek (to appear b) as a consensus judgment across various
speakers in in-person elicitation. As noted in section 2.1 above, we simply annotate degraded examples with * here.

That relative pronouns in RPPP are sensitive to intervention effects but not islands motivates theinterpretation of relative pronouns in-situ through alternative computation (Option 2; 10b), as we
argue in Kotek and Erlewine (2015) and Erlewine and Kotek (to appear b).
We note that we have also discovered a second, distinct pattern of judgments for some native
speakers, thanks to a comment by Amy Rose Deal at the Sinn und Bedeutung 20 meeting. These
speakers report that RPPP is subject to islands, detecting a contrast in pairs such as (11) but that
there is no sensitivity to intervention as in (12). We believe such speakers to represent a minorityof the population who may in fact be interpreting RPPP through Option 1 (10a). For present
purposes we will concentrate on the pattern of judgments presented above and we leave more
careful documentation of this second pattern of judgments for future work.
4. Experiment
We now turn to the contribution of this paper, the results of a web-based grammaticality judgment
survey which corroborates our claim that RPPP is sensitive to intervention effects. The experiment
presented native speakers with sentences to be judged on a 7-point Likert scale.

4.1. Participants
64 participants were recruited for this experiment through Amazon Mechanical Turk. Participants
were paid US$0.40 for their participation. Participants were asked about their native language butwere told that payment was not contingent on their response. To further ensure that only native
speakers of English participated in the experiments, IP addresses of participants were restricted to
the US using Amazon Mechanical Turk’s user interface. The average time for completion of thesurvey was 8 minutes and 5 seconds. Two participants were excluded from the analysis because
they did not indicate that they were native speakers of English.

4.2. Materials and design
The experiment had a 2×2 design, crossing the presence of an intervener (−intervener, +intervener)
with the size of pied-piping (small pied-piping, large pied-piping). Two interveners were used: noand only one. For items without an intervener, the determiners every, some, and a were used. The
small pied-piping option either included movement of the relative pronoun alone or pied-pipingof a preposition along with the relative pronoun; the choice was made based on the option thatsounded more natural to the authors. Large pied-piping was always of DP size. Eight sets of sentences were constructed, each with four different versions as in (14).7 The full set of target items
can be found in the Appendix.

(14) Sample target item:
My student is studying this letter by Lincoln,in the archive].
−int., small p.-p.
a.
[RC which we found a copy ofb.
[RC [RPPP a copy of which] we foundin the archive].
−int., large p.-p.
in the archive].
+int., small p.-p.
c.
[RC which we found only [one]F copy ofd.
[RC [RPPP only [one]F copy of which] we foundin the archive]. +int., large p.-p.
In addition, 24 fillers were included in this study, with the following structure. 6 grammaticalsentences and 6 ungrammatical sentences were chosen from the materials in Sprouse, Schütze,and Almeida (2013). 6 items contained ungrammatical long-distance dependencies. The final 6
contained relative clauses of varying complexity, half appositive and half restrictive, with no piedpiping, which were all grammatical.
To these 32 items, 6 items from a second, separate experiment were added, all containing appositive
relative clauses. The resulting 38 items were randomized, and 8 lists were created using a Latin
Square design. Each two target items had at least one filler item between them, and there were atleast two filler items at the beginning and end of each list. Randomization and list-creation was
done using turktools (Erlewine and Kotek to appear a).
Participants were instructed to rate the sentences on a 7-point Likert scale. They were remindedthat they might not be uttering the sentences by themselves, but might nevertheless have an intuition as to how natural they are. The scale was marked with numbers 1–7, with 1 being themost unnatural and 7 being the most natural. All participants completed the entire experiment. A
counter helped ensure that all sentences were rated.

4.3. Results
Filler items were coded as grammatical or ungrammatical, with grammatical items expected to be
rated as 5–7 and ungrammatical items expected to be rated as 1–3, on the 7-point Likert scale. The
overall accuracy on filler items across participants in this experiment was 88.5%. One filler item
was excluded from consideration because of low accuracy rates (54.8%). No other item had an
average accuracy rate below 80%. Seven participants were excluded from the analysis because of
low accuracy on the remaining 23 filler items (below 75%).8

7

In one item set, (19), an adverb was changed between the +/−intervener conditions, to make each item maximallyplausible.
8
Nine participants would be excluded if the accuracy cutoff were raised to 80%. The major results reported below
remain unchanged in that case.

7

6

Rating (1–7 Likert)

The mean ratings of each condition in the target items
are summarized in the table below and also represented
in the graph at right. Error bars indicate standard errors.
Recall that the crucial condition where an intervention
effect is expected is +intervener, large pied-piping:

5

4

Condition−intervener, small pied-piping−intervener, large pied-piping+intervener, small pied-piping+intervener, large pied-piping

Mean score
4.76
4.45
4.89
3.92

Table 1: Ratings for each condition (1–7 Likert scale)

3

2

1

−int small −int large +int small +int large

A linear mixed effects model was fit to the data using the R package lme4 (Bates and Sarkar2007). The model predicted the mean rating of target sentences from the two factors of interest:
intervener (−intervener vs. +intervener) and pied-piping (small vs. large). The model contained
random intercepts and slopes for both predictors for subjects and items (Baayen 2004, Barr et al.
2013).
The results show a main effect of pied-piping and a intervener×pied-piping size interaction. A log
likelihood test comparing this model to one without the interaction term was significant, p < 0.05.
This result is driven by the fact that items that contain interveners inside large pied-piping are
degraded compared to items with no intervener, smaller pied-piping, or both. The results of themodel are summarized in Table 2.
Predictor
Intercept
intervener
pied-piping sizeintervener×pied-piping size

Coefficient
4.8804−0.1194−0.9673
0.6537

Standard Error t value
0.3421
14.264
0.2668−0.4470.2684−3.6040.2744
2.382

Table 2: Results of the linear mixed effects model
4.4. Discussion
The experimental results reflect a statistically significant effect of intervention, specifically observed in the intervener×pied-piping size interaction term (Table 2). The interaction term showsthat the particular combination of intervener presence and pied-piping size led to a greater effecton item ratings than would be predicted by the effects of intervener presence and pied-piping size
alone. This confirms the prediction that RPPP is sensitive to intervention effects.

5. Discussion and conclusion
As we discussed in section 2.1, judgments concerning intervention effects are notoriously difficult
across languages and constructions. This was reflected in speaker responses to our RPPP intervention paradigm in (12) as well; see footnote 6. The apparent subtlety of the contrasts in RPPP and
potential speaker variation motivated the use of a larger-scale, controlled experiment, to determine
whether such an intervention effect as in (12–13) can be established with statistical significance.
Our experiment finds a significant intervener×pied-piping size interaction, confirming the prediction of intervention effects inside RPPP. However, when examining the raw average ratings acrossconditions in our experiment, the effect of intervention appears small. The condition of interest(+intervener, large pied-piping) was judged with an average rating of 3.92, compared to an average rating of 4.70 across the other conditions, on a 7-point Likert scale. This appears to suggestthat the intervention effect, while real, is not a strong contrast between categorically grammaticaland categorically ungrammatical items.
We would like to offer two thoughts on this issue. First, we are weary of over-interpreting the absolute ratings. Experimental measures of grammaticality are affected by the relative grammaticalityof other items presented, including other target items but also fillers. The fact that non-intervention
conditions—which we believe to be fully grammatical—were judged with an average rating of 4.70
shows that these target items involving non-restrictive relative clauses were in general complex anddifficult to judge. The lower rating of the condition of interest must be judged relative to this lower
ceiling, instead of being evaluated over the full 1–7 scale.
Second, experimental research has motivated the existence of soft constraints in grammar whichlead to gradient judgments of the form reported here (see e.g. Keller 2000, Sorace and Keller
2005, Featherston 2005). The results here may indicate that intervention effects do not result in
categorial ungrammaticality, but rather in a detectable degradation in acceptability. This accords
with the responses to intervention effect items by native speakers in our in-person elicitation, which
we noted above.
There is, however, a potential issue with this account of intervention as a soft constraint. The
widely adopted Beck (2006) account for intervention effects, also adopted in our own previous
work on intervention in English pied-piping, predicts intervention configurations to be completely
uninterpretable, rather than resulting in a systematic minor degradation. We hypothesize that thisreflects that there are two strategies for the interpretation of pied-piping in the grammar: one
preferred strategy, susceptible to intervention, and another strategy which is dispreferred but unaffected by interveners.
There is a precedent for this approach in the domain of interrogative wh-intervention. Multiple
wh-questions can have single-pair or pair-list readings. The addition of interveners in certain English multiple wh configurations leads to an intervention effect, which is detected differently bydifferent speakers. Some speakers report that the resulting question is fully ungrammatical whereas
others report the loss of the pair-list reading only, with a surviving single-pair interpretation (Pesetsky 2000: pp. 60–61, Beck 2006: fn. 4). The apparently gradient judgments for interrogative
wh intervention, then, can be accounted for in this way, as the result of two strategies: a pair-list interpretation strategy which is sensitive to intervention and an alternative strategy which is immune
to intervention but does not yield the pair-list reading.9
Extending this logic to RPPP, we take our results to indicate that a preferred strategy for relative pronoun interpretation is indeed the intervention-sensitive strategy of Rooth-Hamblin alternative computation (Option 2). However, the fact that our crucial intervention items are not strictly
ungrammatical may reflect the existence of an alternative, generally dispreferred interpretational
option available to at least some speakers, which may be a movement-based variant (Option 1).
Further work is necessary, both empirically and theoretically, to understand this aspect of intervention effects.
References
Baayen, R. H. (2004). Statistics in psycholinguistics: A critique of some current gold standards.
In Mental Lexicon Working Papers, Edmonton, pp. 1–45.
Barr, D. J., R. Levy, C. Scheepers, and H. Tily (2013). Random effects structure for confirm-atory
hypothesis testing: Keep it maximal. Journal of Memory and Language 68(3), 225–278.
Bates, D. M. and D. Sarkar (2007). lme4: Linear mixed-effects models using S4 classes. R package
version 0.9975-12, URL http://CRAN.R-project.org/.
Beck, S. (1996). Quantified structures as barriers for LF movement. Natural Language Semantics 4, 1–56.
Beck, S. (2006). Intervention effects follow from focus interpretation. Natural Language Semantics 14, 1–56.
Beck, S. and S.-S. Kim (1997). On wh- and operator scope in Korean. Journal of East Asian
Linguistics 6, 339–384.
Beck, S. and S.-S. Kim (2006). Intervention effects in alternative questions. Journal of Comparative German Linguistics 9, 165–208.
Bhatt, R. (2002). The raising analysis of relative clauses: evidence from adjectival modification.
Natural Language Semantics 10, 43–90.
Butler, A. (2001). Intervention effects in English questions. In Proceedings of Szklarska Poreba
Workshop 2.
Cable, S. (2007). The Grammar of Q. Ph. D. thesis, Massachusetts Institute of Technology.
Cable, S. (2010). The Grammar of Q: Q-particles, wh-movement, and pied-piping. Oxford.
Cheng, L. L.-S. (2009). Wh-in-situ, from the 1980s to now. Language and Linguistics Compass 3(3), 767–791.
Erlewine, M. Y. and H. Kotek (2014). Intervention in focus pied-piping. In H.-L. Huang, E. Poole,9

See Butler (2001) for a sketch of how this may be achieved within a dynamic semantic approach, and Kotek(2014) for the idea that the remaining interpretational mechanism is one that produces echo-questions.

and A. Rysling (Eds.), Proceedings of NELS 43, Volume 1, pp. 117–130.
Erlewine, M. Y. and H. Kotek (to appear a). A streamlined approach to online linguistic surveys.
Natural Language & Linguistic Theory.
Erlewine, M. Y. and H. Kotek (to appear b). The structure and interpretation of non-restrictive
relatives: Evidence from relative pronoun pied-piping. In Proceedings of CLS 51.
Featherston, S. (2005). Magnitude estimation and what it can do for your syntax: some whconstraints in German. Lingua 115, 1525–1550.
Hamblin, C. (1973). Questions in Montague English. Foundations of Language 10(1), 41–53.
Heim, I. and A. Kratzer (1998). Semantics in Generative Grammar. Blackwell.
Kayne, R. (1994). The Antisymmetry of Syntax. MIT Press.
Keller, F. (2000). Gradience in grammar: Experimental and computational aspects of degrees ofgrammaticality. Ph. D. thesis, University of Edinburgh.
Kim, S.-S. (2002). Intervention effects are focus effects. In Japanese/Korean Linguistics 10, pp.
615–628.
Kotek, H. (2014). Composing Questions. Ph. D. thesis, Massachusetts Institute of Technology.
Kotek, H. and M. Y. Erlewine (2015). Relative pronoun pied-piping in English non-restrictive
relatives. Manuscript, McGill University and National University of Singapore.
Kotek, H. and M. Y. Erlewine (to appear). Covert pied-piping in English multiple wh-questions.
Linguistic Inquiry.
Pesetsky, D. (1987). Wh-in-situ: movement and unselective binding. In E. J. Reuland and A. G. B.
ter Meulen (Eds.), The representation of (in)definiteness, pp. 98–129. MIT Press.
Pesetsky, D. M. (2000). Phrasal movement and its kin. Number 37 in Linguistic Inquiry Monographs. MIT Press.
Reinhart, T. (1998). Wh-in-situ in the framework of the Minimalist Program. Natural Language
Semantics 6, 29–56.
Rooth, M. (1985). Association with Focus. Ph. D. thesis, University of Massachusetts, Amherst.
Sauerland, U. and F. Heck (2003). LF-intervention effects in pied-piping. In Proceedings of NELS
33, pp. 347–366.
Sorace, A. and F. Keller (2005). Gradience in linguistic data. Lingua 115, 1497–1524.
Sprouse, J., C. Schütze, and D. Almeida (2013). A comparison of informal and formal acceptability
judgments using a random sample from linguistic inquiry 2001-2010. Lingua 134, 219–248.
Sternefeld, W. (2001). Partial movement constructions, pied piping, and higher order choice functions. In Audiatur Vox Sapientiae: A Festschrift for Arnim von Stechow, pp. 473–486.
Tomioka, S. (2007). Pragmatics of LF intervention effects: Japanese and Korean interrogatives.
Journal of Pragmatics 39, 1570–1590.
Tomioka, S. (2009). Why-questions, presuppositions, and intervention effects. Journal of East
Asian Linguistics 18, 253–271.
Tsai, W.-T. D. (1994). On economizing the theory of A-bar dependencies. Ph. D. thesis, Massachusetts Institute of Technology.

Appendix: experimental items
Below are the target items used in our experiment. Each item set is comprised of four conditions,presented here in this order:
a. −intervener, small pied-piping
b. −intervener, large pied-piping
c. +intervener, small pied-piping
d. +intervener, large pied-piping(15)

The detective solved the Willis murder,a.
which the police had interviewed every witness to.
b.
every witness to which the police had interviewed.
c.
which the police had interviewed only one witness to.
d.
only one witness to which the police had interviewed.

(16)

Susan is preparing a story on the Zika virus,a.
which she’s interviewed some researchers of.
b.
some researchers of which she’s interviewed.
c.
which she’s interviewed no researchers of.
d.
no researchers of which she’s interviewed.

(17)

Agent Sanders was assigned to investigate the use of marijuana,a.
which she recognizes every slang term for.
b.
every slang term for which she recognizes.
c.
which she recognizes no slang term for.
d.
no slang term for which she recognizes.

(18)This is a very rare delicacy,a.
for which a recipe has appeared in print.
b.
a recipe for which has appeared in print.
c.
for which no recipe has appeared in print.
d.
no recipe for which has appeared in print.

(19)

Mathematicians love to discuss the Graph Isomorphism problem,a.
for which a solution has now been found.
b.
a solution for which has now been found.
c.
for which no solution has ever been found.
d.
no solution for which has ever been found.

(20)I want to watch the new Kristovsky film,a.
which I’ve seen a review of.
b.
a review of which I’ve seen.
c.
which I’ve seen only one review of.
d.
only one review of which I’ve seen.

(21)

My student is studying this letter by Lincoln,a.
which we found a copy of in the archive.
b.
a copy of which we found in the archive.
c.
which we found only one copy of in the archive.
d.
only one copy of which we found in the archive.

(22)

Malcolm wrote his thesis on The Cartessan War,a.
which he actually read every book about.
b.
every book about which he actually read.
c.
which he actually read no book about.
d.
no book about which he actually read.

reproduced above as (14)