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Research Interests
  • Monolingual and bilingual first language acquisition

  • Acquisition of words, morphology, and syntax

  • Cross-linguistic differences in language acquisition

  • Adult (native, heritage, L2) morphological and syntactic representations

  • The effects of processing and working-memory limitations in child and adult language acquisition

  • Romance languages (particularly Spanish, but also Catalan, Italian, and French)

Recent and Current Projects
Argument structure and Intervention effects
In the past few years, most of my research has focused on the acquisition of argument structures (i.e., which expressions are syntactically or semantically required by a particular verb) and constructions that involve ‘non-local dependencies’ or ‘intervention.’
Studies on acquisition have established that children exhibit comprehension difficulties with sentences in which a noun phrase intervenes between another noun phrase and the predicate that is associated with it. In the sentence ‘The dog that the cat is chasing _ attacked the child’, ‘the dog’ is the object/patient of the chasing event, but ‘the cat’ is intervening in that non-local dependency. In my research, I have used intervention effects in children as a tool to detect silent arguments or structures that may nevertheless be syntactically represented in child and adult grammars. For instance, investigating the ‘raising’ verbs seem/’parecer’, I found that English-speaking children have difficulties comprehending sentences such as ‘The dog seems _ to be old’ until at least 6 years of age. Whereas Spanish-speaking children comprehend superficially analogous sentences, such as ‘El perro parece _ ser viejo’, by age 4. Corpus results also confirmed that English-speaking children underuse raising structures compared to what is expected given their input, but Spanish-speaking children do not. This behavioral difference allowed me to conclude that while the English raising verb seem always projects an experiencer argument (i.e., The dog seems <to someone> to be old), the Spanish modal-like verb parecer does not (hence the impossibility of *El perro le parece a alguien ser viejo). This and other associated studies (e.g., with ‘control’ verbs like promise) can be found in the links below.


  • Mateu, Victoria & Nina Hyams. (2021). On children’s late acquisition of raising ‘seem’ and control ‘promise’: Is a unified account possible? In Adriana Belletti & Chris Collins (eds.) Smuggling, 222-254. Vol. in Oxford Studies in Comparative Syntax. Oxford: Oxford University Press. [pdf]

  • Mateu, Victoria & Nina Hyams. (2019). On the learnability of implicit arguments. In Tania Ionin & Matthew Rispoli (eds.) Three Streams of Generative Language Acquisition Research, 185-201. Vol. 63 of Language Acquisition & Language Disorders. Philadelphia, PA: John Benjamins. [pdf]

  • Mateu, Victoria. (2019). Intervention effects in the acquisition of raising: Evidence from English and Spanish. Language Acquisition. 1-34. [pdf]

  • Mateu, Victoria. (2018). What cross-linguistic acquisition differences can tell us about invisible syntax: The case of Spanish ‘parecer’. Proceedings of the 41st Boston University Conference on Language Development [BUCLD 41]. 481-494. Somerville, MA: Cascadilla Press. [pdf]

  • Mateu, Victoria. (2016). Intervention Effects in the Acquisition of Raising and Control: Evidence from English and Spanish. Los Angeles, CA: UCLA Dissertation. [link]

In another set of experiments, I further explored the role of intervention in the analysis of ellipsis, specifically elided wh-questions or ‘sluices’. In joint work with Dr. Nina Hyams, I found that children exhibit more difficulties comprehending object sluices (e.g., ‘The boy is chasing someone can you see who <the boy is chasing _>?’) than subject sluices (e.g., ‘Someone is chasing the boy can you see who <_ is chasing the boy>?’) and that their performance on object sluices positively correlated with their performance on object relative clauses (e.g., Point to the boy that the girl is chasing _). These results are most compatible with theoretical analyses that propose that the elided material is in fact syntactically represented and not simply ‘pragmatically’ inferred. In subsequent work with Minqi Liu (C. Phil in Linguistics at UCLA) and Dr. Nina Hyams we have tested these structures in Mandarin-Chinese-speaking children and obtained compatible results.
Currently, I am investigating sluicing in Spanish. According to the P-Stranding Generalization, languages that do not allow preposition stranding should not allow it under sluicing either. Spanish doesn't allow P-stranding in questions (e.g., *¿Quién está María hablando con _? 'Who is Maria speaking with _?'), and thus, sluices should always include an explicit P before the wh-phrase, as a result of pied-piping (e.g., 'María está hablando con alguien, ves con quién <está María hablando _>?' 'Maria is speaking with someone, can you see with whom <she's speaking _>?' should be the only option, and not 'María está hablando con alguien, ves quién <está María hablando con _>? 'Maria is speaking with someone, can you see who <she's speaking with _>?'). However, recently, it has been claimed that Spanish represents an exception to this rule, and that this is evidence for no structure, no movement, or a more complex, non-isomorphic structure at the ellipsis site. Results from an exhaustive corpus study show that children exhibit a subject>object asymmetry, as found in English and Chinese, such that they produce relatively fewer object sluices compared to their input, which suggests structure and movement at the ellipsis site. Moreover, we have been able to confirm that Spanish-speaking adults do indeed produce omitted/stranded prepositions under sluicing (>30%). This represents the first empirical evidence of P-stranding productions in Spanish sluices. Crucially, children frequency-match this pattern, and do not underuse or overuse it relative to their input, which suggests that P-stranding/omission under sluicing is unlikely to involve a much more complex or much simpler derivation than typical sluices, in line with isomorphic accounts. This project earned me the Faculty Career Development Award 2023-2024. Currently I am collecting experimental data from children aged 3-6.


  • Liu, Minqi, Nina Hyams, & Victoria Mateu. (2022). The syntax and acquisition of Mandarin sluice-like constructions. Tsinghua Linguistics, 1(1), 122–171.

  • Mateu, Victoria & Nina Hyams. (2021). Structural intervention effects in the acquisition of sluicing. Language Acquisition 28. 6-38. [pdf]

  • Liu, Minqi, Nina Hyams, & Victoria Mateu. (2020). Late intervention effects in the acquisition of Mandarin sluice-like constructions.  Proceedings of the 44th Boston University Conference on Language Development [BUCLD 44]. 322-335. Somerville, MA: Cascadilla Press. [link]

  • Mateu, Victoria & Nina Hyams. (2020). The structure of silence: A look at children’s comprehension of sluicing. Proceedings of the 49th Annual Meeting of the North East Linguistics Society [NELS 49]. Volume 2. 265-278. Independently published. [pdf]

  • Mateu, Victoria, Nina Hyams & Lauren Winans. (2019). Intervention effects in early grammar: Evidence from sluicing. Proceedings of the 42nd Boston University Conference on Language Development [BUCLD 42].  532-545. Somerville, MA: Cascadilla Press. [pdf]

  • Hyams, Nina, Victoria Mateu, Lauren Winans. (2017). Ellipsis meets wh-movement: Sluicing in early grammar. In Nicholas LaCara, Keir Moulton & Anne-Michelle Tessier (eds.) A Schrift to Fest Kyle Johnson. Linguistics Open Access Publications. 1. [link]

I have also explored intervention in relation to psychological verbs such as ‘gustar’ in Spanish, which exhibit an idiosyncratic syntactico-semantic structure. For instance, in ‘A la maestra le gustan los niños’ (lit. To the teacher to-her like the children, ‘The teacher likes children’) the experiencer is expressed as a dative object (‘a la maestra’), often in pre-verbal position, while the theme is expressed as the nominative subject (‘los niños’), often in post-verbal position. In a corpus study I found that Spanish-speaking children under 7 underuse the theme subject-verb- object experiencer order (SVO) compared to their input. In a receptive experiment I also found that questions such as ‘¿Qué niña le gusta a la maestra _?’ (‘What girl does the teacher like?) were harder to comprehend (by both children and adults) than sentences such as ‘¿A qué niña _ le gusta la maestra?’ (What girl likes the teacher?)  even though the former maintains the canonical SVO order of the language. This asymmetry was particularly exacerbated when the fronted theme and the experiencer shared morphological features (i.e., both were singular nouns, as opposed to one being singular and one being plural). These results confirm syntactic accounts that claim that the experiencer occupies a higher position than the theme in the representation of verbs like ‘gustar’, and that the source of difficulties with theme-extracted questions is indeed ‘intervention effects’, and not word order frequency effects.


  • Mateu, Victoria. (2022). On the acquisition of Spanish psych predicates: When intervention makes extraction of a nominative wh-phrase harder. Isogloss 8(4)/6. 1-27. [link]

  • Mateu, Victoria. (2022). Object Wh-questions with Psych Verbs Are Easy in Child Spanish. Proceedings of the 46th Boston University Conference on Language Development [BUCLD 46].  524-536. Somerville, MA: Cascadilla Press. [link]

In a research project related to Minqi Liu’s dissertation we have also explored intervention effects in children’s comprehension of Mandarin short (no explicit nor implicit external argument in this language) and long passives. Results show that mismatches based on number (canonically a phi feature) or purely semantic features (long thin objects vs. generic objects) do not improve children’s performance with passives, as predicted by language-specific, grammatical accounts such as featural Relativized Minimality, which argue that only features that trigger movement in the target language will induce intervention effects. We presented part of these results at BUCLD 47, and the 2023 LSA annual meeting, and we have recently submitted two papers based on these findings.



  • Liu, Minqi, Victoria Mateu, & Nina Hyams. (2023). Intervention effects in Mandarin-speaking children’s comprehension of passives. Proceedings of the 47th Boston University Conference on Language Development [BUCLD 47].  Somerville, MA: Cascadilla Press. [link]

In collaboration with Dr. Laurel Perkins and Dr. Nina Hyams, I continue to examine the argument structure of Spanish verbs. Intransitive verbs have been traditionally divided into two categories: unergative verbs – those that involve an agent subject (e.g., run/’correr’, yell/’gritar’, dance/‘bailar’), and unaccusative verbs – those that involve a patient subject (e.g., fall/‘caerse’, sink/‘hundirse’, disappear/‘desaparecer’). Syntactic analyses propose that the grammatical subject of unaccusative verbs is in fact initially represented in complement position and then moves to pre-verbal position. In this study we ask what cues are available to Spanish-acquiring children to be able to form these two categories (and derivations). After carefully analyzing over 10,000 utterances with intransitive verbs produced by parents and children, we have been able to identify a four robust features: (i) subjects are more likely to be inanimate with unaccusative verbs than with unergative verbs, (ii) unaccusative verbs appear more frequently with perfective aspect morphology, (iii) subjects are more likely to appear post-verbally with unaccusative verbs than with unergative verbs, and (iv) the anticausative clitic ‘se’ is more likely to appear with unaccusative verbs than with unergative verbs. We presented these results at the 2023 LSA annual meeting.

We are currently running a set of experimental studies that examine at what age Spanish-speaking children start making use of these cues to categorize intransitive verbs.


  • Mateu, Victoria, Laurel Perkins, & Nina Hyams. (2023). Learning unaccusativity: Evidence for split intransitivity in child Spanish. Proceedings of the 97th Annal Meeting of the Linguistic Society of America. 8(1). [link]

The beginnings of word and morphological acquisition
Experimental Methodologies
​Grammatical development depends at least in part on lexical and morphological knowledge. One of the first challenges that infants face in this domain is segmentation of words from fluent, continuous speech. A number of experimental studies have found that English-acquiring infants use prosodic cues to segment words. Specifically, because 90% of English words start with a stressed syllable (e.g., KINGdom), these infants learn to associate stress with word onsets. Thus, by 8 months they can segment trochees from continuous speech, but they fail to segment iambs (e.g., guiTAR) until 11 months of age. Spanish stress is much more variable – only 60% of two-syllable words are trochees. In collaboration with Dr. Megha Sundara, we have found that unlike monolingual English infants, Spanish-English bilingual infants succeed at segmenting English iambs by 8 months, possibly due to the increased percentage of iambs they hear overall due to Spanish exposure, which facilitates their ability to find iambs in English. However, Spanish-English bilingual infants do not segment trochees in Spanish any earlier than their monolingual counterparts. Therefore, greater exposure to a pattern via another language does not guarantee acceleration. We propose that only highly infrequent patterns, those that could be treated as 'noise' and thus underlearned, are susceptible to undergo acceleration if the other language contains greater evidence for it.


  • Mateu, Victoria & Megha Sundara. (2024). Constraints on acceleration in bilingual development: Evidence from word segmentation by Spanish learning infants. Behavioral Sciences, 14(2), 108. [link]

  • Mateu Victoria & Megha Sundara. (2022). Spanish input accelerates bilingual infants' segmentation of English words. Cognition, 218. 104936 [link]

  • Sundara, Megha & Victoria Mateu. (2018). Lexical stress constrains English-learning infants’ segmentation in a non-native language. Cognition 181. 105-116. [link]

A related question is when and how infants start developing representations of individual morphemes, e.g., walk+s/camin+a. Results from English show that 6-month-old infants relate inflected verbs to their stem (i.e., they recognize the nonce verb bab after being familiarized with babs). By 8 months, they can segment the stem out of its inflected form with -ing, which is less frequent than -s. English-acquiring infants have an advantage in that verb stems are able to stand free and are highly frequent in their input. Spanish inflection is much richer, so individual suffixes are much less frequent than in English. In collaboration with Dr. Megha Sundara, we aim to investigate when Spanish infants acquire the representations for different verbal suffixes. We conducted a corpus study that allowed us to conclude that the three most frequent verb inflections in child-directed speech in Spanish are -a, -o, as, and we are currently testing 6mo infants with the most frequent 3sg -a morpheme to establish at what age this morpheme can be segmented.

We are currently also working on two additional spin-offs: French (corpus study completed), and German, a particularly interesting language due to its high frequency circumfixes, e.g., ge-V-en (corpus study completed, currently developing experimental stimuli with Dr. Mireia Marimon and Dr. Barbara Höhle).

Related to this question, Megha Sundara and I are also examining whether a preference for rhyme identity could be used as a bootstrapping mechanism to acquire morphological agreement, which partially overlaps in languages such as Spanish (e.g., las casas 'the-fem-pl house-fem-pl').

Adult linguistic systems
In collaboration with Dr. Bruce Hayes and Kevin Liang, we are investigating the productivity of morphophonological rules in adult Catalan speakers. Catalan exhibits a few puzzling patterns that (should) pose learnability difficulties – exceptionality, opacity, saltation, and UR learning. (i) /r/ and /n/ generally delete in stem-final coda position, such that the feminine form [dur-ə] 'hard' is pronounced as [du] in the masculine. However, there exist numerous exceptions to this rule (e.g., [pur-ə] 'pure-fem' - [pur] 'pure-masc'). (ii) Catalan obligatorily deletes coda [t] when it's part of an [nt] cluster, and yet the [n] never deletes in this context ([santə] 'saint-fem' - [san] 'saint-masc'). (iii) Stems ending in /ʒ/ surface as [t͡ʃ] (e.g., [bɔʒə] 'crazy-fem' - [bɔt͡ʃ] 'crazy-masc'), even though a closer alternative, [ʃ], is a legal coda in Catalan. In this study we conducted a large corpus study to examine the frequencies of these patterns, and later examined the productivity of these rules in adult native speakers using novel words in a wug test. So far we have found strong evidence for frequency matching, but we also observe interesting, unattested patterns, which we attribute to pre-existing biases (e.g., against saltation and opacity), and possible L2-to-L1 transfer as well as orthographic effects. We are currently collecting data for a receptive task to investigate whether these participants accept alternative or multiple options in a receptive task to address the question of whether perception and production follow different rules.
I am also interested in characterizing the morphosyntactic systems of adult speakers. In collaboration with Erin Mauffray (her dissertation work), we are examining Spanish passives in Spanish-dominant native speakers (NSs), heritage speakers (HSs), and L2 speakers. The Spanish periphrastic passive, but not the se-passive, has an analogous structure in English, but the se-passive is 8x more frequent than the periphrastic in Spanish. We ask: How accessible are periphrastic and se-passives for these groups in a production – before and after priming? And do productions by HSs and L2ers  reflect target-like representations of these structures? Results show that NSs, HSs, and L2ers produce a comparable number of passives in immediate and delayed priming. However, results from an AJT reveal non-target-like performance by L2ers on se-passives, suggesting that target-like productions can be a product of superficial, linear-based probabilistic strategies and that transfer and age of acquisition play a greater role than frequency in L2 acquisition.


  • Mauffray , E. & Victoria Mateu. (in press). The acquisition of the periphrastic and se-passives in L2 Spanish: A priming and acceptability task investigation. Proceedings of the 48th Boston University Conference on Language Development [BUCLD 48]. Somerville, MA: Cascadilla Press.

Methodological questions
​Researchers that work with children face specific challenges related to methodology and replicability. ManyBabies is a large-scale, multi-site collaborative project that I joined to investigate and improve methodological practices in developmental research. In the original ManyBabies project, we focused on infants’ preference for infant-directed speech (IDS) over adult-directed speech (ADS). Results revealed that the magnitude of IDS preference is modulated by age, native language experience, and specific testing procedure. In a spin-off of this study, we found that bilingual infants show the same degree of IDS preference. Together, our findings indicate that IDS preference makes a similar contribution to monolingual and bilingual development, and that infants are exquisitely sensitive to the nature and frequency of different types of language input in their early environments.


  • Visser, Ingmar et al. (in press). Improving the generalizability of infant psychological research: The ManyBabies model. Behavioral and Brain Sciences.

  • The ManyBabies Consortium (2021). A multi-lab study of bilingual infants: Exploring the preference for infant-directed speech. Advances in Methods and Practices in Psychological Science. 4(1). 1-30. [pdf]

  • The ManyBabies Consortium. (2020). Quantifying sources of variability in infancy research using the infant-directed speech preference. Advances in Methods and Practices in Psychological Science 3(1). 24-52. [pdf]

Press Coverage (highlights)

Currently I am collaborating in ManyBabies-AtHome, a project that seeks to develop a remote (online) testing framework that can be used across a range of home environments in a wide array of countries.

To request a paper/handout or discuss possible work >>
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