Research Interests
  • Monolingual and bilingual first language acquisition.

  • (Acquisition of) morphology and syntax.

  • Morpheme and word segmentation.

  • The effects of processing and working-memory limitations in language development.

  • Cross-linguistic differences in language acquisition.

  • Romance languages (particularly Spanish).

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.


  • Liu, Minqi, Nina Hyams, & Victoria Mateu. (in press). The syntax and acquisition of Mandarin sluice-like constructions. Theoretical and Experimental Linguistics

  • 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..

  • 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]

Recently, I finalized a study involving the acquisition of 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). 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 an ongoing research project related to Minqi Liu’s dissertation we are now exploring 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 in [animacy] and [number] between the agent and theme ameliorate children’s comprehension of long passives but not actives. Conversely, mismatches based on purely semantic features (long thin objects vs. generic objects) do not improve children’s performance with passives, as predicted by grammatical accounts such as featural Relativized Minimality.


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 object 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 12,000 utterances with transitive and 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 clitic ‘se’ is more likely to appear with unaccusative verbs than with unergative verbs. We are currently creating an experimental study that will examine at what age Spanish-speaking children start making use of these cues to categorize intransitive verbs.

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. We attribute this difference to the increased percentage of iambs they hear overall due to Spanish exposure, which facilitates their ability to find iambs in English. Thus, acceleration is possible in the earliest stages of bilingual development


  • 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.

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 >>