Overview of Ongoing and Recent Studies

1. Impact of Covid-19 social isolation measures on early development

(In collaboration with Natalia Kartushina and Nivedita Mani)

We are leading an international consortium, with researchers from 13 countries, that is investigating the impact of Covid-19 related social isolation measures on 2,200 young infants and toddlers between 8 and 36 months of age. Our first findings provide insights into the effects of lockdown on language acquisition and screen time in the generation of youngsters growing up during this extraordinary period.



Kartushina, N., Mani, ... & Mayor, J. (2022). COVID-19 first lockdown as a unique window into language acquisition: associations between caregiver-child activities and vocabulary gain, Language Development ResearchLink to article

Bergmann et al. (incl. Mayor, J.) (2022). Young children's screen time during the first COVID-19 lockdown in 12 countries, Scientific Reports. Link to article

2. Early language assessments

Early language assessments are typically time-consuming to administer and/or often rely on indirect measures, such as asking parents to indicate whether their child understand words from a list. In the last years, we have made progress to address these shortcomings. In a series of publications, we have introduced computerized adaptive testing such that parents are only asked to respond to just 25 questions (instead of up to 800 questions for full-sized tests). As a result, we can evaluate the vocabulary size of young children in just 2 minutes! You can check an early version of the app here: Android/OS . Additional developments are under way, funded by a SPARK SOCIAL INNOVATION grant awarded to Prof. Julien Mayor and Prof. Nivedita Mani (U. Göttingen.


Chai, J. H., Lo, C. H. & Mayor, J. (2020). A Bayesian-Inspired Item Response Theory–Based Framework to Produce Very Short Versions of MacArthur–Bates Communicative Development Inventories. Journal of Speech, Language and Hearing Research.  ISSN 1092-4388. doi: 10.1044/2020_JSLHR-20-00361.

Mayor, J. & Mani, N. (2018). A short version of the MacArthur–Bates Communicative Development Inventories with high validity. Behavior Research Methods.  ISSN 1554-351X.  51, s 1- 2248. doi: 10.3758/s13428-018-1146-0

In parallel, we are evaluating whether toddlers can use a tablet-based “game” to let us directly evaluate their early word comprehension, without relying on their parents’ intuitions. Our findings suggest this works!


Lo, C. H., Rosslund, A., Chai, J. H., Mayor, J., & Kartushina, N. (2021). Tablet assessment of word comprehension reveals coarse word representations in 18–⁠20-month-old toddlers. Infancy, 26(4), 596–616. https://doi.org/10.1111/infa.12401

Selection of earlier work on infant and toddler language assessments:

Mayor, J. & Plunkett, K. (2014) Shared Understanding and Idiosyncratic Expression in Early Vocabularies. Developmental Science. 17(3), 412-423.

Mayor, J. & Plunkett, K. (2011) A statistical estimate of infant and toddler vocabulary size from CDI analysis. Developmental Science, 14 (4), 769-785.

3. Impact of parental speech on early language development

The role of dialects:

Multi-accent or multi-dialect environments offer rich but inconsistent language input, as words are produced differently across accents. In our lab, we attempt at understanding how early exposure to dialects (and their similarities/dissimilarities) affect early language skills in infants. We use eye-tracking and behavioral (learning words from an audio-book – see images below – read in different dialects) methods to address these questions in Norwegian infants and toddlers. Our initial finding is that children raised in multi-dialectal families learn words better from accented speech than their peers raised in families that speak a single dialect:

Serres, N., Mayor, J. & Kartushina, N. (Stage 1 Registered Report - accepted pending data collection). The Role of Dialect Variability on Mispronunciation Sensitivity: An Insight to Infants’ Early Language Development from a Norwegian Context. Infancy. 

Kartushina, N. & Mayor, J. (2022). Coping with dialects from birth: Role of variability on infants’ early language development. Insights from Norwegian dialects. Developmental Science. (Registered Report)

Kartushina, N., Rosslund, A., & Mayor, J. (2021). Toddlers raised in multi-dialectal families learn words better in accented speech than those raised in monodialectal families. Journal of Child Language, 1–26. https://doi.org/10.1017/S0305000921000520

We are following up with several studies, in particular we are looking at 12- to 14-month-old children (baby-ling@psykologi.uio.no) for an eye-tracking study (a registered report) looking into whether exposure to dialectal variability from birth (parents speaking different dialects) affects early language skills in monolingual Norwegian 12- to 14-month-old infants.

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A longitudinal study on language development

In this study we follow language development of infants from 6- to 18-months of age. This will give us unique insight into how language development happens. During this age, children become experts at the sounds unique to their language, there is a rapid increase in word comprehension, and they are also in the beginning phase of uttering words. We are interested in these aspects of language development, and how they are influenced by environmental factors such as their parents’ speech. In particular, we examine how variations in parents’ voice affect their infant’s ability to discriminate speech sounds and to acquire words. The project is financed by the Norwegian Research Council awarded to Assoc. Prof. N. Kartushina, with Prof. J. Mayor and Dr. A. Cristia, and is conducted by A. Rosslund. See the project’s page for details.

4. Word learning mechanisms

Across a series of studies, we have identified the variety of cues (frequency, syntax, extra-linguistic, …) that infants and young children use when learning new words:

Kartushina, N., & Mayor, J. (2019). Word knowledge in six- to nine-month-old Norwegian infants? Not without additional frequency cues. Royal Society Open Science, 6(9), 180711. https://doi.org/10.1098/rsos.180711

Sia, M. Y., & Mayor, J. (2021). Syntactic Cues Help Disambiguate Objects Referred to With Count Nouns: Illustration With Malay Children. Child development92(1), 101-114.

Chai, J. H., Low, H. M., Wong, T. P., Onnis, L., & Mayor, J. (2021). Extra-linguistic modulation of the English noun-bias: evidence from Malaysian bilingual infants and toddlers. Journal of Cultural Cognitive Science5(1), 49-64.

We have also investigated how memory improvements modulate how children learn words, and showed that, in a tablet-based study, sometimes active learning is not preferrable to passive learning when learning words!

Sia, M. Y. & Mayor, J. (2021). Improvements Of Statistical Learning Skills Allow Older Children To Go Beyond Single-Hypothesis Testing When Learning Words. Journal of Child Language.

Ackermann, L., Lo, C. H., Mani, N., & Mayor, J. (2020). Word learning from a tablet app: Toddlers perform better in a passive context. PLoS One15(12), e0240519.

Finally, we have collected parental reports from 1200 Norwegian parents of 12- and 24-month-old infants, describing their infants’ pacifier use (frequency over time), while filling in a language questionnaire that allows use to evaluate the vocabulary size of their child. Our findings (not peer-reviewed yet) suggest that sustained pacifier use is associated with smaller vocabulary sizes, an effect potentially attributed to pacifiers restricting articulators that infants need to produce speech:

Munoz, L. E., Kartushina, N., & Mayor, J. (under review). Sustained Pacifier Use is Associated with Smaller Vocabulary Sizes at 1 and 2 Years of Age.

Selection of earlier work on early word learning mechanisms:

Mayor, J., & Plunkett, K. (2014). Infant word recognition: Insights from TRACE simulations. Journal of Memory and Language71(1), 89-123.

Mayor, J. & Plunkett, K. (2010) A neuro-computational account of taxonomic responding and fast mapping in early word learning. Psychological Review 117 (1) 1-31.

Gliozzi, V., Mayor, J., Hu, J. F., & Plunkett, K. (2009). Labels as features (not names) for infant categorization: A neurocomputational approach. Cognitive science33(4), 709-738.

5. Large collaborative projects

In collaboration with colleagues from all over the words, we attempt to understand how different factors (e.g., parental speech, child-parent interactions, etc.) affect early language development, under the ManyBabies consortium.

Frank, M.C., et al. (incl. Mayor, J.) (2020). Quantifying sources of variability in infancy research using the infant-directed speech preference. Advances in Methods and Practices in Psychological Science. https://doi.org/10.1177/2515245919900809

Visser, I., et al. (incl. Mayor, J.) (2022). Improving the generalizability of infant psychological research: The ManyBabies model. Behavioral and Brain Scienceshttps://doi.org/10.1017/S0140525X21000455

Visser, I., et al. (incl. Mayor, J.) (under review). ManyBabies3: A multi-lab study of infant algebraic rule learning – (Stage 1 Registered Report).

We have also launched a similar multi-lab, multi-country effort to understand the impact of social isolation, related to the Covid-19 pandemic, on infant development (see top of the page).

Published Sep. 6, 2021 3:25 PM - Last modified Mar. 23, 2022 10:00 AM