Audun Rosslund

Good question, we speculate about both, as well as overall social and cognitive maturation! But this is an avenue for future work for sure!

We invite others to explore and use the child-to-caregiver ratio in their own work via our open Shiny app calculator: 👉 socialnet.uiocloud.no/socialApp/ct... (warning; slow load!). Open data, code, and preregistration: osf.io/pjn8k/ /end

This shift from thinking in terms of birth order to household balance, from siblings as “resource competitors” to potential "language facilitators", offers a more holistic view of how family structure may shape early language development. 5/

As it turns out, the best predictor of infants' vocabulary sizes (over and beyond birth order) was when older siblings were considered "caregivers" from early adolescence, and (the twist): sisters 1–3 years earlier than brothers! 👧💬 4/

To make better sense of this, we introduced a new metric: the child-to-caregiver ratio, a data-driven measure of how many "caregivers" (parents and old-enough siblings) a child has relative to the number of children in the household. A lower ratio was associated with larger vocabularies. 3/

Using parent-reported data from 6,000+ Norwegian infants (8–36 months), we found that expressive and receptive vocabulary sizes tends to decrease with additional older siblings... but only up to a point. For later-borns, vocab. actually starts increasing again. 2/

<em>Child Development</em> | SRCD Journal | Wiley Online Library Growing up with multiple siblings might negatively affect language development. This study examined the associations between birth order, sibling characteristics and parent-reported vocabulary size i....

Do older siblings help or hinder language development? And does it matter if they’re sisters or brothers? In our new paper we revisit the "birth order effect"... and took it a step further! w/ @julienmayor.bsky.social, Nora Serres and Natalia Kartushina 🙌 🧵 1/ #DevSci #langsky #devpsy

Consonants, like vowels, appear to be less distinct in IDS than ADS, thus reinforcing the interpretation that IDS may serve an attentional and/or affective aim, rather than a didactic purpose. /end

We did not find any association between features of VOTs and infants' consonant production and/or babbling as reported by parents. This held whether VOTs were operationalised as the IDS input itself or parents' adjustment/effort in IDS from their ADS. 4/

We found that, compared to adult-directed speech, voiceless stops in IDS had longer VOTs, while voiced stops had shorter, leading to overall less distinct consonant contrasts (/b-p/, /d-t/, /g-k/) in IDS than ADS. From 6 to 12 months, VOTs in IDS became more similar to ADS. 3/

We examined voice onset time (VOT)—the interval between a consonant's release and vocal fold vibration, which distinguishes voiced and voiceless stops (e.g., /b/-/p/)—in speech recorded during shared reading interactions in Norwegian parent-infant and parent-experimenter dyads. 2/

Longitudinal changes in consonant production in infant-directed speech and infants’ early speech production from 6 to 12 months Previous research suggests that acoustic features of infant-directed speech (IDS) might be beneficial for infants’ language development. However, cons…

New paper out! Following from our work on vowels and prosody in infant-directed speech, we turned our attention to features of consonants and their role in language development. Great collab (as always!) w/ @julienmayor.bsky.social, Nina Varjola and Natalia Kartushina 🧵 1/ #DevSci #langsky #devpsy

Doctoral research fellowships in linguistics and verbal communication (272418) | University of Oslo Job title: Doctoral research fellowships in linguistics and verbal communication (272418), Employer: University of Oslo, Deadline: Friday, February 28, 2025

Interested in doing a PhD on language acquisition in Oslo?

Check application process: www.jobbnorge.no/en/available... and feel free to reach out for more information!

PS. We have a nice growing community including Natalia Kartushina, Luca Onnis, @audunrosslund.bsky.social, and many more!

Data, code and materials to the study is of course openly available at OSF. Watch this space for whether and how these parents' acoustic properties relate to their infants’ language skills! /end

Our results show that IDS is both dynamic and static, and we suggest that future studies should investigate how the acoustic constants and variations influence the proposed attentional, socio-emotional, and linguistic functions of speech to infants. 7/

We also found that IDS was characterized by increased vowel variability and decreased vowel distinction, and more so in mothers and fathers, with no change with infant age. In other words, this highlights that IDS is not across-the-board ‘clear’ input. 6/

Analyses of vowel space expansion (vowel hyperarticulation) told a more complicated story; While fathers’ overall expanded their vowel space in IDS, mothers did not, perhaps as they appeared to shift from vowel space reduction to expansion with infant age. 5/

What did we find? Compared to their ADS, both mothers and fathers’ IDS had: Higher pitch, wider pitch range, slower articulation rate, and longer vowels. With infant age, pitch range widened and vowels shortened, while pitch and articulation rate remained relatively stable. 4/

We followed 69 Norwegian families for one year and five lab sessions, from infants were 6–18 months. Parents’ speech were recorded while reading the same picture book to their infant (IDS), and to an experimenter (ADS), ensuring no distortion from different linguistic content of speech. 3/

First things first, this was only possible because of the great team of Natalia Kartushina, @julienmayor.bsky.social, @acristia.bsky.social, Arun Singh, Roger Mundry, fantastic RAs and helpful reviewers! 2/

A longitudinal investigation of the acoustic properties of infant-directed speech from 6 to 18 months | Royal Society Open Science Caregivers often modulate their speech when interacting with infants, adapting a register that has been suggested to have attentional, affective and didactic purposes. The present preregistered study ...

12 months of data collection, 317 lab sessions, 22,958 phrases, 54,594 vowels, and a gazillion supplementary tables later... proud to say that our longitudinal study on the acoustics of infant-directed speech is now out! 👶🧵 1/ #DevSci #langsky #devpsy

royalsocietypublishing.org/doi/10.1098/...

Fantastic! Would you be so kind and add me?

Developmental Cognitive Scientists by @deontbenton.bsky.social

Thanks for the kind words! I am unfortunately not well-versed in that literature, but I believe J. Dynia et al., did some work that could be of interest!

We consider several linguistic and methodological explanations for these findings, incl. the acoustic subtlety of the contrasts, and conclude that our results challenge the strict "universal phoneticians" account while echoing calls for diversity in the literature on perceptual narrowing. 🌍🔍 /end

However, we did find a negative correlation between infants' native and non-native discrimination scores, suggesting that these babies could be on the cusp of reorganizing their speech perception toward their native language. 📉📈 4/

Surprisingly, on a group level, infants' looking behavior were not indicative of discrimination of either contrast—neither in our preregistered pipeline nor from several variations of it that were tested in a multiverse analysis. ❌ 3/

N=67 infants were tested on their discrimination of the native 🇳🇴 vowels /y-i/ and the non-native 🇬🇧 vowels /ʌ-æ/, with an automatised, gaze-contingent habituation procedure. As perceptual narrowing supposedly occurs after 6mo, we predicted successful discrimination of both contrasts. ✅ 2/

Native and non-native vowel discrimination in 6-month-old Norwegian infants In the current preregistered study, we tested n = 67 6-month-old Norwegian infants’ discrimination of a native vowel contrast /y-i/ and a non-native (…

Can't get enough of infant habituation designs!?💥 In our new paper, @julienmayor.bsky.social, Alex Cristia, Natalia Kartushina and I tested native and non-native vowel discrimination in 6-month-old Norwegian infants using eye-tracking. 👶👀 1/

Of course, our study is correlational, and other factors might be moderating the associations. Still, our results support current recommendations to engage in shared reading while limiting screen time early in life. 📚💪 Data, code and materials is of course openly available! 5/5