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Audun Rosslund @audunrosslund.bsky.social · May 6

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

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Audun Rosslund @audunrosslund.bsky.social · May 6

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

socialnet.uiocloud.no

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Audun Rosslund @audunrosslund.bsky.social · May 6

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/

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Audun Rosslund @audunrosslund.bsky.social · May 6

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/

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Audun Rosslund @audunrosslund.bsky.social · May 6

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/

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Audun Rosslund @audunrosslund.bsky.social · May 6

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/

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Audun Rosslund @audunrosslund.bsky.social · May 6

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

<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....

doi.org

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Audun Rosslund @audunrosslund.bsky.social · Jan 10

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

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Audun Rosslund @audunrosslund.bsky.social · Jan 10

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/

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Audun Rosslund @audunrosslund.bsky.social · Jan 10

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/

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Audun Rosslund @audunrosslund.bsky.social · Jan 10

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/

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Audun Rosslund @audunrosslund.bsky.social · Jan 10

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

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…

www.sciencedirect.com

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Reposted by Audun Rosslund

Julien Mayor @julienmayor.bsky.social · Dec 18

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!

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

www.jobbnorge.no

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Audun Rosslund @audunrosslund.bsky.social · Nov 29

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

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Audun Rosslund @audunrosslund.bsky.social · Nov 29

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/

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Audun Rosslund @audunrosslund.bsky.social · Nov 29

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/

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Audun Rosslund @audunrosslund.bsky.social · Nov 29

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/

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Audun Rosslund @audunrosslund.bsky.social · Nov 29

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/

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Audun Rosslund @audunrosslund.bsky.social · Nov 29

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/

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Audun Rosslund @audunrosslund.bsky.social · Nov 29

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/

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Audun Rosslund @audunrosslund.bsky.social · Nov 29

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/...

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 ...

royalsocietypublishing.org

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Audun Rosslund @audunrosslund.bsky.social · Nov 23

Fantastic! Would you be so kind and add me?

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Reposted by Audun Rosslund

Mark Rubin @markrubin.bsky.social · Nov 19

Developmental Cognitive Scientists by @deontbenton.bsky.social

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Audun Rosslund @audunrosslund.bsky.social · Nov 23

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!

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Audun Rosslund @audunrosslund.bsky.social · Oct 24

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

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