Growing out of infant-directed speech

Mother and father interacting with baby - baby is reaching for father's face

The study in a sentence

Caregivers often use infant-directed speech (IDS) when speaking to their babies, which is thought to reflect their accommodation to the infant's immature language knowledge. Infants respond preferentially to IDS over adult-directed speech (ADS). 

This study uses a meta-analysis to show that some properties of IDS change with infant age. The authors propose that this reflects differences in the form and function of IDS: caregivers adapt their speech to their infant's developing language knowledge and attentional preferences.

Child holding a small globe

The question

This study performs a meta-analysis of 88 different studies to find out:

Roughly half of the infants in the study were hearing IDS in English: in Australian English, British English, Canadian English, Jamaican English, New Zealand English, Scottish English and US English.

Key concept: form versus function

Common features of IDS include higher pitch, wider pitch range and slower articulation rate. These are all thought to support language learning for young infants

But, these features, or special forms of speech, may not all serve the same function

Early on, infants are attracted to speech that conveys positive emotion. As they get older and learn more about the surrounding language, they become more interested in speech that supports further language learning.

What forms of IDS occur across languages, and do these relate to changing functions of IDS as the infant develops?

Visualization of a meta-analysis

Visualization of a meta-analysis approach, C. Cox (2022)

Methods: performing a meta-analysis

The study uses a meta-analysis to compare findings from 88 different studies that investigated 33 different languages between them. All the studies compared IDS to ADS in terms of at least one of the following five previously documented features of IDS:

Results from all 88 studies were pooled to see if they produced consistent findings, with a particular focus on how language and infant age affected the different features of IDS compared with ADS.

Try it yourself!

Do your own 'meta-analysis' (e.g. for a language investigation) by selecting a handful of studies that test the same question and comparing the findings.  

Are the results consistent? Which results do you think are the most/least reliable, and why? 

You could address commonly-tested research questions such as:

Explainer: what is 'vowel space'?

In this explainer video we explain:

If you want to learn about the technical details of how vowels are measured see this video by Richard Ogden on measuring the acoustic properties of vowels using the free software Praat. Learning to measure the acoustic properties of vowels is a skill you could develop in a Linguistics degree.

Explainer video (2 mins)

The answer

Across languages, differences were observed in some features, and universality in others:

This suggests that there are both universal tendencies and language-specificity in caregivers' use of IDS.

Across ages, change was observed in some features, and stability in others:

This suggests that caregivers' respond to infants' changing language abilities by adjusting some features of their speech to support further language development towards a more adult-like model. In other features, stability may reflect the fact that these features continue to support learning across the span of early development. 

Classroom activities

Comparing Infant-Directed Speech and Adult-Directed Speech

Comparing Infant-Directed Speech across time and space

In more detail

Pre-workshop taster video (3 mins)


Workshop talk slides

Live Workshop talk video (20 mins)

Meet the authors

Chris Cox  and Tamar Keren-Portnoy

Chris did his BA and MA at York and is now doing a PhD at Aarhus University, Denmark, co-supervised by Tamar Keren-Portnoy (who teaches child language acquisition at York).

Read the paper

Cox, C., Bergmann, C., Fowler, E., Keren-Portnoy, T., Roepstorff, A., Bryant, G., & Fusaroli, R. (submitted). A Systematic Review and Bayesian Meta-Analysis of the Acoustic Features of Infant-Directed Speech. download pdf