Quantifying Sources of Variability in Infancy Research Using the Infant-Directed-Speech Preference
Authors:   The ManyBabies Consortium, Frank Michael C. , Alcock Katherine Jane , Arias-Trejo Natalia , Aschersleben Gisa , Baldwin Dare , Barbu Stéphanie , Bergelson Elika , Bergmann Christina , Black Alexis K. , Blything Ryan , Böhland Maximilian P. , Bolitho Petra , Borovsky Arielle , Brady Shannon M. , Braun Bettina , Brown Anna , Byers-Heinlein Krista , Campbell Linda E. , Cashon Cara , Choi Mihye , Christodoulou Joan , Cirelli Laura K. , Conte Stefania , Cordes Sara , Cox Christopher , Cristia Alejandrina , Cusack Rhodri , Davies Catherine , de Klerk Maartje , Delle Luche Claire , Ruiter Laura de , Dinakar Dhanya , Dixon Kate C. , Durier Virginie , Durrant Samantha , Fennell Christopher , Ferguson Brock , Ferry Alissa , Fikkert Paula , Flanagan Teresa , Floccia Caroline , Foley Megan , Fritzsche Tom , Frost Rebecca L. A. , Gampe Anja , Gervain Judit , Gonzalez-Gomez Nayeli , Gupta Anna , Hahn Laura E. , Kiley Hamlin J. , Hannon Erin E. , Havron Naomi , Hay Jessica , Hernik Mikołaj , Höhle Barbara , Houston Derek M. , Howard Lauren H. , Ishikawa Mitsuhiko , Itakura Shoji , Jackson Iain , Jakobsen Krisztina V. , Jarto Marianna , Johnson Scott P. , Junge Caroline , Karadag Didar , Kartushina Natalia , Kellier Danielle J. , Keren-Portnoy Tamar , Klassen Kelsey , Kline Melissa , Ko Eon-Suk , Kominsky Jonathan F. , Kosie Jessica E. , Kragness Haley E. , Krieger Andrea A. R. , Krieger Florian , Lany Jill , Lazo Roberto J. , Lee Michelle , Leservoisier Chloé , Levelt Claartje , Lew-Williams Casey , Lippold Matthias , Liszkowski Ulf , Liu Liquan , Luke Steven G. , Lundwall Rebecca A. , Macchi Cassia Viola , Mani Nivedita , Marino Caterina , Martin Alia , Mastroberardino Meghan , Mateu Victoria , Mayor Julien , Menn Katharina , Michel Christine , Moriguchi Yusuke , Morris Benjamin , Nave Karli M. , Nazzi Thierry , Noble Claire , Novack Miriam A. , Olesen Nonah M. , John Orena Adriel , Ota Mitsuhiko , Panneton Robin , Esfahani Sara Parvanezadeh , Paulus Markus , Pletti Carolina , Polka Linda , Potter Christine , Rabagliati Hugh , Ramachandran Shruthilaya , Rennels Jennifer L. , Reynolds Greg D. , Roth Kelly C. , Rothwell Charlotte , Rubez Doroteja , Ryjova Yana , Saffran Jenny , Sato Ayumi , Savelkouls Sophie , Schachner Adena , Schafer Graham , Schreiner Melanie S. , Seidl Amanda , Shukla Mohinish , Simpson Elizabeth A. , Singh Leher , Skarabela Barbora , Soley Gaye , Sundara Megha , Theakston Anna , Thompson Abbie , Trainor Laurel J. , Trehub Sandra E. , Trøan Anna S. , Tsui Angeline Sin-Mei , Twomey Katherine , Von Holzen Katie , Wang Yuanyuan , Waxman Sandra , Werker Janet F. , Wermelinger Stephanie , Woolard Alix , Yurovsky Daniel , Zahner Katharina , Zettersten Martin , Soderstrom Melanie 
Published: March 2020

Psychological scientists have become increasingly concerned with issues related to methodology and replicability, and infancy researchers in particular face specific challenges related to replicability: For example, high-powered studies are difficult to conduct, testing conditions vary across labs, and different labs have access to different infant populations. Addressing these concerns, we report on a large-scale, multisite study aimed at (a) assessing the overall replicability of a single theoretically important phenomenon and (b) examining methodological, cultural, and developmental moderators. We focus on infants’ preference for infant-directed speech (IDS) over adult-directed speech (ADS). Stimuli of mothers speaking to their infants and to an adult in North American English were created using seminaturalistic laboratory-based audio recordings. Infants’ relative preference for IDS and ADS was assessed across 67 laboratories in North America, Europe, Australia, and Asia using the three common methods for measuring infants’ discrimination (head-turn preference, central fixation, and eye tracking). The overall meta-analytic effect size (Cohen’s d) was 0.35, 95% confidence interval = [0.29, 0.42], which was reliably above zero but smaller than the meta-analytic mean computed from previous literature (0.67). The IDS preference was significantly stronger in older children, in those children for whom the stimuli matched their native language and dialect, and in data from labs using the head-turn preference procedure. Together, these findings replicate the IDS preference but suggest that its magnitude is modulated by development, native-language experience, and testing procedure.