Quantifying sources of variability in infancy research using the infant-directed speech preference
Article by Michael Frank et al. in Advances in Methods and Practices in Psychological Science, 3(1), published March 16, 2020.
The field of psychology has become increasingly concerned with issues related to methodology and replicability. Infancy researchers face specific challenges related to replicability: high-powered studies are difficult to conduct, testing conditions vary across labs, and different labs have access to different infant populations, amongst other factors. Addressing these concerns, we report on a large-scale, multi-site study aimed at 1) assessing the overall replicability of a single theoretically-important phenomenon and 2) examining methodological, situational, 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 were created using semi-naturalistic laboratory-based audio recordings in North American English. Infants’ relative preference for IDS and ADS was assessed across 67 laboratories in North America, Europe, and Asia using the three commonly-used infant discrimination methods (head-turn preference, central fixation, and eye tracking). The overall meta-analytic effect size (Cohen’s d) was 0.35 [0.29 - 0.42], which was reliably above zero but smaller than that found in a previous meta-analysis (0.72). 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 infant-directed speech preference but suggest that its magnitude is modulated by development, native language experience, and testing procedure.
Michael Frank, Katherine Alcock, Natalia Arias-Trejo, Gisa Ascherslegen, Dare Baldwin, Stephanie Barbu, Elika Bergelson, Christina Bergmann, Natalia Kartushina, Julien Mayor, Anna Stigum Trøan, Alexis Black, Ryan Blything, Maximilian Böhland, Arielle Borovsky, Krista Byers-Heinlein, Alejandrina Cristia, Virginie Durier, Christopher Fennel, Alissa Ferry, Paula Fikkert, Caroline Floccia, Tom Fritzsche, Anja Gampe, Gervain Judith, Nayeli Gonzalez-Gomez, Naomi Havron, Barbara Höhle, Derek Houston, Mitsuhiko Ishikawa, Shoji Itakura, Scott Johnson, Caroline Junge, Danielle Kellier, Melissa Kline, Jonathan Kominsky, Jill Lany, Claartje Levelt, Casey Lew-Williams, Liquan Liu, Nivedita Mani, Yusuke Moriguchi, Thierry Nazzi, Markus Paulus, Linda Polka, Jenny Saffran, Ayumi Sato, Melanie Schreiner, Leher Singh, Megha Sundara, Katherine Twomey, Katie Von Holzen, Sandra Waxman, Janet Werker, Daniel Yurovsky and Melanie Soderstrom. Warning: non-exhaustive list of authors!