The findings reported by Hamlin, Wynn, & Bloom, 2007 sparked a line of research into the development of infants' social evaluations. However, attempts to replicate this method have yielded mixed results.

Developmental research -- particularly with young infants -- comes with a unique set of reproducibility challenges. The ManyBabies project was designed to address these challenges by bringing researchers together to address difficult outstanding theoretical and methodological questions about the nature of early development and how it is studied.

ManyBabies4 aims to to provide a precise estimate of the true effect size of infants’ preference for prosocial over antisocial individuals, and to determine the degree to which infants’ preferences are based on the social features of the helper/hinderer scenarios. Our multi-lab approach will use a consistent methodology across laboratories, allowing us to more directly tease apart sources of variation.