Key Takeaway:
A large-scale replication effort by the ManyBabies consortium has cast doubt on a groundbreaking study that claimed infants could differentiate between “helpers” and “hinderers,” preferring those who assisted others over those who obstructed them. The original study, led by Kiley Hamlin, involved showing six- and ten-month-old infants a puppet show, and 88% of ten-month-olds and every six-month-old reached for the “helper.” The new study, which tested 567 infants, found no evidence that babies preferred the helper character over the hinderer. The debate over infant morality has implications for early childhood education and interventions for at-risk youth.
For decades, the idea that infants might possess an innate sense of morality has captivated psychologists. Nearly 20 years ago, a groundbreaking experiment claimed to provide evidence that even six-month-old babies could differentiate between “helpers” and “hinderers,” preferring those who assisted others over those who obstructed them. However, a recent large-scale replication effort has cast doubt on this iconic study, challenging one of developmental psychology’s most celebrated findings and raising questions about how morality develops in humans.
The original study, led by Kiley Hamlin and her colleagues, involved showing six- and ten-month-old infants a puppet show. In the show, a character struggled to climb a hill, and two other characters intervened—one helping the climber and the other hindering it by pushing it back down. After the show, babies were offered a choice of characters to hold. Remarkably, 88% of ten-month-olds and every six-month-old in the study reached for the “helper,” leading researchers to conclude that even infants might have an early-emerging sense of morality.
But developmental psychology has long grappled with reproducibility issues, and studies involving infants are especially challenging. Babies are unpredictable participants, and gathering reliable data is difficult. The original study involved only a small sample size, prompting some researchers to question whether its results could hold up under larger-scale scrutiny. Enter the ManyBabies consortium, a collaborative effort among developmental psychologists worldwide. By pooling resources and testing a larger sample of infants across 37 labs on five continents, the consortium aimed to robustly replicate Hamlin’s “helper-hinderer” experiment.
This new study, which tested 567 infants, found no evidence that babies preferred the helper character over the hinderer. Unlike the original study, this replication used videos of animated characters rather than live puppet shows. While this approach ensured consistency across labs, it may have influenced how babies engaged with the experiment. Some researchers speculate that the medium change, along with other subtle factors like character design, may explain the differing results. In fact, previous replication attempts have shown that even minor details, such as the orientation of a character’s googly eyes, can significantly impact outcomes.
The results have reignited debates about the nature of morality in infants. Could John Locke’s “blank slate” theory, which posits that humans are born without inherent moral frameworks and learn everything through experience, hold the key? If babies don’t show an innate preference for helping behavior, it might suggest that moral reasoning develops later through environmental influences. However, some scientists caution against jumping to conclusions. Michael Frank, founder of the ManyBabies consortium, emphasized on social media that these findings don’t necessarily disprove the original study. Instead, they highlight the complexity of studying infant behavior and the importance of replication in science.
Kiley Hamlin herself, a co-author of the replication study, has acknowledged the challenges of interpreting these findings. She notes that infants may not exhibit moral preferences in all contexts or that different experimental setups might yield varying results. For example, live puppet shows could elicit stronger emotional responses than videos, potentially influencing babies’ choices.
Beyond methodological considerations, the study raises broader philosophical questions. If morality isn’t innate, how does it emerge? Evolutionary biologists suggest that cooperative behaviors, such as helping others, likely evolved because they offer survival advantages. But does this evolutionary legacy translate into early moral reasoning in infants? Or do humans require years of social and cultural learning to develop a sense of right and wrong?
The debate over infant morality has implications that extend beyond academia. Understanding how morality develops could inform everything from early childhood education to interventions for at-risk youth. Moreover, the controversy underscores the importance of open science and replication efforts in ensuring that psychological research is robust and reliable.
At the very least, this new study has introduced a question mark over one of developmental psychology’s most iconic experiments. Whether babies are born with an innate moral compass or acquire it through experience remains an open question—one that will undoubtedly fuel further research for years to come.
