A foundational finding in psychology—that 7-month-old babies can learn abstract language rules—failed to replicate in a massive study of over 800 infants.
April 1, 2026
Original Paper
ManyBabies 3: A Multi-Lab Study of Infant Algebraic Rule Learning
PsyArXiv · ghrdt_v2
The Takeaway
For decades, textbooks have cited a 1999 study claiming infants can learn 'algebraic' rules (like the pattern in 'ga-ti-ga') after just minutes of exposure. This 30-lab replication effort found no evidence that infants actually do this, suggesting our understanding of how early human logic develops may be based on a fluke.
From the abstract
The ability to learn and apply rules lies at the heart of cognition. In a seminal study, Marcus et al. (1999) reported that 7-month-old infants learned abstract rules over syllable sequences and were able to generalize those rules to novel syllable sequences. Dozens of studies have since replicated that finding and extended it using different rules, modalities, stimuli, participants (human adults and non-human animals) and experimental procedures. Yet questions remain about the generalizability