David Shiffman, Ph.D. 🦈

whysharksmatter.bsky.social

28 September 2026 16:30

Me at 5 years old: I love sharks and I can’t want to spend my whole life looking at sharks and reading about sharks and talking about sharks Me at 42 years old doing that: Hell yeah this rules

New paper 🍼📄 ManyBabies 3 is out (open access, registered report in Developmental Science). 30 labs, 33 languages, 839 infants set out to replicate a textbook finding: 7-month-olds learn abstract rules from speech (@garymarcus.bsky.social et al., 1999). We didn’t find it. 🧵

Martin Zettersten

mzettersten.bsky.social

28 September 2026 16:26

Meta-analytic plot below: only 1 out of the 31 samples find evidence of the effect. Huge effort from the entire ManyBabies 3 team led by @ingmarvisser.bsky.social. Imo an important moment for reflection in infant research (esp. language development) given the centrality of this finding. 2/2

Martin Zettersten

mzettersten.bsky.social

28 September 2026 16:26

Glad to see this large-scale replication attempt of rule learning in infants finally out. Bottom line: we find no evidence for an effect (650 infants from 30 labs) in a close conceptual replication of Marcus et al. 1999; no effect of potential moderators (e.g., age, method). 1/2