Hypothesis
Two-year-olds would look in anticipation to where an agent with a false belief will act, as the widely cited 2007 eye-tracking study reported, showing implicit false-belief attribution.
What failed
A preregistered two-lab replication with 160 infants aged 24–26 months, run with two original authors and the original stimuli and analyses, found no action anticipation: only about half the infants looked to the correct location, both in the simple control condition and in the false-belief condition.
Broken assumption
Anticipatory looking in this paradigm is a reliable readout of toddlers' action predictions.
Why
Taken with other non-replications, the authors conclude the paradigm does not reliably elicit action prediction at all, so it cannot test false-belief understanding at this age.
From the published paper: Kampis et al. Royal Society Open Science, 2021. ↗CC BY