Out of sight, not out of mind: New pupillometric evidence on object permanence in a sample of 10- and 12-month-old German infants

Findings on the emergence and interpretation of early object representation in the first year of life diverge widely between designs that employ looking times versus action-based measures. As a promising new approach, pupillometry has produced evidence for object permanence at 18 months of age, but not younger as of yet. In the current study, we (re)investigated object permanence following occlusion events in a pupillometric violation-of-expectation paradigm optimized for younger infants. During each trial, infants observed a toy object's occlusion and prompt reveal in the expected condition or its absence in the unexpected condition. Across two experiments, we show that 10- and 12-month-old infants' (total N = 82) pupils dilate in response to unexpected object disappearances relative to expected appearances. Control analyses revealed no differences between the scenes before the experimental manipulation, excluding perceptual interpretations. We further report an age-dependent effect of condition on pupil responses, with unexpected outcomes triggering greater pupil dilation in the older group. These results provide positive pupillometric evidence in support of object permanence in the context of a violation-of-expectation paradigm at 10 and 12 months of age.