The widely-used Violation of Expectation (VOE) paradigm has found that young infants look longer at unusual and/or impossible physical events, suggesting some innate or early-emerging knowledge of physical causality. Other research with the VOE paradigm has found that infants smile and laugh at unusual but possible physical events enacted by people, suggesting infants differentiate types of physical VOEs and may rely on context to do so. Drawing on these two bodies of research, we investigate how social context (defined as social agent visibility) and event repetition influence a variety of infants' reactions to physically impossible (vs. possible) events, including looking, smiling/laughter, and reaching in this pre-registered study. We visited 6-month-old infants (N = 88) in their homes and presented them with two physically impossible VOEs reminiscent of the classic literature. VOEs and their respective controls were presented by a social agent that was either fully-visible or whose face and body were hidden, and each event was produced 6 times. Infants looked more often (though not longer) at VOEs and were more likely to reach towards them, corroborating their ability to detect (and presumably their desire to explore) physically impossible events. Smiling was rare but we identified an intriguing temporal dynamic: in early trials, smiles were elicited most by VOEs presented by a fully-visible social agent but, with repetition, smiles were elicited most by ordinary events under the same conditions. Generally, babies turned away more from events presented by agents whose faces and bodies were hidden. Heart rate data provided supplementary evidence that infants' ability to distinguish between these events can be captured non-behaviorally. These novel findings indicate VOE research should incorporate a broad array of dependent measures and contextual factors to better characterize infants' event processing and understanding of possibility. SUMMARY: These findings suggest infants' appraisal of VoE events is context-sensitive and dynamically revised in social settings. Social agent visibility, not event type, extended infants' looking duration during both physically unusual and ordinary events. Repetition of events reduced looking across conditions and dynamically reshaped smiling responses over trials. Infants reached more toward VoE events suggesting active information-seeking beyond passive looking measures.
Mireault et al. (Mon,) studied this question.