The role of emotional consistency in toddlers' social development

Abstract

Emotion plays a fundamental role in early social development. However, much of the existing research on toddlers’ emotion processing has focused on isolated emotional events, often overlooking the dynamic nature of emotional signals. The current the- sis addresses this gap by investigating toddlers’ sensitivity to emotional consistency, defined as the stability of emotional valence over time or across individuals, and how this sensitivity guides social interaction and learning. Across three empirical studies, toddlers aged 12 to 36 months were shown video-based stimuli in which adult infor- mants expressed either consistent or inconsistent emotional reactions to novel objects, either within a single individual or across multiple people. Study 1 demonstrated that by 18 months, toddlers could reliably track emotional consistency within individuals and showed a preference for following the gaze of emotionally consistent informants, suggesting that consistency serves as a cue for social engagement. In contrast, Study 2 revealed that toddlers learned novel words more effectively from emotionally in- consistent informants, indicating that variability in emotion may enhance attention and learning under certain conditions. Study 3 extended these findings by showing that even 12-month-olds may begin to detect emotional consistency across differ- ent individuals and use this group-level information to guide exploratory behaviours. Together, these findings suggest that emotional consistency, in addition to valence and arousal, functions as a dynamic, context-dependent dimension of early emotion processing and understanding. This work contributes to our understanding of the cognitive and social mechanisms underlying early emotional learning and opens new avenues for investigating its developmental trajectory, cultural influences, and neurocognitive underpinnings.