The self-concept questionnaire offers a multidimensional, developmentally sensitive measure of the capacity for self-reflection in young children

Several existing instruments measure development in the content and complexity of young children's self-knowledge, but few measure development in the process of self-reflection. This study aimed to provide a cross-sectional replication and longitudinal extension of the self-concept questionnaire (SCQ), exploring the factor structure and developmental onset patterns proposed in the original paper. We collected parental reports and conceptually replicated the factor structure of the SCQ for 199 participants aged between 14 and 54 months using confirmatory factor analysis. Our data suggest that autonomy first develops at similar to 14-17 months, followed by self-recognition at similar to 18-21 months, and self-description/evaluation and emotional response to wrongdoing at similar to 26-30 months. Contrary to the original scale, we did not find a clear developmental distinction between the onsets of cognitive and emotional self-evaluation. We can conclude that the SCQ factor structure is conceptually replicable and sensitive to developments in the self-system across infancy to early childhood. The SCQ may, therefore, offer a useful alternative or addition to the widely used mirror mark test of self-recognition when measuring the development of self-reflective abilities in young children.