From concrete to abstract: How stimulus concreteness impacts numerical conflict resolution in children

Children's early numerical development involves learning to process numerical information independently of conflicting spatial dimensions such as size or spacing. While abstract representations are commonly used to assess this ability, the impact of more concrete materials remains unclear. Across two experiments, kindergartners completed non-symbolic numerical comparison tasks with manipulated congruence between numerical and non-numerical dimensions. In Experiment 1 ( N = 65), children compared abstract (dots) or concrete (apple drawings) collections while spatial working memory and conceptual size were controlled, and concreteness did not robustly modulate performance. In Experiment 2 ( N = 69), we increased stimulus concreteness (car pictures vs pixelated shapes) and included an additional control task where physical and conceptual size were confounded, replicating known findings. Crucially, even when conceptual size was controlled, concreteness modulated congruency effects, particularly in number/size conflicts. These findings indicate that concreteness influences children's numerical conflict resolution beyond spatial working memory or conceptual knowledge. • Children's numerical conflict processing is modulated by stimulus concreteness. • Concreteness affects the magnitude of numerical congruency effects. • These effects are primarily driven by performance differences on congruent trials. • Concreteness effects tend to be stronger for number–item size conflicts. • Spatial working memory partly explains concreteness effects, but not fully.