Two-Digit Number Processing during Childhood: A Mental Rotation Task?

The association between numerical and spatial thinking manifests itself throughout various cognitive observations, concerning arithmetic problem solving as well as simple number recognition tasks. The spatial component in numerical thinking is assumed to represent the semantic processing pathway, for example, the mental representation of numerical magnitude. There is an interconnection of semantic, linguistic, and visual/symbolic pathways, which is thought to be stronger in adults than in children. During childhood, the semantic pathway is supposed to play a major part in numerical processing. In this study, we conducted a functional magnetic resonance imaging paradigm combining a mental rotation task with a number processing task. The behavioral data showed the highest error rate for two-digit numbers (not for threedigit numbers). In regard to two-digit numbers, we also found the strongest neuronal activation overlap for number processing and mental rotation in the left intraparietal sulcus. This pattern suggests that the mental inversion of digits in native German speakers might be a spatial function related to mental rotation. In terms of overcoming opposed informational input for symbolic and linguistic representation and therefore impeded informational extraction the spatial processing pathway might play a major role. To conclude, spatial training could be an effective educational approach, supporting the interconnection of numerical processing pathways.