Children automatically process order: Evidence from an ‘ordinal Stroop’ task

The current study focuses on the developmental aspect of order and investigates whether young children can automatically perceive the ordinal elements of a non-symbolic numerical sequence. Children aged 6–7, 8–9, and 10–11 completed ordinal Stroop task with quantities (i.e., dot patterns) as the relevant dimension. Convex hull of the stimuli was manipulated into two conditions: congruent or incongruent with the ordinal direction of quantities. Ratio between quantities was manipulated as well. In all three age groups, results showed a congruity effect indicating that convex hull is automatically processed and affects judgments of the ordinal aspect of quantities. Additionally, even though both Order and Ratio produced a significant main effect, they did not interact with each other. These findings support previous results regarding the role of visual properties in numerical discrimination. Further, they suggest that from an early age, humans automatically extract ordinal features from visual properties of the numerical sequence.