Understanding whether a sequence is presented in an order or not (i.e. ordinality) is a robust predictor of adults’ arithmetic performance, but the mechanisms underlying this skill and its relationship with mathematics remain unclear. In this study, we examined: a) the cognitive strategies involved in ordinality inferred from behavioural effects observed in different types of sequences and b) whether ordinality is also related to mathematical reasoning besides arithmetic. In Experiment 1, participants performed an arithmetic, a mathematical reasoning test and an order task, which had balanced trials on the basis of: order, direction, regularity and distance. We observed standard distance effects (DEs) for ordered and non-ordered sequences, which suggests reliance on magnitude comparison strategies. This contradicts past studies that reported reversed distance effects (RDEs) for some types of sequences, which suggest reliance on retrieval strategies. Also, we found that ordinality predicted arithmetic but not mathematical reasoning when controlling for fluid intelligence. In Experiment 2, we investigated whether the aforementioned absence of RDEs was because of our trial list composition. Participants performed two order tasks; in both tasks no RDE was found demonstrating the fragility of the RDE. Additionally, results showed that the strategies used when processing ordinality were modulated by the trial list composition and presentation order of the tasks. Altogether, these findings reveal that ordinality is strongly related to arithmetic and that the strategies used when processing ordinality are highly dependent on the context in which the task is presented.

了解一个序列是否按顺序呈现（即序数）是成人算术表现的可靠预测指标，但该技能背后的机制及其与数学的关系仍不清楚。在这项研究中，我们检查了：a）从在不同类型序列中观察到的行为效应推断出的序数所涉及的认知策略；b）除了算术之外，序数是否也与数学推理有关。在实验 1 中，参与者进行了算术、数学推理测试和顺序任务，这些任务在顺序、方向、规律性和距离的基础上进行了平衡试验。我们观察到有序和无序序列的标准距离效应 (DEs)，这表明依赖于幅度比较策略。这与过去报告某些类型序列的反向距离效应 (RDE) 的研究相矛盾，这表明依赖于检索策略。此外，我们发现在控制流体智能时，序数预测算术而非数学推理。在实验 2 中，我们调查了上述 RDE 的缺失是否是因为我们的试验列表组成。参与者执行了两项订单任务；在这两项任务中，都没有发现 RDE 表明 RDE 的脆弱性。此外，结果表明，处理序数时使用的策略受试验列表组成和任务呈现顺序的调节。共，