A critical review of number order judgements and arithmetic: What do order verification tasks actually measure?

Number order processing is thought to contribute to arithmetic development. Although we typically assess order processing using order verification tasks, there is reason to question what these tasks actually measure. For instance, a supposed hallmark of order verification -the reverse distance effect- has been shown to be frequently absent and inconsistently related to arithmetic. In this critical review, we consider the cognitive mechanisms underlying order verification, including how these may explain both the presence and absence of the reverse distance effect, as well as the association between ordering and arithmetic. Although some studies suggested order verification tasks primarily reflect the use of memory-retrieval strategies, others suggested verification may primarily be influenced by our early experiences with the count-list. Therefore, we highlight establishing the mechanisms underlying this task as an important goal for future research. Furthermore, apparent limitations of this task suggest we should consider alternative methods of assessing order processing.