Ordinal processing of numerical and non-numerical information

Numerical knowledge requires representations of both quantities and ordinal relationships. Furthermore, the basic ability to judge and learn the ordinality of a sequence might be innately available to humans and animals. However, numerical ordinality processing has received much less research interest then quantity processing. In this chapter, we review the literature on ordinal processing, including the different definitions of numerical ordinality, the development of ordinal knowledge and unique effects related to ordinal task (e.g., the distance effect and the spatial numerical association of response codes (SNARC)). Additionally, we discuss cognitive and neurofunctional similarities and differences in processing numerical (ordinality and quantity) and non-numerical sequences. It is argued here that current studies are sometimes controversial and are not directly comparable because of the variance in task, stimuli and instructions that are used, but mainly because of different definitions. We conclude by describing a theoretical model of the neuro-cognitive representations which are required to process ordinal information and suggest ordinality as an additional core cognitive system. The model can contribute a framework for the new scientific field of ordinal processing.