The illusion of numerical value

Numbers constitute the building blocks of higher-level numerical skills. Accordingly, symbolic number processing was shown to correlate with mathematical competence. However, the underlying mechanism subserving symbolic number processing is still a matter of debate. The dominant view suggests that number symbols are mapped onto quantity representations mediated by a primal approximate number system. Alternatively, another view suggests that a primal system subserving size processing was exploited to subserve symbolic number processing. Whereas recent evidence is inconsistent with the dominant view, the alternative view has gained some support. The current study used two psychophysical methods to rigorously examine interaction of symbolic number and size perception. Results indicated that symbolic numerical values created an illusion of size. Namely, the size of a numerically larger number was overestimated, and vice versa for a small number. The current study proposes a novel approach to examining symbolic numbers mentally that might broaden our understating of symbolic numerical processing and its origins.