Sensory Integration Theory: An Alternative to the Approximate Number System

The proficiency and neural underpinnings of human and nonhuman animal ability to estimate or compare different sets of items has been investigated in different fields of research such as evolution, development, and education. The general consensus holds that these abilities are supported by the so-called approximate number system (ANS). In this chapter, we will question the methods used in the ANS studies, challenge the existence of the ANS to some degree, and present an alternative sensory integration theory. First, it is explained how our performance in numerosity judgment tasks can be explained on the basis of a mechanism weighing or integrating the different visual cues. A parallel is drawn between this integration mechanism and conservation abilities. Second, it is discussed how such a integration mechanism can be used to explain the observed relation between performance in numerosity judgment tasks and math achievement.