In Chapter 2, I focus on the acquisition of number concepts related to natural numbers. I review nativist views, as well as Dehaene’s early view that number concepts arise from estimations due to the approximate numbers system. I end up focusing in most detail on the bootstrapping account of Carey and Beck, according to which the object tracking system is the key cognitive resource used in number concept acquisition. However, I endorse a hybrid account that also includes an important role for the approximate numerosity system. I then review some of the criticism against the bootstrapping account, concluding that, while more empirical data is needed to establish its correctness and details, currently it provides the most plausible account of early number concept acquisition.

Numbers are an integral part of our daily lives, essential for making sound decisions. Surprisingly, numerical abilities, often termed number sense, begin developing early in life, shaping our foundational understanding of mathematics. This chapter explores the concept of number sense, demonstrating that even young children exhibit sensitivity to numerical magnitudes in everyday problem-solving scenarios. We delve into the transition from non-symbolic to symbolic numbers and its impact on brain development. As children acquire symbolic numerical skills, brain regions supporting number sense are influenced, and experiences refine these representations. We also explore individual differences in mathematical competence and their neural correlates. Furthermore, we discuss the implications of math interventions on brain development, emphasizing the importance of nurturing numeracy skills from an early age. This understanding has far-reaching implications for education policies, ensuring that every child has the opportunity to unlock their numerical wisdom. This chapter illuminates the journey from number sense to mathematical mastery in the developing mind.

Non-symbolic numerical competences are widespread among preverbal infants and nonhuman animals. Moreover, signature effects that characterize numerical processing are similar between humans and other animals. This suggests a phylogenetically ancient mechanism to support non-symbolic numerical cognition (“number sense”). Here we review studies that used domestic chicks to study the ontogenetic origins of numerical knowledge. This research revealed an association between numbers and space (with smaller numbers associated with the left side of space, and bigger numbers with the right side). This is a crucial feature of non-symbolic numerical cognition, shared between humans and other animals.In the initial part of the chapter, we focus on evidence of chick’s ordinal numerical competence. When tested for their ordinal competence, chicks are predisposed to “count from left to right,” much like most humans. This bias depends on availability of spatial information to solve the ordinal task. When this was prevented, chicks were still able to perform the ordinal tasks, but without any lateralization of performance. Evidence obtained in chicks is discussed also in comparison with primates. This allows addressing whether the degree of visual lateralization and functional segregation between the hemispheres might affect number–space associations in nonhuman animals. In the second part of the chapter, we review evidence from tasks that involve the processing of quantity or number information. Again, domestic chicks showed signs of a number–space association. Even in the absence of any specific numerical training, chicks showed a spontaneous association of bigger numerousness with the right side of space. In a subsequent, strictly controlled experiment, numerical training was used to simultaneously demonstrate a leftward bias for smaller numbers and a rightward bias for bigger numbers. We also obtained evidence that the same number or quantity can be associated with the left or the right space, depending on the reference point to which it is compared. Overall, this tendency to map ordinal information with a left-to-right orientation indicates that number–space associations are not a perquisite of the human species and can occur in the absence of language or formal enculturation.

Research in the field of mathematical learning disability (MLD) is growing. Though a proportion of children in every school appear to struggle with mathematical achievement, MLD characterizes a subgroup of students with poor achievement and skill deficits that differentiate them from their low-achieving peers. This chapter explores some of the characteristics of children with MLD, including underachievement in mathematics, poor number sense, limited working memory, and additional processing deficits. Emerging evidence for universal screening, prevention, and early intervention are also presented. The chapter ends with guidelines for school psychologists to apply the extant literature to their own practice, along with a list of resources to gain further expertise on the typical and atypical development of numerical cognition.