The development of spatial-numerical associations in preschoolers.

Children's mathematical achievement is influenced by both domain-specific and domain-general skills. One important domain-general correlate of mathematical development is visuo-spatial skills, the ability to generate, retrieve and transform visual images. Children with better visuo-spatial skills usually also show better mathematical performance. Interestingly, a recent study observed that visuo-spatial skills significantly predict mathematical achievement but that the strength of this relation varies considerably with age. Therefore, it is essential to investigate the emergence and development of this relationship across age.

One mechanism that has been suggested to support the association between visuo-spatial skills and mathematical performance is the metaphor of a spatially oriented mental number line representing number magnitude directionally. In Western cultures, numbers are typically represented on a mental number line with magnitude increasing from left to right. In recent years there has been a lively debate about whether this directional association between number magnitude and space is innate or emerges with development and to what extent this association is shaped by experience. While some studies have reported spatial associations of small numbers with left and larger numbers with right already in newborns, other studies arguing against innateness have reported that directional spatial-numerical associations were absent in illiterate adults, increased with reading experience in 4 to 6 year-old children, and were shaped by the reading direction of the culture participants were living in. However, there is a clear gap in the research on the existence/emergence of spatial-numerical associations in children aged 2 to 4 years. This is partly due to a lack of appropriate and reliable methods to assess
spatial-numerical associations in this age range.

The aim of this PhD is to investigate the emergence of the directional association between numbers and space (as described by the idea of a mental number line) in children aged 2 to 4 years old by answering the following research questions:
1. How can we reliably measure directional associations between number and space in 2 to 4 year-old children?
2. What factors influence the emergence of spatial-numerical associations in this age
range?
3. Is the development of spatial-numerical associations (i.e., the mental number line)
associated with children's numerical development more generally?