Thesis advisor: Sara Cordes / Thesis advisor: Sophie Savelkouls / Prior research indicates that Spontaneous Focusing On Number (SFON) measured in the preschool years is predictive of mathematical achievement as late as age 12 (Hannula & Lehtinen, 2005; Hannula-Sormunen, Lepola, & Lehtinen, 2010). Therefore, there is great need to examine how young children’s attention to number is affected by various contexts. This study investigated how heterogeneity vs. homogeneity of the arrays, and verbal labels for the quantities presented affected young children’s attention to number, compared to their attention to cumulative surface area. We found that participants preference for and attention to number was correlated with their number knowledge, but only when the items they were presented with were homogeneous, not heterogeneous. This suggests that homogeneous arrays are important for children’s attention to number and individuation and could be used as a tool to help children better hone in on mathematical concepts. / Thesis (BS) — Boston College, 2018. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Departmental Honors. / Discipline: Psychology.