Finger usage and arithmetic in adults with math difficulties: evidence from a case report

The role of finger usage upon learning arith-metic has received increasing interest from various disciplines. In this opinion paper, we would like to emphasize that finger usage in calculation is not a unitary phenomenon. Rather, we propose two different types of finger usage: First, in many countries and independent of the number system in use, typically developing children use fingers as important transitory (and intuitive) tools to represent small quantities ( Butterworth, 1999; Bender and Beller, 2011). According to Di Luca and Pesenti (2011) , finger count-ing habits are needed to build, acquire, and access mental number representations, the building blocks for semantic number knowledge. Second, developmentally inap-propriate finger usage of children with math difficulties (MD) reflects their persistent need to apply back-up strategies to compen-sate for deficient or lacking number repre-sentations (e.g., Brissaud, 1992; Kaufmann, 2002; Wright et al., 2002). Here, we will focus on the second type of finger usage (i.e., persistent finger usage in individuals with MD) and we argue that (a) finger usage in arithmetic is not restricted to children; and (b) finger-based calculation strategies utilized by adults with MD reflect immature calculation strategies that are comparable to those displayed by affected children.