Karin Landerl and a team of researchers at the University of Graz, Austria investigated the numerical processing in elementary school children with dyscalculia and a control group of students with good arithmetic skills.

Dyscalculia is a learning disability that causes difficulty in learning arithmetic. It is highly selective, but it can affect children with normal intellectual ability.

The children in the study repeatedly performed simple arithmetic tasks on the computer. While the efficiency of numerical processing generally improved over time in all children, the children with dyscalculia showed persistent deficits specific to the domain of number. These children also had difficulty to ‘subitize,’ meaning to enumerate between 1 and 3 objects quickly.

From her research, Laderl concluded that a biologically driven deficit causes dyscalculic children to have an imprecise internal representation of numbers, explaining their difficulty with the number line.