ABSTRACT
This chapter explores individual differences in mathematical ability, in mathematics anxiety and in attitudes towards mathematics. It focuses on children whose mathematical performance is consistently at the lower end of the normal distribution of mathematical ability, i.e. children with mathematical difficulties. It would be useful to know whether younger children who go on to develop mathematical difficulties later already show deficits in their early counting performance before primary school. A person was only diagnosed as having a mathematical disorder if their 'mathematical ability, as measured by individually administered standardized tests substantially below that expected given the person's chronological age, measured intelligence and age-appropriate education. The IQ discrepancy criterion has been dropped for the diagnostic and statistical manual of mental disorders V because there is little evidence that the numerical difficulties of children with develop-mental dyscalculia with below average intellectual abilities differ from those of children with developmental dyscalculia with average intellectual abilities.
