Many difficulties learners have with
rational number tasks can be attributed to the "natural number bias",
i.e. the tendency to inappropriately use natural number properties in
rational numbers tasks (Van Hoof, 2015). McMullen and colleagues found a
relevant source of individual differences in the learning of those
aspects of rational numbers that are susceptible to the natural number
bias, namely Spontaneous Focusing On quantitative Relations (SFOR)
(McMullen, 2014). While McMullen and colleagues showed that SFOR relates
to rational number knowledge as a whole, we studied its relation with
several aspects of the natural number bias. Additionally, we 1) included
test items addressing operations with rational numbers and 2)
controlled for general mathematics achievement and age. Results showed
that SFOR related strongly to rational number knowledge, even after
taking into account several control variables. Results are discussed for
each of the three aspects of the natural number bias separately.