Western people tend to represent numbers spatially, with small numbers toward the left of mental space and large numbers towards the right, and responses to small numbers are faster when the effector is in left space; responses to large numbers are faster with the effector in right space (SNARC effect). It is generally claimed that the spatial representation of number is function of the posterior parietal cortex (Hubbard et al 2005), however the representation of space and covert orienting to it can involve frontal brain areas (Corbetta & Shulman 2002)
