We welcome Gevers and Notebaert’s note, whichshows how converging efforts are being made byindependent laboratories and from different per-spectives, in the attempt to reach a better under-standing of the relation between Simon andSNARC (spatial-numerical association ofresponse codes) effects. We would like to drawattention to a crucial distinction between numberand space processing on the one hand andbetween the processes that are involved in theSimon and SNARC effects on the other.Space and number magnitude possess intri-guing similarities and give rise to analogous signa-tures when processed in the context of structurallysimilar tasks (e.g., Hubbard, Piazza, Pinel, D Walsh, 2003; but see alsoRusconi, Umilta`, & Galfano, 2006). In addition,both the core representation of number and thevisuo-motor representation of space are knownto rest massively on parietal networks (e.g.,Andersen & Buneo, 2003; Nieder, 2004). Onelogical possibility is that the mental representationof numbers is intrinsically spatial (Dehaene, 1997).Alternatively, the connection between numbersand space might be a cultural achievement. Infact, these possibilities do not exclude each other,since an original neural overlap may be joint byculture-specific representations, which build onlearnt symbolic tools such as the Cartesian system.It is generally claimed that the mental numberline is a specialized function of posterior parietalcortex, where also the processing of physicalspace takes place (see Hubbard et al., 2005; andRusconi & Umilta`, in press, for reviews). In fact,its behavioural effects could originate from aninteraction between the core representation ofnumber magnitude in the horizontal intraparietalsulcus (e.g., Castelli, Glaser, & Butterworth,