The spatial-numerical association of response codes (SNARC) is an example of the spatial organisation of magnitude information.
Put simply, when presented with smaller numbers (0 to 4), people tend to respond faster if those stimuli are associated with the left extrapersonal hemiside of their perceived surroundings; when presented with larger numbers (6 to 9), people respond faster if those stimuli are instead associated with the right extrapersonal hemiside of their perceived surroundings.
The SNARC effect is this automatic association that occurs between the location of the response hand and the semantic magnitude of a modality-independent number.
The mental number line is assumed to be oriented from left to right in populations with a left-to-right writing system (e.g. English), and oriented from right to left in populations with a right-to-left writing system (e.g. Iranian)[2] The SNARC has been observed primarily in two scenarios: attentional and oculomotor.
[4] Newer research shows a motor bias to also be associated with the SNARC effect.