title: The organization of spatial reference frames involved in the SNARC effect.
abstract: The SNARC effect refers to faster reaction times for larger numbers with right-sided responses and for smaller numbers with left-sided responses, even when numerical magnitude is irrelevant. Although the SNARC is generally thought to reflect a mapping between numbers and space, the question of which spatial reference frame(s) are critical for the effect has not been systematically explored. We propose a dynamic hierarchical organization of the reference frames (from a global left-right frame to body- and object-related frames), where the influence of each frame can be modulated by experimental context. We conducted two experiments based on predictions derived from this organizational system. Experiment 1 compared instructions that differed only in focusing participants' attention on either the response buttons or the hands. Instructions focusing on a hand-based reference frame eliminated the SNARC. Experiment 2 provided the opportunity for an object-centred reference frame to manifest itself in the SNARC. Although we did not observe an effect of an object-centred reference frame, we observed the influence of other reference frames in a context where an object-centred reference frame was emphasized. Altogether, these results support the proposed organization of the reference frames.
authors.affiliation: a Cognitive Neuroimaging Unit, Université Paris-Sud , Orsay , France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Viarouge
authors.forename: Edward M
authors.initials: EM
authors.lastname: Hubbard
authors.forename: Stanislas
authors.initials: S
authors.lastname: Dehaene
mesh_terms: D001244:Association; D001288:Attention; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D010775:Photic Stimulation; D011597:Psychomotor Performance; D011930:Reaction Time / Q000502:physiology; D012044:Regression Analysis; D013028:Space Perception / Q000502:physiology*; D055815:Young Adult
keywords: Numerical cognition; Spatial reference frames; Spatial–numerical association of response codes effect