The brain goes the distance: a shared numerical magnitude representation revealed by a frequency-tagging multi-code EEG study

Although humans can process various numerical codes, whether they all converge on a common magnitude representation remains controversial. Here, we recorded electrophysiological responses to periodic variation of numerosity (1/5) occurring in rapid streams of numbers presented at 6Hz in randomly varying codes – digits, words, dots and fingers. Results demonstrated that numerical information was abstracted and generalized over the different codes by revealing clear discrimination responses (at 1.2 Hz) of the deviant numerosity from the base numerosity. Crucially, the presentation of a deviant numerosity distant from the base (e.g., “2” and “8”) elicited larger responses than the presentation of a close deviant numerosity (e.g., “2” and “3”). This finding nicely represents the neural signature of the distance effect, an interpretation further reinforced by the clear correlation with individuals’ behavioral performance in an independent numerical comparison task. Our results therefore provide a reliable and specific neural marker of magnitude representation common to several numerical codes