The integration between nonsymbolic and symbolic numbers: Evidence from an EEG study

Abstract

IntroductionAdults can represent numerical information in nonsymbolic and symbolic formats and flexibly switch between the two. While some studies suggest a strong link between the two number representation systems (e.g., Piazza, Izard, Pinel, Le Bihan, & Dehaene, 2004 Neuron, 44(3), 547), other studies show evidence against the strong‐link hypothesis (e.g., Lyons, Ansari, & Beilock, 2012 Journal of Experimental Psychology: General, 141(4), 635). This inconsistency could arise from the relation between task demands and the closeness of the link between the two number systems.MethodsWe used a passive viewing task and event‐related potentials (ERP) to examine the temporal dynamics of the implicit integration between the nonsymbolic and symbolic systems. We focused on two ERP components over posterior scalp sites that were found to be sensitive to numerical distances and ratio differences in both numerical formats: a negative component that peaks around 170 ms poststimulus (N1) and a positive component that peaks around 200 ms poststimulus (P2p). We examined adults' (n = 55) ERPs when they were passively viewing simultaneously presented dot quantities and Arabic numerals (i.e., nonsymbolic and symbolic numerical information) in the double‐digit range. For each stimulus, the nonsymbolic and symbolic content either matched or mismatched in number. We also asked each participant to estimate dot quantities in a separate behavioral task and observed that they tended to underestimate the actual dot quantities, suggesting a need to adjust the match between nonsymbolic and symbolic information to reflect the perceived quantity of the nonsymbolic information.ResultsUsing this adjustment, participants showed greater N1 and P2p amplitudes when perceived dot quantities matched Arabic numerals than when there was a mismatch. However, no differences were found between the unadjusted match and mismatch conditions.ConclusionOur findings suggest that adults rapidly integrate nonsymbolic and symbolic formats of double‐digit numbers, but evidence of such integration is best observed when the perceived (rather than veridical) dot quantity is considered.

Automatic integration of numerical formats examined with frequency-tagged EEG

“…The discrepancies observed in the literature might be related to differences in the stimulus characteristics (e.g., number range and numerical correspondence between formats, see also Liu et al 23 , 24 ) and experimental tasks. Indeed, the majority of the studies showing evidence for format interdependence have employed explicit tasks (i.e., required participants to make an intentional numerical decision), while implicit measures are rarely used.…”

“…Consequently making use of implicit paradigms (e.g., passive viewing) —where the numerical representation is probed per se, independently of any decisional strategies 20 , 25 , might be better suited to provide an objective (i.e., free of any intentional confounds) measure of the integration across numerical formats 26 – 28 . Two EEG studies used such implicit measures to examine the integration across numerical formats 23 , 29 . Their findings, however, are somewhat contradicting.…”

Cognitive and Neural Effects of a Brief Nonsymbolic Approximate Arithmetic Training in Healthy First Grade Children

“…As in previous analyses, we compared the data from the Easy and the Hard trials of the Addition, with the identical trials of the Color-Group, in order to avoid that our P2p amplitude analyses were influenced by perceptual factors (e.g., Gebuis and Reynvoet, 2013 ; Liu et al, 2018 ).…”

“…N1 and P2p would represent the early and late steps of the number-related processing. P2p is thought to arise from the recruitment of parietal networks involved in numerical processing (Piazza et al, 2004 ) and the increase of its amplitude would reveal the effort to discriminate between arrays of elements, which is a function of its ratio i.e., the Weber law, (Dehaene, 1996 ; Temple and Posner, 1998 ; Libertus et al, 2007 ; Liu et al, 2018 ). Some studies have reported that P2p amplitude is influenced by the evaluation of the perceptual visual features of dots arrays (e.g., Gebuis and Reynvoet, 2013 ).…”

Controlling Unpleasant Thoughts: Adjustments of Cognitive Control Based on Previous-Trial Load in a Working Memory Task

“…It has been proposed that loading WM with visual-feature maintenance encoding, for example, by increasing the set size for a memory sample of colors, would increase the posterior P2 amplitude (Zhou and Thomas, 2015). It has also been reported that the posterior P2 is related to nonsymbolical numerical processing, with its amplitude increasing according to the effort necessary to discriminate between the numerical magnitude of arrays (Libertus et al, 2007;Hyde and Wood, 2011;Gouet et al, 2018;Liu et al, 2018). This is in agreement with evidence that the posterior P2 component is enhanced by high cognitive demands.…”