García-Orza, J. 1 , Perea, M. 2 , Abu Mallouh, R. 3 & Carreiras, M. 3, 4
1 Universidad de Malaga, Spain
2 Universitat de Valencia, Spain
3 Basque Center for Cognition, Brain, and Language, Donostia-San Sebastian, Spain
4 IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
Numerical quantity seems to affect the response in any task that involves numbers, even when the task does not demand access to quantity (e.g., perceptual tasks). One piece of evidence in favour of this view comes from the “distance effect”: when comparing two numbers, reaction times are a function of the numerical distance between them. However, recent studies suggest that physical similarity between Arabic numbers and the numerical distance are strongly correlated, and the former might be a better predictor of RT data (Cohen, 2009). The present study explored the Persian and Arabic version of Indian numbers (Experiment 1 and 2, respectively). Naive participants (speakers from Spanish) and users of these notations participated in a same/different number matching task. The RTs of users of the Indian notation were regressed on perceptual similarity (estimated from the Spanish participants’ RTs) and the numerical distance effect. In Experiment 1, both distance and perceptual similarity alone were significant predictors of reaction times, however, when both variables were included in the regression, we only found a significant contribution of perceptual similarity. In Experiment 2, only perceptual similarity contributed to the regression. Thus, Indian integers do not automatically activate their quantity representation in simple, perceptual tasks.