Electronic Thesis and Dissertation Repository


Master of Science




Dr. Daniel Ansari


A current debate is whether number is processed using a number-specific system or a general magnitude processing system used for non-numerical magnitudes such as space. Activation likelihood estimation (ALE) was used to conduct the first quantitative meta-analysis of 20 empirical neuroimaging papers examining neural activation during numerical and non-numerical magnitude processing. Foci were compiled to generate probabilistic maps of activation for symbolic numerical magnitudes, nonsymbolic numerical magnitudes and non-numerical magnitudes. Conjunction analyses revealed overlapping activation for symbolic, nonsymbolic and non-numerical magnitudes in frontal and parietal lobes. Contrast analyses revealed specific activation in the left superior parietal lobule (SPL) and right inferior parietal lobule (IPL) for symbolic numerical magnitudes. In contrast, anterior right IPL was specifically activated for nonsymbolic numerical magnitudes. No parietal regions were activated for non-numerical that were not also activated for numerical magnitudes. Therefore, numbers are processed using both a generalized magnitude system and format specific number regions.