Numerical, spatial and material magnitude estimation in left and right brain-damaged patients

In this study, we tested the main prediction derived from the “A Theory Of Magnitude” or ATOM, according to which discrete (e.g., numbers) and continuous (e.g., space, material) magnitudes are processed within the right hemisphere. To do so, we examined 11 right brain-damaged patients, 19 left brain-damaged patients, and 30 healthy subjects on different tasks assessing magnitude estimation: symbolic and non-symbolic numerical magnitude as well as spatial (i.e., length) and material (i.e., weight) magnitude. Contrary to the ATOM’s predictions, we did not find significant correlations between all the magnitude estimation tasks in right brain-damaged patients. Correlations between numerical and length magnitudes were found in left brain-damaged patients and healthy subjects. Our results support the existence of a partial independence between the different forms of magnitude estimation processing.