Deductive Versus Probabilistic Reasoning in Healthy Adults: An EEG Analysis of Neural Differences

This study examined the electrophysiological signatures of deductive and probabilistic reasoning. Deduction is defined as the case in which a conclusion can be found to be true or false due to validity of argument. In probabilistic reasoning, however, conclusions can be considered to be likely or unlikely, but not with certainty due to the lack of validity in the form of the argument. 16 participants were presented with both types of arguments while response times and ERPs were carried out. Participants had to decide with the presentation of each argument, what type of reasoning was appropriate and which of four responses (certainly yes, probably yes, probably no and certainly no) was the most appropriate. Response times indicated faster processing of deductive arguments. N2 amplitude distinguished between positive and negative responses in the deductive condition, but not in the probabilistic one, suggesting partial differentiation between the cognitive processes required for the two types of reasoning.