Einstein's Brain Unlocks Some Mysteries Of The Mind. Brain and Mind. NDG: The SfN Neurosience Database Gateway. Problems with the Logic of Double Dissociations. Suppose that one day your computer’s hard drive stops working, but everything else about the machine is fine. Your friend has an identical computer in which the hard drive works fine, but the keyboard suddenly stopped working. Based on this “double dissociation” between the two different problems, can you safely assume that the “hard drive system” and the “keyboard system” rely on distinct underlying mechanisms? For years, cognitive neuropsychologists have felt safe in making equivalent assumptions about brain damage. If one type of damage leads to difficulty on task A, but not task B, and a different type of damage leads to the opposite pattern of performance, then tasks A and B must rely on distinct neural mechanisms … Right?
Given what everyone knows about computers, you might think this inference is perfectly valid… The brain is a computing machine of some sort. Still, the logic of double dissociations has its defenders. VirtualEEG at Indiana University.