<Dd> (2) In other studies, when cognitive process X was putatively engaged, then brain area Z was active . </Dd> <Dd> (3) Thus, the activity of area Z in the present study demonstrates engagement of cognitive process X by task comparison A . </Dd> <Dd> This is a' reverse inference', in that it reasons backwards from the presence of brain activation to the engagement of a particular cognitive function . </Dd> <P> Reverse inference demonstrates the logical fallacy of affirming what you just found, although this logic could be supported by instances where a certain outcome is generated solely by a specific occurrence . With regard to the brain and brain function it is seldom that a particular brain region is activated solely by one cognitive process . Some suggestions to improve the legitimacy of reverse inference have included both increasing the selectivity of response in the brain region of interest and increasing the prior probability of the cognitive process in question . However, Poldrack suggests that reverse inference should be used merely as a guide to direct further inquiry rather than a direct means to interpret results . </P>

A key advantage of the functional magnetic resonance imaging (fmri) technique is that the method can