Imaging studies of normal subjects, such as those done with PET (positron emission tomography) scans seem to show the same thing. PET scans measure the level of blood flow to different parts of the brain, which in turn shows us areas of activation in those parts. Jaeger et al. (1996) have reported that there are parts of the brain that are activated when subjects are asked to read regularly inflected past tenses that are distinct from those activated in reading or producing irregular past tenses.