these psychopathests have reduction in the volume. and, also, when they contemplate making moral decisions like, shall i kill someone or not? that part of the brain is not as active as in normal people. >> you've done a terrific job of making the science accessible for people. i want to show a couple images that are important here and people should see these, again. you should read the book. take a look there, a scan of the brain, normal on the left and a murderer on the right. what are we looking at there? >> well, we're looking down on the brain. this is a pet scan, so, it's looking at brain functioning and the warm colors, the red and yellow indicate high gluicose metabolism or high brain functioning. and on the left with the normal control, you can see a lot of good functioning in the very frontal region of the brain. right at the top there. >> that orange, yellowish area.