Institute of Gerontology, University of Michigan, Ann Arbor, USA; Department of Psychiatry, Harvard Medical School and Brockton VA Medical Center, Brockton, MA, USA; McLean Hospital Cognitive Neuroscience Laboratory, Belmont, MA, USA; Department of Psychology, University of Massachusetts, Boston, USA; Department of Statistics, Harvard University, Cambridge, MA, USA; Department of Computer Science, University of Utah, Salt Lake City, USA; Department of Psychology, University of Indiana, Bloomington, USA (Blackwell Publishing, 1999-05)