1. A. D. Wagner and M. Rotte, Massachusetts General Hospital NMR Center, Harvard Medical School, Charlestown, MA 02129, USA, and Department of Psychology, Harvard University, Cambridge, MA 02138, USA. D. L. Schacter, W. Koutstaal, A. Maril, Department of Psychology, Harvard University, Cambridge, MA 02138, USA. A. M. Dale and B. R. Rosen, Massachusetts General Hospital NMR Center, Harvard Medical School, Charlestown, MA 02129, USA. R. L. Buckner, Massachusetts General Hospital NMR Center, Harvard...