The differential-severity model comports with burgeoning evidence that psychopathy is underpinned by one or more dimensions rather than by a taxon, or natural category (Edens, Marcus, Lilienfeld, & Poythress, 2006). At the same time, other data are inconsistent with the differential- severity model. Ishikawa, Raine, Lencz, Bihrle, and Lacasse (2001) recruited males from temporary-employment agencies in the Los Angeles area. After identifying those who scored above the threshold for psychopathy on the Psychopathy Checklist–Revised (PCL-R; Hare, 2003), the authors subdivided participants into those who had been convicted (n = 13; unsuccessful psychopaths) and those who had not been convicted (n = 16