Assessment research of forensic populations has largely dealt with finding differences within criminal types. Fourteen of the studies reviewed found no significant differences between types of criminals on test performance. Two of these fourteen found no differences between criminals and noncriminals . The Criminal Thinking Model developed by Yochelson and Samenow proposed a continuum of criminality with every person falling somewhere between the two poles of responsibility and irresponsibility. Perhaps one reason previous research failed to discriminate differences was because they had failed to first establish if criminals differed from noncriminals.