  In a recent overview of the Simon data from the last 10 or so years,  however, Newport 2001, stresses a number of facts that Pinker's  presentation obscures or downplays. First, Simon's performance was  not that of a native signer, although he did develop “his own  version of ASL whose structure was more like that of other natural  languages [than that of his parents' ASL]” (Newport 2001:168). For instance, Simon's morphology stabilized at a level that was  “not as complex as native ASL” and he didn't acquire  standard classifier morphemes if they were not used by his parents  (ibid.). Secondly, Simon's success in learning a given rule  seemed to vary with how well or badly his parents signed. For  instance, Simon's parents used the correct inflectional morphology  60-75% of the time for a large class of verbs of motion, and in this  case, Simon's own use of such morphology was 90% correct. However,  some members of the class of classifier morphemes were correctly used by the parents only 40% of the time, and in this case, although  Simon's performance was better than his parents', it was not at  native signer level.