20.4 present perfect, past simple Persistence (1) has most often been / was most often studied in terms of cultural differences. Blinco (1992) (2) has found / found that Japanese elementary schoolchildren) have shown / showed greater task persistence than their American counterparts. School type and gender (4) have not been / were not factors in moderating task persistence. This (5) has left / left culture as the remaining variable. Heine et al. (2001) (6) has furthered / furthered this idea by testing older American and Japanese subjects on responses after successor failure on task persistence. Japanese subjects (7) have been / were once again found to persist longer (in post-failure conditions, and this (8) has been /
