Clinical trials with RI systems that have obtained regulatory approval for clinical treatment (Argus II system, Ho et al.,
2015; and Alpha IMS system, Zrenner et al.,
2011) report that the patients were able to detect the number and location of stimuli (Stingl et al.,
2017), discriminate orientation and motion direction (Ho et al.,
2015), and even read large letters (Zrenner et al.,
2011). Despite these promising results, the perception gained by RI is still limited (Shepherd et al.,
2013), and there is a large variation of the gained perception according to the few clinical reports (Beyeler, Rokem, Boynton, & Fine,
2017b). For instance, with the Argus II system, whereas some patients did not show improvement in discriminating motion direction after the implantation (Castaldi et al.,
2016), other patients showed enhanced performance after prolonged experience with the system (Dorn et al.,
2013; Ho et al.,
2015). Of importance for the current study, reports of shape recognition have been variable (Stingl et al.,
2017, Zrenner et al.,
2011). Such limitations and variation raise the question whether, and to what extent, RI perception can be improved through training.