In contrast to the behavioral data, the electrophysiologic findings showed evidence of a task-specific impairment of episodic memory processes in schizophrenia. Reference-free, high-density CSDs confirmed largely preserved old/new effects in patients over mid-parietal sites but marked old/new source reductions in patients over lateral parietal regions for words (cf. Kayser et al., 1999, 2009). These late old/new effects, however, were comparable in patients and healthy adults for unknown faces, which is in agreement with previous ERP findings (Guillem et al., 2001). This dissociation is even more surprising when considering that face recognition was clearly the more difficult task, yielding significantly lower recognition accuracy in both groups. This strongly suggests that reduced late old/new effects for words over lateral parietal sites cannot be attributed to a generalized cognitive dysfunction in schizophrenia (Blanchard and Neale, 1994), because this would predict greater deficits with increasing difficulty levels. Rather, this finding is reminiscent of the adequate performance of schizophrenic patients during difficult non-verbal working memory tests in contrast to their subpar performance on easier verbal memory tests (Wexler et al., 1998), and adds to the
