While the above findings provide further evidence that ERP abnormalities in schizophrenia are more prevalent during auditory than visual paradigms (e.g., Duncan, 1988; Pfefferbaum et al., 1989; Egan et al., 1994; Ford et al., 1994; Jeon and Polich, 2003), they do not address whether reduced old/new effects in patients are specific to linguistic or language-related aspects of episodic memory. A meta-analysis of behavioral performance suggested that non-word stimuli yield even larger effect sizes of impaired recognition memory in schizophrenia (Pelletier et al., 2005), and old/new ERP abnormalities have been reported for unfamiliar faces (Guillem et al., 2001). Then again, a direct comparison of old/new effects in schizophrenia using words or faces has not yet been published. Given our interpretation that a dysfunction in temporal integration and retrieval of semantic information is the main contributor to the recognition memory deficits of schizophrenic patients, it is not surprising that their electrophysiologic correlates are more pronounced for auditory stimuli, which require even greater phonological and acoustic processing resources (cf. Penney, 1989). This leads to the hypothesis that group differences in episodic memory will be less prominent for stimuli that are difficult to verbalize, such as faces of strangers.
