Benefitting from the improved spatial resolution and reference-independence of CSD-transformed ERPs, the present study confirmed a largely preserved visual old/new effect in schizophrenia over mid-parietal sites (cf. Kayser et al., 1999), but found marked old/new source reductions over lateral parietal regions for both visual and auditory tasks. Schizophrenic patients also lacked the left-greater-than-right hemisphere asymmetry observed for healthy adults, the typical topographical finding for the late old/new effect (e.g., Johnson, 1995; Allan et al., 1998; Friedman and Johnson, 2000). Most importantly, impairments of these electrophysiologic correlates of conscious memory retrieval were more robust for auditory word recognition, suggesting a particular deficit in encoding and/or retrieval of phonological information. A completely new finding is that the abnormalities of prominent CSD/ERP effects were followed by marked reductions in a distinct, response-related mid-frontal negativity, which is likely associated with performance monitoring (e.g., Luu et al., 2000; Ullsperger, 2006; Botvinick, 2007). These reductions were also most prominent for auditory stimuli.
