generator of the studied ERP phenomena is in close proximity to the EEG reference, as is the case for secondary visual cortex along the ventral processing stream, the surface potentials as measured at nearby sites (e.g., P7/8, P9/10) will be close to zero. In contrast, neuronal generators within auditory cortex will only marginally be affected by this particular EEG reference choice. For these reasons, it may be easier to demonstrate deficits in auditory rather than visual processing in schizophrenia, even if both modalities were equally affected, because existing group or condition differences will be substantially masked for the visual modality by this EEG reference choice. However, this methodological limitation was averted here by employing a reference-free CSD transform.
