Although linked mastoid as reference scheme in this experiment might attenuate effects of laterality, hemispheric asymmetries of dipole P300 amplitude were obvious during auditory P300 paradigm testing in patients with anxiety and depressive disorders. It is not implemented in this paper but deduced that significant asymmetry also existed in these patients when with average mastoid reference scheme. The optimal reference scheme for cognitive ERPs recording in depressive and anxiety disorders still demands a further verification.
