Schizophrenia is a heterogeneous and multidimensional disorder. The different syndromes or dimensions of this disorder represent distinct pathophysio-logical processes. Evidence is growing that each of the composite syndromes or dimensions of this disorder is associated with specific validators. This article reviewed neurophysiological and neuropsychological studies in schizophrenia in order to determine the external validators of its syndromes. The review reveals compelling findings in some instances and contradictory findings in other instances.