Another important issue related to the likelihood of gene finding and the interpretation of results is the specificity of psychophysiological phenotypes. It is reasonable to expect that measures that load strongly on a single specific aspect or mechanisms of neural processing and are less affected by other processes would have a simpler neural and genetic basis. On the other hand, measures reflecting a more integrative level of processing may be a product of multiple interacting processes and have a more complex genetic basis. For example, oddball P3 has been extensively used in genetic psychophysiology research related to psychopathology, particularly alcoholism and schizophrenia, but the degree to which it has contributed to the understanding of the mechanisms mediating genetic influences on these disorders has been limited by its low specificity with respect to distinct neurocognitive processes that might be conceptually implicated in the pathophysiology of these disorders. Given multiple brain regions and mechanism implicated in P3 generation and the diversity of its functional interpretations, oddball P3 is itself a very complex phenotype, for example, fMRI studies have identified 34 regions that
