An important consideration for genetic association studies of psychophysiological phenotypes is standardization of assessments that should enable the replication of results, meta-analyses, as well as pooling data from different studies in order to increase statistical power. Historically, there is a large variability in laboratory protocols, including task design, specific stimuli used, recording parameters, and instructions to the subjects. Even the “classic” oddball P3 amplitude can be measured in a variety of ways. First, paradigms may be different, leading to different cognitive processes engaged by the task (e.g. Hill et al., 1998; Noble et al., 1994). Second, quantification of the neural response may be different, varying from simple peak amplitude of the averaged ERP to more sophisticated algorithms such as event-related band power.
