Other two arguments in favor of EEG/ERP are more specific to genetic psychophysiology research. First, Most EEG/ERP measures show high intraindividual stability, a necessary prerequisite for genetic research: test-retest correlations are in the range of .6-.9 for resting EEG characteristics and .5-.7 for many ERP paradigms, although reliability of other popular psychophysiological indices such as auditory P50 gating and emotion-modulated startle remains questionable. In contrast, a review of test-retest studies of fMRI-based measures of task-related regional activation has revealed modest test-retest reliability (Bennett and Miller, 2010). The problem is exacerbated by the fact that the less reliable the measure is, the larger samples are needed for genetic studies to detect a significant effect, which is particularly undesirable in the case of neuroimaging studies because of the high cost of assessments. Accordingly, another advantage of electrophysiology methods is their low cost and relative portability permitting the assessment of large samples required for genetic research.
