In addition, one critical issue is that of reliability, as the magnitude of genetic influences will be necessarily bounded by the reliability of the discounting assessment over time. For example, the experiential discounting task was intentionally designed to be sensitive to state changes (Reynolds & Schiffbauer, 2004), favoring sensitivity to dynamic changes in preferences as a result of experimental manipulations over general reliability across time. This makes the resulting phenotype more generally fluctuating and in turn less likely to be sensitive to genetic effects. These important differences may clarify variability in findings within studies (e.g., Paloyelis et al., 2010). In general, trait-focused assessments that have established temporal reliabilities would be predicted to be most sensitive as endophenotypic measures.
