the response of rats to isolation housing, specifically the potentiation of the startle reflex induced by isolation (Nair et al., 2005). Manipulations of the pre and postnatal environment using cross fostering and /or ova transplant designs could be applied to prairie voles or other high or low drinking rodent genotypes to begin to tease apart the influences of drinking from observing drinking in cage mates. Similarly, such a study could be performed in a genetically segregating genotype by screening mice at weaning for high or low drinking individuals to use as cage mates. Voles (or possibly mice) could be offered the opportunity to huddle with one of two previous cage mates, a high drinker with which it had previously been paired vs a low drinker. These sorts of designs could be applied to prairie voles or other high or low drinking genotypes to begin to tease apart the influences of drinking from observing drinking in cage mates. It may be useful to pursue the role of vasopressin more widely in such experiments. Similarly, such a study could be performed in a genetically segregating genotype by screening mice at weaning and selecting high or low drinking individuals for cage mates. Such
