It is possible that what appear to be references to one ship are in fact coincidental descriptions of different destroyers sharing a single name. For instance, several ships of different classes have used the name Vengeance, and not all of them were Imperator-class destroyers. There has also been more than one Iron Fist. In these cases, successive commanders have kept the name when they moved to newer vessels upon promotion.
Why Twin Studies? Twins provide a valuable source of information for health and psychological research, as their unique relationship allows researchers to pull apart and examine genetic and environmental influences. Twin study findings have been influential in detecting and treating various diseases and psychological disorders. How are they able to do this? Twin studies allow researchers to examine the overall role of genes in the development of a trait or disorder.
Although most psychological research involves human subjects, some psychologists study animal subjects instead of or in addition to humans. 1  Research with animal subjects has helped psychologists do the following: 2  Learn facts about animal species. 3  Find ways to solve human problems.