One of the Iratus' favorite methods of studying other species' is through something they refer to as Dominion. 

This is essentially a tiered battle to the death that takes place in an arena. This arena is always located on an Iratus ship, and there is room for thousands of Iratus to watch the fights. It is a revered sport among the Iratus, but the people that participate in the "games" are nothing short of victims.

The study of how these people react is particularly interesting to the Iratus; how will another species react in a situation of "kill or be killed".

The few that survive are often scarred for the rest of their lives.