This paper introduces a 3D simulation environment for experiments with behavior-based autonomous agents. The virtual laboratory INSIGHT allows the user to design and run a great variety of experiments in a time- and cost-saving manner. The peculiarity of INSIGHT is the visualization of the internal dynamics, thus the \inner life" of the agent can be made transparent to the user during the run. The virtual laboratory Veriable scientic experiments require that they can be repeated independent from time and space. The experimenter needs to keep certain parameters at constant values while varying others systematically in order to study the eects of those parameters on the whole system. Unfortunately, those requirements cannot be fullled in experiments with physical agents. In general, it is impossible to run exactly the same experiment a second time. Dierent lighting conditions on dierent days or dierent times of day can lead to serious changes in the behavior of the agent. Th...