Familiarity increases consistency in animal tests.

This experiment investigated the effect of identity of the experimenter and familiarity to their test animals on results obtained from a standard test of anxiety. We found that having different experimenters perform the same test (i.e. elevated plus maze) using the same equipment and rats from the same breeding colony within the same room of the same laboratory significantly affects the results if the experimenters are unfamiliar to the animals, but not if they are familiar to them. Familiarity of the test animals with their experimenters should therefore increase consistency in results from animal tests.