Fig. 1.

Testing apparatus for mate-preference tests. The schematic (Middle) illustrates the regions of interest. Experimental animals were considered to have exhibited a preference if all four feet had crossed the dotted line into the right or left third of the chamber. While in these areas, the time spent at the glass sides or engaged in the following behaviors (Still, Standing/Sniffing, Walking, and Grooming) was quantified. Time spent in the left or right third of the chamber was also calculated for three additional behaviors (Plexiglas, Facial Investigation, and Wire Mesh). Finally, time in the center third was calculated. Also illustrated is the testing chamber with Plexiglas release box in place under fluorescent illumination (Top) or under dim red light with animals in place (Bottom).