Our Experimental Journey

Originally, we proposed doing our study on whether presenting a 20 kHz tone affected a rat’s freezing and fear responses as well as marking behaviors in the presence of another rat. We observed our three rats individually for the first trial and recorded how each behaved when she was alone in the aquarium, when another extra rat (who was in a tupperware container) was placed into the aquarium with the observed rat without the presence of the tone, and then when the extra rat was in there in the presence of the tone. Our hypothesis was that when the tone was presented, the rat would exhibit freezing behavior and would limit its approaching behavior toward the extra rat, therefore disturbing its normal approaching and marking behaviors.

Our first trial with the first rat (Bebe) we observed worked beautifully. When the extra rat was placed in the aquarium and there was no tone, Bebe crawled on top of the container and sniffed and bit at it. However, when the tone was presented, Bebe froze by the container housing the extra rat (Sookie) for the whole five minutes in which we played the tone. This behavior was consistent with our hypothesis. Here is a video of Bebe’s very first trial we did with Sookie and the 20 kHz tone:

Unfortunately, when we observed the two other rats (Eloise and Annie) individually, they exhibited minimal to no freezing behavior when the tone was presented while Sookie was in the aquarium. Here is a video of Eloise’s first trial as well. You can see how she behaves much differently than Bebe.

We couldn’t quite understand why the tone appeared to have a significant effect on Bebe while having hardly no impact on the behaviors of the other two rats observed. As a result, we started experimenting with our experiment! We began looking at the effects of presenting different types of rat predator sounds such as that of a hawk, a rattlesnake, a raccoon, etc. None of these sounds appeared to be having any effects on the behaviors of the rats we observed.

Finally, after much contemplation over what to do about our failing experiment, we decided to look at whether each of the rats behaved differently when the extra rat Sookie was placed in the aquarium with them as opposed to when they were placed in there alone when the sound of a shrieking rat was played. SO, we basically replaced sound with social interaction for the independent variable (IV).  Our objective, as is further explained in our experimental method, is to see whether the presence of a scary shrieking rat sound affects how the rat we are observing behaves in terms of marking and fear responses when alone as opposed to when in the presence of another “extra” rat.

I think this is a fascinating experiment because it evolved into a topic that could potentially tell us about how fear affects social interaction, which is a question that could reveal information that could help us to not only understand more about rats but potentially more about humans.

Here is a video of Eloise during the first trial of our newly designed experiment! This is condition one in which the shrieking rat sound is presented while she is alone.

Here is another video of her in Trial 1, Condition 2 in which Sookie is put in the aquarium with her while the shrieking rat sound is presented.