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Discussion

The results of this study demonstrate that the physical presence of a predator instigates the most intense fear response, and that scent is a discriminating factor for rats to interpret the potential threat of a predator. This is supported by the fact that the rats continued to sniff excessively in each trial of this study, even though in two of the conditions there was no scent stimuli. Freezing and hypervigilance behaviors are hypothesized to be the most extreme indicator of fear of a stimuli for rats, and the visual condition instigated the longest total duration of freezing behavior.

The rats did not indicate freezing behaviors during the scent condition, but did show some grooming and rearing. Grooming, specifically, in response to the cat scent may be relevant to species specific fear and defense behavior. Rats groom themselves in order to cleanse any cuts or wounds inflicted from a predator. What specifically about the scent of a cat that may indicate a need to cleanse the body or raise the front legs of the body is unknown, and may be further researched in subsequent studies of fear and defense behaviors. Other test conditions of the study elicited different responses.

The audio condition received more rearing behavior and freezing behavior. This indicates that the audio of two cats fighting instigated the same instinct to rear but also to freeze, meaning that the audio condition was more threatening to the rats than the scent alone. Whether the rats were responding to the audio tape of two cats fighting because it was a startling noise or if their perceived a predatory threat is unable to determine, but what was observable was that the sounds of fighting cats does instigate fear. The actual presence of a cat, however, instigated the most fear for the rats.

In the visual condition, where the cat was physically presented, the rats sniffed the air mostly in the first half of the test, but then spent most of the second half of the test freezing in fear. The animals may have been able to detect the scent of the cat because of the presence, even when the aquarium they were in was covered with wood. When the rats froze and stopped sniffing the air, this could have been because the rats had identified the cat as a predatory threat and were responding in the way that would be most likely to keep them safe and alive. Without the three dimensional presentation of a cat, the rats may not have displayed the same fear behaviors or have frozen for the same amount of time they had.

The response to cues of a cat, a predatory threat for rats, is unique in specificity because these rats are responding on instinct. Laboratory rats have not been exposed to animals or environments outside of their cages or the rooms they are tested in, and therefore have not learned what a cat looks like, sounds like, or smells like, meaning that this behavior must be attributed entirely to innate animal instincts.

When the initial intention for this study was not met with expectation, it could have been modified in a variety of ways. Cats appeared to be a commonly known predator to rats and the intention of this study was to find differences in behavioral responding to different predatory stimuli. Therefore the direction of the study was altered to examine different responding to different cues or predation, appealing to the senses. When the corresponding scent to the sight or sound of a predator is presented in conjunction with other stimuli, the rats might be able to distinguish the stimuli as a threat and respond faster, and this could be determined in further research. If the fabric with the cat scent on it was presented during the audio and visual tests, the rats could have responded with more fear behaviors because they would then have two stimuli stimulating the senses. By comparison, the rats might have been less inclined to show fear behaviors if they had a comforting stimuli, such as fabric with their own scent on it inside the aquarium with them during each condition.