Hoarding Experiment Proposal
Hoarding is defined as a behavior in which a rat will remove piece after piece of food, add each to its store in a specific place, and then return for more. Generally we are looking to find out what factors influence the hoarding response of rats. More specifically, we would like to know whether hoarding would increase or decrease in the presence of another rat, rather than when the rat is alone.
There are many other manipulations that could be investigated in relation to their affects on hoarding, and time willing, we hope to be able to explore as many of these as possible. These variables include pellet size, how hungry the rat is, the addition of fear, temperature of the environment, etc. It would also be interesting to look into whether rats would prefer to hide their hoarded food in or under something, and whether the same rat could remember where it had hidden its food over a period of time.
Penelope and Louise will be put on the same feeding schedule for about a week before the experiment begins. They will be fed at the same time with the same amount of food each day, and deprived for the same amount of time before trials. Our apparatus will include one glass aquarium with a removable piece of hardware cloth that will cut the aquarium in half down the middle. The hardware cloth will enable the rats to both see and smell each other. For the beginning trials, each rat will be put into one side of the the split aquarium with a single pile of food. The pile of food will be weighed before we add it to the aquarium so the amount of food stays consistent between both rats. Although there will be no rat placed on the other side of the aquarium for these particular trials, we want to use the divider in order to control for the size of the “hoarding space.” Once the rat is placed in the tank with the food, the number of pellets hoarded and the number of pellets eaten in a five minute period will be recorded. We will count hoarding as any movement of the pellets to a consistent area. Furthermore, the pile of food will already be in the aquarium before the rat is added.
The next set of trials will again include dividing the aquarium in half with the hardware cloth; however, this time both rats will be involved. There will also be two piles of food, one on each side of the glass. The food will be placed in such a way that the rats are facing each other. Each rat will be placed on one side of the aquarium with the hardware cloth dividing the two rats. The number of pellets each rat hoards and the number of pellets each rat eats in five minutes will once again be recorded.
Finally, the last set of trials will include the aquarium without the divider. One pile of food will be placed in the aquarium. This pile will be the equivalent of the combination of each rat’s individual pile (i.e., an individual rat pile x2.) Both rats will be placed in the aquarium at the same time (undivided) and the number of pellets hoarded and eaten by each rat in a five minute period will be recorded. Once this task is completed, we will include an additional stage in which both rats are put into the aquarium without the divider; however, in this case there will be two individual piles of food. We will again record the number of pellets hoarded and eaten by each rat.
If time allows, further tests of the affects of additional variables on hoarding will be examined. One such test includes manipulating how hungry the rat is and repeating the above procedures. The rats will be tested after 12 hours without food, 24 hours without food, and immediately after being fed their daily ration (complete satiation.) Another potential manipulation is to add boxes, tubes, or pieces of cloth to the aquarium to see if the rats hide their food or simply hoard in an open space. Once the rats have hoarded, they will be removed from the aquarium for a single day. Upon being placed back into the aquarium, we will observe whether the rats show recall of their particular “hoarding spot” by returning to the area in which they had hoarded their food the previous day.
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